Minor tweak to avoid an extra reg-reg copy that the register allocator has to eliminate
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12680 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/InstSelectSimple.cpp b/lib/Target/X86/InstSelectSimple.cpp
index 25f67ec..6144b62 100644
--- a/lib/Target/X86/InstSelectSimple.cpp
+++ b/lib/Target/X86/InstSelectSimple.cpp
@@ -1109,12 +1109,21 @@
Value *Val = VR.Val;
const Type *Ty = VR.Ty;
- if (Val)
+ if (Val) {
if (Constant *C = dyn_cast<Constant>(Val)) {
Val = ConstantExpr::getCast(C, Type::IntTy);
Ty = Type::IntTy;
}
+ // If this is a simple constant, just emit a MOVri directly to avoid the
+ // copy.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
+ int TheVal = CI->getRawValue() & 0xFFFFFFFF;
+ BuildMI(BB, X86::MOV32ri, 1, targetReg).addImm(TheVal);
+ return;
+ }
+ }
+
// Make sure we have the register number for this value...
unsigned Reg = Val ? getReg(Val) : VR.Reg;