[llvm] [InstCombine] Handle scalable geps in EmitGEPOffset (PR #71565)

[David Green via llvm-commits]

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@@ -70,10 +71,12 @@ Value *llvm::emitGEPOffset(IRBuilderBase *Builder, const DataLayout &DL,
     // Convert to correct type.
     if (Op->getType() != IntIdxTy)
       Op = Builder->CreateIntCast(Op, IntIdxTy, true, Op->getName() + ".c");
-    if (Size != 1) {
+    if (Size != 1 || TSize.isScalable()) {
       // We'll let instcombine(mul) convert this to a shl if possible.
-      Op = Builder->CreateMul(Op, ConstantInt::get(IntIdxTy, Size),
-                              GEP->getName() + ".idx", false /*NUW*/,
+      auto *ScaleC = ConstantInt::get(IntIdxTy, Size);
+      Value *Scale =
+          !TSize.isScalable() ? ScaleC : Builder->CreateVScale(ScaleC);
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davemgreen wrote:

Thanks for the suggestion. It looks like the above CreateVectorSplat wouldn't handle scalable vectors either. That is actually a different form of scalable vector, but I'll try and address that in a separate patch.

https://github.com/llvm/llvm-project/pull/71565