GlobalISel: Use helper function for MMO splitting

[arsenm]

Summary

Also fix an alignment bug getMachineMemOperand. If the
tracked value is null, the offset isn't tracked so the
base alignment needs to be reduced.

[paquette]

lib/CodeGen/GlobalISel/LegalizerHelper.cpp

501–502

I assume that MMO.getAAInfo(), MMO.getRanges(), etc are automatically handled by the call to getMachineMemOperand in copyWithSizeAndOffset? Or are they no longer relevant?

[arsenm]

It turns out this already exists, just in MachineFunction. It does require fixing a bug in how alignment is handled when there's no base value

[paquette]

LGTM

[arsenm]

r352716

lib/CodeGen/GlobalISel/LegalizerHelper.cpp

501–502

It turns out this already exists, it's just in MachineFunction instead of MMO

include/llvm/CodeGen/MachineMemOperand.h

public:
 
   /// Change the SourceValue for this MachineMemOperand. This should only be
   /// used when an object is being relocated and all references to it are being
   /// updated.
   void setValue(const Value *NewSV) { PtrInfo.V = NewSV; }
   void setValue(const PseudoSourceValue *NewSV) { PtrInfo.V = NewSV; }
   void setOffset(int64_t NewOffset) { PtrInfo.Offset = NewOffset; }
 
+  /// Create new MachineMemOperand that represents a \p Size byte subset located
+  /// at \p Offset.
+  MachineMemOperand *copyWithSizeAndOffset(MachineFunction &MF, unsigned Size,
+                                           unsigned Offset) const;
   /// Profile - Gather unique data for the object.
   ///
   void Profile(FoldingSetNodeID &ID) const;
 
   /// Support for operator<<.
   /// @{
   void print(raw_ostream &OS) const;
   void print(raw_ostream &OS, ModuleSlotTracker &MST) const;

lib/CodeGen/GlobalISel/LegalizerHelper.cpp

case TargetOpcode::G_LOAD: {
     int NumParts = SizeOp0 / NarrowSize;
     LLT OffsetTy = LLT::scalar(
         MRI.getType(MI.getOperand(1).getReg()).getScalarSizeInBits());
 
     SmallVector<unsigned, 2> DstRegs;
     for (int i = 0; i < NumParts; ++i) {
       unsigned DstReg = MRI.createGenericVirtualRegister(NarrowTy);
       unsigned SrcReg = 0;
-      unsigned Adjustment = i * NarrowSize / 8;
-      unsigned Alignment = MinAlign(MMO.getAlignment(), Adjustment);
+      unsigned Offset = i * NarrowSize / 8;
 
-      MachineMemOperand *SplitMMO = MIRBuilder.getMF().getMachineMemOperand(
-          MMO.getPointerInfo().getWithOffset(Adjustment), MMO.getFlags(),
-          NarrowSize / 8, Alignment, MMO.getAAInfo(), MMO.getRanges(),
-          MMO.getSyncScopeID(), MMO.getOrdering(), MMO.getFailureOrdering());
+      MachineMemOperand *SplitMMO = MMO.copyWithSizeAndOffset(
+          MIRBuilder.getMF(), NarrowSize / 8, Offset);
 
       MIRBuilder.materializeGEP(SrcReg, MI.getOperand(1).getReg(), OffsetTy,
-                                Adjustment);
+                                Offset);
 
       MIRBuilder.buildLoad(DstReg, SrcReg, *SplitMMO);
 
       DstRegs.push_back(DstReg);
     }
     unsigned DstReg = MI.getOperand(0).getReg();
     if(MRI.getType(DstReg).isVector())
       MIRBuilder.buildBuildVector(DstReg, DstRegs);
case TargetOpcode::G_STORE: {
     LLT OffsetTy = LLT::scalar(
         MRI.getType(MI.getOperand(1).getReg()).getScalarSizeInBits());
 
     SmallVector<unsigned, 2> SrcRegs;
     extractParts(MI.getOperand(0).getReg(), NarrowTy, NumParts, SrcRegs);
 
     for (int i = 0; i < NumParts; ++i) {
       unsigned DstReg = 0;
-      unsigned Adjustment = i * NarrowSize / 8;
-      unsigned Alignment = MinAlign(MMO.getAlignment(), Adjustment);
+      unsigned Offset = i * NarrowSize / 8;
 
-      MachineMemOperand *SplitMMO = MIRBuilder.getMF().getMachineMemOperand(
-          MMO.getPointerInfo().getWithOffset(Adjustment), MMO.getFlags(),
-          NarrowSize / 8, Alignment, MMO.getAAInfo(), MMO.getRanges(),
-          MMO.getSyncScopeID(), MMO.getOrdering(), MMO.getFailureOrdering());
+      MachineMemOperand *SplitMMO =
+          MMO.copyWithSizeAndOffset(MIRBuilder.getMF(), NarrowSize / 8, Offset);
 
       MIRBuilder.materializeGEP(DstReg, MI.getOperand(1).getReg(), OffsetTy,
-                                Adjustment);
+                                Offset);
 
       MIRBuilder.buildStore(SrcRegs[i], DstReg, *SplitMMO);
     }
     MI.eraseFromParent();
     return Legalized;
   }
   case TargetOpcode::G_CONSTANT: {
     // FIXME: add support for when SizeOp0 isn't an exact multiple of

lib/CodeGen/MachineOperand.cpp

MachineMemOperand::MachineMemOperand(MachinePointerInfo ptrinfo, Flags f,
   AtomicInfo.SSID = static_cast<unsigned>(SSID);
   assert(getSyncScopeID() == SSID && "Value truncated");
   AtomicInfo.Ordering = static_cast<unsigned>(Ordering);
   assert(getOrdering() == Ordering && "Value truncated");
   AtomicInfo.FailureOrdering = static_cast<unsigned>(FailureOrdering);
   assert(getFailureOrdering() == FailureOrdering && "Value truncated");
 }
 
+MachineMemOperand *
+MachineMemOperand::copyWithSizeAndOffset(MachineFunction &MF, unsigned Size,
+                                         unsigned Offset) const {
+  return MF.getMachineMemOperand(getPointerInfo().getWithOffset(Offset),
+                                 getFlags(), Size,
+                                 MinAlign(getAlignment(), Offset));
+}
+
 /// Profile - Gather unique data for the object.
 ///
 void MachineMemOperand::Profile(FoldingSetNodeID &ID) const {
   ID.AddInteger(getOffset());
   ID.AddInteger(Size);
   ID.AddPointer(getOpaqueValue());
   ID.AddInteger(getFlags());
   ID.AddInteger(getBaseAlignment());