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Re: [PR64164] drop copyrename, integrate into expand


On Apr 27, 2015, Richard Biener <richard.guenther@gmail.com> wrote:

> This should also mention that is_gimple_reg vars do not have their
> address taken.

check

>> +static tree
>> +leader_merge (tree cur, tree next)

> Ick - presumably you can't use sth better than a TREE_LIST here?

The list was an experiment that never really worked, and when I tried to
make it work after the patch, it proved to be unworkable, so I dropped
it, and rewrote leader_merge to choose either of the params, preferring
anonymous over ignored over named, so as to reduce the likelihood of
misreading of debug dumps, since that's all they're used for.

>> static void
>> -expand_one_stack_var (tree var)
>> +expand_one_stack_var_1 (tree var)
>> {
>> HOST_WIDE_INT size, offset;
>> unsigned byte_align;
>> 
>> -  size = tree_to_uhwi (DECL_SIZE_UNIT (SSAVAR (var)));
>> -  byte_align = align_local_variable (SSAVAR (var));
>> +  if (TREE_CODE (var) != SSA_NAME || SSA_NAME_VAR (var))
>> +    {
>> +      size = tree_to_uhwi (DECL_SIZE_UNIT (SSAVAR (var)));
>> +      byte_align = align_local_variable (SSAVAR (var));
>> +    }
>> +  else

> I'd go here for all TREE_CODE (var) == SSA_NAME

Check

> (and get rid of the SSAVAR macro?)

There are remaining uses that don't seem worth dropping it for.

>> +/* Return the promoted mode for name.  If it is a named SSA_NAME, it
>> +   is the same as promote_decl_mode.  Otherwise, it is the promoted
>> +   mode of a temp decl of same type as the SSA_NAME, if we had created
>> +   one.  */
>> +
>> +machine_mode
>> +promote_ssa_mode (const_tree name, int *punsignedp)
>> +{
>> +  gcc_assert (TREE_CODE (name) == SSA_NAME);
>> +
>> +  if (SSA_NAME_VAR (name))
>> +    return promote_decl_mode (SSA_NAME_VAR (name), punsignedp);

> As above I'd rather not have different paths for anonymous vs. non-anonymous
> vars (so just delete the above two lines).

Check

>> @@ -9668,6 +9678,11 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
>> pmode = promote_function_mode (type, mode, &unsignedp,
>> gimple_call_fntype (g),
>> 2);
>> +         else if (!exp)
>> +           {
>> +             gcc_assert (code == SSA_NAME);

> promote_ssa_mode should assert this.

>> +             pmode = promote_ssa_mode (ssa_name, &unsignedp);

It does, so...  check.


>> @@ -2121,6 +2122,15 @@ aggregate_value_p (const_tree exp, const_tree fntype)
>> bool
>> use_register_for_decl (const_tree decl)
>> {
>> +  if (TREE_CODE (decl) == SSA_NAME)
>> +    {
>> +      if (!SSA_NAME_VAR (decl))
>> +       return TYPE_MODE (TREE_TYPE (decl)) != BLKmode
>> +         && !(flag_float_store && FLOAT_TYPE_P (TREE_TYPE (decl)));
>> +
>> +      decl = SSA_NAME_VAR (decl);

> See above.  Please drop the SSA_NAME_VAR != NULL path.

Check, then taken back, after a bootstrap failure and some debugging
made me realize this would be wrong.  Here are the nearly-added comments
that explain why:

      /* We often try to use the SSA_NAME, instead of its underlying
	 decl, to get type information and guide decisions, to avoid
	 differences of behavior between anonymous and named
	 variables, but in this one case we have to go for the actual
	 variable if there is one.  The main reason is that, at least
	 at -O0, we want to place user variables on the stack, but we
	 don't mind using pseudos for anonymous or ignored temps.
	 Should we take the SSA_NAME, we'd conclude all SSA_NAMEs
	 should go in pseudos, whereas their corresponding variables
	 might have to go on the stack.  So, disregarding the decl
	 here would negatively impact debug info at -O0, enable
	 coalescing between SSA_NAMEs that ought to get different
	 stack/pseudo assignments, and get the incoming argument
	 processing thoroughly confused by PARM_DECLs expected to live
	 in stack slots but assigned to pseudos.  */


>> +++ b/gcc/gimple-expr.h
>> +/* Defined in tree-ssa-coalesce.c.   */
>> +extern bool gimple_can_coalesce_p (tree, tree);

> Err, put it to tree-ssa-coalesce.h?

Check.  Lots of additional headers required to be able to include
tree-ssa-coalesce.h, though.


>> -  gcc_assert (src_mode == TYPE_MODE (TREE_TYPE (var)));
>> +  gcc_assert (src_mode == TYPE_MODE (TREE_TYPE (var ? var : name)));

> The TREE_TYPE of name and its SSA_NAME_VAR are always the same.  So just
> use TREE_TYPE (name) here.

Check

>> gcc_assert (!REG_P (dest_rtx)
>> -             || dest_mode == promote_decl_mode (var, &unsignedp));
>> +             || dest_mode == promote_ssa_mode (name, &unsignedp));
>> 
>> if (src_mode != dest_mode)
>> {
>> @@ -714,12 +715,12 @@ static rtx
>> get_temp_reg (tree name)
>> {
>> tree var = TREE_CODE (name) == SSA_NAME ? SSA_NAME_VAR (name) : name;
>> -  tree type = TREE_TYPE (var);
>> +  tree type = var ? TREE_TYPE (var) : TREE_TYPE (name);

> See above.

Check


Here's the revised patch, regstrapped on x86_64-linux-gnu and
i686-linux-gnu.  The first attempt failed to compile libjava on x86_64,
requiring the new change in tree-ssa-loop-niter.c to pass.  It didn't
occur in the unpatched tree because the differences between anon or
named SSA_NAMEs in copyrename changed costs and caused different choices
in ivopts, which ultimately failed to expose the problem in loop-niter
during vrp.

At the end, I enclose the incremental changes since the previous
revision of the patch, to ease the incremental review.

Ok to install?


for  gcc/ChangeLog

	PR rtl-optimization/64164
	* Makefile.in (OBJS): Drop tree-ssa-copyrename.o.
	* tree-ssa-copyrename.c: Removed.
	* opts.c (default_options_table): Drop -ftree-copyrename.  Add
	-ftree-coalesce-vars.
	* passes.def: Drop all occurrences of pass_rename_ssa_copies.
	* common.opt (ftree-copyrename): Ignore.
	(ftree-coalesce-inlined-vars): Likewise.
	* doc/invoke.texi: Remove the ignored options above.
	* gimple-expr.h (gimple_can_coalesce_p): Move declaration
	* tree-ssa-coalesce.h: ... here.
	* tree-ssa-uncprop.c: Include tree-ssa-coalesce.h and other
	headers required by it.
	* gimple-expr.c (gimple_can_coalesce_p): Allow coalescing
	across variables when flag_tree_coalesce_vars.  Check register
	use and promoted modes to allow coalescing.  Moved to
	tree-ssa-coalesce.c.
	* tree-ssa-live.c (struct tree_int_map_hasher): Move along
	with its member functions to tree-ssa-coalesce.c.
	(var_map_base_init): Likewise.  Renamed to
	compute_samebase_partition_bases.
	(partition_view_normal): Drop want_bases parameter.
	(partition_view_bitmap): Likewise.
	* tree-ssa-live.h: Adjust declarations.
	* tree-ssa-coalesce.c: Include explow.h.
	(build_ssa_conflict_graph): Process PARM_ and RESULT_DECLs's
	default defs at the entry point.
	(dump_part_var_map): New.
	(compute_optimized_partition_bases): New, called by...
	(coalesce_ssa_name): ... when flag_tree_coalesce_vars, instead
	of compute_samebase_partition_bases.  Adjust.
	* alias.c (nonoverlapping_memrefs_p): Disregard gimple-regs.
	* cfgexpand.c (leader_merge): New.
	(get_rtl_for_parm_ssa_default_def): New.
	(set_rtl): Merge exprs and attrs, even for MEMs and non-SSA
	vars.  Update DECL_RTL for PARM_DECLs and RESULT_DECLs too.
	(expand_one_stack_var_at): Handle anonymous SSA_NAMEs.  Drop
	redundant MEM attr setting.
	(expand_one_stack_var_1): Handle anonymous SSA_NAMEs.  Renamed
	from...
	(expand_one_stack_var): ... this.  New wrapper to check and
	skip already expanded SSA partitions.
	(record_alignment_for_reg_var): New, factored out of...
	(expand_one_var): ... this.
	(expand_one_ssa_partition): New.
	(adjust_one_expanded_partition_var): New.
	(expand_one_register_var): Check and skip already expanded SSA
	partitions.
	(expand_used_vars): Don't create DECLs for anonymous SSA
	names.  Expand all SSA partitions, then adjust all SSA names.
	(pass::execute): Replace the loops that set
	SA.partition_to_pseudo from partition leaders and cleared
	DECL_RTL for multi-location variables, and that which used to
	rename vars and set attrs, with one that clears DECL_RTL and
	checks that PARMs and RESULTs default_defs match DECL_RTL.
	* cfgexpand.h (get_rtl_for_parm_ssa_default_def): Declare.
	* emit-rtl.c (set_reg_attrs_for_parm): Handle NULL decl.
	* explow.c (promote_ssa_mode): New.
	* explow.h (promote_ssa_mode): Declare.
	* expr.c (expand_expr_real_1): Handle anonymous SSA_NAMEs.
	* function.c: Include cfgexpand.h.
	(use_register_for_decl): Handle SSA_NAMEs, anonymous or not.
	(use_register_for_parm_decl): Wrapper for the above to
	special-case the result_ptr.
	(rtl_for_parm): Ditto for get_rtl_for_parm_ssa_default_def.
	(maybe_reset_rtl_for_parm): Reset DECL_RTL of parms with
	multiple locations.
	(assign_parm_adjust_stack_rtl): Add all and parm arguments,
	for rtl_for_parm.  For SSA-assigned parms, zero stack_parm.
	(assign_parm_setup_block): Prefer SSA-assigned location.
	(assign_parm_setup_reg): Likewise.  Use entry_parm for equiv
	if stack_parm is NULL.
	(assign_parm_setup_stack): Prefer SSA-assigned location.
	(assign_parms): Maybe reset DECL_RTL of params.  Adjust stack
	rtl before testing for pointer bounds.  Special-case result_ptr.
	(expand_function_start): Maybe reset DECL_RTL of result.
	Prefer SSA-assigned location for result and static chain.
	Factor out DECL_RESULT and SET_DECL_RTL.
	* tree-outof-ssa.c (insert_value_copy_on_edge): Handle
	anonymous SSA names.  Use promote_ssa_mode.
	(get_temp_reg): Likewise.
	(remove_ssa_form): Adjust.
	* var-tracking.c (dataflow_set_clear_at_call): Take call_insn
	and get its reg_usage for reg invalidation.
	(compute_bb_dataflow): Pass it insn.
	(emit_notes_in_bb): Likewise.
	* tree-ssa-loop-niter.c (loop_exits_before_overflow): Don't
	fail assert on conversion between unsigned types.

for  gcc/testsuite/ChangeLog

	* gcc.dg/guality/pr54200.c: Add -fno-tree-coalesce-vars.
	* gcc.dg/ssp-1.c: Make counter a register.
	* gcc.dg/ssp-2.c: Likewise.
	* gcc.dg/torture/parm-coalesce.c: New.
---
 gcc/Makefile.in                              |    1 
 gcc/alias.c                                  |   13 +
 gcc/cfgexpand.c                              |  370 ++++++++++++++-----
 gcc/cfgexpand.h                              |    2 
 gcc/common.opt                               |   12 -
 gcc/doc/invoke.texi                          |   48 +--
 gcc/emit-rtl.c                               |    5 
 gcc/explow.c                                 |   22 +
 gcc/explow.h                                 |    3 
 gcc/expr.c                                   |   39 +-
 gcc/function.c                               |  226 +++++++++---
 gcc/gimple-expr.c                            |   39 --
 gcc/gimple-expr.h                            |    1 
 gcc/opts.c                                   |    2 
 gcc/passes.def                               |    5 
 gcc/testsuite/gcc.dg/guality/pr54200.c       |    2 
 gcc/testsuite/gcc.dg/ssp-1.c                 |    2 
 gcc/testsuite/gcc.dg/ssp-2.c                 |    2 
 gcc/testsuite/gcc.dg/torture/parm-coalesce.c |   40 ++
 gcc/tree-outof-ssa.c                         |   16 -
 gcc/tree-ssa-coalesce.c                      |  380 +++++++++++++++++++-
 gcc/tree-ssa-coalesce.h                      |    1 
 gcc/tree-ssa-copyrename.c                    |  499 --------------------------
 gcc/tree-ssa-live.c                          |  101 -----
 gcc/tree-ssa-live.h                          |    4 
 gcc/tree-ssa-loop-niter.c                    |    6 
 gcc/tree-ssa-uncprop.c                       |    5 
 gcc/var-tracking.c                           |   12 -
 28 files changed, 984 insertions(+), 874 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/parm-coalesce.c
 delete mode 100644 gcc/tree-ssa-copyrename.c

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 3d14938..2a03223 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -1441,7 +1441,6 @@ OBJS = \
 	tree-ssa-ccp.o \
 	tree-ssa-coalesce.o \
 	tree-ssa-copy.o \
-	tree-ssa-copyrename.o \
 	tree-ssa-dce.o \
 	tree-ssa-dom.o \
 	tree-ssa-dse.o \
diff --git a/gcc/alias.c b/gcc/alias.c
index ea539c5..5a031d9 100644
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -2552,6 +2552,19 @@ nonoverlapping_memrefs_p (const_rtx x, const_rtx y, bool loop_invariant)
   if (! DECL_P (exprx) || ! DECL_P (expry))
     return 0;
 
+  /* If we refer to different gimple registers, or one gimple register
+     and one non-gimple-register, we know they can't overlap.  First,
+     gimple registers don't have their addresses taken.  Now, there
+     could be more than one stack slot for (different versions of) the
+     same gimple register, but we can presumably tell they don't
+     overlap based on offsets from stack base addresses elsewhere.
+     It's important that we don't proceed to DECL_RTL, because gimple
+     registers may not pass DECL_RTL_SET_P, and make_decl_rtl won't be
+     able to do anything about them since no SSA information will have
+     remained to guide it.  */
+  if (is_gimple_reg (exprx) || is_gimple_reg (expry))
+    return exprx != expry;
+
   /* With invalid code we can end up storing into the constant pool.
      Bail out to avoid ICEing when creating RTL for this.
      See gfortran.dg/lto/20091028-2_0.f90.  */
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index b190f91..bf972fc 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -179,21 +179,121 @@ gimple_assign_rhs_to_tree (gimple stmt)
 
 #define SSAVAR(x) (TREE_CODE (x) == SSA_NAME ? SSA_NAME_VAR (x) : x)
 
