[GlobalISel][KnownBits] Simplify G_CONSTANT handling (#91946)
We called getIConstantVRegVal which again queried MRI to get the VReg
def. We already have the def, so just get the CImm directly. It can't
fail.
diff --git a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
index c8199a4..32d607c 100644
--- a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
@@ -256,10 +256,7 @@
break;
}
case TargetOpcode::G_CONSTANT: {
- auto CstVal = getIConstantVRegVal(R, MRI);
- if (!CstVal)
- break;
- Known = KnownBits::makeConstant(*CstVal);
+ Known = KnownBits::makeConstant(MI.getOperand(1).getCImm()->getValue());
break;
}
case TargetOpcode::G_FRAME_INDEX: {
