[PATCH] tree-optimization/97151 - improve PTA for C++ operator delete

[Richard Biener]

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.

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))
-- 
2.26.2