middle-end/101480 - overloaded global new/delete

The following fixes the issue of ignoring side-effects on memory
from overloaded global new/delete operators by not marking them
as effectively 'const' apart from other explicitely specified
side-effects.

This will cause

FAIL: g++.dg/warn/Warray-bounds-16.C  -std=gnu++1? (test for excess errors)

because we now no longer statically see the initialization loop
never executes because the call to operator new can now clobber 'a.m'.
This seems to be an issue with the warning code and/or ranger so
I'm leaving this FAIL to be addressed as followup.

2021-10-11  Richard Biener  <rguenther@suse.de>

	PR middle-end/101480
	* gimple.c (gimple_call_fnspec): Do not mark operator new/delete
	as const.

	* g++.dg/torture/pr10148.C: New testcase.

(cherry picked from commit 09a0affdb0598a54835ac4bb0dd6b54122c12916)

diff --git a/gcc/gimple.c b/gcc/gimple.c
index c6f7c2d49002a64b133f6c8d1f9d14e7ab84f60f..61126cf94b3b2eb7999d48333fec80199e2f54e4 100644 (file)
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -1516,12 +1516,12 @@ gimple_call_fnspec (const gcall *stmt)
       && DECL_IS_OPERATOR_DELETE_P (fndecl)
       && DECL_IS_REPLACEABLE_OPERATOR (fndecl)
       && gimple_call_from_new_or_delete (stmt))
-    return ".co ";
+    return ". o ";
   /* Similarly operator new can be treated as malloc.  */
   if (fndecl
       && DECL_IS_REPLACEABLE_OPERATOR_NEW_P (fndecl)
       && gimple_call_from_new_or_delete (stmt))
-    return "mC";
+    return "m ";
   return "";
 }
 

diff --git a/gcc/testsuite/g++.dg/torture/pr10148.C b/gcc/testsuite/g++.dg/torture/pr10148.C
new file mode 100644 (file)
index 0000000..ed278f9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr10148.C
@@ -0,0 +1,52 @@
+/* { dg-do run } */
+
+#include <stdlib.h>
+#include <assert.h>
+
+static bool flag = false;
+
+class C
+{
+  bool prev;
+
+public:
+  C() : prev(flag)
+  {
+    flag = true;
+  }
+
+  ~C() {
+    flag = prev;
+  }
+};
+
+void* operator new(size_t size)
+{
+  assert(flag);
+  return malloc(size);
+}
+
+void operator delete(void *p)
+{
+  free(p);
+}
+
+void g(int* p)
+{
+  delete p;
+}
+
+void f()
+{
+  int* p;
+  {
+    C c;
+    p = new int;
+  }
+  g(p);
+}
+
+int main(int, char**)
+{
+  f();
+}