Various improvements related to legalization code.

src/IceTargetLoweringX8632.cpp

Index: src/IceTargetLoweringX8632.cpp
diff --git a/src/IceTargetLoweringX8632.cpp b/src/IceTargetLoweringX8632.cpp
index f1b8c25097a151564c54f72d6190b7846d311cde..48058dd5b48a44124c1c8357c7227e666dde83e5 100644
--- a/src/IceTargetLoweringX8632.cpp
+++ b/src/IceTargetLoweringX8632.cpp
@@ -2576,7 +2576,7 @@ void TargetX8632::lowerUnreachable(const InstUnreachable * /*Inst*/) {
 Variable *TargetX8632::copyToReg(Operand *Src, int32_t RegNum) {
   Type Ty = Src->getType();
   Variable *Reg = makeReg(Ty, RegNum);
-  if (isVectorType(Src->getType())) {
+  if (isVectorType(Ty)) {
     _movp(Reg, Src);
   } else {
     _mov(Reg, Src);
@@ -2647,6 +2647,8 @@ Operand *TargetX8632::legalize(Operand *From, LegalMask Allowed,
         From = Ctx->getConstantZero(From->getType());
       }
     }
+    // There should be no constants of vector type (other than undef).
+    assert(!isVectorType(From->getType()));
     bool NeedsReg = false;
     if (!(Allowed & Legal_Imm))
       // Immediate specifically not allowed
@@ -2670,9 +2672,9 @@ Operand *TargetX8632::legalize(Operand *From, LegalMask Allowed,
     //   Mem is not allowed and Var isn't guaranteed a physical
     //   register, or
     //   RegNum is required and Var->getRegNum() doesn't match.
-    bool WillHaveRegister =
+    bool AlreadyInRegister =

[Jim Stichnoth, 2014/07/14 19:44:17]

To me, WillHaveRegister captures the situation where no specific physical
register has been assigned/precolored, but it has been assigned infinite weight
so it is guaranteed to have a physical register in the future.

AlreadyInRegister only captures the precolored variable situation, IMO.

I would either find a more perfect name :) , or perhaps better yet just add this
clarification to the comment.

[wala, 2014/07/14 20:40:03]

How about MustHaveRegister?

For me, WillHaveRegister suggests the meaning that the variable will be assigned
to a register (and it's not necessarily precolored or infinite weight), which of
course can't be computed at this stage.

         (Var->hasReg() || Var->getWeight() == RegWeight::Inf);
-    if ((!(Allowed & Legal_Mem) && !WillHaveRegister) ||
+    if ((!(Allowed & Legal_Mem) && !AlreadyInRegister) ||
         (RegNum != Variable::NoRegister && RegNum != Var->getRegNum())) {
       Variable *Reg = copyToReg(From, RegNum);
       if (RegNum == Variable::NoRegister) {