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

src/arm64/assembler-arm64-inl.h

Index: src/arm64/assembler-arm64-inl.h
diff --git a/src/arm64/assembler-arm64-inl.h b/src/arm64/assembler-arm64-inl.h
index bbd44c5f106bec92a28db8075c26ecdb1ebcf500..ff5c8af0fdd815f5e5221e86b665cd081a6f4c45 100644
--- a/src/arm64/assembler-arm64-inl.h
+++ b/src/arm64/assembler-arm64-inl.h
@@ -17,7 +17,7 @@ namespace internal {
 bool CpuFeatures::SupportsCrankshaft() { return true; }
 
 
-void RelocInfo::apply(intptr_t delta, ICacheFlushMode icache_flush_mode) {
+void RelocInfo::apply(intptr_t delta) {
   // On arm64 only internal references need extra work.
   DCHECK(RelocInfo::IsInternalReference(rmode_));
 
@@ -611,11 +611,6 @@ Address Assembler::target_address_from_return_address(Address pc) {
 }
 
 
-Address Assembler::break_address_from_return_address(Address pc) {
-  return pc - Assembler::kPatchDebugBreakSlotReturnOffset;
-}
-
-
 Address Assembler::return_address_from_call_start(Address pc) {
   // The call, generated by MacroAssembler::Call, is one of two possible
   // sequences:
@@ -825,18 +820,18 @@ void RelocInfo::set_code_age_stub(Code* stub,
 }
 
 
-Address RelocInfo::call_address() {
-  DCHECK((IsJSReturn(rmode()) && IsPatchedReturnSequence()) ||
-         (IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence()));
+Address RelocInfo::debug_call_address() {
+  DCHECK(IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence());
   // For the above sequences the Relocinfo points to the load literal loading
   // the call address.
+  STATIC_ASSERT(Assembler::kPatchDebugBreakSlotAddressOffset == 0);
   return Assembler::target_address_at(pc_, host_);
 }
 
 
-void RelocInfo::set_call_address(Address target) {
-  DCHECK((IsJSReturn(rmode()) && IsPatchedReturnSequence()) ||
-         (IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence()));
+void RelocInfo::set_debug_call_address(Address target) {
+  DCHECK(IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence());
+  STATIC_ASSERT(Assembler::kPatchDebugBreakSlotAddressOffset == 0);
   Assembler::set_target_address_at(pc_, host_, target);
   if (host() != NULL) {
     Object* target_code = Code::GetCodeFromTargetAddress(target);
@@ -862,7 +857,7 @@ bool RelocInfo::IsPatchedReturnSequence() {
   // The sequence must be:
   //   ldr ip0, [pc, #offset]
   //   blr ip0
-  // See arm64/debug-arm64.cc BreakLocation::SetDebugBreakAtReturn().
+  // See arm64/debug-arm64.cc DebugCodegen::PatchDebugBreakSlot
   Instruction* i1 = reinterpret_cast<Instruction*>(pc_);
   Instruction* i2 = i1->following();
   return i1->IsLdrLiteralX() && (i1->Rt() == kIp0Code) &&
@@ -888,10 +883,8 @@ void RelocInfo::Visit(Isolate* isolate, ObjectVisitor* visitor) {
     visitor->VisitExternalReference(this);
   } else if (mode == RelocInfo::INTERNAL_REFERENCE) {
     visitor->VisitInternalReference(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 (RelocInfo::IsRuntimeEntry(mode)) {
@@ -914,10 +907,8 @@ void RelocInfo::Visit(Heap* heap) {
   } else if (mode == RelocInfo::INTERNAL_REFERENCE) {
     StaticVisitor::VisitInternalReference(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 (RelocInfo::IsRuntimeEntry(mode)) {
     StaticVisitor::VisitRuntimeEntry(this);