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[PATCH] Merge flow-sensitive info in merge_alias_info
- From: Richard Guenther <rguenther at suse dot de>
- To: gcc-patches at gcc dot gnu dot org
- Cc: Daniel Berlin <dberlin at dberlin dot org>, dnovillo at google dot com
- Date: Thu, 22 Nov 2007 14:49:41 +0100 (CET)
- Subject: [PATCH] Merge flow-sensitive info in merge_alias_info
This patch makes us merge flow-sensitive alias info in simple propagation
cases where we previously failed to do so. I am not sure if this just
increases precision or also fixes correctness, so if it is appropriate
for stage3 or not.
Bootstrapped and tested on x86_64-unknown-linux-gnu, ok for mainline?
Thanks,
Richard.
2007-11-22 Richard Guenther <rguenther@suse.de>
* tree-ssa-copy.c (may_propagate_copy): Remove redundant
checks.
(merge_alias_info): Do verification only if checking is
enabled. Merge flow-sensitive alias information in simple
cases.
* tree-ssa-operands.c (get_addr_dereference_operands): Also
complain about missing NMTs.
* gcc.dg/tree-ssa/alias-17.c: New testcase.
Index: tree-ssa-operands.c
===================================================================
*** tree-ssa-operands.c (revision 130328)
--- tree-ssa-operands.c (working copy)
*************** get_addr_dereference_operands (tree stmt
*** 1643,1658 ****
/* If we are emitting debugging dumps, display a warning if
PTR is an SSA_NAME with no flow-sensitive alias
information. That means that we may need to compute
! aliasing again. */
if (dump_file
&& TREE_CODE (ptr) == SSA_NAME
! && pi == NULL)
{
fprintf (dump_file,
"NOTE: no flow-sensitive alias info for ");
print_generic_expr (dump_file, ptr, dump_flags);
fprintf (dump_file, " in ");
! print_generic_stmt (dump_file, stmt, dump_flags);
}
if (TREE_CODE (ptr) == SSA_NAME)
--- 1643,1660 ----
/* If we are emitting debugging dumps, display a warning if
PTR is an SSA_NAME with no flow-sensitive alias
information. That means that we may need to compute
! aliasing again or that a propagation pass forgot to
! update the alias information on the pointers. */
if (dump_file
&& TREE_CODE (ptr) == SSA_NAME
! && (pi == NULL
! || pi->name_mem_tag == NULL_TREE))
{
fprintf (dump_file,
"NOTE: no flow-sensitive alias info for ");
print_generic_expr (dump_file, ptr, dump_flags);
fprintf (dump_file, " in ");
! print_generic_stmt (dump_file, stmt, 0);
}
if (TREE_CODE (ptr) == SSA_NAME)
Index: testsuite/gcc.dg/tree-ssa/alias-17.c
===================================================================
*** testsuite/gcc.dg/tree-ssa/alias-17.c (revision 0)
--- testsuite/gcc.dg/tree-ssa/alias-17.c (revision 0)
***************
*** 0 ****
--- 1,18 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O -fno-early-inlining -fdump-tree-ccp2" } */
+
+ int *p;
+ int inline bar(void) { return 0; }
+ int foo(int x)
+ {
+ int i;
+ int *q;
+ if (bar())
+ q = &i;
+ else
+ q = p;
+ return *q + *p;
+ }
+
+ /* { dg-final { scan-tree-dump-not "NOTE: no flow-sensitive alias info for" "ccp2" } } */
+ /* { dg-final { cleanup-tree-dump "ccp2" } } */
Index: tree-ssa-copy.c
===================================================================
*** tree-ssa-copy.c (revision 130328)
--- tree-ssa-copy.c (working copy)
*************** may_propagate_copy (tree dest, tree orig
*** 129,136 ****
tree mt_orig = symbol_mem_tag (SSA_NAME_VAR (orig));
if (mt_dest && mt_orig && mt_dest != mt_orig)
return false;
- else if (!useless_type_conversion_p (type_d, type_o))
- return false;
else if (get_alias_set (TREE_TYPE (type_d)) !=
get_alias_set (TREE_TYPE (type_o)))
return false;
--- 129,134 ----
*************** merge_alias_info (tree orig_name, tree n
*** 217,247 ****
return;
}
! gcc_assert (POINTER_TYPE_P (TREE_TYPE (orig_name)));
! gcc_assert (POINTER_TYPE_P (TREE_TYPE (new_name)));
#if defined ENABLE_CHECKING
gcc_assert (useless_type_conversion_p (TREE_TYPE (orig_name),
TREE_TYPE (new_name)));
