X87: Refactor BreakLocationIterator

port 1a608493 (r26983)

original commit message:

   Refactor BreakLocationIterator.

   We now have BreakLocation::Iterator to iterate via RelocIterator, and
   create a BreakLocation when we are done iterating. The reloc info is
   stored in BreakLocation in a GC-safe way and instantiated on demand.

BUG=

Review URL: https://codereview.chromium.org/978183002

Cr-Commit-Position: refs/heads/master@{#27003}

src/x87/assembler-x87.cc

@@ -102,6 +102,37 @@ bool RelocInfo::IsInConstantPool() {
 }
 
 
+// Patch the code at the current PC with a call to the target address.
+// Additional guard int3 instructions can be added if required.
+void RelocInfo::PatchCodeWithCall(Address target, int guard_bytes) {
+  // Call instruction takes up 5 bytes and int3 takes up one byte.
+  static const int kCallCodeSize = 5;
+  int code_size = kCallCodeSize + guard_bytes;
+
+  // Create a code patcher.
+  CodePatcher patcher(pc_, code_size);
+
+// Add a label for checking the size of the code used for returning.
+#ifdef DEBUG
+  Label check_codesize;
+  patcher.masm()->bind(&check_codesize);
+#endif
+
+  // Patch the code.
+  patcher.masm()->call(target, RelocInfo::NONE32);
+
+  // Check that the size of the code generated is as expected.
+  DCHECK_EQ(kCallCodeSize,
+            patcher.masm()->SizeOfCodeGeneratedSince(&check_codesize));
+
+  // Add the requested number of int3 instructions after the call.
+  DCHECK_GE(guard_bytes, 0);
+  for (int i = 0; i < guard_bytes; i++) {
+    patcher.masm()->int3();
+  }
+}
+
+
 // -----------------------------------------------------------------------------
 // Implementation of Operand
 

src/x87/debug-x87.cc

@@ -15,7 +15,7 @@ namespace internal {
 
 // Patch the code at the current PC with a call to the target address.
 // Additional guard int3 instructions can be added if required.
-void RelocInfo::PatchCodeWithCall(Address pc, Address target, int guard_bytes) {
+void PatchCodeWithCall(Address pc, Address target, int guard_bytes) {
   // Call instruction takes up 5 bytes and int3 takes up one byte.
   static const int kCallCodeSize = 5;
   int code_size = kCallCodeSize + guard_bytes;
@@ -58,10 +58,10 @@ void BreakLocation::SetDebugBreakAtReturn() {
 }
 
 
-void BreakLocationIterator::SetDebugBreakAtSlot() {
+void BreakLocation::SetDebugBreakAtSlot() {
   DCHECK(IsDebugBreakSlot());
   Isolate* isolate = debug_info_->GetIsolate();
-  rinfo().PatchCodeWithCall(
+  PatchCodeWithCall(
       pc(), isolate->builtins()->Slot_DebugBreak()->entry(),
       Assembler::kDebugBreakSlotLength - Assembler::kCallInstructionLength);
 }