+/* Choose either CUR or NEXT as the leader DECL for a partition.
+   Prefer ignored decls, to simplify debug dumps and reduce ambiguity
+   out of the same user variable being in multiple partitions (this is
+   less likely for compiler-introduced temps).  */
+
+static tree
+leader_merge (tree cur, tree next)
+{
+  if (cur == NULL || cur == next)
+    return next;
+
+  if (DECL_P (cur) && DECL_IGNORED_P (cur))
+    return cur;
+
+  if (DECL_P (next) && DECL_IGNORED_P (next))
+    return next;
+
+  return cur;
+}
+
+
+/* Return the RTL for the default SSA def of a PARM or RESULT, if
+   there is one.  */
+
+rtx
+get_rtl_for_parm_ssa_default_def (tree var)
+{
+  gcc_assert (TREE_CODE (var) == PARM_DECL || TREE_CODE (var) == RESULT_DECL);
+
+  if (!is_gimple_reg (var))
+    return NULL_RTX;
+
+  /* If we've already determined RTL for the decl, use it.  This is
+     not just an optimization: if VAR is a PARM whose incoming value
+     is unused, we won't find a default def to use its partition, but
+     we still want to use the location of the parm, if it was used at
+     all.  During assign_parms, until a location is assigned for the
+     VAR, RTL can only for a parm or result if we're not coalescing
+     across variables, when we know we're coalescing all SSA_NAMEs of
+     each parm or result, and we're not coalescing them with names
+     pertaining to other variables, such as other parms' default
+     defs.  */
+  if (DECL_RTL_SET_P (var))
+    {
+      gcc_assert (DECL_RTL (var) != pc_rtx);
+      return DECL_RTL (var);
+    }
+
+  tree name = ssa_default_def (cfun, var);
+
+  if (!name)
+    return NULL_RTX;
+
+  int part = var_to_partition (SA.map, name);
+  if (part == NO_PARTITION)
+    return NULL_RTX;
+
+  return SA.partition_to_pseudo[part];
+}
+
 /* Associate declaration T with storage space X.  If T is no
    SSA name this is exactly SET_DECL_RTL, otherwise make the
    partition of T associated with X.  */
 static inline void
 set_rtl (tree t, rtx x)
 {
+  if (x && SSAVAR (t))
+    {
+      bool skip = false;
+      tree cur = NULL_TREE;
+
+      if (MEM_P (x))
+	cur = MEM_EXPR (x);
+      else if (REG_P (x))
+	cur = REG_EXPR (x);
+      else if (GET_CODE (x) == CONCAT
+	       && REG_P (XEXP (x, 0)))
+	cur = REG_EXPR (XEXP (x, 0));
+      else if (GET_CODE (x) == PARALLEL)
+	cur = REG_EXPR (XVECEXP (x, 0, 0));
+      else if (x == pc_rtx)
+	skip = true;
+      else
+	gcc_unreachable ();
+
+      tree next = skip ? cur : leader_merge (cur, SSAVAR (t));
+
+      if (cur != next)
+	{
+	  if (MEM_P (x))
+	    set_mem_attributes (x, next, true);
+	  else
+	    set_reg_attrs_for_decl_rtl (next, x);
+	}
+    }
+
   if (TREE_CODE (t) == SSA_NAME)
     {
-      SA.partition_to_pseudo[var_to_partition (SA.map, t)] = x;
-      if (x && !MEM_P (x))
-	set_reg_attrs_for_decl_rtl (SSA_NAME_VAR (t), x);
-      /* For the benefit of debug information at -O0 (where vartracking
-         doesn't run) record the place also in the base DECL if it's
-	 a normal variable (not a parameter).  */
-      if (x && x != pc_rtx && TREE_CODE (SSA_NAME_VAR (t)) == VAR_DECL)
+      int part = var_to_partition (SA.map, t);
+      if (part != NO_PARTITION)
+	{
+	  if (SA.partition_to_pseudo[part])
+	    gcc_assert (SA.partition_to_pseudo[part] == x);
+	  else
+	    SA.partition_to_pseudo[part] = x;
+	}
+      /* For the benefit of debug information at -O0 (where
+         vartracking doesn't run) record the place also in the base
+         DECL.  For PARMs and RESULTs, we may end up resetting these
+         in function.c:maybe_reset_rtl_for_parm, but in some rare
+         cases we may need them (unused and overwritten incoming
+         value, that at -O0 must share the location with the other
+         uses in spite of the missing default def), and this may be
+         the only chance to preserve them.  */
+      if (x && x != pc_rtx && SSA_NAME_VAR (t))
 	{
 	  tree var = SSA_NAME_VAR (t);
 	  /* If we don't yet have something recorded, just record it now.  */
@@ -909,7 +1009,9 @@ expand_one_stack_var_at (tree decl, rtx base, unsigned base_align,
   gcc_assert (offset == trunc_int_for_mode (offset, Pmode));
 
   x = plus_constant (Pmode, base, offset);
-  x = gen_rtx_MEM (DECL_MODE (SSAVAR (decl)), x);
+  x = gen_rtx_MEM (TREE_CODE (decl) == SSA_NAME
+		   ? TYPE_MODE (TREE_TYPE (decl))
+		   : DECL_MODE (SSAVAR (decl)), x);
 
   if (TREE_CODE (decl) != SSA_NAME)
     {
@@ -931,7 +1033,6 @@ expand_one_stack_var_at (tree decl, rtx base, unsigned base_align,
       DECL_USER_ALIGN (decl) = 0;
     }
 
-  set_mem_attributes (x, SSAVAR (decl), true);
   set_rtl (decl, x);
 }
 
@@ -1146,13 +1247,22 @@ account_stack_vars (void)
    to a variable to be allocated in the stack frame.  */
 
 static void
-expand_one_stack_var (tree var)
+expand_one_stack_var_1 (tree var)
 {
   HOST_WIDE_INT size, offset;
   unsigned byte_align;
 
-  size = tree_to_uhwi (DECL_SIZE_UNIT (SSAVAR (var)));
-  byte_align = align_local_variable (SSAVAR (var));
+  if (TREE_CODE (var) == SSA_NAME)
+    {
+      tree type = TREE_TYPE (var);
+      size = tree_to_uhwi (TYPE_SIZE_UNIT (type));
+      byte_align = TYPE_ALIGN_UNIT (type);
+    }
+  else
+    {
+      size = tree_to_uhwi (DECL_SIZE_UNIT (var));
+      byte_align = align_local_variable (var);
+    }
 
   /* We handle highly aligned variables in expand_stack_vars.  */
   gcc_assert (byte_align * BITS_PER_UNIT <= MAX_SUPPORTED_STACK_ALIGNMENT);
@@ -1163,6 +1273,27 @@ expand_one_stack_var (tree var)
 			   crtl->max_used_stack_slot_alignment, offset);
 }
 
+/* Wrapper for expand_one_stack_var_1 that checks SSA_NAMEs are
+   already assigned some MEM.  */
+
+static void
+expand_one_stack_var (tree var)
+{
+  if (TREE_CODE (var) == SSA_NAME)
+    {
+      int part = var_to_partition (SA.map, var);
+      if (part != NO_PARTITION)
+	{
+	  rtx x = SA.partition_to_pseudo[part];
+	  gcc_assert (x);
+	  gcc_assert (MEM_P (x));
+	  return;
+	}
+    }
+
+  return expand_one_stack_var_1 (var);
+}
+
 /* A subroutine of expand_one_var.  Called to assign rtl to a VAR_DECL
    that will reside in a hard register.  */
 
@@ -1172,13 +1303,114 @@ expand_one_hard_reg_var (tree var)
   rest_of_decl_compilation (var, 0, 0);
 }
 
+/* Record the alignment requirements of some variable assigned to a
+   pseudo.  */
+
+static void
+record_alignment_for_reg_var (unsigned int align)
+{
+  if (SUPPORTS_STACK_ALIGNMENT
+      && crtl->stack_alignment_estimated < align)
+    {
+      /* stack_alignment_estimated shouldn't change after stack
+         realign decision made */
+      gcc_assert (!crtl->stack_realign_processed);
+      crtl->stack_alignment_estimated = align;
+    }
+
+  /* stack_alignment_needed > PREFERRED_STACK_BOUNDARY is permitted.
+     So here we only make sure stack_alignment_needed >= align.  */
+  if (crtl->stack_alignment_needed < align)
+    crtl->stack_alignment_needed = align;
+  if (crtl->max_used_stack_slot_alignment < align)
+    crtl->max_used_stack_slot_alignment = align;
+}
+
+/* Create RTL for an SSA partition.  */
+
+static void
+expand_one_ssa_partition (tree var)
+{
+  int part = var_to_partition (SA.map, var);
+  gcc_assert (part != NO_PARTITION);
+
+  if (SA.partition_to_pseudo[part])
+    return;
+
+  if (!use_register_for_decl (var))
+    {
+      expand_one_stack_var_1 (var);
+      return;
+    }
+
+  unsigned int align = MINIMUM_ALIGNMENT (TREE_TYPE (var),
+					  TYPE_MODE (TREE_TYPE (var)),
+					  TYPE_ALIGN (TREE_TYPE (var)));
+
+  /* If the variable alignment is very large we'll dynamicaly allocate
+     it, which means that in-frame portion is just a pointer.  */
+  if (align > MAX_SUPPORTED_STACK_ALIGNMENT)
+    align = POINTER_SIZE;
+
+  record_alignment_for_reg_var (align);
+
+  machine_mode reg_mode = promote_ssa_mode (var, NULL);
+
+  rtx x = gen_reg_rtx (reg_mode);
+
+  set_rtl (var, x);
+}
+
+/* Record the association between the RTL generated for a partition
+   and the underlying variable of the SSA_NAME.  */
+
+static void
+adjust_one_expanded_partition_var (tree var)
+{
+  if (!var)
+    return;
+
+  tree decl = SSA_NAME_VAR (var);
+
+  int part = var_to_partition (SA.map, var);
+  if (part == NO_PARTITION)
+    return;
+
+  rtx x = SA.partition_to_pseudo[part];
+
+  set_rtl (var, x);
+
+  if (!REG_P (x))
+    return;
+
+  /* Note if the object is a user variable.  */
+  if (decl && !DECL_ARTIFICIAL (decl))
+    mark_user_reg (x);
+
+  if (POINTER_TYPE_P (decl ? TREE_TYPE (decl) : TREE_TYPE (var)))
+    mark_reg_pointer (x, get_pointer_alignment (var));
+}
+
 /* A subroutine of expand_one_var.  Called to assign rtl to a VAR_DECL
    that will reside in a pseudo register.  */
 
 static void
 expand_one_register_var (tree var)
 {
-  tree decl = SSAVAR (var);
+  if (TREE_CODE (var) == SSA_NAME)
+    {
+      int part = var_to_partition (SA.map, var);
+      if (part != NO_PARTITION)
+	{
+	  rtx x = SA.partition_to_pseudo[part];
+	  gcc_assert (x);
+	  gcc_assert (REG_P (x));
+	  return;
+	}
+      gcc_unreachable ();
+    }
+
+  tree decl = var;
   tree type = TREE_TYPE (decl);
   machine_mode reg_mode = promote_decl_mode (decl, NULL);
   rtx x = gen_reg_rtx (reg_mode);
@@ -1312,21 +1544,7 @@ expand_one_var (tree var, bool toplevel, bool really_expand)
 	align = POINTER_SIZE;
     }
 
-  if (SUPPORTS_STACK_ALIGNMENT
-      && crtl->stack_alignment_estimated < align)
-    {
-      /* stack_alignment_estimated shouldn't change after stack
-         realign decision made */
-      gcc_assert (!crtl->stack_realign_processed);
-      crtl->stack_alignment_estimated = align;
-    }
-
-  /* stack_alignment_needed > PREFERRED_STACK_BOUNDARY is permitted.
-     So here we only make sure stack_alignment_needed >= align.  */
-  if (crtl->stack_alignment_needed < align)
-    crtl->stack_alignment_needed = align;
-  if (crtl->max_used_stack_slot_alignment < align)
-    crtl->max_used_stack_slot_alignment = align;
+  record_alignment_for_reg_var (align);
 
   if (TREE_CODE (origvar) == SSA_NAME)
     {
@@ -1760,48 +1978,18 @@ expand_used_vars (void)
   if (targetm.use_pseudo_pic_reg ())
     pic_offset_table_rtx = gen_reg_rtx (Pmode);
 
-  hash_map<tree, tree> ssa_name_decls;
   for (i = 0; i < SA.map->num_partitions; i++)
     {
       tree var = partition_to_var (SA.map, i);
 
       gcc_assert (!virtual_operand_p (var));
 
-      /* Assign decls to each SSA name partition, share decls for partitions
-         we could have coalesced (those with the same type).  */
-      if (SSA_NAME_VAR (var) == NULL_TREE)
-	{
-	  tree *slot = &ssa_name_decls.get_or_insert (TREE_TYPE (var));
-	  if (!*slot)
-	    *slot = create_tmp_reg (TREE_TYPE (var));
-	  replace_ssa_name_symbol (var, *slot);
-	}
-
-      /* Always allocate space for partitions based on VAR_DECLs.  But for
-	 those based on PARM_DECLs or RESULT_DECLs and which matter for the
-	 debug info, there is no need to do so if optimization is disabled
-	 because all the SSA_NAMEs based on these DECLs have been coalesced
-	 into a single partition, which is thus assigned the canonical RTL
-	 location of the DECLs.  If in_lto_p, we can't rely on optimize,
-	 a function could be compiled with -O1 -flto first and only the
-	 link performed at -O0.  */
-      if (TREE_CODE (SSA_NAME_VAR (var)) == VAR_DECL)
-	expand_one_var (var, true, true);
-      else if (DECL_IGNORED_P (SSA_NAME_VAR (var)) || optimize || in_lto_p)
-	{
-	  /* This is a PARM_DECL or RESULT_DECL.  For those partitions that
-	     contain the default def (representing the parm or result itself)
-	     we don't do anything here.  But those which don't contain the
-	     default def (representing a temporary based on the parm/result)
-	     we need to allocate space just like for normal VAR_DECLs.  */
-	  if (!bitmap_bit_p (SA.partition_has_default_def, i))
-	    {
-	      expand_one_var (var, true, true);
-	      gcc_assert (SA.partition_to_pseudo[i]);
-	    }
-	}
+      expand_one_ssa_partition (var);
     }
 
+  for (i = 1; i < num_ssa_names; i++)
+    adjust_one_expanded_partition_var (ssa_name (i));
+
   if (flag_stack_protect == SPCT_FLAG_STRONG)
       gen_stack_protect_signal
 	= stack_protect_decl_p () || stack_protect_return_slot_p ();
@@ -5961,35 +6149,6 @@ pass_expand::execute (function *fun)
       parm_birth_insn = var_seq;
     }
 
-  /* Now that we also have the parameter RTXs, copy them over to our
-     partitions.  */
-  for (i = 0; i < SA.map->num_partitions; i++)
-    {
-      tree var = SSA_NAME_VAR (partition_to_var (SA.map, i));
-
-      if (TREE_CODE (var) != VAR_DECL
-	  && !SA.partition_to_pseudo[i])
-	SA.partition_to_pseudo[i] = DECL_RTL_IF_SET (var);
-      gcc_assert (SA.partition_to_pseudo[i]);
-
-      /* If this decl was marked as living in multiple places, reset
-	 this now to NULL.  */
-      if (DECL_RTL_IF_SET (var) == pc_rtx)
-	SET_DECL_RTL (var, NULL);
-
-      /* Some RTL parts really want to look at DECL_RTL(x) when x
-	 was a decl marked in REG_ATTR or MEM_ATTR.  We could use
-	 SET_DECL_RTL here making this available, but that would mean
-	 to select one of the potentially many RTLs for one DECL.  Instead
-	 of doing that we simply reset the MEM_EXPR of the RTL in question,
-	 then nobody can get at it and hence nobody can call DECL_RTL on it.  */
-      if (!DECL_RTL_SET_P (var))
-	{
-	  if (MEM_P (SA.partition_to_pseudo[i]))
-	    set_mem_expr (SA.partition_to_pseudo[i], NULL);
-	}
-    }
-
   /* If we have a class containing differently aligned pointers
      we need to merge those into the corresponding RTL pointer
      alignment.  */
@@ -5997,7 +6156,6 @@ pass_expand::execute (function *fun)
     {
       tree name = ssa_name (i);
       int part;
-      rtx r;
 
       if (!name
 	  /* We might have generated new SSA names in
@@ -6010,20 +6168,24 @@ pass_expand::execute (function *fun)
       if (part == NO_PARTITION)
 	continue;
 
-      /* Adjust all partition members to get the underlying decl of
-	 the representative which we might have created in expand_one_var.  */
-      if (SSA_NAME_VAR (name) == NULL_TREE)
+      gcc_assert (SA.partition_to_pseudo[part]);
+
+      /* If this decl was marked as living in multiple places, reset
+	 this now to NULL.  */
+      tree var = SSA_NAME_VAR (name);
+      if (var && DECL_RTL_IF_SET (var) == pc_rtx)
+	SET_DECL_RTL (var, NULL);
+      /* Check that the pseudos chosen by assign_parms are those of
+	 the corresponding default defs.  */
+      else if (SSA_NAME_IS_DEFAULT_DEF (name)
+	       && (TREE_CODE (var) == PARM_DECL
+		   || TREE_CODE (var) == RESULT_DECL))
 	{
-	  tree leader = partition_to_var (SA.map, part);
-	  gcc_assert (SSA_NAME_VAR (leader) != NULL_TREE);
-	  replace_ssa_name_symbol (name, SSA_NAME_VAR (leader));
+	  rtx in = DECL_RTL_IF_SET (var);
+	  gcc_assert (in);
+	  rtx out = SA.partition_to_pseudo[part];
+	  gcc_assert (in == out || rtx_equal_p (in, out));
 	}
-      if (!POINTER_TYPE_P (TREE_TYPE (name)))
-	continue;
-
-      r = SA.partition_to_pseudo[part];
-      if (REG_P (r))
-	mark_reg_pointer (r, get_pointer_alignment (name));
     }
 
   /* If this function is `main', emit a call to `__main'
diff --git a/gcc/cfgexpand.h b/gcc/cfgexpand.h
index a0b6e3e..602579d 100644
--- a/gcc/cfgexpand.h
+++ b/gcc/cfgexpand.h
@@ -22,5 +22,7 @@ along with GCC; see the file COPYING3.  If not see
 
 extern tree gimple_assign_rhs_to_tree (gimple);
 extern HOST_WIDE_INT estimated_stack_frame_size (struct cgraph_node *);
+extern rtx get_rtl_for_parm_ssa_default_def (tree var);
+
 
