From 0a774c9c1870ccbec049f8d34b79da1396e31f74 Mon Sep 17 00:00:00 2001
From: "whesse@chromium.org"
 <whesse@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Fri, 3 Jul 2009 13:30:15 +0000
Subject: [PATCH] X64: Use low bits of registers in emit_sse_operand.  Enable
 --stop-at flag. Review URL: http://codereview.chromium.org/155052

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2356 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/x64/assembler-x64.cc |  4 ++--
 src/x64/assembler-x64.h  | 11 +++++++++++
 src/x64/codegen-x64.cc   |  3 +--
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/x64/assembler-x64.cc b/src/x64/assembler-x64.cc
index 3ca55bc..2ccfd15 100644
--- a/src/x64/assembler-x64.cc
+++ b/src/x64/assembler-x64.cc
@@ -2022,11 +2022,11 @@ void Assembler::emit_sse_operand(XMMRegister reg, const Operand& adr) {
 
 
 void Assembler::emit_sse_operand(XMMRegister dst, XMMRegister src) {
-  emit(0xC0 | (dst.code() << 3) | src.code());
+  emit(0xC0 | (dst.low_bits() << 3) | src.low_bits());
 }
 
 void Assembler::emit_sse_operand(XMMRegister dst, Register src) {
-  emit(0xC0 | (dst.code() << 3) | src.code());
+  emit(0xC0 | (dst.low_bits() << 3) | src.low_bits());
 }
 
 
diff --git a/src/x64/assembler-x64.h b/src/x64/assembler-x64.h
index e25a18b..d99401b 100644
--- a/src/x64/assembler-x64.h
+++ b/src/x64/assembler-x64.h
@@ -160,6 +160,17 @@ struct XMMRegister {
     return code_;
   }
 
+  // Return the high bit of the register code as a 0 or 1.  Used often
+  // when constructing the REX prefix byte.
+  int high_bit() const {
+    return code_ >> 3;
+  }
+  // Return the 3 low bits of the register code.  Used when encoding registers
+  // in modR/M, SIB, and opcode bytes.
+  int low_bits() const {
+    return code_ & 0x7;
+  }
+
   int code_;
 };
 
diff --git a/src/x64/codegen-x64.cc b/src/x64/codegen-x64.cc
index b226375..3748651 100644
--- a/src/x64/codegen-x64.cc
+++ b/src/x64/codegen-x64.cc
@@ -154,8 +154,7 @@ void CodeGenerator::GenCode(FunctionLiteral* function) {
 
 #ifdef DEBUG
   if (strlen(FLAG_stop_at) > 0 &&
-      //    fun->name()->IsEqualTo(CStrVector(FLAG_stop_at))) {
-      false) {
+      function->name()->IsEqualTo(CStrVector(FLAG_stop_at))) {
     frame_->SpillAll();
     __ int3();
   }
-- 
2.7.4