GlobalISel: Reimplement moreElementsVectorDst
Use pad with undef and unmerge with unused results. This is annoyingly
similar to several other places in LegalizerHelper, but they're all
slightly different.
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 920c9e0..c11f91b 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -1317,10 +1317,8 @@
void LegalizerHelper::moreElementsVectorDst(MachineInstr &MI, LLT WideTy,
unsigned OpIdx) {
MachineOperand &MO = MI.getOperand(OpIdx);
- Register DstExt = MRI.createGenericVirtualRegister(WideTy);
MIRBuilder.setInsertPt(MIRBuilder.getMBB(), ++MIRBuilder.getInsertPt());
- MIRBuilder.buildExtract(MO, DstExt, 0);
- MO.setReg(DstExt);
+ MO.setReg(widenWithUnmerge(WideTy, MO.getReg()));
}
void LegalizerHelper::moreElementsVectorSrc(MachineInstr &MI, LLT MoreTy,
@@ -1488,6 +1486,40 @@
return Legalized;
}
+Register LegalizerHelper::widenWithUnmerge(LLT WideTy, Register OrigReg) {
+ Register WideReg = MRI.createGenericVirtualRegister(WideTy);
+ LLT OrigTy = MRI.getType(OrigReg);
+ LLT LCMTy = getLCMType(WideTy, OrigTy);
+
+ const int NumMergeParts = LCMTy.getSizeInBits() / WideTy.getSizeInBits();
+ const int NumUnmergeParts = LCMTy.getSizeInBits() / OrigTy.getSizeInBits();
+
+ Register UnmergeSrc = WideReg;
+
+ // Create a merge to the LCM type, padding with undef
+ // %0:_(<3 x s32>) = G_FOO => <4 x s32>
+ // =>
+ // %1:_(<4 x s32>) = G_FOO
+ // %2:_(<4 x s32>) = G_IMPLICIT_DEF
+ // %3:_(<12 x s32>) = G_CONCAT_VECTORS %1, %2, %2
+ // %0:_(<3 x s32>), %4:_, %5:_, %6:_ = G_UNMERGE_VALUES %3
+ if (NumMergeParts > 1) {
+ Register Undef = MIRBuilder.buildUndef(WideTy).getReg(0);
+ SmallVector<Register, 8> MergeParts(NumMergeParts, Undef);
+ MergeParts[0] = WideReg;
+ UnmergeSrc = MIRBuilder.buildMerge(LCMTy, MergeParts).getReg(0);
+ }
+
+ // Unmerge to the original register and pad with dead defs.
+ SmallVector<Register, 8> UnmergeResults(NumUnmergeParts);
+ UnmergeResults[0] = OrigReg;
+ for (int I = 1; I != NumUnmergeParts; ++I)
+ UnmergeResults[I] = MRI.createGenericVirtualRegister(OrigTy);
+
+ MIRBuilder.buildUnmerge(UnmergeResults, UnmergeSrc);
+ return WideReg;
+}
+
LegalizerHelper::LegalizeResult
LegalizerHelper::widenScalarUnmergeValues(MachineInstr &MI, unsigned TypeIdx,
LLT WideTy) {
