[llvm] [GlobalIsel] Combine zext of trunc (episode II) (PR #108305)

[Thorsten Schütt via llvm-commits]

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@@ -333,8 +333,10 @@ MachineInstrBuilder CSEMIRBuilder::buildConstant(const DstOp &Res,
 
   // For vectors, CSE the element only for now.
   LLT Ty = Res.getLLTTy(*getMRI());
-  if (Ty.isVector())
+  if (Ty.isFixedVector())
     return buildSplatBuildVector(Res, buildConstant(Ty.getElementType(), Val));
+  if (Ty.isScalableVector())
+    return buildSplatVector(Res, buildConstant(Ty.getElementType(), Val));
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tschuett wrote:

G_BUILD_VECTOR is for fixed-length vectors. G_SPLAT_VECTOR is for scalable vectors. It takes a register and implicitly broadcasts it over the scalable vector.

https://github.com/llvm/llvm-project/pull/108305