On 9/23/20 2:42 PM, Richard Biener wrote:
On September 23, 2020 7:53:18 PM GMT+02:00, Jason Merrill <ja...@redhat.com>
wrote:
On 9/23/20 4:14 AM, Richard Biener wrote:
C++ operator delete, when DECL_IS_REPLACEABLE_OPERATOR_DELETE_P,
does not cause the deleted object to be escaped. It also has no
other interesting side-effects for PTA so skip it like we do
for BUILT_IN_FREE.
Hmm, this is true of the default implementation, but since the function
is replaceable, we don't know what a user definition might do with the
pointer.
But can the object still be 'used' after delete? Can delete fail / throw?
What guarantee does the predicate give us?
The deallocation function is called as part of a delete expression in
order to release the storage for an object, ending its lifetime (if it
was not ended by a destructor), so no, the object can't be used afterward.
A deallocation function that throws has undefined behavior.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
Richard.
2020-09-23 Richard Biener <rguent...@suse.de>
PR tree-optimization/97151
* tree-ssa-structalias.c (find_func_aliases_for_call):
DECL_IS_REPLACEABLE_OPERATOR_DELETE_P has no effect on
arguments.
* g++.dg/cpp1y/new1.C: Adjust for two more handled transforms.
---
gcc/testsuite/g++.dg/cpp1y/new1.C | 4 ++--
gcc/tree-ssa-structalias.c | 2 ++
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/gcc/testsuite/g++.dg/cpp1y/new1.C
b/gcc/testsuite/g++.dg/cpp1y/new1.C
index aa5f647d535..fec0088cb40 100644
--- a/gcc/testsuite/g++.dg/cpp1y/new1.C
+++ b/gcc/testsuite/g++.dg/cpp1y/new1.C
@@ -69,5 +69,5 @@ test_unused() {
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"} } */
+/* { dg-final { scan-tree-dump-times "Deleting : operator delete" 6
"cddce1"} } */
+/* { dg-final { scan-tree-dump-times "Deleting : _\\d+ = operator
new" 8 "cddce1"} } */
diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index 44fe52e0f65..f676bf91e95 100644
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -4857,6 +4857,8 @@ find_func_aliases_for_call (struct function
*fn, gcall *t)
point for reachable memory of their arguments. */
else if (flags & (ECF_PURE|ECF_LOOPING_CONST_OR_PURE))
handle_pure_call (t, &rhsc);
+ else if (fndecl && DECL_IS_REPLACEABLE_OPERATOR_DELETE_P
(fndecl))
+ ;
else
handle_rhs_call (t, &rhsc);
if (gimple_call_lhs (t))
