GlobalISel: Avoid use of G_INSERT in insertParts
G_INSERT legalization is incomplete and doesn't work very
well. Instead try to use sequences of G_MERGE_VALUES/G_UNMERGE_VALUES
padding with undef values (although this can get pretty large).
For the case of load/store narrowing, this is still performing the
load/stores in irregularly sized pieces. It might be cleaner to split
this down into equal sized pieces, and rely on load/store merging to
optimize it.
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 448e809..f9de820 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -220,29 +220,16 @@
return;
}
- unsigned PartSize = PartTy.getSizeInBits();
- unsigned LeftoverPartSize = LeftoverTy.getSizeInBits();
+ SmallVector<Register> GCDRegs;
+ LLT GCDTy;
+ for (Register PartReg : PartRegs)
+ GCDTy = extractGCDType(GCDRegs, ResultTy, LeftoverTy, PartReg);
- Register CurResultReg = MRI.createGenericVirtualRegister(ResultTy);
- MIRBuilder.buildUndef(CurResultReg);
+ for (Register PartReg : LeftoverRegs)
+ extractGCDType(GCDRegs, ResultTy, LeftoverTy, PartReg);
- unsigned Offset = 0;
- for (Register PartReg : PartRegs) {
- Register NewResultReg = MRI.createGenericVirtualRegister(ResultTy);
- MIRBuilder.buildInsert(NewResultReg, CurResultReg, PartReg, Offset);
- CurResultReg = NewResultReg;
- Offset += PartSize;
- }
-
- for (unsigned I = 0, E = LeftoverRegs.size(); I != E; ++I) {
- // Use the original output register for the final insert to avoid a copy.
- Register NewResultReg = (I + 1 == E) ?
- DstReg : MRI.createGenericVirtualRegister(ResultTy);
-
- MIRBuilder.buildInsert(NewResultReg, CurResultReg, LeftoverRegs[I], Offset);
- CurResultReg = NewResultReg;
- Offset += LeftoverPartSize;
- }
+ LLT ResultLCMTy = buildLCMMergePieces(ResultTy, LeftoverTy, GCDTy, GCDRegs);
+ buildWidenedRemergeToDst(DstReg, ResultLCMTy, GCDRegs);
}
/// Append the result registers of G_UNMERGE_VALUES \p MI to \p Regs.
