Fix legalization of source operand to bsr and bsf.

src/IceTargetLoweringX8632.cpp

Index: src/IceTargetLoweringX8632.cpp
diff --git a/src/IceTargetLoweringX8632.cpp b/src/IceTargetLoweringX8632.cpp
index bfb7274e621b16744303c02d86793b5f3c2d1265..3808ecbb85cabb7ed570f2c82a6d8cabf93d07a6 100644
--- a/src/IceTargetLoweringX8632.cpp
+++ b/src/IceTargetLoweringX8632.cpp
@@ -3014,10 +3014,11 @@ void TargetX8632::lowerCountZeros(bool Cttz, Type Ty, Variable *Dest,
   // bit position conversion, and the speculation is reversed.
   assert(Ty == IceType_i32 || Ty == IceType_i64);
   Variable *T = makeReg(IceType_i32);
+  Operand *FirstValRM = legalize(FirstVal, Legal_Mem | Legal_Reg);
   if (Cttz) {
-    _bsf(T, FirstVal);
+    _bsf(T, FirstValRM);
   } else {
-    _bsr(T, FirstVal);
+    _bsr(T, FirstValRM);
   }
   Variable *T_Dest = makeReg(IceType_i32);
   Constant *ThirtyTwo = Ctx->getConstantInt(IceType_i32, 32);