Patch to enhance the source code line information for profiler.

src/ia32/lithium-codegen-ia32.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 332 matching lines @@
 
     if (FLAG_code_comments && instr->HasInterestingComment(this)) {
       Comment(";;; <@%d,#%d> %s",
               current_instruction_,
               instr->hydrogen_value()->id(),
               instr->Mnemonic());
     }
 
     if (!CpuFeatures::IsSupported(SSE2)) FlushX87StackIfNecessary(instr);
 
+    int pos = instr->position();
+    if (pos >= 0) RecordPosition(pos);

[danno, 2013/07/29 12:29:01]

In order to optimize the size of the source pos tables, don't output the pos
again if it's the same as the pos for the last instruction.

+
     instr->CompileToNative(this);

[danno, 2013/07/29 12:29:01]

Not that your solution doesn't handle deferred code correctly, which is all
output at the end of a routine. Please take a look at GenerateDeferredCode.

 
     if (!CpuFeatures::IsSupported(SSE2)) {
       if (FLAG_debug_code && FLAG_enable_slow_asserts) {
         __ VerifyX87StackDepth(x87_stack_depth_);
       }
     }
   }
   EnsureSpaceForLazyDeopt();
   return !is_aborted();
 }
@@ skipping 6120 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32