[llvm] [LV] Use shl for (VFxUF * vscale) when creating minimum iter check. (PR #153495)

[Florian Hahn via llvm-commits]

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@@ -2298,7 +2304,10 @@ Value *InnerLoopVectorizer::createIterationCountCheck(ElementCount VF,
   // Reuse existing vector loop preheader for TC checks.
   // Note that new preheader block is generated for vector loop.
   BasicBlock *const TCCheckBlock = LoopVectorPreHeader;
-  IRBuilder<> Builder(TCCheckBlock->getTerminator());
+  IRBuilder<InstSimplifyFolder> Builder(
+      TCCheckBlock->getContext(),
+      InstSimplifyFolder(TCCheckBlock->getDataLayout()));
+  Builder.SetInsertPoint(TCCheckBlock->getTerminator());
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fhahn wrote:

note: this helps to remove some redundant `shl x, 0` instructions

https://github.com/llvm/llvm-project/pull/153495