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backport: re PR tree-optimization/82060 (ICE in refs_may_alias_p_1 with devirtualization enabled)

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2017-12-15  Richard Biener  <rguenther@suse.de>

	Backport from mainline
	PR tree-optimization/82060
	* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
	Move devirtualization after stmt folding and before EH/AB/noreturn
	cleanup to get the stmt refs canonicalized.  Use a bool instead
	of gimple_modified_p since that doesn't work for NOPs.  Schedule
	NOPs generated by folding for removal.

	* g++.dg/torture/pr82060.C: New testcase.

From-SVN: r255682
This commit is contained in:
Richard Biener 2017-12-15 10:12:08 +00:00 committed by Richard Biener
parent c49c3117e3
commit 2c44df49aa
4 changed files with 102 additions and 46 deletions
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10
gcc/ChangeLog
View File

@ -1,3 +1,13 @@
2017-12-15 Richard Biener <rguenther@suse.de>
Backport from mainline
PR tree-optimization/82060
* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
Move devirtualization after stmt folding and before EH/AB/noreturn
cleanup to get the stmt refs canonicalized. Use a bool instead
of gimple_modified_p since that doesn't work for NOPs. Schedule
NOPs generated by folding for removal.
2017-12-15 Richard Biener <rguenther@suse.de>
Backport from mainline

6
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,9 @@
2017-12-15 Richard Biener <rguenther@suse.de>
Backport from mainline
PR tree-optimization/82060
* g++.dg/torture/pr82060.C: New testcase.
2017-12-15 Sudakshina Das <sudi.das@arm.com>
* gcc.target/arm/armv8_2-fp16-move-2.c: Remove dg-add-options.

32
gcc/testsuite/g++.dg/torture/pr82060.C Normal file
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@ -0,0 +1,32 @@
// { dg-do compile }
struct A
{
char a[1]; // must be char array
};
struct B
{
A& a() { return ma; } // must be accessed through a getter
A ma;
};
struct C
{
B& b() { return mb; } // must be accessed through a getter
B mb;
};
struct D
{
virtual A getA() = 0; // must be virtual
};
void
foo(D& d) // The D object must not be created locally
// (so that getA implementation is not known at compile time?)
{
C c;
for (;;) // must be in a loop
c.b().a() = d.getA();
}

82
gcc/tree-ssa-pre.c
View File

@ -4566,6 +4566,7 @@ eliminate_dom_walker::before_dom_children (basic_block b)
/* If we didn't replace the whole stmt (or propagate the result
into all uses), replace all uses on this stmt with their
leaders. */
bool modified = false;
use_operand_p use_p;
ssa_op_iter iter;
FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
@ -4587,7 +4588,7 @@ eliminate_dom_walker::before_dom_children (basic_block b)
|| !bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (sprime))))
{
propagate_value (use_p, sprime);
gimple_set_modified (stmt, true);
modified = true;
if (TREE_CODE (sprime) == SSA_NAME
&& !is_gimple_debug (stmt))
gimple_set_plf (SSA_NAME_DEF_STMT (sprime),
@ -4595,8 +4596,34 @@ eliminate_dom_walker::before_dom_children (basic_block b)
}
}
/* Fold the stmt if modified, this canonicalizes MEM_REFs we propagated
into which is a requirement for the IPA devirt machinery. */
gimple *old_stmt = stmt;
if (modified)
{
/* If a formerly non-invariant ADDR_EXPR is turned into an
invariant one it was on a separate stmt. */
if (gimple_assign_single_p (stmt)
&& TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR)
recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
if (is_gimple_call (stmt))
{
/* ??? Only fold calls inplace for now, this may create new
SSA names which in turn will confuse free_scc_vn SSA name
release code. */
fold_stmt_inplace (&gsi);
}
else
{
fold_stmt (&gsi);
stmt = gsi_stmt (gsi);
}
}
/* Visit indirect calls and turn them into direct calls if
possible using the devirtualization machinery. */
possible using the devirtualization machinery. Do this before
checking for required EH/abnormal/noreturn cleanup as devird
may expose more of those. */
if (gcall *call_stmt = dyn_cast <gcall *> (stmt))
{
tree fn = gimple_call_fn (call_stmt);
@ -4605,24 +4632,21 @@ eliminate_dom_walker::before_dom_children (basic_block b)
&& virtual_method_call_p (fn))
{
tree otr_type = obj_type_ref_class (fn);
unsigned HOST_WIDE_INT otr_tok
= tree_to_uhwi (OBJ_TYPE_REF_TOKEN (fn));
tree instance;
ipa_polymorphic_call_context context (current_function_decl, fn, stmt, &instance);
ipa_polymorphic_call_context context (current_function_decl,
fn, stmt, &instance);
context.get_dynamic_type (instance, OBJ_TYPE_REF_OBJECT (fn),
otr_type, stmt);
bool final;
context.get_dynamic_type (instance, OBJ_TYPE_REF_OBJECT (fn), otr_type, stmt);
vec <cgraph_node *> targets
= possible_polymorphic_call_targets (obj_type_ref_class (fn),
tree_to_uhwi
(OBJ_TYPE_REF_TOKEN (fn)),
context,
&final);
otr_tok, context, &final);
if (dump_file)
dump_possible_polymorphic_call_targets (dump_file,
obj_type_ref_class (fn),
tree_to_uhwi
(OBJ_TYPE_REF_TOKEN (fn)),
context);
otr_tok, context);
if (final && targets.length () <= 1 && dbg_cnt (devirt))
{
tree fn;
@ -4632,7 +4656,7 @@ eliminate_dom_walker::before_dom_children (basic_block b)
fn = builtin_decl_implicit (BUILT_IN_UNREACHABLE);
if (dump_enabled_p ())
{
location_t loc = gimple_location_safe (stmt);
location_t loc = gimple_location (stmt);
dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, loc,
"converting indirect call to "
"function %s\n",
@ -4654,38 +4678,22 @@ eliminate_dom_walker::before_dom_children (basic_block b)
}
}
if (gimple_modified_p (stmt))
if (modified)
{
/* If a formerly non-invariant ADDR_EXPR is turned into an
invariant one it was on a separate stmt. */
if (gimple_assign_single_p (stmt)
&& TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR)
recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
gimple *old_stmt = stmt;
if (is_gimple_call (stmt))
{
/* ??? Only fold calls inplace for now, this may create new
SSA names which in turn will confuse free_scc_vn SSA name
release code. */
fold_stmt_inplace (&gsi);
/* When changing a call into a noreturn call, cfg cleanup
is needed to fix up the noreturn call. */
if (!was_noreturn && gimple_call_noreturn_p (stmt))
if (!was_noreturn
&& is_gimple_call (stmt) && gimple_call_noreturn_p (stmt))
el_to_fixup.safe_push (stmt);
}
else
{
fold_stmt (&gsi);
stmt = gsi_stmt (gsi);
/* When changing a condition or switch into one we know what
edge will be executed, schedule a cfg cleanup. */
if ((gimple_code (stmt) == GIMPLE_COND
&& (gimple_cond_true_p (as_a <gcond *> (stmt))
|| gimple_cond_false_p (as_a <gcond *> (stmt))))
|| (gimple_code (stmt) == GIMPLE_SWITCH
&& TREE_CODE (gimple_switch_index (
as_a <gswitch *> (stmt)))
== INTEGER_CST))
&& TREE_CODE (gimple_switch_index
(as_a <gswitch *> (stmt))) == INTEGER_CST))
el_todo |= TODO_cleanup_cfg;
}
/* If we removed EH side-effects from the statement, clean
its EH information. */
if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))