Patch to enhance the source code line information for profiler.

src/arm/lithium-codegen-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 238 matching lines @@
   if (FLAG_trace && info()->IsOptimizing()) {
     __ CallRuntime(Runtime::kTraceEnter, 0);
   }
   return !is_aborted();
 }
 
 
 bool LCodeGen::GenerateBody() {
   ASSERT(is_generating());
   bool emit_instructions = true;
+  int old_position = RelocInfo::kNoPosition;
   for (current_instruction_ = 0;
        !is_aborted() && current_instruction_ < instructions_->length();
        current_instruction_++) {
     LInstruction* instr = instructions_->at(current_instruction_);
 
     // Don't emit code for basic blocks with a replacement.
     if (instr->IsLabel()) {
       emit_instructions = !LLabel::cast(instr)->HasReplacement();
     }
     if (!emit_instructions) continue;
 
     if (FLAG_code_comments && instr->HasInterestingComment(this)) {
       Comment(";;; <@%d,#%d> %s",
               current_instruction_,
               instr->hydrogen_value()->id(),
               instr->Mnemonic());
     }
 
+    int pos = instr->position();
+    if (pos >= 0 && pos != old_position) {
+      RecordPosition(pos);
+      old_position = pos;
+    }
+
     instr->CompileToNative(this);
   }
   EnsureSpaceForLazyDeopt();
   last_lazy_deopt_pc_ = masm()->pc_offset();
   return !is_aborted();
 }
 
 
 bool LCodeGen::GenerateDeferredCode() {
   ASSERT(is_generating());
   if (deferred_.length() > 0) {
     for (int i = 0; !is_aborted() && i < deferred_.length(); i++) {
       LDeferredCode* code = deferred_[i];
+
+      int pos = instructions_->at(code->instruction_index())->position();
+      if (pos >=0) RecordPosition(pos);

[danno, 2013/08/02 10:53:16]

Since code is ouput linearly, I think it makes sense to have a old_position
member on the codegen object and a method RecordAndUpdatePosition(pos) that has
the logic that encapsulates the logic for eliding repeating positions, and call
that thing here and above. Same applies to other platforms.

+
       Comment(";;; <@%d,#%d> "
               "-------------------- Deferred %s --------------------",
               code->instruction_index(),
               code->instr()->hydrogen_value()->id(),
               code->instr()->Mnemonic());
       __ bind(code->entry());
       if (NeedsDeferredFrame()) {
         Comment(";;; Build frame");
         ASSERT(!frame_is_built_);
         ASSERT(info()->IsStub());
@@ skipping 5531 matching lines @@
   __ sub(scratch, result, Operand::PointerOffsetFromSmiKey(index));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal