Automatically fold COPY instructions into stack load/store.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108012 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/TargetInstrInfoImpl.cpp b/lib/CodeGen/TargetInstrInfoImpl.cpp
index cc6431d..56cb4b1 100644
--- a/lib/CodeGen/TargetInstrInfoImpl.cpp
+++ b/lib/CodeGen/TargetInstrInfoImpl.cpp
@@ -190,6 +190,47 @@
return FnSize;
}
+// If the COPY instruction in MI can be folded to a stack operation, return
+// the register class to use.
+static const TargetRegisterClass *canFoldCopy(const MachineInstr *MI,
+ unsigned FoldIdx) {
+ assert(MI->isCopy() && "MI must be a COPY instruction");
+ if (MI->getNumOperands() != 2)
+ return 0;
+ assert(FoldIdx<2 && "FoldIdx refers no nonexistent operand");
+
+ const MachineOperand &FoldOp = MI->getOperand(FoldIdx);
+ const MachineOperand &LiveOp = MI->getOperand(1-FoldIdx);
+
+ if (FoldOp.getSubReg() || LiveOp.getSubReg())
+ return 0;
+
+ unsigned FoldReg = FoldOp.getReg();
+ unsigned LiveReg = LiveOp.getReg();
+
+ assert(TargetRegisterInfo::isVirtualRegister(FoldReg) &&
+ "Cannot fold physregs");
+
+ const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
+ const TargetRegisterClass *RC = MRI.getRegClass(FoldReg);
+
+ if (TargetRegisterInfo::isPhysicalRegister(LiveOp.getReg()))
+ return RC->contains(LiveOp.getReg()) ? RC : 0;
+
+ const TargetRegisterClass *LiveRC = MRI.getRegClass(LiveReg);
+ if (RC == LiveRC || RC->hasSubClass(LiveRC))
+ return RC;
+
+ // FIXME: Allow folding when register classes are memory compatible.
+ return 0;
+}
+
+bool TargetInstrInfoImpl::
+canFoldMemoryOperand(const MachineInstr *MI,
+ const SmallVectorImpl<unsigned> &Ops) const {
+ return MI->isCopy() && Ops.size() == 1 && canFoldCopy(MI, Ops[0]);
+}
+
/// foldMemoryOperand - Attempt to fold a load or store of the specified stack
/// slot into the specified machine instruction for the specified operand(s).
/// If this is possible, a new instruction is returned with the specified
@@ -199,7 +240,7 @@
MachineInstr*
TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
const SmallVectorImpl<unsigned> &Ops,
- int FrameIndex) const {
+ int FI) const {
unsigned Flags = 0;
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
if (MI->getOperand(Ops[i]).isDef())
@@ -207,14 +248,39 @@
else
Flags |= MachineMemOperand::MOLoad;
- MachineBasicBlock &MBB = *MI->getParent();
- MachineFunction &MF = *MBB.getParent();
+ MachineBasicBlock *MBB = MI->getParent();
+ assert(MBB && "foldMemoryOperand needs an inserted instruction");
+ MachineFunction &MF = *MBB->getParent();
// Ask the target to do the actual folding.
- MachineInstr *NewMI = foldMemoryOperandImpl(MF, MI, Ops, FrameIndex);
+ MachineInstr *NewMI = foldMemoryOperandImpl(MF, MI, Ops, FI);
+
+ // Straight COPY may fold as load/store.
+ if (!NewMI) {
+ if (!MI->isCopy() || Ops.size() != 1)
+ return 0;
+
+ const TargetRegisterClass *RC = canFoldCopy(MI, Ops[0]);
+ if (!RC)
+ return 0;
+
+ const MachineOperand &MO = MI->getOperand(1-Ops[0]);
+ MachineBasicBlock::iterator Pos = MI;
+ const TargetRegisterInfo *TRI = MF.getTarget().getRegisterInfo();
+
+ if (Flags == MachineMemOperand::MOStore)
+ storeRegToStackSlot(*MBB, Pos, MO.getReg(), MO.isKill(), FI, RC, TRI);
+ else
+ loadRegFromStackSlot(*MBB, Pos, MO.getReg(), FI, RC, TRI);
+
+ NewMI = --Pos;
+ } else {
+ // FIXME: change foldMemoryOperandImpl semantics to also insert NewMI.
+ NewMI = MBB->insert(MI, NewMI);
+ }
+
if (!NewMI) return 0;
- NewMI = MBB.insert(MI, NewMI);
assert((!(Flags & MachineMemOperand::MOStore) ||
NewMI->getDesc().mayStore()) &&
@@ -223,12 +289,12 @@
NewMI->getDesc().mayLoad()) &&
"Folded a use to a non-load!");
const MachineFrameInfo &MFI = *MF.getFrameInfo();
- assert(MFI.getObjectOffset(FrameIndex) != -1);
+ assert(MFI.getObjectOffset(FI) != -1);
MachineMemOperand *MMO =
- MF.getMachineMemOperand(PseudoSourceValue::getFixedStack(FrameIndex),
+ MF.getMachineMemOperand(PseudoSourceValue::getFixedStack(FI),
Flags, /*Offset=*/0,
- MFI.getObjectSize(FrameIndex),
- MFI.getObjectAlignment(FrameIndex));
+ MFI.getObjectSize(FI),
+ MFI.getObjectAlignment(FI));
NewMI->addMemOperand(MF, MMO);
return NewMI;
diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 902a29c..6a4bc7c 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -1204,7 +1204,7 @@
// FIXME: VMOVQQ and VMOVQQQQ?
- return false;
+ return TargetInstrInfoImpl::canFoldMemoryOperand(MI, Ops);
}
/// Create a copy of a const pool value. Update CPI to the new index and return
diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index cda31db..6e8239a 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -2733,7 +2733,7 @@
if (I != OpcodeTablePtr->end())
return true;
}
- return false;
+ return TargetInstrInfoImpl::canFoldMemoryOperand(MI, Ops);
}
bool X86InstrInfo::unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI,