[gcc r11-5748] gimple: Return fnspec only for replaceable new/delete operators called from new/delete [PR98130]

[gcc r11-5748] gimple: Return fnspec only for replaceable new/delete operators called from new/delete [PR98130]

[Jakub Jelinek]

https://gcc.gnu.org/g:78c4a9feceaccf487516aa1eff417e0741556e10

commit r11-5748-g78c4a9feceaccf487516aa1eff417e0741556e10
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Dec 4 19:10:56 2020 +0100

    gimple: Return fnspec only for replaceable new/delete operators called from new/delete [PR98130]
    
    As mentioned in the PR, we shouldn't treat non-replaceable operator
    new/delete (e.g. with the placement new) as replaceable ones.
    
    There is some pending discussion that perhaps operator delete called from
    delete if not replaceable should return some other fnspec, but can we handle
    that incrementally, fix this wrong-code and then deal with a missed
    optimization?  I really don't know what exactly should be returned.
    
    2020-12-04  Jakub Jelinek  <jakub@redhat.com>
    
            PR c++/98130
            * gimple.c (gimple_call_fnspec): Only return ".co " for replaceable
            operator delete or ".mC" for replaceable operator new called from
            new/delete.
    
            * g++.dg/opt/pr98130.C: New test.

Diff:
---
 gcc/gimple.c                       |  3 ++-
 gcc/testsuite/g++.dg/opt/pr98130.C | 25 +++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/gcc/gimple.c b/gcc/gimple.c
index e8246b72cc9..bb1345875c2 100644
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -1514,11 +1514,12 @@ gimple_call_fnspec (const gcall *stmt)
      such operator, then we can treat it as free.  */
   if (fndecl
       && DECL_IS_OPERATOR_DELETE_P (fndecl)
+      && DECL_IS_REPLACEABLE_OPERATOR (fndecl)
       && gimple_call_from_new_or_delete (stmt))
     return ".co ";
   /* Similarly operator new can be treated as malloc.  */
   if (fndecl
-      && DECL_IS_OPERATOR_NEW_P (fndecl)
+      && DECL_IS_REPLACEABLE_OPERATOR_NEW_P (fndecl)
       && gimple_call_from_new_or_delete (stmt))
     return "mC";
   return "";
diff --git a/gcc/testsuite/g++.dg/opt/pr98130.C b/gcc/testsuite/g++.dg/opt/pr98130.C
new file mode 100644
index 00000000000..0af55ef0444
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/pr98130.C
@@ -0,0 +1,25 @@
+// PR c++/98130
+// { dg-do run { target c++11 } }
+// { dg-options "-O2" }
+
+#include <new>
+
+typedef int *T;
+
+static unsigned char storage[sizeof (T)] alignas (T);
+static T *p = (T *) storage;
+
+static inline __attribute__((__always_inline__)) void
+foo (T value)
+{
+  new (p) T(value);
+}
+
+int
+main ()
+{
+  int a;
+  foo (&a);
+  if (!*p)
+    __builtin_abort ();
+}