Turn stack walking verification into a flag

runtime/vm/profiler.cc

Index: runtime/vm/profiler.cc
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index a80809cb43754027b476c64ea464ac6b8f7bb65f..0eb106f2d53588e6c93682f9243f285daa4c3dd8 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -33,6 +33,8 @@ DEFINE_FLAG(int, profile_period, 1000,
             "Time between profiler samples in microseconds. Minimum 250.");
 DEFINE_FLAG(int, profile_depth, 8,
             "Maximum number stack frames walked. Minimum 1. Maximum 255.");
+DEFINE_FLAG(bool, profile_verify_stack_walk, false,
+            "Verify instruction addresses while walking the stack.");
 
 bool Profiler::initialized_ = false;
 SampleBuffer* Profiler::sample_buffer_ = NULL;
@@ -889,13 +891,7 @@ class ProfilerSampleStackWalker : public ValueObject {
     ASSERT(sample_ != NULL);
   }
 
-#if defined(DEBUG_STACK_WALK)
-  void set_heap(Heap* heap) {
-    heap_ = heap;
-  }
-#endif
-
-  int walk() {
+  int walk(Heap* heap) {
     const intptr_t kMaxStep = 0x1000;  // 4K.
     const bool kWalkStack = true;  // Walk the stack.
     // Always store the exclusive PC.
@@ -924,9 +920,9 @@ class ProfilerSampleStackWalker : public ValueObject {
     }
     int i = 0;
     for (; i < FLAG_profile_depth; i++) {
-#if defined(DEBUG_STACK_WALK)
-      VerifyCodeAddress(i, reinterpret_cast<uword>(pc));
-#endif
+      if (FLAG_profile_verify_stack_walk) {
+        VerifyCodeAddress(heap, i, reinterpret_cast<uword>(pc));
+      }
       sample_->SetAt(i, reinterpret_cast<uword>(pc));
       if (!ValidFramePointer(fp)) {
         return i + 1;
@@ -948,10 +944,9 @@ class ProfilerSampleStackWalker : public ValueObject {
   }
 
  private:
-#if defined(DEBUG_STACK_WALK)
-  void VerifyCodeAddress(int i, uword pc) {
-    if (heap_ != NULL) {
-      if (heap_->Contains(pc) && !heap_->CodeContains(pc)) {
+  void VerifyCodeAddress(Heap* heap, int i, uword pc) {
+    if (heap != NULL) {
+      if (heap->Contains(pc) && !heap->CodeContains(pc)) {
         for (int j = 0; j < i; j++) {
           OS::Print("%d %" Px "\n", j, sample_->At(j));
         }
@@ -962,7 +957,6 @@ class ProfilerSampleStackWalker : public ValueObject {
       }
     }
   }
-#endif
 
   uword* CallerPC(uword* fp) const {
     ASSERT(fp != NULL);
@@ -984,9 +978,7 @@ class ProfilerSampleStackWalker : public ValueObject {
     return r;
   }
 
-#if defined(DEBUG_STACK_WALK)
-  Heap* heap_;
-#endif
+
   Sample* sample_;
   const uword stack_upper_;
   const uword original_pc_;
@@ -1021,10 +1013,7 @@ void Profiler::RecordSampleInterruptCallback(
   }
   ProfilerSampleStackWalker stackWalker(sample, stack_lower, stack_upper,
                                         state.pc, state.fp, state.sp);
-#if defined(DEBUG_STACK_WALK)
-  stackWalker.set_heap(isolate->heap());
-#endif
-  stackWalker.walk();
+  stackWalker.walk(isolate->heap());
 }