[GlobalISel](NFC) Refactor construction of LLTs in LegalizerHelper

[cofibrant]

I spotted a number of places where we're duplicating logic provided by the LLT class inline in LegalizerHelper. This PR tidies up these spots.

[llvmbot]

@llvm/pr-subscribers-llvm-globalisel

Author: Nathan Corbyn (cofibrant)

Changes

I spotted a number of places where we're duplicating logic provided by the LLT class inline in LegalizerHelper. This PR tidies up these spots.

---

Full diff: https://github.com/llvm/llvm-project/pull/170664.diff

1 Files Affected:

• (modified) llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp (+19-20)

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 1aa1d465d8da6..b7287db59318f 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -70,9 +70,8 @@ getNarrowTypeBreakDown(LLT OrigTy, LLT NarrowTy, LLT &LeftoverTy) {
     unsigned EltSize = OrigTy.getScalarSizeInBits();
     if (LeftoverSize % EltSize != 0)
       return {-1, -1};
-    LeftoverTy =
-        LLT::scalarOrVector(ElementCount::getFixed(LeftoverSize / EltSize),
-                            OrigTy.getElementType());
+    LeftoverTy = OrigTy.changeElementCount(
+        ElementCount::getFixed(LeftoverSize / EltSize));
   } else {
     LeftoverTy = LLT::scalar(LeftoverSize);
   }
@@ -1560,7 +1559,7 @@ LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
     if (SizeOp0 % NarrowSize != 0) {
       LLT ImplicitTy = NarrowTy;
       if (DstTy.isVector())
-        ImplicitTy = LLT::vector(DstTy.getElementCount(), ImplicitTy);
+        ImplicitTy = DstTy.changeElementType(ImplicitTy);
 
       Register ImplicitReg = MIRBuilder.buildUndef(ImplicitTy).getReg(0);
       MIRBuilder.buildAnyExt(DstReg, ImplicitReg);
@@ -3289,7 +3288,7 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
       Observer.changingInstr(MI);
 
       widenScalarSrc(
-          MI, LLT::vector(VecTy.getElementCount(), WideTy.getSizeInBits()), 1,
+          MI, VecTy.changeElementType(LLT::scalar(WideTy.getSizeInBits())), 1,
           TargetOpcode::G_ANYEXT);
 
       widenScalarDst(MI, WideTy, 0);
@@ -3321,7 +3320,7 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
 
       Register VecReg = MI.getOperand(1).getReg();
       LLT VecTy = MRI.getType(VecReg);
-      LLT WideVecTy = LLT::vector(VecTy.getElementCount(), WideTy);
+      LLT WideVecTy = VecTy.changeElementType(WideTy);
 
       widenScalarSrc(MI, WideVecTy, 1, TargetOpcode::G_ANYEXT);
       widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ANYEXT);
@@ -3522,9 +3521,7 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
     Observer.changingInstr(MI);
     Register VecReg = MI.getOperand(1).getReg();
     LLT VecTy = MRI.getType(VecReg);
-    LLT WideVecTy = VecTy.isVector()
-                        ? LLT::vector(VecTy.getElementCount(), WideTy)
-                        : WideTy;
+    LLT WideVecTy = VecTy.isVector() ? VecTy.changeElementType(WideTy) : WideTy;
     widenScalarSrc(MI, WideVecTy, 1, TargetOpcode::G_FPEXT);
     widenScalarDst(MI, WideTy, 0, TargetOpcode::G_FPTRUNC);
     Observer.changedInstr(MI);
@@ -3658,7 +3655,8 @@ LegalizerHelper::lowerBitcast(MachineInstr &MI) {
         // %3:_(<2 x s8>) = G_BITCAST %2
         // %4:_(<2 x s8>) = G_BITCAST %3
         // %1:_(<4 x s16>) = G_CONCAT_VECTORS %3, %4
-        DstCastTy = LLT::fixed_vector(NumDstElt / NumSrcElt, DstEltTy);
+        DstCastTy = DstEltTy.changeElementCount(
+            ElementCount::getFixed(NumDstElt / NumSrcElt));
         SrcPartTy = SrcEltTy;
       } else if (NumSrcElt > NumDstElt) { // Source element type is smaller.
         //
@@ -3670,7 +3668,8 @@ LegalizerHelper::lowerBitcast(MachineInstr &MI) {
         // %3:_(s16) = G_BITCAST %2
         // %4:_(s16) = G_BITCAST %3
         // %1:_(<2 x s16>) = G_BUILD_VECTOR %3, %4
-        SrcPartTy = LLT::fixed_vector(NumSrcElt / NumDstElt, SrcEltTy);
+        SrcPartTy = SrcEltTy.changeElementCount(
+            ElementCount::getFixed(NumSrcElt / NumDstElt));
         DstCastTy = DstEltTy;
       }
 
