From 5cb7e512ecdda74351bb010985f7e8f099467a14 Mon Sep 17 00:00:00 2001
From: "weiliang.lin@intel.com"
 <weiliang.lin@intel.com@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Mon, 2 Jun 2014 13:50:59 +0000
Subject: [PATCH] X87: Simplify known successor block lowering.

Port r21589 (a9f3228)

BUG=
R=danno@chromium.org

Review URL: https://codereview.chromium.org/309043002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21611 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/x87/lithium-x87.cc | 23 ++++++++---------------
 src/x87/lithium-x87.h  |  2 --
 2 files changed, 8 insertions(+), 17 deletions(-)

diff --git a/src/x87/lithium-x87.cc b/src/x87/lithium-x87.cc
index 1a862fd88d..89bca54484 100644
--- a/src/x87/lithium-x87.cc
+++ b/src/x87/lithium-x87.cc
@@ -868,7 +868,14 @@ void LChunkBuilder::VisitInstruction(HInstruction* current) {
       chunk_->AddInstruction(dummy, current_block_);
     }
   } else {
-    instr = current->CompileToLithium(this);
+    HBasicBlock* successor;
+    if (current->IsControlInstruction() &&
+        HControlInstruction::cast(current)->KnownSuccessorBlock(&successor) &&
+        successor != NULL) {
+      instr = new(zone()) LGoto(successor);
+    } else {
+      instr = current->CompileToLithium(this);
+    }
   }
 
   argument_count_ += current->argument_delta();
@@ -963,9 +970,6 @@ LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
 
 
 LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
-  LInstruction* goto_instr = CheckElideControlInstruction(instr);
-  if (goto_instr != NULL) return goto_instr;
-
   HValue* value = instr->value();
   Representation r = value->representation();
   HType type = value->type();
@@ -991,9 +995,6 @@ LInstruction* LChunkBuilder::DoDebugBreak(HDebugBreak* instr) {
 
 
 LInstruction* LChunkBuilder::DoCompareMap(HCompareMap* instr) {
-  LInstruction* goto_instr = CheckElideControlInstruction(instr);
-  if (goto_instr != NULL) return goto_instr;
-
   ASSERT(instr->value()->representation().IsTagged());
   LOperand* value = UseRegisterAtStart(instr->value());
   return new(zone()) LCmpMapAndBranch(value);
@@ -1630,8 +1631,6 @@ LInstruction* LChunkBuilder::DoCompareGeneric(HCompareGeneric* instr) {
 
 LInstruction* LChunkBuilder::DoCompareNumericAndBranch(
     HCompareNumericAndBranch* instr) {
-  LInstruction* goto_instr = CheckElideControlInstruction(instr);
-  if (goto_instr != NULL) return goto_instr;
   Representation r = instr->representation();
   if (r.IsSmiOrInteger32()) {
     ASSERT(instr->left()->representation().Equals(r));
@@ -1662,8 +1661,6 @@ LInstruction* LChunkBuilder::DoCompareNumericAndBranch(
 
 LInstruction* LChunkBuilder::DoCompareObjectEqAndBranch(
     HCompareObjectEqAndBranch* instr) {
-  LInstruction* goto_instr = CheckElideControlInstruction(instr);
-  if (goto_instr != NULL) return goto_instr;
   LOperand* left = UseRegisterAtStart(instr->left());
   LOperand* right = UseOrConstantAtStart(instr->right());
   return new(zone()) LCmpObjectEqAndBranch(left, right);
@@ -1679,8 +1676,6 @@ LInstruction* LChunkBuilder::DoCompareHoleAndBranch(
 
 LInstruction* LChunkBuilder::DoCompareMinusZeroAndBranch(
     HCompareMinusZeroAndBranch* instr) {
-  LInstruction* goto_instr = CheckElideControlInstruction(instr);
-  if (goto_instr != NULL) return goto_instr;
   LOperand* value = UseRegister(instr->value());
   LOperand* scratch = TempRegister();
   return new(zone()) LCompareMinusZeroAndBranch(value, scratch);
@@ -2545,8 +2540,6 @@ LInstruction* LChunkBuilder::DoTypeof(HTypeof* instr) {
 
 
 LInstruction* LChunkBuilder::DoTypeofIsAndBranch(HTypeofIsAndBranch* instr) {
-  LInstruction* goto_instr = CheckElideControlInstruction(instr);
-  if (goto_instr != NULL) return goto_instr;
   return new(zone()) LTypeofIsAndBranch(UseTempRegister(instr->value()));
 }
 
diff --git a/src/x87/lithium-x87.h b/src/x87/lithium-x87.h
index 5c7b5899ce..a95039533f 100644
--- a/src/x87/lithium-x87.h
+++ b/src/x87/lithium-x87.h
@@ -2704,8 +2704,6 @@ class LChunkBuilder V8_FINAL : public LChunkBuilderBase {
   // Build the sequence for the graph.
   LPlatformChunk* Build();
 
-  LInstruction* CheckElideControlInstruction(HControlInstruction* instr);
-
   // Declare methods that deal with the individual node types.
 #define DECLARE_DO(type) LInstruction* Do##type(H##type* node);
   HYDROGEN_CONCRETE_INSTRUCTION_LIST(DECLARE_DO)