On 7/25/19 3:30 PM, Martin Liška wrote:
> On 7/25/19 2:18 PM, Marc Glisse wrote:
>> On Thu, 25 Jul 2019, Martin Liška wrote:
>>
>>>> DCE has special code to avoid removing the LHS of malloc when it is
>>>> unused. Is there something different about operator new that makes it not
>>>> need the same handling?
>>
>> If you take gcc.dg/torture/pr51692.c and replace __builtin_calloc (1, sizeof
>> (double)) with new double(), we get an ICE with -O or higher...
>>
>
> I can see, I'm working on that.
>
> Martin
>
There's a patch candidate I've been testing right now.
Ready to be installed after tests?
Thanks,
Martin
>From 4a7d515eda8591277dad01e1cd43a33883f2dcef Mon Sep 17 00:00:00 2001
From: Martin Liska <mli...@suse.cz>
Date: Thu, 25 Jul 2019 17:24:51 +0200
Subject: [PATCH] Fix ICE seen in tree-ssa-dce.c for new/delete pair.
gcc/ChangeLog:
2019-07-25 Martin Liska <mli...@suse.cz>
* tree-ssa-dce.c (eliminate_unnecessary_stmts): Do not
remove LHS of operator new call. It's handled latter.
gcc/testsuite/ChangeLog:
2019-07-25 Martin Liska <mli...@suse.cz>
* g++.dg/cpp1y/new1.C (test_unused): Add new case that causes
ICE.
---
gcc/testsuite/g++.dg/cpp1y/new1.C | 8 ++++++++
gcc/tree-ssa-dce.c | 13 +++++++------
2 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/gcc/testsuite/g++.dg/cpp1y/new1.C b/gcc/testsuite/g++.dg/cpp1y/new1.C
index a95dd4d1ee3..5e4f1bf6b0b 100644
--- a/gcc/testsuite/g++.dg/cpp1y/new1.C
+++ b/gcc/testsuite/g++.dg/cpp1y/new1.C
@@ -61,5 +61,13 @@ new_array_load() {
delete [] x;
}
+void
+test_unused() {
+ volatile double d = 0.0;
+ double *p = new double ();
+ d += 1.0;
+ delete p;
+}
+
/* { dg-final { scan-tree-dump-times "Deleting : operator delete" 5 "cddce1"} } */
/* { dg-final { scan-tree-dump-times "Deleting : _\\d+ = operator new" 7 "cddce1"} } */
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index 90b3f4d7c45..cf507fa0453 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -1341,12 +1341,13 @@ eliminate_unnecessary_stmts (void)
did not mark as necessary, it will confuse the
special logic we apply to malloc/free pair removal. */
&& (!(call = gimple_call_fndecl (stmt))
- || DECL_BUILT_IN_CLASS (call) != BUILT_IN_NORMAL
- || (DECL_FUNCTION_CODE (call) != BUILT_IN_ALIGNED_ALLOC
- && DECL_FUNCTION_CODE (call) != BUILT_IN_MALLOC
- && DECL_FUNCTION_CODE (call) != BUILT_IN_CALLOC
- && !ALLOCA_FUNCTION_CODE_P
- (DECL_FUNCTION_CODE (call)))))
+ || ((DECL_BUILT_IN_CLASS (call) != BUILT_IN_NORMAL
+ || (DECL_FUNCTION_CODE (call) != BUILT_IN_ALIGNED_ALLOC
+ && DECL_FUNCTION_CODE (call) != BUILT_IN_MALLOC
+ && DECL_FUNCTION_CODE (call) != BUILT_IN_CALLOC
+ && !ALLOCA_FUNCTION_CODE_P
+ (DECL_FUNCTION_CODE (call))))
+ && !DECL_IS_REPLACEABLE_OPERATOR_NEW_P (call))))
{
something_changed = true;
if (dump_file && (dump_flags & TDF_DETAILS))
--
2.22.0
