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[PATCH] Allow MEM_REF lhs on gimple_clobber_p stmts (PR c++/34949)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Richard Biener <rguenther at suse dot de>, Jason Merrill <jason at redhat dot com>, Martin Jambor <mjambor at suse dot cz>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 2 Apr 2013 13:05:50 +0200
- Subject: [PATCH] Allow MEM_REF lhs on gimple_clobber_p stmts (PR c++/34949)
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
Jason's http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34949#c12
patch attempts to emit a clobber for *this at the end of the destructor,
so that we can DSE stores into the object when the object is dead, but
so far only VAR_DECLs have been allowed on the lhs of gimple_clobber_p
stmts.
This incremental patch allows there either a VAR_DECL, or MEM_REF.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
(Jason's patch can be just committed as the last thing in the series).
2013-04-02 Jakub Jelinek <jakub@redhat.com>
PR c++/34949
* tree-cfg.c (verify_gimple_assign_single): Allow lhs
of gimple_clobber_p to be MEM_REF.
* gimplify.c (gimplify_modify_expr): Gimplify *to_p of
an assignment from TREE_CLOBBER_P. Allow it to be MEM_REF
after gimplification.
* asan.c (get_mem_ref_of_assignment): Don't instrument
gimple_clobber_p stmts.
* tree-ssa-dse.c (dse_optimize_stmt): Allow DSE of
gimple_clobber_p stmt if they have MEM_REF lhs and
are dead because of another gimple_clobber_p stmt.
* tree-ssa-live.c (clear_unused_block_pointer): Treat
gimple_clobber_p stmts like debug stmts.
(remove_unused_locals): Remove clobbers with MEM_REF lhs
that refer to unused VAR_DECLs or uninitialized values.
* tree-sra.c (sra_ipa_reset_debug_stmts): Also remove
gimple_clobber_p stmts if they refer to removed parameters.
(get_repl_default_def_ssa_name, sra_ipa_modify_expr): Fix up
formatting.
--- gcc/tree-cfg.c.jj 2013-03-21 18:34:11.000000000 +0100
+++ gcc/tree-cfg.c 2013-03-27 13:44:59.475007635 +0100
@@ -3812,9 +3812,9 @@ verify_gimple_assign_single (gimple stmt
}
if (gimple_clobber_p (stmt)
- && !DECL_P (lhs))
+ && !(DECL_P (lhs) || TREE_CODE (lhs) == MEM_REF))
{
- error ("non-decl LHS in clobber statement");
+ error ("non-decl/MEM_REF LHS in clobber statement");
debug_generic_expr (lhs);
return true;
}
--- gcc/gimplify.c.jj 2013-03-21 18:34:11.000000000 +0100
+++ gcc/gimplify.c 2013-03-27 13:38:30.988181267 +0100
@@ -4840,7 +4840,12 @@ gimplify_modify_expr (tree *expr_p, gimp
so handle it here. */
if (TREE_CLOBBER_P (*from_p))
{
- gcc_assert (!want_value && TREE_CODE (*to_p) == VAR_DECL);
+ ret = gimplify_expr (to_p, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
+ if (ret == GS_ERROR)
+ return ret;
+ gcc_assert (!want_value
+ && (TREE_CODE (*to_p) == VAR_DECL
+ || TREE_CODE (*to_p) == MEM_REF));
gimplify_seq_add_stmt (pre_p, gimple_build_assign (*to_p, *from_p));
*expr_p = NULL;
return GS_ALL_DONE;
--- gcc/asan.c.jj 2013-02-28 22:22:03.000000000 +0100
+++ gcc/asan.c 2013-03-27 14:29:54.531785577 +0100
@@ -412,7 +412,8 @@ get_mem_ref_of_assignment (const gimple
{
gcc_assert (gimple_assign_single_p (assignment));
- if (gimple_store_p (assignment))
+ if (gimple_store_p (assignment)
+ && !gimple_clobber_p (assignment))
{
ref->start = gimple_assign_lhs (assignment);
*ref_is_store = true;
--- gcc/tree-ssa-dse.c.jj 2013-01-11 09:02:37.000000000 +0100
+++ gcc/tree-ssa-dse.c 2013-03-27 17:14:27.424466023 +0100
@@ -218,7 +218,10 @@ dse_optimize_stmt (gimple_stmt_iterator