@@ -4231,8 +4230,8 @@ LegalizerHelper::LegalizeResult LegalizerHelper::lowerLoad(GAnyLoad &LoadMI) {
     // the size of the load without needing to scalarize it.
     if (Alignment.value() * 8 > MemSizeInBits &&
         isPowerOf2_64(DstTy.getScalarSizeInBits())) {
-      LLT MoreTy = LLT::fixed_vector(NextPowerOf2(DstTy.getNumElements()),
-                                     DstTy.getElementType());
+      LLT MoreTy = DstTy.changeElementCount(
+          ElementCount::getFixed(NextPowerOf2(DstTy.getNumElements())));
       MachineMemOperand *NewMMO = MF.getMachineMemOperand(&MMO, 0, MoreTy);
       auto NewLoad = MIRBuilder.buildLoad(MoreTy, PtrReg, *NewMMO);
       MIRBuilder.buildDeleteTrailingVectorElements(LoadMI.getReg(0),
@@ -5023,8 +5022,7 @@ static void makeDstOps(SmallVectorImpl<DstOp> &DstOps, LLT Ty,
                        unsigned NumElts) {
   LLT LeftoverTy;
   assert(Ty.isVector() && "Expected vector type");
-  LLT EltTy = Ty.getElementType();
-  LLT NarrowTy = (NumElts == 1) ? EltTy : LLT::fixed_vector(NumElts, EltTy);
+  LLT NarrowTy = Ty.changeElementCount(ElementCount::getFixed(NumElts));
   int NumParts, NumLeftover;
   std::tie(NumParts, NumLeftover) =
       getNarrowTypeBreakDown(Ty, NarrowTy, LeftoverTy);
@@ -5705,7 +5703,8 @@ LegalizerHelper::fewerElementsBitcast(MachineInstr &MI, unsigned int TypeIdx,
     auto Unmerge = MIRBuilder.buildUnmerge(SrcNarrowTy, SrcReg);
     getUnmergeResults(SrcVRegs, *Unmerge);
   } else {
-    LLT SrcNarrowTy = LLT::fixed_vector(NewElemCount, SrcTy.getElementType());
+    LLT SrcNarrowTy =
+        SrcTy.changeElementCount(ElementCount::getFixed(NewElemCount));
 
     // Split the Src and Dst Reg into smaller registers
     if (extractGCDType(SrcVRegs, DstTy, SrcNarrowTy, SrcReg) != SrcNarrowTy)
@@ -6837,8 +6836,7 @@ LegalizerHelper::moreElementsVector(MachineInstr &MI, unsigned TypeIdx,
     Observer.changingInstr(MI);
     moreElementsVectorSrc(MI, MoreTy, 2);
     moreElementsVectorSrc(MI, MoreTy, 3);
-    LLT CondTy = LLT::fixed_vector(
-        MoreTy.getNumElements(),
+    LLT CondTy = MoreTy.changeElementType(
         MRI.getType(MI.getOperand(0).getReg()).getElementType());
     moreElementsVectorDst(MI, CondTy, 0);
     Observer.changedInstr(MI);
@@ -6930,7 +6928,8 @@ LegalizerHelper::equalizeVectorShuffleLengths(MachineInstr &MI) {
 
   unsigned PaddedMaskNumElts = alignTo(MaskNumElts, SrcNumElts);
   unsigned NumConcat = PaddedMaskNumElts / SrcNumElts;
-  LLT PaddedTy = LLT::fixed_vector(PaddedMaskNumElts, DestEltTy);
+  LLT PaddedTy =
+      DstTy.changeElementCount(ElementCount::getFixed(PaddedMaskNumElts));
 
   // Create new source vectors by concatenating the initial
   // source vectors with undefined vectors of the same size.
@@ -9896,7 +9895,7 @@ LegalizerHelper::lowerISFPCLASS(MachineInstr &MI) {
 
   LLT IntTy = LLT::scalar(BitSize);
   if (SrcTy.isVector())
-    IntTy = LLT::vector(SrcTy.getElementCount(), IntTy);
+    IntTy = SrcTy.changeElementType(IntTy);
   auto AsInt = MIRBuilder.buildCopy(IntTy, SrcReg);
 
   // Various masks.

[arsenm]

The cases directly using LLT::vector/fixed_vector are slightly different, since this doesn't handle scalar inputs which are presumed impossible. This is a direct replacement for the scalarOrVector cases