 #endif /* GCC_CFGEXPAND_H */
diff --git a/gcc/common.opt b/gcc/common.opt
index 32b416a..051f824 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2227,16 +2227,16 @@ Common Report Var(flag_tree_ch) Optimization
 Enable loop header copying on trees
 
 ftree-coalesce-inlined-vars
-Common Report Var(flag_ssa_coalesce_vars,1) Init(2) RejectNegative Optimization
-Enable coalescing of copy-related user variables that are inlined
+Common Ignore RejectNegative
+Does nothing.  Preserved for backward compatibility.
 
 ftree-coalesce-vars
-Common Report Var(flag_ssa_coalesce_vars,2) Optimization
-Enable coalescing of all copy-related user variables
+Common Report Var(flag_tree_coalesce_vars) Optimization
+Enable SSA coalescing of user variables
 
 ftree-copyrename
-Common Report Var(flag_tree_copyrename) Optimization
-Replace SSA temporaries with better names in copies
+Common Ignore
+Does nothing.  Preserved for backward compatibility.
 
 ftree-copy-prop
 Common Report Var(flag_tree_copy_prop) Optimization
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index e25bd62..e359be2 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -339,7 +339,6 @@ Objective-C and Objective-C++ Dialects}.
 -fdump-tree-phiprop@r{[}-@var{n}@r{]} @gol
 -fdump-tree-phiopt@r{[}-@var{n}@r{]} @gol
 -fdump-tree-forwprop@r{[}-@var{n}@r{]} @gol
--fdump-tree-copyrename@r{[}-@var{n}@r{]} @gol
 -fdump-tree-nrv -fdump-tree-vect @gol
 -fdump-tree-sink @gol
 -fdump-tree-sra@r{[}-@var{n}@r{]} @gol
@@ -445,9 +444,8 @@ Objective-C and Objective-C++ Dialects}.
 -fstack-protector-explicit -fstdarg-opt -fstrict-aliasing @gol
 -fstrict-overflow -fthread-jumps -ftracer -ftree-bit-ccp @gol
 -ftree-builtin-call-dce -ftree-ccp -ftree-ch @gol
--ftree-coalesce-inline-vars -ftree-coalesce-vars -ftree-copy-prop @gol
--ftree-copyrename -ftree-dce -ftree-dominator-opts -ftree-dse @gol
--ftree-forwprop -ftree-fre -ftree-loop-if-convert @gol
+-ftree-coalesce-vars -ftree-copy-prop -ftree-dce -ftree-dominator-opts @gol
+-ftree-dse -ftree-forwprop -ftree-fre -ftree-loop-if-convert @gol
 -ftree-loop-if-convert-stores -ftree-loop-im @gol
 -ftree-phiprop -ftree-loop-distribution -ftree-loop-distribute-patterns @gol
 -ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
@@ -7076,11 +7074,6 @@ name is made by appending @file{.phiopt} to the source file name.
 Dump each function after forward propagating single use variables.  The file
 name is made by appending @file{.forwprop} to the source file name.
 
-@item copyrename
-@opindex fdump-tree-copyrename
-Dump each function after applying the copy rename optimization.  The file
-name is made by appending @file{.copyrename} to the source file name.
-
 @item nrv
 @opindex fdump-tree-nrv
 Dump each function after applying the named return value optimization on
@@ -7545,8 +7538,8 @@ compilation time.
 -ftree-ccp @gol
 -fssa-phiopt @gol
 -ftree-ch @gol
+-ftree-coalesce-vars @gol
 -ftree-copy-prop @gol
--ftree-copyrename @gol
 -ftree-dce @gol
 -ftree-dominator-opts @gol
 -ftree-dse @gol
@@ -8815,6 +8808,15 @@ profitable to parallelize the loops.
 Compare the results of several data dependence analyzers.  This option
 is used for debugging the data dependence analyzers.
 
+@item -ftree-coalesce-vars
+@opindex ftree-coalesce-vars
+Tell the compiler to attempt to combine small user-defined variables
+too, instead of just compiler temporaries.  This may severely limit the
+ability to debug an optimized program compiled with
+@option{-fno-var-tracking-assignments}.  In the negated form, this flag
+prevents SSA coalescing of user variables.  This option is enabled by
+default if optimization is enabled.
+
 @item -ftree-loop-if-convert
 @opindex ftree-loop-if-convert
 Attempt to transform conditional jumps in the innermost loops to
@@ -8928,32 +8930,6 @@ Perform scalar replacement of aggregates.  This pass replaces structure
 references with scalars to prevent committing structures to memory too
 early.  This flag is enabled by default at @option{-O} and higher.
 
-@item -ftree-copyrename
-@opindex ftree-copyrename
-Perform copy renaming on trees.  This pass attempts to rename compiler
-temporaries to other variables at copy locations, usually resulting in
-variable names which more closely resemble the original variables.  This flag
-is enabled by default at @option{-O} and higher.
-
-@item -ftree-coalesce-inlined-vars
-@opindex ftree-coalesce-inlined-vars
-Tell the copyrename pass (see @option{-ftree-copyrename}) to attempt to
-combine small user-defined variables too, but only if they are inlined
-from other functions.  It is a more limited form of
-@option{-ftree-coalesce-vars}.  This may harm debug information of such
-inlined variables, but it keeps variables of the inlined-into
-function apart from each other, such that they are more likely to
-contain the expected values in a debugging session.
-
-@item -ftree-coalesce-vars
-@opindex ftree-coalesce-vars
-Tell the copyrename pass (see @option{-ftree-copyrename}) to attempt to
-combine small user-defined variables too, instead of just compiler
-temporaries.  This may severely limit the ability to debug an optimized
-program compiled with @option{-fno-var-tracking-assignments}.  In the
-negated form, this flag prevents SSA coalescing of user variables,
-including inlined ones.  This option is enabled by default.
-
 @item -ftree-ter
 @opindex ftree-ter
 Perform temporary expression replacement during the SSA->normal phase.  Single
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 49a1509..2b98946 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -1249,6 +1249,9 @@ set_reg_attrs_for_parm (rtx parm_rtx, rtx mem)
 void
 set_reg_attrs_for_decl_rtl (tree t, rtx x)
 {
+  if (!t)
+    return;
+  tree tdecl = t;
   if (GET_CODE (x) == SUBREG)
     {
       gcc_assert (subreg_lowpart_p (x));
@@ -1257,7 +1260,7 @@ set_reg_attrs_for_decl_rtl (tree t, rtx x)
   if (REG_P (x))
     REG_ATTRS (x)
       = get_reg_attrs (t, byte_lowpart_offset (GET_MODE (x),
-					       DECL_MODE (t)));
+					       DECL_MODE (tdecl)));
   if (GET_CODE (x) == CONCAT)
     {
       if (REG_P (XEXP (x, 0)))
diff --git a/gcc/explow.c b/gcc/explow.c
index 8745aea..5b0d49c 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -856,6 +856,28 @@ promote_decl_mode (const_tree decl, int *punsignedp)
   return pmode;
 }
 
+/* Return the promoted mode for name.  If it is a named SSA_NAME, it
+   is the same as promote_decl_mode.  Otherwise, it is the promoted
+   mode of a temp decl of same type as the SSA_NAME, if we had created
+   one.  */
+
+machine_mode
+promote_ssa_mode (const_tree name, int *punsignedp)
+{
+  gcc_assert (TREE_CODE (name) == SSA_NAME);
+
+  tree type = TREE_TYPE (name);
+  int unsignedp = TYPE_UNSIGNED (type);
+  machine_mode mode = TYPE_MODE (type);
+
+  machine_mode pmode = promote_mode (type, mode, &unsignedp);
+  if (punsignedp)
+    *punsignedp = unsignedp;
+
+  return pmode;
+}
+
+
 
 /* Controls the behaviour of {anti_,}adjust_stack.  */
 static bool suppress_reg_args_size;
diff --git a/gcc/explow.h b/gcc/explow.h
index 94613de..52113db 100644
--- a/gcc/explow.h
+++ b/gcc/explow.h
@@ -57,6 +57,9 @@ extern machine_mode promote_mode (const_tree, machine_mode, int *);
 /* Return mode and signedness to use when object is promoted.  */
 machine_mode promote_decl_mode (const_tree, int *);
 
+/* Return mode and signedness to use when object is promoted.  */
+machine_mode promote_ssa_mode (const_tree, int *);
+
 /* Remove some bytes from the stack.  An rtx says how many.  */
 extern void adjust_stack (rtx);
 
diff --git a/gcc/expr.c b/gcc/expr.c
index 5a931dc..5b6e16e 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -9301,7 +9301,7 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
   rtx op0, op1, temp, decl_rtl;
   tree type;
   int unsignedp;
-  machine_mode mode;
+  machine_mode mode, dmode;
   enum tree_code code = TREE_CODE (exp);
   rtx subtarget, original_target;
   int ignore;
@@ -9432,7 +9432,8 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
       if (g == NULL
 	  && modifier == EXPAND_INITIALIZER
 	  && !SSA_NAME_IS_DEFAULT_DEF (exp)
-	  && (optimize || DECL_IGNORED_P (SSA_NAME_VAR (exp)))
+	  && (optimize || !SSA_NAME_VAR (exp)
+	      || DECL_IGNORED_P (SSA_NAME_VAR (exp)))
 	  && stmt_is_replaceable_p (SSA_NAME_DEF_STMT (exp)))
 	g = SSA_NAME_DEF_STMT (exp);
       if (g)
@@ -9511,15 +9512,18 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
       /* Ensure variable marked as used even if it doesn't go through
 	 a parser.  If it hasn't be used yet, write out an external
 	 definition.  */
-      TREE_USED (exp) = 1;
+      if (exp)
+	TREE_USED (exp) = 1;
 
       /* Show we haven't gotten RTL for this yet.  */
       temp = 0;
 
       /* Variables inherited from containing functions should have
 	 been lowered by this point.  */
-      context = decl_function_context (exp);
-      gcc_assert (SCOPE_FILE_SCOPE_P (context)
+      if (exp)
+	context = decl_function_context (exp);
+      gcc_assert (!exp
+		  || SCOPE_FILE_SCOPE_P (context)
 		  || context == current_function_decl
 		  || TREE_STATIC (exp)
 		  || DECL_EXTERNAL (exp)
@@ -9543,7 +9547,8 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
 	  decl_rtl = use_anchored_address (decl_rtl);
 	  if (modifier != EXPAND_CONST_ADDRESS
 	      && modifier != EXPAND_SUM
-	      && !memory_address_addr_space_p (DECL_MODE (exp),
+	      && !memory_address_addr_space_p (exp ? DECL_MODE (exp)
+					       : GET_MODE (decl_rtl),
 					       XEXP (decl_rtl, 0),
 					       MEM_ADDR_SPACE (decl_rtl)))
 	    temp = replace_equiv_address (decl_rtl,
@@ -9554,12 +9559,17 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
 	 if the address is a register.  */
       if (temp != 0)
 	{
-	  if (MEM_P (temp) && REG_P (XEXP (temp, 0)))
+	  if (exp && MEM_P (temp) && REG_P (XEXP (temp, 0)))
 	    mark_reg_pointer (XEXP (temp, 0), DECL_ALIGN (exp));
 
 	  return temp;
 	}
 
+      if (exp)
+	dmode = DECL_MODE (exp);
+      else
+	dmode = TYPE_MODE (TREE_TYPE (ssa_name));
+
       /* If the mode of DECL_RTL does not match that of the decl,
 	 there are two cases: we are dealing with a BLKmode value
 	 that is returned in a register, or we are dealing with
@@ -9567,22 +9577,23 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
 	 of the wanted mode, but mark it so that we know that it
 	 was already extended.  */
       if (REG_P (decl_rtl)
-	  && DECL_MODE (exp) != BLKmode
-	  && GET_MODE (decl_rtl) != DECL_MODE (exp))
+	  && dmode != BLKmode
+	  && GET_MODE (decl_rtl) != dmode)
 	{
 	  machine_mode pmode;
 
 	  /* Get the signedness to be used for this variable.  Ensure we get
 	     the same mode we got when the variable was declared.  */
-	  if (code == SSA_NAME
-	      && (g = SSA_NAME_DEF_STMT (ssa_name))
-	      && gimple_code (g) == GIMPLE_CALL
-	      && !gimple_call_internal_p (g))
+	  if (code != SSA_NAME)
+	    pmode = promote_decl_mode (exp, &unsignedp);
+	  else if ((g = SSA_NAME_DEF_STMT (ssa_name))
+		   && gimple_code (g) == GIMPLE_CALL
+		   && !gimple_call_internal_p (g))
 	    pmode = promote_function_mode (type, mode, &unsignedp,
 					   gimple_call_fntype (g),
 					   2);
 	  else
-	    pmode = promote_decl_mode (exp, &unsignedp);
+	    pmode = promote_ssa_mode (ssa_name, &unsignedp);
 	  gcc_assert (GET_MODE (decl_rtl) == pmode);
 
 	  temp = gen_lowpart_SUBREG (mode, decl_rtl);
diff --git a/gcc/function.c b/gcc/function.c
index 7d2d7e4..58e2498 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -87,6 +87,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "cfganal.h"
 #include "cfgbuild.h"
 #include "cfgcleanup.h"
+#include "cfgexpand.h"
 #include "basic-block.h"
 #include "df.h"
 #include "params.h"
@@ -2121,6 +2122,30 @@ aggregate_value_p (const_tree exp, const_tree fntype)
 bool
 use_register_for_decl (const_tree decl)
 {
+  if (TREE_CODE (decl) == SSA_NAME)
+    {
+      /* We often try to use the SSA_NAME, instead of its underlying
+	 decl, to get type information and guide decisions, to avoid
+	 differences of behavior between anonymous and named
+	 variables, but in this one case we have to go for the actual
+	 variable if there is one.  The main reason is that, at least
+	 at -O0, we want to place user variables on the stack, but we
+	 don't mind using pseudos for anonymous or ignored temps.
+	 Should we take the SSA_NAME, we'd conclude all SSA_NAMEs
+	 should go in pseudos, whereas their corresponding variables
+	 might have to go on the stack.  So, disregarding the decl
+	 here would negatively impact debug info at -O0, enable
+	 coalescing between SSA_NAMEs that ought to get different
+	 stack/pseudo assignments, and get the incoming argument
+	 processing thoroughly confused by PARM_DECLs expected to live
+	 in stack slots but assigned to pseudos.  */
+      if (!SSA_NAME_VAR (decl))
+	return TYPE_MODE (TREE_TYPE (decl)) != BLKmode
+	  && !(flag_float_store && FLOAT_TYPE_P (TREE_TYPE (decl)));
+
+      decl = SSA_NAME_VAR (decl);
+    }
+
   if (!targetm.calls.allocate_stack_slots_for_args ())
     return true;
 
@@ -2804,23 +2829,88 @@ assign_parm_remove_parallels (struct assign_parm_data_one *data)
   data->entry_parm = entry_parm;
 }
 
+/* Wrapper for use_register_for_decl, that special-cases the
+   .result_ptr as the function's RESULT_DECL when the RESULT_DECL is
+   passed by reference.  */
+
+static bool
+use_register_for_parm_decl (struct assign_parm_data_all *all, tree parm)
+{
+  if (parm == all->function_result_decl)
+    {
+      tree result = DECL_RESULT (current_function_decl);
+
+      if (DECL_BY_REFERENCE (result))
+	parm = result;
+    }
+
+  return use_register_for_decl (parm);
+}
+
+/* Wrapper for get_rtl_for_parm_ssa_default_def, that special-cases
+   the .result_ptr as the function's RESULT_DECL when the RESULT_DECL
+   is passed by reference.  */
+
+static rtx
+rtl_for_parm (struct assign_parm_data_all *all, tree parm)
+{
+  if (parm == all->function_result_decl)
+    {
+      tree result = DECL_RESULT (current_function_decl);
+
+      if (!DECL_BY_REFERENCE (result))
+	return NULL_RTX;
+
+      parm = result;
+    }
+
+  return get_rtl_for_parm_ssa_default_def (parm);
+}
+
+/* Reset the location of PARM_DECLs and RESULT_DECLs that had
+   SSA_NAMEs in multiple partitions, so that assign_parms will choose
+   the default def, if it exists, or create new RTL to hold the unused
+   entry value.  If we are coalescing across variables, we want to
+   reset the location too, because a parm without a default def
+   (incoming value unused) might be coalesced with one with a default
+   def, and then assign_parms would copy both incoming values to the
+   same location, which might cause the wrong value to survive.  */
+static void
+maybe_reset_rtl_for_parm (tree parm)
+{
+  gcc_assert (TREE_CODE (parm) == PARM_DECL
+	      || TREE_CODE (parm) == RESULT_DECL);
+  if ((flag_tree_coalesce_vars
+       || (DECL_RTL_SET_P (parm) && DECL_RTL (parm) == pc_rtx))
+      && is_gimple_reg (parm))
+    SET_DECL_RTL (parm, NULL_RTX);
+}
+
 /* A subroutine of assign_parms.  Adjust DATA->STACK_RTL such that it's
    always valid and properly aligned.  */
 
 static void
-assign_parm_adjust_stack_rtl (struct assign_parm_data_one *data)
+assign_parm_adjust_stack_rtl (struct assign_parm_data_all *all, tree parm,
+			      struct assign_parm_data_one *data)
 {
   rtx stack_parm = data->stack_parm;
 
