[turbofan] Clean up and factor out branch generation logic.

src/compiler/ia32/code-generator-ia32.cc

Index: src/compiler/ia32/code-generator-ia32.cc
diff --git a/src/compiler/ia32/code-generator-ia32.cc b/src/compiler/ia32/code-generator-ia32.cc
index e226aafb908b5f9f32166e794afffa524267db1a..8c619f826c53900e625f80b156e9a46d56835658 100644
--- a/src/compiler/ia32/code-generator-ia32.cc
+++ b/src/compiler/ia32/code-generator-ia32.cc
@@ -195,7 +195,7 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       break;
     }
     case kArchJmp:
-      __ jmp(GetLabel(i.InputRpo(0)));
+      AssembleArchJump(i.InputRpo(0));
       break;
     case kArchNop:
       // don't emit code for nops.
@@ -485,23 +485,14 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
 }
 
 
-// Assembles branches after an instruction.
-void CodeGenerator::AssembleArchBranch(Instruction* instr,
-                                       FlagsCondition condition) {
+// Assembles a branch after an instruction.
+void CodeGenerator::AssembleArchBranch(Instruction* instr, BranchInfo* branch) {
   IA32OperandConverter i(this, instr);
-  Label done;
-
-  // Emit a branch. The true and false targets are always the last two inputs
-  // to the instruction.
-  BasicBlock::RpoNumber tblock =
-      i.InputRpo(static_cast<int>(instr->InputCount()) - 2);
-  BasicBlock::RpoNumber fblock =
-      i.InputRpo(static_cast<int>(instr->InputCount()) - 1);
-  bool fallthru = IsNextInAssemblyOrder(fblock);
-  Label* tlabel = GetLabel(tblock);
-  Label* flabel = fallthru ? &done : GetLabel(fblock);
-  Label::Distance flabel_distance = fallthru ? Label::kNear : Label::kFar;
-  switch (condition) {
+  Label::Distance flabel_distance =
+      branch->fallthru ? Label::kNear : Label::kFar;
+  Label* tlabel = branch->true_label;
+  Label* flabel = branch->false_label;
+  switch (branch->condition) {
     case kUnorderedEqual:
       __ j(parity_even, flabel, flabel_distance);
     // Fall through.
@@ -557,8 +548,13 @@ void CodeGenerator::AssembleArchBranch(Instruction* instr,
       __ j(no_overflow, tlabel);
       break;
   }
-  if (!fallthru) __ jmp(flabel, flabel_distance);  // no fallthru to flabel.
-  __ bind(&done);
+  // Add a jump if not falling through to the next block.
+  if (!branch->fallthru) __ jmp(flabel);
+}
+
+
+void CodeGenerator::AssembleArchJump(BasicBlock::RpoNumber target) {
+  if (!IsNextInAssemblyOrder(target)) __ jmp(GetLabel(target));
 }