- /* If the pointed-to alias sets are different, these two pointers
- would never have the same memory tag. In this case, NEW should
- not have been propagated into ORIG. */
- gcc_assert (get_alias_set (TREE_TYPE (TREE_TYPE (new_sym)))
- == get_alias_set (TREE_TYPE (TREE_TYPE (orig_sym))));
- #endif
-
- /* Synchronize the symbol tags. If both pointers had a tag and they
- are different, then something has gone wrong. Symbol tags can
- always be merged because they are flow insensitive, all the SSA
- names of the same base DECL share the same symbol tag. */
- if (new_ann->symbol_mem_tag == NULL_TREE)
- new_ann->symbol_mem_tag = orig_ann->symbol_mem_tag;
- else if (orig_ann->symbol_mem_tag == NULL_TREE)
- orig_ann->symbol_mem_tag = new_ann->symbol_mem_tag;
- else
- gcc_assert (new_ann->symbol_mem_tag == orig_ann->symbol_mem_tag);
-
/* Check that flow-sensitive information is compatible. Notice that
we may not merge flow-sensitive information here. This function
is called when propagating equivalences dictated by the IL, like
--- 215,227 ----
return;
}
! gcc_assert (POINTER_TYPE_P (TREE_TYPE (orig_name))
! && POINTER_TYPE_P (TREE_TYPE (new_name)));
#if defined ENABLE_CHECKING
gcc_assert (useless_type_conversion_p (TREE_TYPE (orig_name),
TREE_TYPE (new_name)));
/* Check that flow-sensitive information is compatible. Notice that
we may not merge flow-sensitive information here. This function
is called when propagating equivalences dictated by the IL, like
*************** merge_alias_info (tree orig_name, tree n
*** 257,263 ****
Since we cannot distinguish one case from another in this
function, we can only make sure that if P_i and Q_j have
! flow-sensitive information, they should be compatible. */
if (SSA_NAME_PTR_INFO (orig_name) && SSA_NAME_PTR_INFO (new_name))
{
struct ptr_info_def *orig_ptr_info = SSA_NAME_PTR_INFO (orig_name);
--- 237,247 ----
Since we cannot distinguish one case from another in this
function, we can only make sure that if P_i and Q_j have
! flow-sensitive information, they should be compatible.
!
! As callers of merge_alias_info are supposed to call may_propagate_copy
! first, the following check is redundant. Thus, only do it if checking
! is enabled. */
if (SSA_NAME_PTR_INFO (orig_name) && SSA_NAME_PTR_INFO (new_name))
{
struct ptr_info_def *orig_ptr_info = SSA_NAME_PTR_INFO (orig_name);
*************** merge_alias_info (tree orig_name, tree n
*** 278,284 ****
gcc_assert (bitmap_intersect_p (new_ptr_info->pt_vars,
orig_ptr_info->pt_vars));
}
! }
/* Common code for propagate_value and replace_exp.
--- 262,294 ----
gcc_assert (bitmap_intersect_p (new_ptr_info->pt_vars,
orig_ptr_info->pt_vars));
}
! #endif
!
! /* Synchronize the symbol tags. If both pointers had a tag and they
! are different, then something has gone wrong. Symbol tags can
! always be merged because they are flow insensitive, all the SSA
! names of the same base DECL share the same symbol tag. */
! if (new_ann->symbol_mem_tag == NULL_TREE)
! new_ann->symbol_mem_tag = orig_ann->symbol_mem_tag;
! else if (orig_ann->symbol_mem_tag == NULL_TREE)
! orig_ann->symbol_mem_tag = new_ann->symbol_mem_tag;
! else
! gcc_assert (new_ann->symbol_mem_tag == orig_ann->symbol_mem_tag);
!
! /* Copy flow-sensitive alias information in case that NEW_NAME
! didn't get a NMT but was set to pt_anything for optimization
! purposes. In case ORIG_NAME has a NMT we can safely use its
! flow-sensitive alias information as a conservative estimate. */
! if (SSA_NAME_PTR_INFO (orig_name)
! && SSA_NAME_PTR_INFO (orig_name)->name_mem_tag
! && (!SSA_NAME_PTR_INFO (new_name)
! || !SSA_NAME_PTR_INFO (new_name)->name_mem_tag))
! {
! struct ptr_info_def *orig_ptr_info = SSA_NAME_PTR_INFO (orig_name);
! struct ptr_info_def *new_ptr_info = get_ptr_info (new_name);
! memcpy (new_ptr_info, orig_ptr_info, sizeof (struct ptr_info_def));
! }
! }
/* Common code for propagate_value and replace_exp.