+  /* If out-of-SSA assigned RTL to the parm default def, make sure we
+     don't use what we might have computed before.  */
+  rtx ssa_assigned = rtl_for_parm (all, parm);
+  if (ssa_assigned)
+    stack_parm = NULL;
+
   /* If we can't trust the parm stack slot to be aligned enough for its
      ultimate type, don't use that slot after entry.  We'll make another
      stack slot, if we need one.  */
-  if (stack_parm
-      && ((STRICT_ALIGNMENT
-	   && GET_MODE_ALIGNMENT (data->nominal_mode) > MEM_ALIGN (stack_parm))
-	  || (data->nominal_type
-	      && TYPE_ALIGN (data->nominal_type) > MEM_ALIGN (stack_parm)
-	      && MEM_ALIGN (stack_parm) < PREFERRED_STACK_BOUNDARY)))
+  else if (stack_parm
+	   && ((STRICT_ALIGNMENT
+		&& (GET_MODE_ALIGNMENT (data->nominal_mode)
+		    > MEM_ALIGN (stack_parm)))
+	       || (data->nominal_type
+		   && TYPE_ALIGN (data->nominal_type) > MEM_ALIGN (stack_parm)
+		   && MEM_ALIGN (stack_parm) < PREFERRED_STACK_BOUNDARY)))
     stack_parm = NULL;
 
   /* If parm was passed in memory, and we need to convert it on entry,
@@ -2882,11 +2972,16 @@ assign_parm_setup_block (struct assign_parm_data_all *all,
 
   size = int_size_in_bytes (data->passed_type);
   size_stored = CEIL_ROUND (size, UNITS_PER_WORD);
+
   if (stack_parm == 0)
     {
       DECL_ALIGN (parm) = MAX (DECL_ALIGN (parm), BITS_PER_WORD);
-      stack_parm = assign_stack_local (BLKmode, size_stored,
-				       DECL_ALIGN (parm));
+      stack_parm = rtl_for_parm (all, parm);
+      if (!stack_parm)
+	stack_parm = assign_stack_local (BLKmode, size_stored,
+					 DECL_ALIGN (parm));
+      else
+	stack_parm = copy_rtx (stack_parm);
       if (GET_MODE_SIZE (GET_MODE (entry_parm)) == size)
 	PUT_MODE (stack_parm, GET_MODE (entry_parm));
       set_mem_attributes (stack_parm, parm, 1);
@@ -3027,10 +3122,19 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
     = promote_function_mode (data->nominal_type, data->nominal_mode, &unsignedp,
 			     TREE_TYPE (current_function_decl), 2);
 
-  parmreg = gen_reg_rtx (promoted_nominal_mode);
+  rtx from_expand = rtl_for_parm (all, parm);
 
-  if (!DECL_ARTIFICIAL (parm))
-    mark_user_reg (parmreg);
+  if (from_expand && !data->passed_pointer)
+    {
+      parmreg = from_expand;
+      gcc_assert (GET_MODE (parmreg) == promoted_nominal_mode);
+    }
+  else
+    {
+      parmreg = gen_reg_rtx (promoted_nominal_mode);
+      if (!DECL_ARTIFICIAL (parm))
+	mark_user_reg (parmreg);
+    }
 
   /* If this was an item that we received a pointer to,
      set DECL_RTL appropriately.  */
@@ -3049,6 +3153,8 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
      assign_parm_find_data_types and expand_expr_real_1.  */
 
   equiv_stack_parm = data->stack_parm;
+  if (!equiv_stack_parm)
+    equiv_stack_parm = data->entry_parm;
   validated_mem = validize_mem (copy_rtx (data->entry_parm));
 
   need_conversion = (data->nominal_mode != data->passed_mode
@@ -3189,11 +3295,17 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
 
   /* If we were passed a pointer but the actual value can safely live
      in a register, retrieve it and use it directly.  */
-  if (data->passed_pointer && TYPE_MODE (TREE_TYPE (parm)) != BLKmode)
+  if (data->passed_pointer
+      && (from_expand || TYPE_MODE (TREE_TYPE (parm)) != BLKmode))
     {
       /* We can't use nominal_mode, because it will have been set to
 	 Pmode above.  We must use the actual mode of the parm.  */
-      if (use_register_for_decl (parm))
+      if (from_expand)
+	{
+	  parmreg = from_expand;
+	  gcc_assert (GET_MODE (parmreg) == TYPE_MODE (TREE_TYPE (parm)));
+	}
+      else if (use_register_for_decl (parm))
 	{
 	  parmreg = gen_reg_rtx (TYPE_MODE (TREE_TYPE (parm)));
 	  mark_user_reg (parmreg);
@@ -3233,7 +3345,7 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
 
       /* STACK_PARM is the pointer, not the parm, and PARMREG is
 	 now the parm.  */
-      data->stack_parm = NULL;
+      data->stack_parm = equiv_stack_parm = NULL;
     }
 
   /* Mark the register as eliminable if we did no conversion and it was
@@ -3243,11 +3355,11 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
      make here would screw up life analysis for it.  */
   if (data->nominal_mode == data->passed_mode
       && !did_conversion
-      && data->stack_parm != 0
-      && MEM_P (data->stack_parm)
+      && equiv_stack_parm != 0
+      && MEM_P (equiv_stack_parm)
       && data->locate.offset.var == 0
       && reg_mentioned_p (virtual_incoming_args_rtx,
-			  XEXP (data->stack_parm, 0)))
+			  XEXP (equiv_stack_parm, 0)))
     {
       rtx_insn *linsn = get_last_insn ();
       rtx_insn *sinsn;
@@ -3260,8 +3372,8 @@ assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
 	    = GET_MODE_INNER (GET_MODE (parmreg));
 	  int regnor = REGNO (XEXP (parmreg, 0));
 	  int regnoi = REGNO (XEXP (parmreg, 1));
-	  rtx stackr = adjust_address_nv (data->stack_parm, submode, 0);
-	  rtx stacki = adjust_address_nv (data->stack_parm, submode,
+	  rtx stackr = adjust_address_nv (equiv_stack_parm, submode, 0);
+	  rtx stacki = adjust_address_nv (equiv_stack_parm, submode,
 					  GET_MODE_SIZE (submode));
 
 	  /* Scan backwards for the set of the real and
@@ -3334,6 +3446,13 @@ assign_parm_setup_stack (struct assign_parm_data_all *all, tree parm,
 
       if (data->stack_parm == 0)
 	{
+	  rtx x = data->stack_parm = rtl_for_parm (all, parm);
+	  if (x)
+	    gcc_assert (GET_MODE (x) == GET_MODE (data->entry_parm));
+	}
+
+      if (data->stack_parm == 0)
+	{
 	  int align = STACK_SLOT_ALIGNMENT (data->passed_type,
 					    GET_MODE (data->entry_parm),
 					    TYPE_ALIGN (data->passed_type));
@@ -3592,6 +3711,8 @@ assign_parms (tree fndecl)
 	  DECL_INCOMING_RTL (parm) = DECL_RTL (parm);
 	  continue;
 	}
+      else
+	maybe_reset_rtl_for_parm (parm);
 
       /* Estimate stack alignment from parameter alignment.  */
       if (SUPPORTS_STACK_ALIGNMENT)
@@ -3641,7 +3762,9 @@ assign_parms (tree fndecl)
       else
 	set_decl_incoming_rtl (parm, data.entry_parm, false);
 
-      /* Boudns should be loaded in the particular order to
+      assign_parm_adjust_stack_rtl (&all, parm, &data);
+
+      /* Bounds should be loaded in the particular order to
 	 have registers allocated correctly.  Collect info about
 	 input bounds and load them later.  */
       if (POINTER_BOUNDS_TYPE_P (data.passed_type))
@@ -3658,11 +3781,10 @@ assign_parms (tree fndecl)
 	}
       else
 	{
-	  assign_parm_adjust_stack_rtl (&data);
-
 	  if (assign_parm_setup_block_p (&data))
 	    assign_parm_setup_block (&all, parm, &data);
-	  else if (data.passed_pointer || use_register_for_decl (parm))
+	  else if (data.passed_pointer
+		   || use_register_for_parm_decl (&all, parm))
 	    assign_parm_setup_reg (&all, parm, &data);
 	  else
 	    assign_parm_setup_stack (&all, parm, &data);
@@ -5004,7 +5126,9 @@ expand_function_start (tree subr)
      before any library calls that assign parms might generate.  */
 
   /* Decide whether to return the value in memory or in a register.  */
-  if (aggregate_value_p (DECL_RESULT (subr), subr))
+  tree res = DECL_RESULT (subr);
+  maybe_reset_rtl_for_parm (res);
+  if (aggregate_value_p (res, subr))
     {
       /* Returning something that won't go in a register.  */
       rtx value_address = 0;
@@ -5012,7 +5136,7 @@ expand_function_start (tree subr)
 #ifdef PCC_STATIC_STRUCT_RETURN
       if (cfun->returns_pcc_struct)
 	{
-	  int size = int_size_in_bytes (TREE_TYPE (DECL_RESULT (subr)));
+	  int size = int_size_in_bytes (TREE_TYPE (res));
 	  value_address = assemble_static_space (size);
 	}
       else
@@ -5024,36 +5148,45 @@ expand_function_start (tree subr)
 	     it.  */
 	  if (sv)
 	    {
-	      value_address = gen_reg_rtx (Pmode);
+	      if (DECL_BY_REFERENCE (res))
+		value_address = get_rtl_for_parm_ssa_default_def (res);
+	      if (!value_address)
+		value_address = gen_reg_rtx (Pmode);
 	      emit_move_insn (value_address, sv);
 	    }
 	}
       if (value_address)
 	{
 	  rtx x = value_address;
-	  if (!DECL_BY_REFERENCE (DECL_RESULT (subr)))
+	  if (!DECL_BY_REFERENCE (res))
 	    {
-	      x = gen_rtx_MEM (DECL_MODE (DECL_RESULT (subr)), x);
-	      set_mem_attributes (x, DECL_RESULT (subr), 1);
+	      x = get_rtl_for_parm_ssa_default_def (res);
+	      if (!x)
+		{
+		  x = gen_rtx_MEM (DECL_MODE (res), value_address);
+		  set_mem_attributes (x, res, 1);
+		}
 	    }
-	  SET_DECL_RTL (DECL_RESULT (subr), x);
+	  SET_DECL_RTL (res, x);
 	}
     }
-  else if (DECL_MODE (DECL_RESULT (subr)) == VOIDmode)
+  else if (DECL_MODE (res) == VOIDmode)
     /* If return mode is void, this decl rtl should not be used.  */
-    SET_DECL_RTL (DECL_RESULT (subr), NULL_RTX);
+    SET_DECL_RTL (res, NULL_RTX);
   else
     {
       /* Compute the return values into a pseudo reg, which we will copy
 	 into the true return register after the cleanups are done.  */
-      tree return_type = TREE_TYPE (DECL_RESULT (subr));
-      if (TYPE_MODE (return_type) != BLKmode
-	  && targetm.calls.return_in_msb (return_type))
+      tree return_type = TREE_TYPE (res);
+      rtx x = get_rtl_for_parm_ssa_default_def (res);
+      if (x)
+	/* Use it.  */;
+      else if (TYPE_MODE (return_type) != BLKmode
+	       && targetm.calls.return_in_msb (return_type))
 	/* expand_function_end will insert the appropriate padding in
 	   this case.  Use the return value's natural (unpadded) mode
 	   within the function proper.  */
-	SET_DECL_RTL (DECL_RESULT (subr),
-		      gen_reg_rtx (TYPE_MODE (return_type)));
+	x = gen_reg_rtx (TYPE_MODE (return_type));
       else
 	{
 	  /* In order to figure out what mode to use for the pseudo, we
@@ -5064,25 +5197,26 @@ expand_function_start (tree subr)
 	  /* Structures that are returned in registers are not
 	     aggregate_value_p, so we may see a PARALLEL or a REG.  */
 	  if (REG_P (hard_reg))
-	    SET_DECL_RTL (DECL_RESULT (subr),
-			  gen_reg_rtx (GET_MODE (hard_reg)));
+	    x = gen_reg_rtx (GET_MODE (hard_reg));
 	  else
 	    {
 	      gcc_assert (GET_CODE (hard_reg) == PARALLEL);
-	      SET_DECL_RTL (DECL_RESULT (subr), gen_group_rtx (hard_reg));
+	      x = gen_group_rtx (hard_reg);
 	    }
 	}
 
+      SET_DECL_RTL (res, x);
+
       /* Set DECL_REGISTER flag so that expand_function_end will copy the
 	 result to the real return register(s).  */
-      DECL_REGISTER (DECL_RESULT (subr)) = 1;
+      DECL_REGISTER (res) = 1;
 
       if (chkp_function_instrumented_p (current_function_decl))
 	{
-	  tree return_type = TREE_TYPE (DECL_RESULT (subr));
+	  tree return_type = TREE_TYPE (res);
 	  rtx bounds = targetm.calls.chkp_function_value_bounds (return_type,
 								 subr, 1);
-	  SET_DECL_BOUNDS_RTL (DECL_RESULT (subr), bounds);
+	  SET_DECL_BOUNDS_RTL (res, bounds);
 	}
     }
 
@@ -5097,7 +5231,9 @@ expand_function_start (tree subr)
       rtx local, chain;
      rtx_insn *insn;
 
-      local = gen_reg_rtx (Pmode);
+      local = get_rtl_for_parm_ssa_default_def (parm);
+      if (!local)
+	local = gen_reg_rtx (Pmode);
       chain = targetm.calls.static_chain (current_function_decl, true);
 
       set_decl_incoming_rtl (parm, chain, false);
diff --git a/gcc/gimple-expr.c b/gcc/gimple-expr.c
index 4d683d6..d3d1c5f 100644
--- a/gcc/gimple-expr.c
+++ b/gcc/gimple-expr.c
@@ -391,45 +391,6 @@ copy_var_decl (tree var, tree name, tree type)
   return copy;
 }
 
