Debugger: use debug break slot to break on call.

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index e6aaa914bfe308e290f60f79718d3d750d9b005d..eec0398539c85d9c70788f6a85549413b27319f8 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -380,23 +380,24 @@ void RelocInfoWriter::WriteExtraTaggedPC(uint32_t pc_delta, int extra_tag) {
 }
 
 
-void RelocInfoWriter::WriteExtraTaggedIntData(int data_delta, int top_tag) {
-  WriteExtraTag(kDataJumpExtraTag, top_tag);
+void RelocInfoWriter::WriteInt(int number) {
   for (int i = 0; i < kIntSize; i++) {
-    *--pos_ = static_cast<byte>(data_delta);
+    *--pos_ = static_cast<byte>(number);
     // Signed right shift is arithmetic shift.  Tested in test-utils.cc.
-    data_delta = data_delta >> kBitsPerByte;
+    number = number >> kBitsPerByte;
   }
 }
 
 
+void RelocInfoWriter::WriteExtraTaggedIntData(int data_delta, int top_tag) {
+  WriteExtraTag(kDataJumpExtraTag, top_tag);
+  WriteInt(data_delta);
+}
+
+
 void RelocInfoWriter::WriteExtraTaggedPoolData(int data, int pool_type) {
   WriteExtraTag(kPoolExtraTag, pool_type);
-  for (int i = 0; i < kIntSize; i++) {
-    *--pos_ = static_cast<byte>(data);
-    // Signed right shift is arithmetic shift.  Tested in test-utils.cc.
-    data = data >> kBitsPerByte;
-  }
+  WriteInt(data);
 }
 
 
@@ -498,10 +499,10 @@ void RelocInfoWriter::Write(const RelocInfo* rinfo) {
     WriteExtraTaggedData(rinfo->data(), kCommentTag);
     DCHECK(begin_pos - pos_ >= RelocInfo::kMinRelocCommentSize);
   } else if (RelocInfo::IsConstPool(rmode) || RelocInfo::IsVeneerPool(rmode)) {
-      WriteExtraTaggedPC(pc_delta, kPCJumpExtraTag);
-      WriteExtraTaggedPoolData(static_cast<int>(rinfo->data()),
-                               RelocInfo::IsConstPool(rmode) ? kConstPoolTag
-                                                             : kVeneerPoolTag);
+    WriteExtraTaggedPC(pc_delta, kPCJumpExtraTag);
+    WriteExtraTaggedPoolData(
+        static_cast<int>(rinfo->data()),
+        RelocInfo::IsConstPool(rmode) ? kConstPoolTag : kVeneerPoolTag);
   } else {
     DCHECK(rmode > RelocInfo::LAST_COMPACT_ENUM);
     DCHECK(rmode <= RelocInfo::LAST_STANDARD_NONCOMPACT_ENUM);
@@ -513,6 +514,9 @@ void RelocInfoWriter::Write(const RelocInfo* rinfo) {
     // None of these modes need a data component.
     DCHECK(0 <= saved_mode && saved_mode < kPoolExtraTag);
     WriteExtraTaggedPC(pc_delta, saved_mode);
+    if (RelocInfo::IsDebugBreakSlot(rmode)) {

[ulan, 2015/07/07 13:31:31]

Let's make it into a method with descriptive name e.g. WriteDebugBreakData()

[Yang, 2015/07/07 14:39:00]

Done.

+      WriteInt(reinterpret_cast<int>(rinfo->data()));
+    }
   }
   last_pc_ = rinfo->pc();
   last_mode_ = rmode;
@@ -557,7 +561,7 @@ void RelocIterator::AdvanceReadId() {
 }
 
 
-void RelocIterator::AdvanceReadPoolData() {
+void RelocIterator::AdvanceReadInt() {
   int x = 0;
   for (int i = 0; i < kIntSize; i++) {
     x |= static_cast<int>(*--pos_) << i * kBitsPerByte;
@@ -712,14 +716,19 @@ void RelocIterator::next() {
         RelocInfo::Mode rmode = (pool_type == kConstPoolTag) ?
           RelocInfo::CONST_POOL : RelocInfo::VENEER_POOL;
         if (SetMode(rmode)) {
-          AdvanceReadPoolData();
+          AdvanceReadInt();

[ulan, 2015/07/07 13:31:31]

The old name was more discriptive: AdvanceReadPoolData. Can we restore it?

[Yang, 2015/07/07 14:39:00]

Done.

           return;
         }
         Advance(kIntSize);
       } else {
         AdvanceReadPC();
-        int rmode = extra_tag + RelocInfo::LAST_COMPACT_ENUM + 1;
-        if (SetMode(static_cast<RelocInfo::Mode>(rmode))) return;
+        RelocInfo::Mode rmode = static_cast<RelocInfo::Mode>(
+            extra_tag + RelocInfo::LAST_COMPACT_ENUM + 1);
+        if (RelocInfo::IsDebugBreakSlot(rmode)) {

[ulan, 2015/07/07 13:31:31]

Let's extract this into a separate function "AdvanceReadDebugSlotData"

[Yang, 2015/07/07 14:38:59]

Done.

+          if (SetMode(rmode)) return AdvanceReadInt();
+          Advance(kIntSize);
+        }
+        if (SetMode(rmode)) return;
       }
     }
   }
@@ -883,6 +892,12 @@ void RelocInfo::Print(Isolate* isolate, std::ostream& os) {  // NOLINT
     }
   } else if (IsConstPool(rmode_)) {
     os << " (size " << static_cast<int>(data_) << ")";
+  } else if (IsDebugBreakSlot(rmode_)) {
+    if (DebugBreakIsCall()) {
+      os << " (call with " << DebugBreakCallArgumentsCount() << " args)";
+    } else {
+      os << " (slot)";
+    }
   }
 
   os << "\n";
@@ -946,6 +961,18 @@ void RelocInfo::Verify(Isolate* isolate) {
 #endif  // VERIFY_HEAP
 
 
+bool RelocInfo::DebugBreakIsCall() {
+  DCHECK(IsDebugBreakSlot(rmode_));
+  return data_ >= kDebugBreakCallArgsOffset;
+}
+
+
+int RelocInfo::DebugBreakCallArgumentsCount() {
+  DCHECK(DebugBreakIsCall());
+  return data_ - kDebugBreakCallArgsOffset;
+}
+
+
 // -----------------------------------------------------------------------------
 // Implementation of ExternalReference
 
@@ -1869,7 +1896,16 @@ void Assembler::RecordJSReturn() {
 
 void Assembler::RecordDebugBreakSlot() {
   EnsureSpace ensure_space(this);
-  RecordRelocInfo(RelocInfo::DEBUG_BREAK_SLOT);
+  intptr_t data = reinterpret_cast<intptr_t>(RelocInfo::kDebugBreakNonCallArgs);
+  RecordRelocInfo(RelocInfo::DEBUG_BREAK_SLOT, data);
+}
+
+
+void Assembler::RecordDebugBreakSlotForCall(int argc) {
+  EnsureSpace ensure_space(this);
+  intptr_t data =
+      reinterpret_cast<intptr_t>(argc + RelocInfo::kDebugBreakCallArgsOffset);
+  RecordRelocInfo(RelocInfo::DEBUG_BREAK_SLOT, data);
 }