[llvm] [GlobalISel] Refactor extractParts() (PR #75223)

[David Green via llvm-commits]

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@@ -335,53 +336,45 @@ void applyExtAddvToUdotAddv(MachineInstr &MI, MachineRegisterInfo &MRI,
     SmallVector<Register, 4> Ext1UnmergeReg;
     SmallVector<Register, 4> Ext2UnmergeReg;
     if (SrcTy.getNumElements() % 16 != 0) {
-      // Unmerge source to v8i8, append a new v8i8 of 0s and the merge to v16s
-      SmallVector<Register, 4> PadUnmergeDstReg1;
-      SmallVector<Register, 4> PadUnmergeDstReg2;
-      unsigned NumOfVec = SrcTy.getNumElements() / 8;
-
-      // Unmerge the source to v8i8
-      MachineInstr *PadUnmerge1 =
-          Builder.buildUnmerge(LLT::fixed_vector(8, 8), Ext1SrcReg);
-      MachineInstr *PadUnmerge2 =
-          Builder.buildUnmerge(LLT::fixed_vector(8, 8), Ext2SrcReg);
-      for (unsigned i = 0; i < NumOfVec; i++) {
-        PadUnmergeDstReg1.push_back(PadUnmerge1->getOperand(i).getReg());
-        PadUnmergeDstReg2.push_back(PadUnmerge2->getOperand(i).getReg());
+      SmallVector<Register, 1> Leftover1;
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davemgreen wrote:

Can use `SmallVector<Register>`

https://github.com/llvm/llvm-project/pull/75223