-/* Given SSA_NAMEs NAME1 and NAME2, return true if they are candidates for
-   coalescing together, false otherwise.
-
-   This must stay consistent with var_map_base_init in tree-ssa-live.c.  */
-
-bool
-gimple_can_coalesce_p (tree name1, tree name2)
-{
-  /* First check the SSA_NAME's associated DECL.  We only want to
-     coalesce if they have the same DECL or both have no associated DECL.  */
-  tree var1 = SSA_NAME_VAR (name1);
-  tree var2 = SSA_NAME_VAR (name2);
-  var1 = (var1 && (!VAR_P (var1) || !DECL_IGNORED_P (var1))) ? var1 : NULL_TREE;
-  var2 = (var2 && (!VAR_P (var2) || !DECL_IGNORED_P (var2))) ? var2 : NULL_TREE;
-  if (var1 != var2)
-    return false;
-
-  /* Now check the types.  If the types are the same, then we should
-     try to coalesce V1 and V2.  */
-  tree t1 = TREE_TYPE (name1);
-  tree t2 = TREE_TYPE (name2);
-  if (t1 == t2)
-    return true;
-
-  /* If the types are not the same, check for a canonical type match.  This
-     (for example) allows coalescing when the types are fundamentally the
-     same, but just have different names. 
-
-     Note pointer types with different address spaces may have the same
-     canonical type.  Those are rejected for coalescing by the
-     types_compatible_p check.  */
-  if (TYPE_CANONICAL (t1)
-      && TYPE_CANONICAL (t1) == TYPE_CANONICAL (t2)
-      && types_compatible_p (t1, t2))
-    return true;
-
-  return false;
-}
-
 /* Strip off a legitimate source ending from the input string NAME of
    length LEN.  Rather than having to know the names used by all of
    our front ends, we strip off an ending of a period followed by
diff --git a/gcc/gimple-expr.h b/gcc/gimple-expr.h
index ed23eb2..3d1c89f 100644
--- a/gcc/gimple-expr.h
+++ b/gcc/gimple-expr.h
@@ -28,7 +28,6 @@ extern gimple_seq gimple_body (tree);
 extern bool gimple_has_body_p (tree);
 extern const char *gimple_decl_printable_name (tree, int);
 extern tree copy_var_decl (tree, tree, tree);
-extern bool gimple_can_coalesce_p (tree, tree);
 extern tree create_tmp_var_name (const char *);
 extern tree create_tmp_var_raw (tree, const char * = NULL);
 extern tree create_tmp_var (tree, const char * = NULL);
diff --git a/gcc/opts.c b/gcc/opts.c
index 9793999..5305299 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -448,12 +448,12 @@ static const struct default_options default_options_table[] =
     { OPT_LEVELS_1_PLUS, OPT_fsplit_wide_types, NULL, 1 },
     { OPT_LEVELS_1_PLUS, OPT_ftree_ccp, NULL, 1 },
     { OPT_LEVELS_1_PLUS_NOT_DEBUG, OPT_ftree_bit_ccp, NULL, 1 },
+    { OPT_LEVELS_1_PLUS, OPT_ftree_coalesce_vars, NULL, 1 },
     { OPT_LEVELS_1_PLUS, OPT_ftree_dce, NULL, 1 },
     { OPT_LEVELS_1_PLUS, OPT_ftree_dominator_opts, NULL, 1 },
     { OPT_LEVELS_1_PLUS, OPT_ftree_dse, NULL, 1 },
     { OPT_LEVELS_1_PLUS, OPT_ftree_ter, NULL, 1 },
     { OPT_LEVELS_1_PLUS_NOT_DEBUG, OPT_ftree_sra, NULL, 1 },
-    { OPT_LEVELS_1_PLUS, OPT_ftree_copyrename, NULL, 1 },
     { OPT_LEVELS_1_PLUS, OPT_ftree_fre, NULL, 1 },
     { OPT_LEVELS_1_PLUS, OPT_ftree_copy_prop, NULL, 1 },
     { OPT_LEVELS_1_PLUS, OPT_ftree_sink, NULL, 1 },
diff --git a/gcc/passes.def b/gcc/passes.def
index 4690e23..230e089 100644
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -77,7 +77,6 @@ along with GCC; see the file COPYING3.  If not see
       NEXT_PASS (pass_all_early_optimizations);
       PUSH_INSERT_PASSES_WITHIN (pass_all_early_optimizations)
 	  NEXT_PASS (pass_remove_cgraph_callee_edges);
-	  NEXT_PASS (pass_rename_ssa_copies);
 	  NEXT_PASS (pass_object_sizes);
 	  NEXT_PASS (pass_ccp);
 	  /* After CCP we rewrite no longer addressed locals into SSA
@@ -155,7 +154,6 @@ along with GCC; see the file COPYING3.  If not see
       /* Initial scalar cleanups before alias computation.
 	 They ensure memory accesses are not indirect wherever possible.  */
       NEXT_PASS (pass_strip_predict_hints);
-      NEXT_PASS (pass_rename_ssa_copies);
       NEXT_PASS (pass_ccp);
       /* After CCP we rewrite no longer addressed locals into SSA
 	 form if possible.  */
@@ -183,7 +181,6 @@ along with GCC; see the file COPYING3.  If not see
       NEXT_PASS (pass_ch);
       NEXT_PASS (pass_lower_complex);
       NEXT_PASS (pass_sra);
-      NEXT_PASS (pass_rename_ssa_copies);
       /* The dom pass will also resolve all __builtin_constant_p calls
          that are still there to 0.  This has to be done after some
 	 propagations have already run, but before some more dead code
@@ -291,7 +288,6 @@ along with GCC; see the file COPYING3.  If not see
       NEXT_PASS (pass_fold_builtins);
       NEXT_PASS (pass_optimize_widening_mul);
       NEXT_PASS (pass_tail_calls);
-      NEXT_PASS (pass_rename_ssa_copies);
       /* FIXME: If DCE is not run before checking for uninitialized uses,
 	 we may get false warnings (e.g., testsuite/gcc.dg/uninit-5.c).
 	 However, this also causes us to misdiagnose cases that should be
@@ -326,7 +322,6 @@ along with GCC; see the file COPYING3.  If not see
       NEXT_PASS (pass_dce);
       NEXT_PASS (pass_asan);
       NEXT_PASS (pass_tsan);
-      NEXT_PASS (pass_rename_ssa_copies);
       /* ???  We do want some kind of loop invariant motion, but we possibly
          need to adjust LIM to be more friendly towards preserving accurate
 	 debug information here.  */
diff --git a/gcc/testsuite/gcc.dg/guality/pr54200.c b/gcc/testsuite/gcc.dg/guality/pr54200.c
index 9b17187..e1e7293 100644
--- a/gcc/testsuite/gcc.dg/guality/pr54200.c
+++ b/gcc/testsuite/gcc.dg/guality/pr54200.c
@@ -1,6 +1,6 @@
 /* PR tree-optimization/54200 */
 /* { dg-do run } */
-/* { dg-options "-g -fno-var-tracking-assignments" } */
+/* { dg-options "-g -fno-var-tracking-assignments -fno-tree-coalesce-vars" } */
 
 int o __attribute__((used));
 
diff --git a/gcc/testsuite/gcc.dg/ssp-1.c b/gcc/testsuite/gcc.dg/ssp-1.c
index 5467f4d..db69332 100644
--- a/gcc/testsuite/gcc.dg/ssp-1.c
+++ b/gcc/testsuite/gcc.dg/ssp-1.c
@@ -12,7 +12,7 @@ __stack_chk_fail (void)
 
 int main ()
 {
-  int i;
+  register int i;
   char foo[255];
 
   // smash stack
diff --git a/gcc/testsuite/gcc.dg/ssp-2.c b/gcc/testsuite/gcc.dg/ssp-2.c
index 9a7ac32..752fe53 100644
--- a/gcc/testsuite/gcc.dg/ssp-2.c
+++ b/gcc/testsuite/gcc.dg/ssp-2.c
@@ -14,7 +14,7 @@ __stack_chk_fail (void)
 void
 overflow()
 {
-  int i = 0;
+  register int i = 0;
   char foo[30];
 
   /* Overflow buffer.  */
diff --git a/gcc/testsuite/gcc.dg/torture/parm-coalesce.c b/gcc/testsuite/gcc.dg/torture/parm-coalesce.c
new file mode 100644
index 0000000..dbd81c1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/parm-coalesce.c
@@ -0,0 +1,40 @@
+/* { dg-do run } */
+
+#include <stdlib.h>
+
+/* Make sure we don't coalesce both incoming parms, one whose incoming
+   value is unused, to the same location, so as to overwrite one of
+   them with the incoming value of the other.  */
+
+int __attribute__((noinline, noclone))
+foo (int i, int j)
+{
+  j = i; /* The incoming value for J is unused.  */
+  i = 2;
+  if (j)
+    j++;
+  j += i + 1;
+  return j;
+}
+
+/* Same as foo, but with swapped parameters.  */
+int __attribute__((noinline, noclone))
+bar (int j, int i)
+{
+  j = i; /* The incoming value for J is unused.  */
+  i = 2;
+  if (j)
+    j++;
+  j += i + 1;
+  return j;
+}
+
+int
+main (void)
+{
+  if (foo (0, 1) != 3)
+    abort ();
+  if (bar (1, 0) != 3)
+    abort ();
+  return 0;
+}
diff --git a/gcc/tree-outof-ssa.c b/gcc/tree-outof-ssa.c
index e23bc0b..59d91c6 100644
--- a/gcc/tree-outof-ssa.c
+++ b/gcc/tree-outof-ssa.c
@@ -305,7 +305,6 @@ insert_value_copy_on_edge (edge e, int dest, tree src, source_location locus)
   rtx dest_rtx, seq, x;
   machine_mode dest_mode, src_mode;
   int unsignedp;
-  tree var;
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
@@ -327,12 +326,12 @@ insert_value_copy_on_edge (edge e, int dest, tree src, source_location locus)
 
   start_sequence ();
 
-  var = SSA_NAME_VAR (partition_to_var (SA.map, dest));
+  tree name = partition_to_var (SA.map, dest);
   src_mode = TYPE_MODE (TREE_TYPE (src));
   dest_mode = GET_MODE (dest_rtx);
-  gcc_assert (src_mode == TYPE_MODE (TREE_TYPE (var)));
+  gcc_assert (src_mode == TYPE_MODE (TREE_TYPE (name)));
   gcc_assert (!REG_P (dest_rtx)
-	      || dest_mode == promote_decl_mode (var, &unsignedp));
+	      || dest_mode == promote_ssa_mode (name, &unsignedp));
 
   if (src_mode != dest_mode)
     {
@@ -708,13 +707,12 @@ elim_backward (elim_graph g, int T)
 static rtx
 get_temp_reg (tree name)
 {
-  tree var = TREE_CODE (name) == SSA_NAME ? SSA_NAME_VAR (name) : name;
-  tree type = TREE_TYPE (var);
+  tree type = TREE_TYPE (name);
   int unsignedp;
-  machine_mode reg_mode = promote_decl_mode (var, &unsignedp);
+  machine_mode reg_mode = promote_ssa_mode (name, &unsignedp);
   rtx x = gen_reg_rtx (reg_mode);
   if (POINTER_TYPE_P (type))
-    mark_reg_pointer (x, TYPE_ALIGN (TREE_TYPE (TREE_TYPE (var))));
+    mark_reg_pointer (x, TYPE_ALIGN (TREE_TYPE (type)));
   return x;
 }
 
@@ -1014,7 +1012,7 @@ remove_ssa_form (bool perform_ter, struct ssaexpand *sa)
 
   /* Return to viewing the variable list as just all reference variables after
      coalescing has been performed.  */
-  partition_view_normal (map, false);
+  partition_view_normal (map);
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
diff --git a/gcc/tree-ssa-coalesce.c b/gcc/tree-ssa-coalesce.c
index b05a860..9ffa3f1 100644
--- a/gcc/tree-ssa-coalesce.c
+++ b/gcc/tree-ssa-coalesce.c
@@ -58,6 +58,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-ssanames.h"
 #include "tree-ssa-live.h"
 #include "tree-ssa-coalesce.h"
+#include "explow.h"
 #include "diagnostic-core.h"
 
 
@@ -830,6 +831,16 @@ build_ssa_conflict_graph (tree_live_info_p liveinfo)
   basic_block bb;
   ssa_op_iter iter;
   live_track_p live;
+  basic_block entry;
+
+  /* If inter-variable coalescing is enabled, we may attempt to
+     coalesce variables from different base variables, including
+     different parameters, so we have to make sure default defs live
+     at the entry block conflict with each other.  */
+  if (flag_tree_coalesce_vars)
+    entry = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+  else
+    entry = NULL;
 
   map = live_var_map (liveinfo);
   graph = ssa_conflicts_new (num_var_partitions (map));
@@ -888,6 +899,30 @@ build_ssa_conflict_graph (tree_live_info_p liveinfo)
 	    live_track_process_def (live, result, graph);
 	}
 
+      /* Pretend there are defs for params' default defs at the start
+	 of the (post-)entry block.  */
+      if (bb == entry)
+	{
+	  unsigned base;
+	  bitmap_iterator bi;
+	  EXECUTE_IF_SET_IN_BITMAP (live->live_base_var, 0, base, bi)
+	    {
+	      bitmap_iterator bi2;
+	      unsigned part;
+	      EXECUTE_IF_SET_IN_BITMAP (live->live_base_partitions[base],
+					0, part, bi2)
+		{
+		  tree var = partition_to_var (map, part);
+		  if (!SSA_NAME_VAR (var)
+		      || (TREE_CODE (SSA_NAME_VAR (var)) != PARM_DECL
+			  && TREE_CODE (SSA_NAME_VAR (var)) != RESULT_DECL)
+		      || !SSA_NAME_IS_DEFAULT_DEF (var))
+		    continue;
+		  live_track_process_def (live, var, graph);
+		}
+	    }
+	}
+
      live_track_clear_base_vars (live);
     }
 
@@ -1156,6 +1191,7 @@ attempt_coalesce (var_map map, ssa_conflicts_p graph, int x, int y,
     {
       var1 = partition_to_var (map, p1);
       var2 = partition_to_var (map, p2);
+
       z = var_union (map, var1, var2);
       if (z == NO_PARTITION)
 	{
@@ -1173,6 +1209,7 @@ attempt_coalesce (var_map map, ssa_conflicts_p graph, int x, int y,
 
       if (debug)
 	fprintf (debug, ": Success -> %d\n", z);
+
       return true;
     }
 
@@ -1270,6 +1307,330 @@ ssa_name_var_hash::equal (const tree_node *n1, const tree_node *n2)
 }
 
