MemorySanitizer support.

runtime/vm/stack_frame.cc

Index: runtime/vm/stack_frame.cc
===================================================================
--- runtime/vm/stack_frame.cc	(revision 42458)
+++ runtime/vm/stack_frame.cc	(working copy)
@@ -4,6 +4,7 @@
 
 #include "vm/stack_frame.h"
 
+#include "platform/memory_sanitizer.h"
 #include "vm/assembler.h"
 #include "vm/deopt_instructions.h"
 #include "vm/isolate.h"
@@ -278,6 +279,14 @@
 }
 
 
+// Tell MemorySanitizer that generated code initializes part of the stack.
+// TODO(koda): Limit to frames that are actually written by generated code.
+static void UnpoisonStack(Isolate* isolate) {

[siva, 2014/12/22 17:01:53]

ASSERT(isolate->stack_limit() != ~static_cast<uword>(0));

[koda, 2014/12/22 23:05:52]

Changed to instead take an explicit 'fp' argument, and unpoison the area around
it.

+  __msan_unpoison(reinterpret_cast<void*>(isolate->stack_limit()),
+                  isolate->GetSpecifiedStackSize());
+}
+
+
 StackFrameIterator::StackFrameIterator(bool validate, Isolate* isolate)
     : validate_(validate),
       entry_(isolate),
@@ -287,6 +296,7 @@
       isolate_(isolate) {
   ASSERT((isolate_ == Isolate::Current()) ||
          OS::AllowStackFrameIteratorFromAnotherThread());
+  UnpoisonStack(isolate);
   SetupLastExitFrameData();  // Setup data for last exit frame.
 }
 
@@ -301,6 +311,7 @@
       isolate_(isolate) {
   ASSERT((isolate_ == Isolate::Current()) ||
          OS::AllowStackFrameIteratorFromAnotherThread());
+  UnpoisonStack(isolate);
   frames_.fp_ = last_fp;
   frames_.sp_ = 0;
   frames_.pc_ = 0;
@@ -317,6 +328,7 @@
       isolate_(isolate) {
   ASSERT((isolate_ == Isolate::Current()) ||
          OS::AllowStackFrameIteratorFromAnotherThread());
+  UnpoisonStack(isolate);
   frames_.fp_ = fp;
   frames_.sp_ = sp;
   frames_.pc_ = pc;