[llvm] [RISCV] Allow folding vmerge into masked ops when mask is the same (PR #97989)

[Craig Topper via llvm-commits]

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@@ -3523,24 +3523,26 @@ bool RISCVDAGToDAGISel::doPeepholeSExtW(SDNode *N) {
   return false;
 }
 
-static bool usesAllOnesMask(SDValue MaskOp, SDValue GlueOp) {
+// After ISel, a vector pseudo's mask will be copied to V0, and the CopyToReg
+// will be glued to the pseudo. This tries to up the value that was copied to
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topperc wrote:

"up the value"? I'm not sure what that means

https://github.com/llvm/llvm-project/pull/97989