if (is_gimple_call (stmt) && gimple_call_fndecl (stmt))
return;
- if (gimple_has_volatile_ops (stmt))
+ /* Don't return early on *this_2(D) ={v} {CLOBBER}. */
+ if (gimple_has_volatile_ops (stmt)
+ && (!gimple_clobber_p (stmt)
+ || TREE_CODE (gimple_assign_lhs (stmt)) != MEM_REF))
return;
if (is_gimple_assign (stmt))
@@ -228,6 +231,12 @@ dse_optimize_stmt (gimple_stmt_iterator
if (!dse_possible_dead_store_p (stmt, &use_stmt))
return;
+ /* But only remove *this_2(D) ={v} {CLOBBER} if killed by
+ another clobber stmt. */
+ if (gimple_clobber_p (stmt)
+ && !gimple_clobber_p (use_stmt))
+ return;
+
/* If we have precisely one immediate use at this point and the
stores are to the same memory location or there is a chain of
virtual uses from stmt and the stmt which stores to that same
--- gcc/tree-ssa-live.c.jj 2013-03-21 18:34:11.000000000 +0100
+++ gcc/tree-ssa-live.c 2013-03-28 11:10:15.889669796 +0100
@@ -623,8 +623,8 @@ clear_unused_block_pointer_1 (tree *tp,
return NULL_TREE;
}
-/* Set all block pointer in debug stmt to NULL if the block is unused,
- so that they will not be streamed out. */
+/* Set all block pointer in debug or clobber stmt to NULL if the block
+ is unused, so that they will not be streamed out. */
static void
clear_unused_block_pointer (void)
@@ -639,7 +639,7 @@ clear_unused_block_pointer (void)
tree b;
gimple stmt = gsi_stmt (gsi);
- if (!is_gimple_debug (stmt))
+ if (!is_gimple_debug (stmt) && !gimple_clobber_p (stmt))
continue;
b = gimple_block (stmt);
if (b && !TREE_USED (b))
@@ -827,7 +827,26 @@ remove_unused_locals (void)
if (gimple_clobber_p (stmt))
{
tree lhs = gimple_assign_lhs (stmt);
+ bool remove = false;
+ /* Remove clobbers referencing unused vars, or clobbers
+ with MEM_REF lhs referencing unused vars or uninitialized
+ pointers. */
if (TREE_CODE (lhs) == VAR_DECL && !is_used_p (lhs))
+ remove = true;
+ else if (TREE_CODE (lhs) == MEM_REF)
+ {
+ ssa_op_iter iter;
+ tree op;
+ FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE)
+ if (SSA_NAME_VAR (op)
+ && TREE_CODE (SSA_NAME_VAR (op)) == VAR_DECL
+ && !is_used_p (SSA_NAME_VAR (op)))
+ remove = true;
+ else if (SSA_NAME_IS_DEFAULT_DEF (op)
+ && TREE_CODE (SSA_NAME_VAR (op)) != PARM_DECL)
+ remove = true;
+ }
+ if (remove)
{
unlink_stmt_vdef (stmt);
gsi_remove (&gsi, true);
--- gcc/tree-sra.c.jj 2013-03-21 18:34:11.000000000 +0100
+++ gcc/tree-sra.c 2013-04-02 09:44:29.225462112 +0200
@@ -2965,8 +2965,8 @@ sra_modify_constructor_assign (gimple *s
static tree
get_repl_default_def_ssa_name (struct access *racc)
{
- gcc_checking_assert (!racc->grp_to_be_replaced &&
- !racc->grp_to_be_debug_replaced);
+ gcc_checking_assert (!racc->grp_to_be_replaced
+ && !racc->grp_to_be_debug_replaced);
if (!racc->replacement_decl)
racc->replacement_decl = create_access_replacement (racc);
return get_or_create_ssa_default_def (cfun, racc->replacement_decl);
@@ -4462,8 +4462,8 @@ sra_ipa_modify_expr (tree *expr, bool co
{
adj = &adjustments[i];
- if (adj->base == base &&
- (adj->offset == offset || adj->remove_param))
+ if (adj->base == base
+ && (adj->offset == offset || adj->remove_param))
{
cand = adj;
break;
@@ -4676,6 +4676,14 @@ sra_ipa_reset_debug_stmts (ipa_parm_adju
if (name)
FOR_EACH_IMM_USE_STMT (stmt, ui, name)
{
+ if (gimple_clobber_p (stmt))
+ {
+ gimple_stmt_iterator cgsi = gsi_for_stmt (stmt);
+ unlink_stmt_vdef (stmt);
+ gsi_remove (&cgsi, true);
+ release_defs (stmt);
+ continue;
+ }
/* All other users must have been removed by
ipa_sra_modify_function_body. */
gcc_assert (is_gimple_debug (stmt));
Jakub