[PING] Re: [PATCH] c++/67913, 67917 - fix new expression with wrong number of elements

[Ramana Radhakrishnan]

> Cookies on ARM are 8-bytes [1], but sizeof ((size_t) n) is only 4-bytes,
> so this check will fail (We'll ask for 500 bytes, the test here will only
> be looking for 496).
> 
> Would it undermine the test for other architectures if I were to swap out
> the != for a >= ? I think that is in line with the "argument large enough
> for the array" that this test is looking for, but would not catch bugs where
> we were allocating more memory than neccessary.
> 
> Otherwise I can spin a patch which skips the test for ARM targets.
> 

I didn't want to skip this for ARM, instead something that takes into account the cookie size - (very gratuitous hack was to just add 4 in a #ifdef __arm__ block). Something like attached, brown paper bag warning ;)
 

* g++.dg/init/new45.C: Adjust for cookie size on arm.

regards
Ramana

> Thanks,
> James
> 
-------------- next part --------------
diff --git a/gcc/testsuite/g++.dg/init/new45.C b/gcc/testsuite/g++.dg/init/new45.C
index 92dac18..31473a3 100644
--- a/gcc/testsuite/g++.dg/init/new45.C
+++ b/gcc/testsuite/g++.dg/init/new45.C
@@ -29,8 +29,16 @@ void* operator new[] (size_t n)
     // Verify that array new is invoked with an argument large enough
     // for the array and a size_t cookie to store the number of elements.
     // (This holds for classes with user-defined types but not POD types).
-    if (n != N * sizeof (UDClass) + sizeof n) abort ();
-    return malloc (n);
+  size_t val = N * sizeof (UDClass) + sizeof n;
+
+    // On ARM EABI the cookie is always 8 bytes as per Section 3.2.2
+    // of http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041d/IHI0041D_cppabi.pdf
+#if defined( __arm__) && defined(__ARM_EABI__)
+  val = val + 4;
+#endif
+
+  if (n != val) abort ();
+  return malloc (n);
 }
 
 inline __attribute__ ((always_inline))
@@ -60,8 +68,16 @@ void* operator new[] (size_t n, UDClass *p)
     // Verify that placement array new overload for a class type with
     // a user-defined ctor and dtor is invoked with an argument large
     // enough for the array and a cookie.
-    if (n != N * sizeof (UDClass) + sizeof n) abort ();
-    return p;
+  size_t val = N * sizeof (UDClass) + sizeof n;
+
+    // On ARM EABI the cookie is always 8 bytes as per Section 3.2.2
+    // of http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041d/IHI0041D_cppabi.pdf
+#if defined( __arm__) && defined(__ARM_EABI__)
+  val = val + 4;
+#endif
+
+  if (n != val) abort ();
+  return p;
 }
 
 // UDClassllocate a sufficiently large buffer to construct arrays into.