[llvm] [GlobalISel] Combine G_UNMERGE_VALUES with anyext and build vector (PR #112370)

[Thorsten Schütt via llvm-commits]

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@@ -7611,3 +7611,66 @@ bool CombinerHelper::matchFoldAMinusC1PlusC2(const MachineInstr &MI,
 
   return true;
 }
+
+bool CombinerHelper::matchUnmergeValuesAnyExtBuildVector(const MachineInstr &MI,
+                                                         BuildFnTy &MatchInfo) {
+  const GUnmerge *Unmerge = cast<GUnmerge>(&MI);
+
+  if (!MRI.hasOneNonDBGUse(Unmerge->getSourceReg()))
+    return false;
+
+  const MachineInstr *Source = MRI.getVRegDef(Unmerge->getSourceReg());
+
+  LLT DstTy = MRI.getType(Unmerge->getReg(0));
+
+  // We want to unmerge into vectors.
+  if (!DstTy.isFixedVector())
+    return false;
+
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tschuett wrote:

Is the doc sufficient?

https://github.com/llvm/llvm-project/pull/112370