Debugger: use debug break slots to break at function exit.

src/ia32/assembler-ia32-inl.h

Index: src/ia32/assembler-ia32-inl.h
diff --git a/src/ia32/assembler-ia32-inl.h b/src/ia32/assembler-ia32-inl.h
index 26e8c6cb0ff38df8e35281613789addffd5d5556..80b92ec95ebf8dc44df1a201cf6b4fe3961d3d2d 100644
--- a/src/ia32/assembler-ia32-inl.h
+++ b/src/ia32/assembler-ia32-inl.h
@@ -55,34 +55,29 @@ static const int kNoCodeAgeSequenceLength = 5;
 // The modes possibly affected by apply must be in kApplyMask.
 void RelocInfo::apply(intptr_t delta, ICacheFlushMode icache_flush_mode) {
   bool flush_icache = icache_flush_mode != SKIP_ICACHE_FLUSH;
+  int32_t* p;
   if (IsRuntimeEntry(rmode_) || IsCodeTarget(rmode_)) {
-    int32_t* p = reinterpret_cast<int32_t*>(pc_);
+    p = reinterpret_cast<int32_t*>(pc_);
     *p -= delta;  // Relocate entry.
-    if (flush_icache) CpuFeatures::FlushICache(p, sizeof(uint32_t));
   } else if (IsCodeAgeSequence(rmode_)) {
     if (*pc_ == kCallOpcode) {
       int32_t* p = reinterpret_cast<int32_t*>(pc_ + 1);
       *p -= delta;  // Relocate entry.
-    if (flush_icache) CpuFeatures::FlushICache(p, sizeof(uint32_t));
     }
-  } else if (IsJSReturn(rmode_) && IsPatchedReturnSequence()) {
-    // Special handling of js_return when a break point is set (call
-    // instruction has been inserted).
-    int32_t* p = reinterpret_cast<int32_t*>(pc_ + 1);
-    *p -= delta;  // Relocate entry.
-    if (flush_icache) CpuFeatures::FlushICache(p, sizeof(uint32_t));
   } else if (IsDebugBreakSlot(rmode_) && IsPatchedDebugBreakSlotSequence()) {
     // Special handling of a debug break slot when a break point is set (call
     // instruction has been inserted).
-    int32_t* p = reinterpret_cast<int32_t*>(pc_ + 1);
+    p = reinterpret_cast<int32_t*>(
+        pc_ + Assembler::kPatchDebugBreakSlotAddressOffset);
     *p -= delta;  // Relocate entry.
-    if (flush_icache) CpuFeatures::FlushICache(p, sizeof(uint32_t));
   } else if (IsInternalReference(rmode_)) {
     // absolute code pointer inside code object moves with the code object.
-    int32_t* p = reinterpret_cast<int32_t*>(pc_);
+    p = reinterpret_cast<int32_t*>(pc_);
     *p += delta;  // Relocate entry.
-    if (flush_icache) CpuFeatures::FlushICache(p, sizeof(uint32_t));
+  } else {
+    return;

[ulan, 2015/07/14 09:12:45]

I think it is cleaner to just set flush_icache to false.

[Yang, 2015/07/14 12:00:57]

apply is only ever called with SKIP_ICACHE_FLUSH. So I'm going to remove this
parameter and make this simpler. I added a comment to the function declaration.

Also icache_flush_mode is not even honored on ARM and ARM64.

   }
+  if (flush_icache) CpuFeatures::FlushICache(p, sizeof(uint32_t));
 }
 
 
@@ -244,17 +239,17 @@ void RelocInfo::set_code_age_stub(Code* stub,
 }
 
 
-Address RelocInfo::call_address() {
-  DCHECK((IsJSReturn(rmode()) && IsPatchedReturnSequence()) ||
-         (IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence()));
-  return Assembler::target_address_at(pc_ + 1, host_);
+Address RelocInfo::debug_call_address() {
+  DCHECK(IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence());
+  Address location = pc_ + Assembler::kPatchDebugBreakSlotAddressOffset;
+  return Assembler::target_address_at(location, host_);
 }
 
 
-void RelocInfo::set_call_address(Address target) {
-  DCHECK((IsJSReturn(rmode()) && IsPatchedReturnSequence()) ||
-         (IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence()));
-  Assembler::set_target_address_at(pc_ + 1, host_, target);
+void RelocInfo::set_debug_call_address(Address target) {
+  DCHECK(IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence());
+  Address location = pc_ + Assembler::kPatchDebugBreakSlotAddressOffset;
+  Assembler::set_target_address_at(location, host_, target);
   if (host() != NULL) {
     Object* target_code = Code::GetCodeFromTargetAddress(target);
     host()->GetHeap()->incremental_marking()->RecordWriteIntoCode(
@@ -263,23 +258,6 @@ void RelocInfo::set_call_address(Address target) {
 }
 
 
-Object* RelocInfo::call_object() {
-  return *call_object_address();
-}
-
-
-void RelocInfo::set_call_object(Object* target) {
-  *call_object_address() = target;
-}
-
-
-Object** RelocInfo::call_object_address() {
-  DCHECK((IsJSReturn(rmode()) && IsPatchedReturnSequence()) ||
-         (IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence()));
-  return reinterpret_cast<Object**>(pc_ + 1);
-}
-
-
 void RelocInfo::WipeOut() {
   if (IsEmbeddedObject(rmode_) || IsExternalReference(rmode_) ||
       IsInternalReference(rmode_)) {
@@ -318,10 +296,8 @@ void RelocInfo::Visit(Isolate* isolate, ObjectVisitor* visitor) {
     visitor->VisitInternalReference(this);
   } else if (RelocInfo::IsCodeAgeSequence(mode)) {
     visitor->VisitCodeAgeSequence(this);
-  } else if (((RelocInfo::IsJSReturn(mode) &&
-              IsPatchedReturnSequence()) ||
-             (RelocInfo::IsDebugBreakSlot(mode) &&
-              IsPatchedDebugBreakSlotSequence())) &&
+  } else if (RelocInfo::IsDebugBreakSlot(mode) &&
+             IsPatchedDebugBreakSlotSequence() &&
              isolate->debug()->has_break_points()) {
     visitor->VisitDebugTarget(this);
   } else if (IsRuntimeEntry(mode)) {
@@ -347,10 +323,8 @@ void RelocInfo::Visit(Heap* heap) {
   } else if (RelocInfo::IsCodeAgeSequence(mode)) {
     StaticVisitor::VisitCodeAgeSequence(heap, this);
   } else if (heap->isolate()->debug()->has_break_points() &&
-             ((RelocInfo::IsJSReturn(mode) &&
-              IsPatchedReturnSequence()) ||
-             (RelocInfo::IsDebugBreakSlot(mode) &&
-              IsPatchedDebugBreakSlotSequence()))) {
+             RelocInfo::IsDebugBreakSlot(mode) &&
+             IsPatchedDebugBreakSlotSequence()) {
     StaticVisitor::VisitDebugTarget(heap, this);
   } else if (IsRuntimeEntry(mode)) {
     StaticVisitor::VisitRuntimeEntry(this);
@@ -502,11 +476,6 @@ Address Assembler::target_address_from_return_address(Address pc) {
 }
 
 
-Address Assembler::break_address_from_return_address(Address pc) {
-  return pc - Assembler::kPatchDebugBreakSlotReturnOffset;
-}
-
-
 Displacement Assembler::disp_at(Label* L) {
   return Displacement(long_at(L->pos()));
 }