Fix GC-unsafe corner case in bit-not on ARM

src/arm/code-stubs-arm.cc

Index: src/arm/code-stubs-arm.cc
===================================================================
--- src/arm/code-stubs-arm.cc	(revision 8053)
+++ src/arm/code-stubs-arm.cc	(working copy)
@@ -1926,11 +1926,17 @@
 
     __ bind(&slow_allocate_heapnumber);
     __ EnterInternalFrame();
-    __ push(r1);
-      __ CallRuntime(Runtime::kNumberAlloc, 0);
-    __ pop(r1);
+    __ push(r0);  // Push the heap number, not the untagged int32.

[Lasse Reichstein, 2011/05/25 08:44:49]

Are you sure that AllocateHeapNumber above doesn't clobber r0 if it fails to
allocate? (If so, make a comment to that effect).

+    __ CallRuntime(Runtime::kNumberAlloc, 0);
+    // Get the heap number into r2, now that the new heap number is in r0.
+    __ pop(r2);
     __ LeaveInternalFrame();
 
+    // Convert the heap number in r2 to an untagged integer in r1.
+    // This can't go slow-case because it's the same number we already
+    // converted once again.
+    __ ConvertToInt32(r2, r1, r3, r4, d0, slow);

[Lasse Reichstein, 2011/05/25 08:44:49]

Don't forget to negate the result.
(If this isn't caught by a test, maybe we need one).

+
     __ bind(&heapnumber_allocated);
   }