 
+/* Output partition map MAP with coalescing plan PART to file F.  */
+
+void
+dump_part_var_map (FILE *f, partition part, var_map map)
+{
+  int t;
+  unsigned x, y;
+  int p;
+
+  fprintf (f, "\nCoalescible Partition map \n\n");
+
+  for (x = 0; x < map->num_partitions; x++)
+    {
+      if (map->view_to_partition != NULL)
+	p = map->view_to_partition[x];
+      else
+	p = x;
+
+      if (ssa_name (p) == NULL_TREE
+	  || virtual_operand_p (ssa_name (p)))
+        continue;
+
+      t = 0;
+      for (y = 1; y < num_ssa_names; y++)
+        {
+	  tree var = version_to_var (map, y);
+	  if (!var)
+	    continue;
+	  int q = var_to_partition (map, var);
+	  p = partition_find (part, q);
+	  gcc_assert (map->partition_to_base_index[q]
+		      == map->partition_to_base_index[p]);
+
+	  if (p == (int)x)
+	    {
+	      if (t++ == 0)
+	        {
+		  fprintf (f, "Partition %d, base %d (", x,
+			   map->partition_to_base_index[q]);
+		  print_generic_expr (f, partition_to_var (map, q), TDF_SLIM);
+		  fprintf (f, " - ");
+		}
+	      fprintf (f, "%d ", y);
+	    }
+	}
+      if (t != 0)
+	fprintf (f, ")\n");
+    }
+  fprintf (f, "\n");
+}
+
+/* Given SSA_NAMEs NAME1 and NAME2, return true if they are candidates for
+   coalescing together, false otherwise.
+
+   This must stay consistent with var_map_base_init in tree-ssa-live.c.  */
+
+bool
+gimple_can_coalesce_p (tree name1, tree name2)
+{
+  /* First check the SSA_NAME's associated DECL.  Without
+     optimization, we only want to coalesce if they have the same DECL
+     or both have no associated DECL.  */
+  tree var1 = SSA_NAME_VAR (name1);
+  tree var2 = SSA_NAME_VAR (name2);
+  var1 = (var1 && (!VAR_P (var1) || !DECL_IGNORED_P (var1))) ? var1 : NULL_TREE;
+  var2 = (var2 && (!VAR_P (var2) || !DECL_IGNORED_P (var2))) ? var2 : NULL_TREE;
+  if (var1 != var2 && !flag_tree_coalesce_vars)
+    return false;
+
+  /* Now check the types.  If the types are the same, then we should
+     try to coalesce V1 and V2.  */
+  tree t1 = TREE_TYPE (name1);
+  tree t2 = TREE_TYPE (name2);
+  if (t1 == t2)
+    {
+    check_modes:
+      /* If the base variables are the same, we're good: none of the
+	 other tests below could possibly fail.  */
+      var1 = SSA_NAME_VAR (name1);
+      var2 = SSA_NAME_VAR (name2);
+      if (var1 == var2)
+	return true;
+
+      /* We don't want to coalesce two SSA names if one of the base
+	 variables is supposed to be a register while the other is
+	 supposed to be on the stack.  Anonymous SSA names take
+	 registers, but when not optimizing, user variables should go
+	 on the stack, so coalescing them with the anonymous variable
+	 as the partition leader would end up assigning the user
+	 variable to a register.  Don't do that!  */
+      bool reg1 = !var1 || use_register_for_decl (var1);
+      bool reg2 = !var2 || use_register_for_decl (var2);
+      if (reg1 != reg2)
+	return false;
+
+      /* Check that the promoted modes are the same.  We don't want to
+	 coalesce if the promoted modes would be different.  Only
+	 PARM_DECLs and RESULT_DECLs have different promotion rules,
+	 so skip the test if we both are variables or anonymous
+	 SSA_NAMEs.  */
+      return ((!var1 || VAR_P (var1)) && (!var2 || VAR_P (var2)))
+	|| promote_ssa_mode (name1, NULL) == promote_ssa_mode (name2, NULL);
+    }
+
+  /* If the types are not the same, check for a canonical type match.  This
+     (for example) allows coalescing when the types are fundamentally the
+     same, but just have different names. 
+
+     Note pointer types with different address spaces may have the same
+     canonical type.  Those are rejected for coalescing by the
+     types_compatible_p check.  */
+  if (TYPE_CANONICAL (t1)
+      && TYPE_CANONICAL (t1) == TYPE_CANONICAL (t2)
+      && types_compatible_p (t1, t2))
+    goto check_modes;
+
+  return false;
+}
+
+/* Fill in MAP's partition_to_base_index, with one index for each
+   partition of SSA names USED_IN_COPIES and related by CL coalesce
+   possibilities.  This must match gimple_can_coalesce_p in the
+   optimized case.  */
+
+static void
+compute_optimized_partition_bases (var_map map, bitmap used_in_copies,
+				   coalesce_list_p cl)
+{
+  int parts = num_var_partitions (map);
+  partition tentative = partition_new (parts);
+
+  /* Partition the SSA versions so that, for each coalescible
+     pair, both of its members are in the same partition in
+     TENTATIVE.  */
+  gcc_assert (!cl->sorted);
+  coalesce_pair_p node;
+  coalesce_iterator_type ppi;
+  FOR_EACH_PARTITION_PAIR (node, ppi, cl)
+    {
+      tree v1 = ssa_name (node->first_element);
+      int p1 = partition_find (tentative, var_to_partition (map, v1));
+      tree v2 = ssa_name (node->second_element);
+      int p2 = partition_find (tentative, var_to_partition (map, v2));
+
+      if (p1 == p2)
+	continue;
+
+      partition_union (tentative, p1, p2);
+    }
+
+  /* We have to deal with cost one pairs too.  */
+  for (cost_one_pair_d *co = cl->cost_one_list; co; co = co->next)
+    {
+      tree v1 = ssa_name (co->first_element);
+      int p1 = partition_find (tentative, var_to_partition (map, v1));
+      tree v2 = ssa_name (co->second_element);
+      int p2 = partition_find (tentative, var_to_partition (map, v2));
+
+      if (p1 == p2)
+	continue;
+
+      partition_union (tentative, p1, p2);
+    }
+
+  /* And also with abnormal edges.  */
+  basic_block bb;
+  edge e;
+  edge_iterator ei;
+  FOR_EACH_BB_FN (bb, cfun)
+    {
+      FOR_EACH_EDGE (e, ei, bb->preds)
+	if (e->flags & EDGE_ABNORMAL)
+	  {
+	    gphi_iterator gsi;
+	    for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
+		 gsi_next (&gsi))
+	      {
+		gphi *phi = gsi.phi ();
+		tree arg = PHI_ARG_DEF (phi, e->dest_idx);
+		if (SSA_NAME_IS_DEFAULT_DEF (arg)
+		    && (!SSA_NAME_VAR (arg)
+			|| TREE_CODE (SSA_NAME_VAR (arg)) != PARM_DECL))
+		  continue;
+
+		tree res = PHI_RESULT (phi);
+
+		int p1 = partition_find (tentative, var_to_partition (map, res));
+		int p2 = partition_find (tentative, var_to_partition (map, arg));
+
+		if (p1 == p2)
+		  continue;
+
+		partition_union (tentative, p1, p2);
+	      }
+	  }
+    }
+
+  map->partition_to_base_index = XCNEWVEC (int, parts);
+  auto_vec<unsigned int> index_map (parts);
+  if (parts)
+    index_map.quick_grow (parts);
+
+  const unsigned no_part = -1;
+  unsigned count = parts;
+  while (count)
+    index_map[--count] = no_part;
+
+  /* Initialize MAP's mapping from partition to base index, using
+     as base indices an enumeration of the TENTATIVE partitions in
+     which each SSA version ended up, so that we compute conflicts
+     between all SSA versions that ended up in the same potential
+     coalesce partition.  */
+  bitmap_iterator bi;
+  unsigned i;
+  EXECUTE_IF_SET_IN_BITMAP (used_in_copies, 0, i, bi)
+    {
+      int pidx = var_to_partition (map, ssa_name (i));
+      int base = partition_find (tentative, pidx);
+      if (index_map[base] != no_part)
+	continue;
+      index_map[base] = count++;
+    }
+
+  map->num_basevars = count;
+
+  EXECUTE_IF_SET_IN_BITMAP (used_in_copies, 0, i, bi)
+    {
+      int pidx = var_to_partition (map, ssa_name (i));
+      int base = partition_find (tentative, pidx);
+      gcc_assert (index_map[base] < count);
+      map->partition_to_base_index[pidx] = index_map[base];
+    }
+
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    dump_part_var_map (dump_file, tentative, map);
+
+  partition_delete (tentative);
+}
+
+/* Hashtable helpers.  */
+
+struct tree_int_map_hasher : typed_noop_remove <tree_int_map>
+{
+  typedef tree_int_map *value_type;
+  typedef tree_int_map *compare_type;
+  static inline hashval_t hash (const tree_int_map *);
+  static inline bool equal (const tree_int_map *, const tree_int_map *);
+};
+
+inline hashval_t
+tree_int_map_hasher::hash (const tree_int_map *v)
+{
+  return tree_map_base_hash (v);
+}
+
+inline bool
+tree_int_map_hasher::equal (const tree_int_map *v, const tree_int_map *c)
+{
+  return tree_int_map_eq (v, c);
+}
+
+/* This routine will initialize the basevar fields of MAP with base
+   names.  Partitions will share the same base if they have the same
+   SSA_NAME_VAR, or, being anonymous variables, the same type.  This
+   must match gimple_can_coalesce_p in the non-optimized case.  */
+
+static void
+compute_samebase_partition_bases (var_map map)
+{
+  int x, num_part;
+  tree var;
+  struct tree_int_map *m, *mapstorage;
+
+  num_part = num_var_partitions (map);
+  hash_table<tree_int_map_hasher> tree_to_index (num_part);
+  /* We can have at most num_part entries in the hash tables, so it's
+     enough to allocate so many map elements once, saving some malloc
+     calls.  */
+  mapstorage = m = XNEWVEC (struct tree_int_map, num_part);
+
+  /* If a base table already exists, clear it, otherwise create it.  */
+  free (map->partition_to_base_index);
+  map->partition_to_base_index = (int *) xmalloc (sizeof (int) * num_part);
+
+  /* Build the base variable list, and point partitions at their bases.  */
+  for (x = 0; x < num_part; x++)
+    {
+      struct tree_int_map **slot;
+      unsigned baseindex;
+      var = partition_to_var (map, x);
+      if (SSA_NAME_VAR (var)
+	  && (!VAR_P (SSA_NAME_VAR (var))
+	      || !DECL_IGNORED_P (SSA_NAME_VAR (var))))
+	m->base.from = SSA_NAME_VAR (var);
+      else
+	/* This restricts what anonymous SSA names we can coalesce
+	   as it restricts the sets we compute conflicts for.
+	   Using TREE_TYPE to generate sets is the easies as
+	   type equivalency also holds for SSA names with the same
+	   underlying decl.
+
+	   Check gimple_can_coalesce_p when changing this code.  */
+	m->base.from = (TYPE_CANONICAL (TREE_TYPE (var))
+			? TYPE_CANONICAL (TREE_TYPE (var))
+			: TREE_TYPE (var));
+      /* If base variable hasn't been seen, set it up.  */
+      slot = tree_to_index.find_slot (m, INSERT);
+      if (!*slot)
+	{
+	  baseindex = m - mapstorage;
+	  m->to = baseindex;
+	  *slot = m;
+	  m++;
+	}
+      else
+	baseindex = (*slot)->to;
+      map->partition_to_base_index[x] = baseindex;
+    }
+
+  map->num_basevars = m - mapstorage;
+
+  free (mapstorage);
+}
+
 /* Reduce the number of copies by coalescing variables in the function.  Return
    a partition map with the resulting coalesces.  */
 
@@ -1286,9 +1647,10 @@ coalesce_ssa_name (void)
   cl = create_coalesce_list ();
   map = create_outofssa_var_map (cl, used_in_copies);
 
-  /* If optimization is disabled, we need to coalesce all the names originating
-     from the same SSA_NAME_VAR so debug info remains undisturbed.  */
-  if (!optimize)
+  /* If this optimization is disabled, we need to coalesce all the
+     names originating from the same SSA_NAME_VAR so debug info
+     remains undisturbed.  */
+  if (!flag_tree_coalesce_vars)
     {
       hash_table<ssa_name_var_hash> ssa_name_hash (10);
 
@@ -1329,8 +1691,13 @@ coalesce_ssa_name (void)
   if (dump_file && (dump_flags & TDF_DETAILS))
     dump_var_map (dump_file, map);
 
-  /* Don't calculate live ranges for variables not in the coalesce list.  */
-  partition_view_bitmap (map, used_in_copies, true);
+  partition_view_bitmap (map, used_in_copies);
+
+  if (flag_tree_coalesce_vars)
+    compute_optimized_partition_bases (map, used_in_copies, cl);
+  else
+    compute_samebase_partition_bases (map);
+
   BITMAP_FREE (used_in_copies);
 
   if (num_var_partitions (map) < 1)
@@ -1369,8 +1736,7 @@ coalesce_ssa_name (void)
 
   /* Now coalesce everything in the list.  */
   coalesce_partitions (map, graph, cl,
-		       ((dump_flags & TDF_DETAILS) ? dump_file
-						   : NULL));
+		       ((dump_flags & TDF_DETAILS) ? dump_file : NULL));
 
   delete_coalesce_list (cl);
   ssa_conflicts_delete (graph);
diff --git a/gcc/tree-ssa-coalesce.h b/gcc/tree-ssa-coalesce.h
index 99b188a..ae289b4 100644
--- a/gcc/tree-ssa-coalesce.h
+++ b/gcc/tree-ssa-coalesce.h
@@ -21,5 +21,6 @@ along with GCC; see the file COPYING3.  If not see
 #define GCC_TREE_SSA_COALESCE_H
 
 extern var_map coalesce_ssa_name (void);
+extern bool gimple_can_coalesce_p (tree, tree);
 
