[RFC][SelectionDAG] Add and use SDNode::getAsZExtVal() helper (#76710)

This follows on from #76708, allowing
`cast<ConstantSDNode>(N)->getZExtValue()` to be replaced with just
`N->getAsZextVal();`
    
Introduced via `git grep -l "cast<ConstantSDNode>\(.*\).*getZExtValue" |
xargs sed -E -i
's/cast<ConstantSDNode>\((.*)\)->getZExtValue/\1->getAsZExtVal/'` and
then using `git clang-format` on the result.

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/Target/AVR/AVRISelLowering.cpp b/llvm/lib/Target/AVR/AVRISelLowering.cpp
index d36bfb188..f91e77ad 100644
--- a/llvm/lib/Target/AVR/AVRISelLowering.cpp
+++ b/llvm/lib/Target/AVR/AVRISelLowering.cpp
@@ -660,7 +660,7 @@ SDValue AVRTargetLowering::getAVRCmp(SDValue LHS, SDValue RHS,
   SDValue Cmp;
 
   if (LHS.getSimpleValueType() == MVT::i16 && isa<ConstantSDNode>(RHS)) {
-    uint64_t Imm = cast<ConstantSDNode>(RHS)->getZExtValue();
+    uint64_t Imm = RHS->getAsZExtVal();
     // Generate a CPI/CPC pair if RHS is a 16-bit constant. Use the zero
     // register for the constant RHS if its lower or higher byte is zero.
     SDValue LHSlo = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, MVT::i8, LHS,
@@ -680,7 +680,7 @@ SDValue AVRTargetLowering::getAVRCmp(SDValue LHS, SDValue RHS,
   } else if (RHS.getSimpleValueType() == MVT::i16 && isa<ConstantSDNode>(LHS)) {
     // Generate a CPI/CPC pair if LHS is a 16-bit constant. Use the zero
     // register for the constant LHS if its lower or higher byte is zero.
-    uint64_t Imm = cast<ConstantSDNode>(LHS)->getZExtValue();
+    uint64_t Imm = LHS->getAsZExtVal();
     SDValue LHSlo = (Imm & 0xff) == 0
                         ? DAG.getRegister(Subtarget.getZeroRegister(), MVT::i8)
                         : DAG.getNode(ISD::EXTRACT_ELEMENT, DL, MVT::i8, LHS,