Simplify known successor block lowering.

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index 9565a08ebae41a4506a2e5a09f1cf100066b5780..5d024faaf46b2b38d5fb87e16d829a8f99fd933f 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -882,7 +882,14 @@ 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();
@@ -968,9 +975,6 @@ 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();
@@ -996,9 +1000,6 @@ 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);
@@ -1644,8 +1645,6 @@ 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));
@@ -1676,8 +1675,6 @@ 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);
@@ -1693,8 +1690,6 @@ 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);
@@ -2568,8 +2563,6 @@ 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()));
 }