[llvm] [AArch64] Refactor creation of a shuffle mask for TBL (NFC) (PR #92529)

[Momchil Velikov via llvm-commits]

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@@ -15916,21 +15919,30 @@ bool AArch64TargetLowering::optimizeExtendOrTruncateConversion(
 
       DstTy = TruncDstType;
     }
-
-    return createTblShuffleForZExt(ZExt, DstTy, Subtarget->isLittleEndian());
+    IRBuilder<> Builder(ZExt);
+    Value *Result = createTblShuffleForZExt(
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momchil-velikov wrote:

I pulled the erasing out of `createTblShuffleForZExt` to avoid the situation down below in the `UIToFPInst` case where a `zext` is created and immediately deleted.

https://github.com/llvm/llvm-project/pull/92529