From 8069a76100a7c6f1bbbdaf69af2ad8f3f606f668 Mon Sep 17 00:00:00 2001
From: Anthony Pesch <inolen@gmail.com>
Date: Wed, 23 Mar 2016 18:59:14 -0700
Subject: [PATCH] move select condition out of arg0 to optimize register
 allocation when select is true

---
 src/jit/backend/x64/x64_emitter.cc | 16 +++++++++++-----
 src/jit/ir/ir_builder.cc           | 12 ++++--------
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/src/jit/backend/x64/x64_emitter.cc b/src/jit/backend/x64/x64_emitter.cc
index ce55f58f..7e2877b3 100644
--- a/src/jit/backend/x64/x64_emitter.cc
+++ b/src/jit/backend/x64/x64_emitter.cc
@@ -906,13 +906,19 @@ EMITTER(FTRUNC) {
 
 EMITTER(SELECT) {
   const Xbyak::Reg result = e.GetRegister(instr);
-  const Xbyak::Reg cond = e.GetRegister(instr->arg0());
-  const Xbyak::Reg a = e.GetRegister(instr->arg1());
-  const Xbyak::Reg b = e.GetRegister(instr->arg2());
+  const Xbyak::Reg a = e.GetRegister(instr->arg0());
+  const Xbyak::Reg b = e.GetRegister(instr->arg1());
+  const Xbyak::Reg cond = e.GetRegister(instr->arg2());
+
+  // convert result to Reg32e to please xbyak
+  CHECK_GE(result.getBit(), 32);
+  Xbyak::Reg32e result_32e(result.getIdx(), result.getBit());
 
   e.test(cond, cond);
-  e.cmovnz(result.cvt32(), a);
-  e.cmovz(result.cvt32(), b);
+  if (result_32e != a) {
+    e.cmovnz(result_32e, a);
+  }
+  e.cmovz(result_32e, b);
 }
 
 EMITTER(CMP) {
diff --git a/src/jit/ir/ir_builder.cc b/src/jit/ir/ir_builder.cc
index 8014dcb9..9c643391 100644
--- a/src/jit/ir/ir_builder.cc
+++ b/src/jit/ir/ir_builder.cc
@@ -217,16 +217,12 @@ Instr *IRBuilder::FTrunc(Value *v, ValueType dest_type) {
 }
 
 Instr *IRBuilder::Select(Value *cond, Value *t, Value *f) {
-  CHECK_EQ(t->type(), f->type());
-
-  if (cond->type() != VALUE_I8) {
-    cond = CmpNE(cond, AllocConstant(0));
-  }
+  CHECK(IsIntType(cond->type()) && IsIntType(t->type()) && t->type() == f->type());
 
   Instr *instr = AppendInstr(OP_SELECT, t->type());
-  instr->set_arg0(cond);
-  instr->set_arg1(t);
-  instr->set_arg2(f);
+  instr->set_arg0(t);
+  instr->set_arg1(f);
+  instr->set_arg2(cond);
   return instr;
 }