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.

diff --git a/gcc/gimple.c b/gcc/gimple.c
index bed7ff9e71c8fc227a5498739fbf38b4e29835b7..cc7a88e822b1f859512c6da86896d73d5a94bd39 100644 (file)
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -1549,12 +1549,12 @@ 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();
+}