GlobalISel: Implement fewerElementsVector for phi
llvm-svn: 355048
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 8491763..54dd644 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -34,8 +34,10 @@
/// Returns the number of \p NarrowTy elements needed to reconstruct \p OrigTy,
/// with any leftover piece as type \p LeftoverTy
///
-/// Returns -1 if the breakdown is not satisfiable.
-static int getNarrowTypeBreakDown(LLT OrigTy, LLT NarrowTy, LLT &LeftoverTy) {
+/// Returns -1 in the first element of the pair if the breakdown is not
+/// satisfiable.
+static std::pair<int, int>
+getNarrowTypeBreakDown(LLT OrigTy, LLT NarrowTy, LLT &LeftoverTy) {
assert(!LeftoverTy.isValid() && "this is an out argument");
unsigned Size = OrigTy.getSizeInBits();
@@ -45,18 +47,19 @@
assert(Size > NarrowSize);
if (LeftoverSize == 0)
- return NumParts;
+ return {NumParts, 0};
if (NarrowTy.isVector()) {
unsigned EltSize = OrigTy.getScalarSizeInBits();
if (LeftoverSize % EltSize != 0)
- return -1;
+ return {-1, -1};
LeftoverTy = LLT::scalarOrVector(LeftoverSize / EltSize, EltSize);
} else {
LeftoverTy = LLT::scalar(LeftoverSize);
}
- return NumParts;
+ int NumLeftover = LeftoverSize / LeftoverTy.getSizeInBits();
+ return std::make_pair(NumParts, NumLeftover);
}
LegalizerHelper::LegalizerHelper(MachineFunction &MF,
@@ -1759,10 +1762,12 @@
LLT DstTy = MRI.getType(DstReg);
LLT LeftoverTy0;
+ int NumParts, NumLeftover;
// All of the operands need to have the same number of elements, so if we can
// determine a type breakdown for the result type, we can for all of the
// source types.
- int NumParts = getNarrowTypeBreakDown(DstTy, NarrowTy0, LeftoverTy0);
+ std::tie(NumParts, NumLeftover)
+ = getNarrowTypeBreakDown(DstTy, NarrowTy0, LeftoverTy0);
if (NumParts < 0)
return UnableToLegalize;
@@ -2018,6 +2023,73 @@
}
LegalizerHelper::LegalizeResult
+LegalizerHelper::fewerElementsVectorPhi(MachineInstr &MI, unsigned TypeIdx,
+ LLT NarrowTy) {
+ const unsigned DstReg = MI.getOperand(0).getReg();
+ LLT PhiTy = MRI.getType(DstReg);
+ LLT LeftoverTy;
+
+ // All of the operands need to have the same number of elements, so if we can
+ // determine a type breakdown for the result type, we can for all of the
+ // source types.
+ int NumParts, NumLeftover;
+ std::tie(NumParts, NumLeftover)
+ = getNarrowTypeBreakDown(PhiTy, NarrowTy, LeftoverTy);
+ if (NumParts < 0)
+ return UnableToLegalize;
+
+ SmallVector<unsigned, 4> DstRegs, LeftoverDstRegs;
+ SmallVector<MachineInstrBuilder, 4> NewInsts;
+
+ const int TotalNumParts = NumParts + NumLeftover;
+
+ // Insert the new phis in the result block first.
+ for (int I = 0; I != TotalNumParts; ++I) {
+ LLT Ty = I < NumParts ? NarrowTy : LeftoverTy;
+ unsigned PartDstReg = MRI.createGenericVirtualRegister(Ty);
+ NewInsts.push_back(MIRBuilder.buildInstr(TargetOpcode::G_PHI)
+ .addDef(PartDstReg));
+ if (I < NumParts)
+ DstRegs.push_back(PartDstReg);
+ else
+ LeftoverDstRegs.push_back(PartDstReg);
+ }
+
+ MachineBasicBlock *MBB = MI.getParent();
+ MIRBuilder.setInsertPt(*MBB, MBB->getFirstNonPHI());
+ insertParts(DstReg, PhiTy, NarrowTy, DstRegs, LeftoverTy, LeftoverDstRegs);
+
+ SmallVector<unsigned, 4> PartRegs, LeftoverRegs;
+
+ // Insert code to extract the incoming values in each predecessor block.
+ for (unsigned I = 1, E = MI.getNumOperands(); I != E; I += 2) {
+ PartRegs.clear();
+ LeftoverRegs.clear();
+
+ unsigned SrcReg = MI.getOperand(I).getReg();
+ MachineBasicBlock &OpMBB = *MI.getOperand(I + 1).getMBB();
+ MIRBuilder.setInsertPt(OpMBB, OpMBB.getFirstTerminator());
+
+ LLT Unused;
+ if (!extractParts(SrcReg, PhiTy, NarrowTy, Unused, PartRegs,
+ LeftoverRegs))
+ return UnableToLegalize;
+
+ // Add the newly created operand splits to the existing instructions. The
+ // odd-sized pieces are ordered after the requested NarrowTyArg sized
+ // pieces.
+ for (int J = 0; J != TotalNumParts; ++J) {
+ MachineInstrBuilder MIB = NewInsts[J];
+ MIB.addUse(J < NumParts ? PartRegs[J] : LeftoverRegs[J - NumParts]);
+ MIB.addMBB(&OpMBB);
+ }
+ }
+
+ MI.eraseFromParent();
+ return Legalized;
+}
+
+LegalizerHelper::LegalizeResult
LegalizerHelper::reduceLoadStoreWidth(MachineInstr &MI, unsigned TypeIdx,
LLT NarrowTy) {
// FIXME: Don't know how to handle secondary types yet.
@@ -2038,14 +2110,17 @@
LLT ValTy = MRI.getType(ValReg);
int NumParts = -1;
+ int NumLeftover = -1;
LLT LeftoverTy;
SmallVector<unsigned, 8> NarrowRegs, NarrowLeftoverRegs;
if (IsLoad) {
- NumParts = getNarrowTypeBreakDown(ValTy, NarrowTy, LeftoverTy);
+ std::tie(NumParts, NumLeftover) = getNarrowTypeBreakDown(ValTy, NarrowTy, LeftoverTy);
} else {
if (extractParts(ValReg, ValTy, NarrowTy, LeftoverTy, NarrowRegs,
- NarrowLeftoverRegs))
+ NarrowLeftoverRegs)) {
NumParts = NarrowRegs.size();
+ NumLeftover = NarrowLeftoverRegs.size();
+ }
}
if (NumParts == -1)
@@ -2169,6 +2244,8 @@
return fewerElementsVectorCmp(MI, TypeIdx, NarrowTy);
case G_SELECT:
return fewerElementsVectorSelect(MI, TypeIdx, NarrowTy);
+ case G_PHI:
+ return fewerElementsVectorPhi(MI, TypeIdx, NarrowTy);
case G_LOAD:
case G_STORE:
return reduceLoadStoreWidth(MI, TypeIdx, NarrowTy);