[llvm] [IR] Add new CreateVectorInterleave interface and constant fold (PR #150931)

[David Sherwood via llvm-commits]

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@@ -189,6 +189,24 @@ class LLVM_ABI TargetFolder final : public IRBuilderFolder {
     return nullptr;
   }
 
+  Value *FoldVectorInterleave(ArrayRef<Value *> Ops) const override {
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david-arm wrote:

The places where I'd like to see these constant folds happening are where we're using a default version of IRBuilder, which uses ConstantFolder. However, the ConstantFolder.h version of FoldBinaryIntrinsic says the caller should be using TargetFolder or InstSimplifyFolder instead. So I could change FoldBinaryIntrinsic in llvm/Analysis/ConstantFolding.h (used by TargetFolder.h), but then I wouldn't see any improvements in generated code for IRBuilder instances using the default version.

To be honest, I'm not really sure the best way to proceed now. Would it be acceptable to add a variant of FoldIntrinsic to ConstantFolder.h as well, or is the preferred solution to just change all the IRBuilder instances I care about to use the TargetFolder instead?

https://github.com/llvm/llvm-project/pull/150931