 #endif /* GCC_TREE_SSA_COALESCE_H */
diff --git a/gcc/tree-ssa-copyrename.c b/gcc/tree-ssa-copyrename.c
deleted file mode 100644
index f3cb56e..0000000
--- a/gcc/tree-ssa-copyrename.c
+++ /dev/null
@@ -1,499 +0,0 @@
-/* Rename SSA copies.
-   Copyright (C) 2004-2015 Free Software Foundation, Inc.
-   Contributed by Andrew MacLeod <amacleod@redhat.com>
-
-This file is part of GCC.
-
-GCC is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 3, or (at your option)
-any later version.
-
-GCC is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING3.  If not see
-<http://www.gnu.org/licenses/>.  */
-
-#include "config.h"
-#include "system.h"
-#include "coretypes.h"
-#include "tm.h"
-#include "hash-set.h"
-#include "machmode.h"
-#include "vec.h"
-#include "double-int.h"
-#include "input.h"
-#include "alias.h"
-#include "symtab.h"
-#include "wide-int.h"
-#include "inchash.h"
-#include "tree.h"
-#include "fold-const.h"
-#include "predict.h"
-#include "hard-reg-set.h"
-#include "function.h"
-#include "dominance.h"
-#include "cfg.h"
-#include "basic-block.h"
-#include "tree-ssa-alias.h"
-#include "internal-fn.h"
-#include "gimple-expr.h"
-#include "is-a.h"
-#include "gimple.h"
-#include "gimple-iterator.h"
-#include "flags.h"
-#include "tree-pretty-print.h"
-#include "bitmap.h"
-#include "gimple-ssa.h"
-#include "stringpool.h"
-#include "tree-ssanames.h"
-#include "hashtab.h"
-#include "rtl.h"
-#include "statistics.h"
-#include "real.h"
-#include "fixed-value.h"
-#include "insn-config.h"
-#include "expmed.h"
-#include "dojump.h"
-#include "explow.h"
-#include "calls.h"
-#include "emit-rtl.h"
-#include "varasm.h"
-#include "stmt.h"
-#include "expr.h"
-#include "tree-dfa.h"
-#include "tree-inline.h"
-#include "tree-ssa-live.h"
-#include "tree-pass.h"
-#include "langhooks.h"
-
-static struct
-{
-  /* Number of copies coalesced.  */
-  int coalesced;
-} stats;
-
-/* The following routines implement the SSA copy renaming phase.
-
-   This optimization looks for copies between 2 SSA_NAMES, either through a
-   direct copy, or an implicit one via a PHI node result and its arguments.
-
-   Each copy is examined to determine if it is possible to rename the base
-   variable of one of the operands to the same variable as the other operand.
-   i.e.
-   T.3_5 = <blah>
-   a_1 = T.3_5
-
-   If this copy couldn't be copy propagated, it could possibly remain in the
-   program throughout the optimization phases.   After SSA->normal, it would
-   become:
-
-   T.3 = <blah>
-   a = T.3
-
-   Since T.3_5 is distinct from all other SSA versions of T.3, there is no
-   fundamental reason why the base variable needs to be T.3, subject to
-   certain restrictions.  This optimization attempts to determine if we can
-   change the base variable on copies like this, and result in code such as:
-
-   a_5 = <blah>
-   a_1 = a_5
-
-   This gives the SSA->normal pass a shot at coalescing a_1 and a_5. If it is
-   possible, the copy goes away completely. If it isn't possible, a new temp
-   will be created for a_5, and you will end up with the exact same code:
-
-   a.8 = <blah>
-   a = a.8
-
-   The other benefit of performing this optimization relates to what variables
-   are chosen in copies.  Gimplification of the program uses temporaries for
-   a lot of things. expressions like
-
-   a_1 = <blah>
-   <blah2> = a_1
-
-   get turned into
-
-   T.3_5 = <blah>
-   a_1 = T.3_5
-   <blah2> = a_1
-
-   Copy propagation is done in a forward direction, and if we can propagate
-   through the copy, we end up with:
-
-   T.3_5 = <blah>
-   <blah2> = T.3_5
-
-   The copy is gone, but so is all reference to the user variable 'a'. By
-   performing this optimization, we would see the sequence:
-
-   a_5 = <blah>
-   a_1 = a_5
-   <blah2> = a_1
-
-   which copy propagation would then turn into:
-
-   a_5 = <blah>
-   <blah2> = a_5
-
-   and so we still retain the user variable whenever possible.  */
-
-
-/* Coalesce the partitions in MAP representing VAR1 and VAR2 if it is valid.
-   Choose a representative for the partition, and send debug info to DEBUG.  */
-
-static void
-copy_rename_partition_coalesce (var_map map, tree var1, tree var2, FILE *debug)
-{
-  int p1, p2, p3;
-  tree root1, root2;
-  tree rep1, rep2;
-  bool ign1, ign2, abnorm;
-
-  gcc_assert (TREE_CODE (var1) == SSA_NAME);
-  gcc_assert (TREE_CODE (var2) == SSA_NAME);
-
-  register_ssa_partition (map, var1);
-  register_ssa_partition (map, var2);
-
-  p1 = partition_find (map->var_partition, SSA_NAME_VERSION (var1));
-  p2 = partition_find (map->var_partition, SSA_NAME_VERSION (var2));
-
-  if (debug)
-    {
-      fprintf (debug, "Try : ");
-      print_generic_expr (debug, var1, TDF_SLIM);
-      fprintf (debug, "(P%d) & ", p1);
-      print_generic_expr (debug, var2, TDF_SLIM);
-      fprintf (debug, "(P%d)", p2);
-    }
-
-  gcc_assert (p1 != NO_PARTITION);
-  gcc_assert (p2 != NO_PARTITION);
-
-  if (p1 == p2)
-    {
-      if (debug)
-	fprintf (debug, " : Already coalesced.\n");
-      return;
-    }
-
-  rep1 = partition_to_var (map, p1);
-  rep2 = partition_to_var (map, p2);
-  root1 = SSA_NAME_VAR (rep1);
-  root2 = SSA_NAME_VAR (rep2);
-  if (!root1 && !root2)
-    return;
-
-  /* Don't coalesce if one of the variables occurs in an abnormal PHI.  */
-  abnorm = (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rep1)
-	    || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rep2));
-  if (abnorm)
-    {
-      if (debug)
-	fprintf (debug, " : Abnormal PHI barrier.  No coalesce.\n");
-      return;
-    }
-
-  /* Partitions already have the same root, simply merge them.  */
-  if (root1 == root2)
-    {
-      p1 = partition_union (map->var_partition, p1, p2);
-      if (debug)
-	fprintf (debug, " : Same root, coalesced --> P%d.\n", p1);
-      return;
-    }
-
-  /* Never attempt to coalesce 2 different parameters.  */
-  if ((root1 && TREE_CODE (root1) == PARM_DECL)
-      && (root2 && TREE_CODE (root2) == PARM_DECL))
-    {
-      if (debug)
-        fprintf (debug, " : 2 different PARM_DECLS. No coalesce.\n");
-      return;
-    }
-
-  if ((root1 && TREE_CODE (root1) == RESULT_DECL)
-      != (root2 && TREE_CODE (root2) == RESULT_DECL))
-    {
-      if (debug)
-        fprintf (debug, " : One root a RESULT_DECL. No coalesce.\n");
-      return;
-    }
-
-  ign1 = !root1 || (TREE_CODE (root1) == VAR_DECL && DECL_IGNORED_P (root1));
-  ign2 = !root2 || (TREE_CODE (root2) == VAR_DECL && DECL_IGNORED_P (root2));
-
-  /* Refrain from coalescing user variables, if requested.  */
-  if (!ign1 && !ign2)
-    {
-      if (flag_ssa_coalesce_vars && DECL_FROM_INLINE (root2))
-	ign2 = true;
-      else if (flag_ssa_coalesce_vars && DECL_FROM_INLINE (root1))
-	ign1 = true;
-      else if (flag_ssa_coalesce_vars != 2)
-	{
-	  if (debug)
-	    fprintf (debug, " : 2 different USER vars. No coalesce.\n");
-	  return;
-	}
-      else
-	ign2 = true;
-    }
-
-  /* If both values have default defs, we can't coalesce.  If only one has a
-     tag, make sure that variable is the new root partition.  */
-  if (root1 && ssa_default_def (cfun, root1))
-    {
-      if (root2 && ssa_default_def (cfun, root2))
-	{
-	  if (debug)
-	    fprintf (debug, " : 2 default defs. No coalesce.\n");
-	  return;
-	}
-      else
-        {
-	  ign2 = true;
-	  ign1 = false;
-	}
-    }
-  else if (root2 && ssa_default_def (cfun, root2))
-    {
-      ign1 = true;
-      ign2 = false;
-    }
-
-  /* Do not coalesce if we cannot assign a symbol to the partition.  */
-  if (!(!ign2 && root2)
-      && !(!ign1 && root1))
-    {
-      if (debug)
-	fprintf (debug, " : Choosen variable has no root.  No coalesce.\n");
-      return;
-    }
-
-  /* Don't coalesce if the new chosen root variable would be read-only.
-     If both ign1 && ign2, then the root var of the larger partition
-     wins, so reject in that case if any of the root vars is TREE_READONLY.
-     Otherwise reject only if the root var, on which replace_ssa_name_symbol
-     will be called below, is readonly.  */
-  if (((root1 && TREE_READONLY (root1)) && ign2)
-      || ((root2 && TREE_READONLY (root2)) && ign1))
-    {
-      if (debug)
-	fprintf (debug, " : Readonly variable.  No coalesce.\n");
-      return;
-    }
-
-  /* Don't coalesce if the two variables aren't type compatible .  */
-  if (!types_compatible_p (TREE_TYPE (var1), TREE_TYPE (var2))
-      /* There is a disconnect between the middle-end type-system and
-         VRP, avoid coalescing enum types with different bounds.  */
-      || ((TREE_CODE (TREE_TYPE (var1)) == ENUMERAL_TYPE
-	   || TREE_CODE (TREE_TYPE (var2)) == ENUMERAL_TYPE)
-	  && TREE_TYPE (var1) != TREE_TYPE (var2)))
-    {
-      if (debug)
-	fprintf (debug, " : Incompatible types.  No coalesce.\n");
-      return;
-    }
-
-  /* Merge the two partitions.  */
-  p3 = partition_union (map->var_partition, p1, p2);
-
-  /* Set the root variable of the partition to the better choice, if there is
-     one.  */
-  if (!ign2 && root2)
-    replace_ssa_name_symbol (partition_to_var (map, p3), root2);
-  else if (!ign1 && root1)
-    replace_ssa_name_symbol (partition_to_var (map, p3), root1);
-  else
-    gcc_unreachable ();
-
-  if (debug)
-    {
-      fprintf (debug, " --> P%d ", p3);
-      print_generic_expr (debug, SSA_NAME_VAR (partition_to_var (map, p3)),
-			  TDF_SLIM);
-      fprintf (debug, "\n");
-    }
-}
-
-
-namespace {
-
-const pass_data pass_data_rename_ssa_copies =
-{
-  GIMPLE_PASS, /* type */
-  "copyrename", /* name */
-  OPTGROUP_NONE, /* optinfo_flags */
-  TV_TREE_COPY_RENAME, /* tv_id */
-  ( PROP_cfg | PROP_ssa ), /* properties_required */
-  0, /* properties_provided */
-  0, /* properties_destroyed */
-  0, /* todo_flags_start */
-  0, /* todo_flags_finish */
-};
-
-class pass_rename_ssa_copies : public gimple_opt_pass
-{
-public:
-  pass_rename_ssa_copies (gcc::context *ctxt)
-    : gimple_opt_pass (pass_data_rename_ssa_copies, ctxt)
-  {}
-
-  /* opt_pass methods: */
-  opt_pass * clone () { return new pass_rename_ssa_copies (m_ctxt); }
-  virtual bool gate (function *) { return flag_tree_copyrename != 0; }
-  virtual unsigned int execute (function *);
-
-}; // class pass_rename_ssa_copies
-
-/* This function will make a pass through the IL, and attempt to coalesce any
-   SSA versions which occur in PHI's or copies.  Coalescing is accomplished by
-   changing the underlying root variable of all coalesced version.  This will
-   then cause the SSA->normal pass to attempt to coalesce them all to the same
-   variable.  */
-
-unsigned int
-pass_rename_ssa_copies::execute (function *fun)
-{
-  var_map map;
-  basic_block bb;
-  tree var, part_var;
-  gimple stmt;
-  unsigned x;
-  FILE *debug;
-
-  memset (&stats, 0, sizeof (stats));
-
-  if (dump_file && (dump_flags & TDF_DETAILS))
-    debug = dump_file;
-  else
-    debug = NULL;
-
-  map = init_var_map (num_ssa_names);
-
-  FOR_EACH_BB_FN (bb, fun)
-    {
-      /* Scan for real copies.  */
-      for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
-	   gsi_next (&gsi))
-	{
-	  stmt = gsi_stmt (gsi);
-	  if (gimple_assign_ssa_name_copy_p (stmt))
-	    {
-	      tree lhs = gimple_assign_lhs (stmt);
-	      tree rhs = gimple_assign_rhs1 (stmt);
-
-	      copy_rename_partition_coalesce (map, lhs, rhs, debug);
-	    }
-	}
-    }
-
-  FOR_EACH_BB_FN (bb, fun)
-    {
-      /* Treat PHI nodes as copies between the result and each argument.  */
-      for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
-	   gsi_next (&gsi))
-        {
-          size_t i;
-	  tree res;
-	  gphi *phi = gsi.phi ();
-	  res = gimple_phi_result (phi);
-
-	  /* Do not process virtual SSA_NAMES.  */
-	  if (virtual_operand_p (res))
-	    continue;
-
-	  /* Make sure to only use the same partition for an argument
-	     as the result but never the other way around.  */
-	  if (SSA_NAME_VAR (res)
-	      && !DECL_IGNORED_P (SSA_NAME_VAR (res)))
-	    for (i = 0; i < gimple_phi_num_args (phi); i++)
-	      {
-		tree arg = PHI_ARG_DEF (phi, i);
-		if (TREE_CODE (arg) == SSA_NAME)
-		  copy_rename_partition_coalesce (map, res, arg,
-						  debug);
-	      }
-	  /* Else if all arguments are in the same partition try to merge
-	     it with the result.  */
-	  else
-	    {
-	      int all_p_same = -1;
-	      int p = -1;
-	      for (i = 0; i < gimple_phi_num_args (phi); i++)
-		{
-		  tree arg = PHI_ARG_DEF (phi, i);
-		  if (TREE_CODE (arg) != SSA_NAME)
-		    {
-		      all_p_same = 0;
-		      break;
-		    }
-		  else if (all_p_same == -1)
-		    {
-		      p = partition_find (map->var_partition,
-					  SSA_NAME_VERSION (arg));
-		      all_p_same = 1;
-		    }
-		  else if (all_p_same == 1
-			   && p != partition_find (map->var_partition,
-						   SSA_NAME_VERSION (arg)))
-		    {
-		      all_p_same = 0;
-		      break;
-		    }
-		}
-	      if (all_p_same == 1)
-		copy_rename_partition_coalesce (map, res,
-						PHI_ARG_DEF (phi, 0),
-						debug);
-	    }
-        }
-    }
-
-  if (debug)
-    dump_var_map (debug, map);
-
-  /* Now one more pass to make all elements of a partition share the same
-     root variable.  */
-
-  for (x = 1; x < num_ssa_names; x++)
-    {
-      part_var = partition_to_var (map, x);
-      if (!part_var)
-        continue;
-      var = ssa_name (x);
-      if (SSA_NAME_VAR (var) == SSA_NAME_VAR (part_var))
-	continue;
-      if (debug)
-        {
-	  fprintf (debug, "Coalesced ");
-	  print_generic_expr (debug, var, TDF_SLIM);
-	  fprintf (debug, " to ");
-	  print_generic_expr (debug, part_var, TDF_SLIM);
-	  fprintf (debug, "\n");
-	}
-      stats.coalesced++;
-      replace_ssa_name_symbol (var, SSA_NAME_VAR (part_var));
-    }
-
-  statistics_counter_event (fun, "copies coalesced",
-			    stats.coalesced);
-  delete_var_map (map);
-  return 0;
-}
-
-} // anon namespace
-
-gimple_opt_pass *
-make_pass_rename_ssa_copies (gcc::context *ctxt)
-{
-  return new pass_rename_ssa_copies (ctxt);
-}
diff --git a/gcc/tree-ssa-live.c b/gcc/tree-ssa-live.c
index 2c7c072..821b2f4 100644
--- a/gcc/tree-ssa-live.c
+++ b/gcc/tree-ssa-live.c
@@ -100,90 +100,6 @@ static void  verify_live_on_entry (tree_live_info_p);
    ssa_name or variable, and vice versa.  */
 
 
-/* Hashtable helpers.  */
-
-struct tree_int_map_hasher : typed_noop_remove <tree_int_map>
-{
-  typedef tree_int_map *value_type;
-  typedef tree_int_map *compare_type;
-  static inline hashval_t hash (const tree_int_map *);
-  static inline bool equal (const tree_int_map *, const tree_int_map *);
-};
-
-inline hashval_t
-tree_int_map_hasher::hash (const tree_int_map *v)
-{
-  return tree_map_base_hash (v);
-}
-
-inline bool
-tree_int_map_hasher::equal (const tree_int_map *v, const tree_int_map *c)
-{
-  return tree_int_map_eq (v, c);
-}
-
-
-/* This routine will initialize the basevar fields of MAP.  */
-
-static void
-var_map_base_init (var_map map)
-{
-  int x, num_part;
-  tree var;
-  struct tree_int_map *m, *mapstorage;
-
-  num_part = num_var_partitions (map);
-  hash_table<tree_int_map_hasher> tree_to_index (num_part);
-  /* We can have at most num_part entries in the hash tables, so it's
-     enough to allocate so many map elements once, saving some malloc
-     calls.  */
-  mapstorage = m = XNEWVEC (struct tree_int_map, num_part);
-
-  /* If a base table already exists, clear it, otherwise create it.  */
-  free (map->partition_to_base_index);
-  map->partition_to_base_index = (int *) xmalloc (sizeof (int) * num_part);
-
-  /* Build the base variable list, and point partitions at their bases.  */
-  for (x = 0; x < num_part; x++)
-    {
-      struct tree_int_map **slot;
-      unsigned baseindex;
-      var = partition_to_var (map, x);
-      if (SSA_NAME_VAR (var)
-	  && (!VAR_P (SSA_NAME_VAR (var))
-	      || !DECL_IGNORED_P (SSA_NAME_VAR (var))))
-	m->base.from = SSA_NAME_VAR (var);
-      else
-	/* This restricts what anonymous SSA names we can coalesce
-	   as it restricts the sets we compute conflicts for.
-	   Using TREE_TYPE to generate sets is the easies as
-	   type equivalency also holds for SSA names with the same
-	   underlying decl. 
-
-	   Check gimple_can_coalesce_p when changing this code.  */
-	m->base.from = (TYPE_CANONICAL (TREE_TYPE (var))
-			? TYPE_CANONICAL (TREE_TYPE (var))
-			: TREE_TYPE (var));
-      /* If base variable hasn't been seen, set it up.  */
-      slot = tree_to_index.find_slot (m, INSERT);
-      if (!*slot)
-	{
-	  baseindex = m - mapstorage;
-	  m->to = baseindex;
-	  *slot = m;
-	  m++;
-	}
-      else
-	baseindex = (*slot)->to;
-      map->partition_to_base_index[x] = baseindex;
-    }
-
-  map->num_basevars = m - mapstorage;
-
-  free (mapstorage);
-}
-
-
 /* Remove the base table in MAP.  */
 
 static void
@@ -361,21 +277,17 @@ partition_view_fini (var_map map, bitmap selected)
 }
 
 
-/* Create a partition view which includes all the used partitions in MAP.  If
-   WANT_BASES is true, create the base variable map as well.  */
+/* Create a partition view which includes all the used partitions in MAP.  */
 
 void
-partition_view_normal (var_map map, bool want_bases)
+partition_view_normal (var_map map)
 {
   bitmap used;
 
   used = partition_view_init (map);
   partition_view_fini (map, used);
 
-  if (want_bases)
-    var_map_base_init (map);
-  else
-    var_map_base_fini (map);
+  var_map_base_fini (map);
 }
 
 
@@ -384,7 +296,7 @@ partition_view_normal (var_map map, bool want_bases)
    as well.  */
 
 void
-partition_view_bitmap (var_map map, bitmap only, bool want_bases)
+partition_view_bitmap (var_map map, bitmap only)
 {
   bitmap used;
   bitmap new_partitions = BITMAP_ALLOC (NULL);
@@ -400,10 +312,7 @@ partition_view_bitmap (var_map map, bitmap only, bool want_bases)
     }
   partition_view_fini (map, new_partitions);
 
-  if (want_bases)
-    var_map_base_init (map);
-  else
-    var_map_base_fini (map);
+  var_map_base_fini (map);
 }
 
 
diff --git a/gcc/tree-ssa-live.h b/gcc/tree-ssa-live.h
index d5d7820..1f88358 100644
--- a/gcc/tree-ssa-live.h
+++ b/gcc/tree-ssa-live.h
@@ -71,8 +71,8 @@ typedef struct _var_map
 extern var_map init_var_map (int);
 extern void delete_var_map (var_map);
 extern int var_union (var_map, tree, tree);
-extern void partition_view_normal (var_map, bool);
-extern void partition_view_bitmap (var_map, bitmap, bool);
+extern void partition_view_normal (var_map);
+extern void partition_view_bitmap (var_map, bitmap);
 extern void dump_scope_blocks (FILE *, int);
 extern void debug_scope_block (tree, int);
 extern void debug_scope_blocks (int);
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
index 3f6bebe..7bef8cf 100644
--- a/gcc/tree-ssa-loop-niter.c
+++ b/gcc/tree-ssa-loop-niter.c
@@ -3964,7 +3964,11 @@ loop_exits_before_overflow (tree base, tree step,
 	if (!CONVERT_EXPR_P (e) || !operand_equal_p (e, unsigned_base, 0))
 	  continue;
 	e = TREE_OPERAND (e, 0);
-	gcc_assert (operand_equal_p (e, base, 0));
+	/* If E has an unsigned type, the operand equality test below
+	   would fail, but the equality test above would have already
+	   verified the equality, so we can proceed with it.  */
+	gcc_assert (TYPE_UNSIGNED (TREE_TYPE (e))
+		    || operand_equal_p (e, base, 0));
 	if (tree_int_cst_sign_bit (step))
 	  {
 	    code = LT_EXPR;
diff --git a/gcc/tree-ssa-uncprop.c b/gcc/tree-ssa-uncprop.c
index f75a7f1..0982305 100644
--- a/gcc/tree-ssa-uncprop.c
+++ b/gcc/tree-ssa-uncprop.c
@@ -59,6 +59,11 @@ along with GCC; see the file COPYING3.  If not see
 #include "domwalk.h"
 #include "tree-pass.h"
 #include "tree-ssa-propagate.h"
+#include "bitmap.h"
+#include "stringpool.h"
+#include "tree-ssanames.h"
+#include "tree-ssa-live.h"
+#include "tree-ssa-coalesce.h"
 
 /* The basic structure describing an equivalency created by traversing
    an edge.  Traversing the edge effectively means that we can assume
diff --git a/gcc/var-tracking.c b/gcc/var-tracking.c
index 0b24007..acdcd46 100644
--- a/gcc/var-tracking.c
+++ b/gcc/var-tracking.c
@@ -4931,12 +4931,16 @@ dataflow_set_remove_mem_locs (variable_def **slot, dataflow_set *set)
    registers, as well as associations between MEMs and VALUEs.  */
 
 static void
-dataflow_set_clear_at_call (dataflow_set *set)
+dataflow_set_clear_at_call (dataflow_set *set, rtx_insn *call_insn)
 {
   unsigned int r;
   hard_reg_set_iterator hrsi;
+  HARD_REG_SET invalidated_regs;
 
-  EXECUTE_IF_SET_IN_HARD_REG_SET (regs_invalidated_by_call, 0, r, hrsi)
+  get_call_reg_set_usage (call_insn, &invalidated_regs,
+			  regs_invalidated_by_call);
+
+  EXECUTE_IF_SET_IN_HARD_REG_SET (invalidated_regs, 0, r, hrsi)
     var_regno_delete (set, r);
 
   if (MAY_HAVE_DEBUG_INSNS)
@@ -6720,7 +6724,7 @@ compute_bb_dataflow (basic_block bb)
       switch (mo->type)
 	{
 	  case MO_CALL:
-	    dataflow_set_clear_at_call (out);
+	    dataflow_set_clear_at_call (out, insn);
 	    break;
 
 	  case MO_USE:
@@ -9182,7 +9186,7 @@ emit_notes_in_bb (basic_block bb, dataflow_set *set)
       switch (mo->type)
 	{
 	  case MO_CALL:
-	    dataflow_set_clear_at_call (set);
+	    dataflow_set_clear_at_call (set, insn);
 	    emit_notes_for_changes (insn, EMIT_NOTE_AFTER_CALL_INSN, set->vars);
 	    {
 	      rtx arguments = mo->u.loc, *p = &arguments;



And here's the incremental patch:

---
 gcc/alias.c               |   17 +++++++------
 gcc/cfgexpand.c           |   57 +++++++++++++++++----------------------------
 gcc/emit-rtl.c            |    2 --
 gcc/explow.c              |    3 --
 gcc/expr.c                |   16 +++++--------
 gcc/function.c            |   15 ++++++++++++
 gcc/gimple-expr.h         |    4 ---
 gcc/tree-outof-ssa.c      |    7 ++----
 gcc/tree-ssa-coalesce.h   |    1 +
 gcc/tree-ssa-loop-niter.c |    6 ++++-
 gcc/tree-ssa-uncprop.c    |    5 ++++
 11 files changed, 64 insertions(+), 69 deletions(-)

diff --git a/gcc/alias.c b/gcc/alias.c
index 7a74e81..5a031d9 100644
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -2553,14 +2553,15 @@ nonoverlapping_memrefs_p (const_rtx x, const_rtx y, bool loop_invariant)
     return 0;
 
   /* If we refer to different gimple registers, or one gimple register
-     and one non-gimple-register, we know they can't overlap.  Now,
-     there could be more than one stack slot for (different versions
-     of) the same gimple register, but we can presumably tell they
-     don't overlap based on offsets from stack base addresses
-     elsewhere.  It's important that we don't proceed to DECL_RTL,
-     because gimple registers may not pass DECL_RTL_SET_P, and
-     make_decl_rtl won't be able to do anything about them since no
-     SSA information will have remained to guide it.  */
+     and one non-gimple-register, we know they can't overlap.  First,
+     gimple registers don't have their addresses taken.  Now, there
+     could be more than one stack slot for (different versions of) the
+     same gimple register, but we can presumably tell they don't
+     overlap based on offsets from stack base addresses elsewhere.
+     It's important that we don't proceed to DECL_RTL, because gimple
+     registers may not pass DECL_RTL_SET_P, and make_decl_rtl won't be
+     able to do anything about them since no SSA information will have
+     remained to guide it.  */
   if (is_gimple_reg (exprx) || is_gimple_reg (expry))
     return exprx != expry;
 
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 3e80b4a..bf972fc 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -179,11 +179,10 @@ gimple_assign_rhs_to_tree (gimple stmt)
 
 #define SSAVAR(x) (TREE_CODE (x) == SSA_NAME ? SSA_NAME_VAR (x) : x)
 
-/* NEXT is a DECL to be associated with some RTL, CUR is a DECL or a
-   TREE_LIST of DECLs.  If NEXT is covered by CUR, return CUR
-   unchanged.  Otherwise, return a list with all entries of CUR, with
-   NEXT at the end.  If CUR was a list, it will be modified in
-   place.  */
+/* Choose either CUR or NEXT as the leader DECL for a partition.
+   Prefer ignored decls, to simplify debug dumps and reduce ambiguity
+   out of the same user variable being in multiple partitions (this is
+   less likely for compiler-introduced temps).  */
 
 static tree
 leader_merge (tree cur, tree next)
@@ -191,26 +190,11 @@ leader_merge (tree cur, tree next)
   if (cur == NULL || cur == next)
     return next;
 
-  tree list;
+  if (DECL_P (cur) && DECL_IGNORED_P (cur))
+    return cur;
 
-  if (TREE_CODE (cur) == TREE_LIST)
-    {
-      /* Look for NEXT in the list.  Stop at the last node to insert
-	 there.  */
-      for (list = cur; ; list = TREE_CHAIN (list))
-	{
-	  if (TREE_VALUE (list) == next)
-	    return cur;
-	  if (!TREE_CHAIN (list))
-	    break;
-	}
-    }
-  else
-    /* Create the first node.  */
-    list = build_tree_list (NULL, cur);
-
-  next = build_tree_list (NULL, next);
-  TREE_CHAIN (list) = next;
+  if (DECL_P (next) && DECL_IGNORED_P (next))
+    return next;
 
   return cur;
 }
@@ -285,9 +269,9 @@ set_rtl (tree t, rtx x)
       if (cur != next)
 	{
 	  if (MEM_P (x))
-	    set_mem_attributes (x, SSAVAR (t), true);
+	    set_mem_attributes (x, next, true);
 	  else
-	    set_reg_attrs_for_decl_rtl (SSAVAR (t), x);
+	    set_reg_attrs_for_decl_rtl (next, x);
 	}
     }
 
@@ -1025,9 +1009,9 @@ expand_one_stack_var_at (tree decl, rtx base, unsigned base_align,
   gcc_assert (offset == trunc_int_for_mode (offset, Pmode));
 
   x = plus_constant (Pmode, base, offset);
-  x = gen_rtx_MEM ((TREE_CODE (decl) != SSA_NAME || SSA_NAME_VAR (decl))
-		   ? DECL_MODE (SSAVAR (decl))
-		   : TYPE_MODE (TREE_TYPE (decl)), x);
+  x = gen_rtx_MEM (TREE_CODE (decl) == SSA_NAME
+		   ? TYPE_MODE (TREE_TYPE (decl))
+		   : DECL_MODE (SSAVAR (decl)), x);
 
   if (TREE_CODE (decl) != SSA_NAME)
     {
@@ -1268,17 +1252,17 @@ expand_one_stack_var_1 (tree var)
   HOST_WIDE_INT size, offset;
   unsigned byte_align;
 
-  if (TREE_CODE (var) != SSA_NAME || SSA_NAME_VAR (var))
-    {
-      size = tree_to_uhwi (DECL_SIZE_UNIT (SSAVAR (var)));
-      byte_align = align_local_variable (SSAVAR (var));
-    }
-  else
+  if (TREE_CODE (var) == SSA_NAME)
     {
       tree type = TREE_TYPE (var);
       size = tree_to_uhwi (TYPE_SIZE_UNIT (type));
       byte_align = TYPE_ALIGN_UNIT (type);
     }
+  else
+    {
+      size = tree_to_uhwi (DECL_SIZE_UNIT (var));
+      byte_align = align_local_variable (var);
+    }
 
   /* We handle highly aligned variables in expand_stack_vars.  */
   gcc_assert (byte_align * BITS_PER_UNIT <= MAX_SUPPORTED_STACK_ALIGNMENT);
@@ -1423,9 +1407,10 @@ expand_one_register_var (tree var)
 	  gcc_assert (REG_P (x));
 	  return;
 	}
+      gcc_unreachable ();
     }
 
-  tree decl = SSAVAR (var);
+  tree decl = var;
   tree type = TREE_TYPE (decl);
   machine_mode reg_mode = promote_decl_mode (decl, NULL);
   rtx x = gen_reg_rtx (reg_mode);
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 308da40..2b98946 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -1252,8 +1252,6 @@ set_reg_attrs_for_decl_rtl (tree t, rtx x)
   if (!t)
     return;
   tree tdecl = t;
-  if (TREE_CODE (t) == TREE_LIST)
-    tdecl = TREE_VALUE (t);
   if (GET_CODE (x) == SUBREG)
     {
       gcc_assert (subreg_lowpart_p (x));
diff --git a/gcc/explow.c b/gcc/explow.c
index e09c032e1..5b0d49c 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -866,9 +866,6 @@ promote_ssa_mode (const_tree name, int *punsignedp)
 {
   gcc_assert (TREE_CODE (name) == SSA_NAME);
 
-  if (SSA_NAME_VAR (name))
-    return promote_decl_mode (SSA_NAME_VAR (name), punsignedp);
-
   tree type = TREE_TYPE (name);
   int unsignedp = TYPE_UNSIGNED (type);
   machine_mode mode = TYPE_MODE (type);
diff --git a/gcc/expr.c b/gcc/expr.c
index effe379..5b6e16e 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -9584,20 +9584,16 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
 
 	  /* Get the signedness to be used for this variable.  Ensure we get
 	     the same mode we got when the variable was declared.  */
-	  if (code == SSA_NAME
-	      && (g = SSA_NAME_DEF_STMT (ssa_name))
-	      && gimple_code (g) == GIMPLE_CALL
-	      && !gimple_call_internal_p (g))
+	  if (code != SSA_NAME)
+	    pmode = promote_decl_mode (exp, &unsignedp);
+	  else if ((g = SSA_NAME_DEF_STMT (ssa_name))
+		   && gimple_code (g) == GIMPLE_CALL
+		   && !gimple_call_internal_p (g))
 	    pmode = promote_function_mode (type, mode, &unsignedp,
 					   gimple_call_fntype (g),
 					   2);
-	  else if (!exp)
-	    {
-	      gcc_assert (code == SSA_NAME);
-	      pmode = promote_ssa_mode (ssa_name, &unsignedp);
-	    }
 	  else
-	    pmode = promote_decl_mode (exp, &unsignedp);
+	    pmode = promote_ssa_mode (ssa_name, &unsignedp);
 	  gcc_assert (GET_MODE (decl_rtl) == pmode);
 
 	  temp = gen_lowpart_SUBREG (mode, decl_rtl);
diff --git a/gcc/function.c b/gcc/function.c
index dc9e77f..58e2498 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -2124,6 +2124,21 @@ use_register_for_decl (const_tree decl)
 {
   if (TREE_CODE (decl) == SSA_NAME)
     {
+      /* We often try to use the SSA_NAME, instead of its underlying
+	 decl, to get type information and guide decisions, to avoid
+	 differences of behavior between anonymous and named
+	 variables, but in this one case we have to go for the actual
+	 variable if there is one.  The main reason is that, at least
+	 at -O0, we want to place user variables on the stack, but we
+	 don't mind using pseudos for anonymous or ignored temps.
+	 Should we take the SSA_NAME, we'd conclude all SSA_NAMEs
+	 should go in pseudos, whereas their corresponding variables
+	 might have to go on the stack.  So, disregarding the decl
+	 here would negatively impact debug info at -O0, enable
+	 coalescing between SSA_NAMEs that ought to get different
+	 stack/pseudo assignments, and get the incoming argument
+	 processing thoroughly confused by PARM_DECLs expected to live
+	 in stack slots but assigned to pseudos.  */
       if (!SSA_NAME_VAR (decl))
 	return TYPE_MODE (TREE_TYPE (decl)) != BLKmode
 	  && !(flag_float_store && FLOAT_TYPE_P (TREE_TYPE (decl)));
diff --git a/gcc/gimple-expr.h b/gcc/gimple-expr.h
index 146cede..3d1c89f 100644
--- a/gcc/gimple-expr.h
+++ b/gcc/gimple-expr.h
@@ -55,10 +55,6 @@ extern bool is_gimple_mem_ref_addr (tree);
 extern void mark_addressable (tree);
 extern bool is_gimple_reg_rhs (tree);
 
-/* Defined in tree-ssa-coalesce.c.   */
-extern bool gimple_can_coalesce_p (tree, tree);
-
-
 /* Return true if a conversion from either type of TYPE1 and TYPE2
    to the other is not required.  Otherwise return false.  */
 
diff --git a/gcc/tree-outof-ssa.c b/gcc/tree-outof-ssa.c
index dda9973..59d91c6 100644
--- a/gcc/tree-outof-ssa.c
+++ b/gcc/tree-outof-ssa.c
@@ -305,7 +305,6 @@ insert_value_copy_on_edge (edge e, int dest, tree src, source_location locus)
   rtx dest_rtx, seq, x;
   machine_mode dest_mode, src_mode;
   int unsignedp;
-  tree var;
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
@@ -328,10 +327,9 @@ insert_value_copy_on_edge (edge e, int dest, tree src, source_location locus)
   start_sequence ();
 
   tree name = partition_to_var (SA.map, dest);
-  var = SSA_NAME_VAR (name);
   src_mode = TYPE_MODE (TREE_TYPE (src));
   dest_mode = GET_MODE (dest_rtx);
-  gcc_assert (src_mode == TYPE_MODE (TREE_TYPE (var ? var : name)));
+  gcc_assert (src_mode == TYPE_MODE (TREE_TYPE (name)));
   gcc_assert (!REG_P (dest_rtx)
 	      || dest_mode == promote_ssa_mode (name, &unsignedp));
 
@@ -709,8 +707,7 @@ elim_backward (elim_graph g, int T)
 static rtx
 get_temp_reg (tree name)
 {
-  tree var = TREE_CODE (name) == SSA_NAME ? SSA_NAME_VAR (name) : name;
-  tree type = var ? TREE_TYPE (var) : TREE_TYPE (name);
+  tree type = TREE_TYPE (name);
   int unsignedp;
   machine_mode reg_mode = promote_ssa_mode (name, &unsignedp);
   rtx x = gen_reg_rtx (reg_mode);
diff --git a/gcc/tree-ssa-coalesce.h b/gcc/tree-ssa-coalesce.h
index 99b188a..ae289b4 100644
--- a/gcc/tree-ssa-coalesce.h
+++ b/gcc/tree-ssa-coalesce.h
@@ -21,5 +21,6 @@ along with GCC; see the file COPYING3.  If not see
 #define GCC_TREE_SSA_COALESCE_H
 
 extern var_map coalesce_ssa_name (void);
+extern bool gimple_can_coalesce_p (tree, tree);
 
 #endif /* GCC_TREE_SSA_COALESCE_H */
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
index 3f6bebe..7bef8cf 100644
--- a/gcc/tree-ssa-loop-niter.c
+++ b/gcc/tree-ssa-loop-niter.c
@@ -3964,7 +3964,11 @@ loop_exits_before_overflow (tree base, tree step,
 	if (!CONVERT_EXPR_P (e) || !operand_equal_p (e, unsigned_base, 0))
 	  continue;
 	e = TREE_OPERAND (e, 0);
-	gcc_assert (operand_equal_p (e, base, 0));
+	/* If E has an unsigned type, the operand equality test below
+	   would fail, but the equality test above would have already
+	   verified the equality, so we can proceed with it.  */
+	gcc_assert (TYPE_UNSIGNED (TREE_TYPE (e))
+		    || operand_equal_p (e, base, 0));
 	if (tree_int_cst_sign_bit (step))
 	  {
 	    code = LT_EXPR;
diff --git a/gcc/tree-ssa-uncprop.c b/gcc/tree-ssa-uncprop.c
index f75a7f1..0982305 100644
--- a/gcc/tree-ssa-uncprop.c
+++ b/gcc/tree-ssa-uncprop.c
@@ -59,6 +59,11 @@ along with GCC; see the file COPYING3.  If not see
 #include "domwalk.h"
 #include "tree-pass.h"
 #include "tree-ssa-propagate.h"
+#include "bitmap.h"
+#include "stringpool.h"
+#include "tree-ssanames.h"
+#include "tree-ssa-live.h"
+#include "tree-ssa-coalesce.h"
 
 /* The basic structure describing an equivalency created by traversing
    an edge.  Traversing the edge effectively means that we can assume



-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist|Red Hat Brasil GNU Toolchain Engineer


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