#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/DenseMap.h"
/// in one of several ways: if the register is available in a physical
/// register already, it uses that physical register. If the value is not
/// in a physical register, and if there are physical registers available,
- /// it loads it into a register. If register pressure is high, and it is
- /// possible, it tries to fold the load of the virtual register into the
- /// instruction itself. It avoids doing this if register pressure is low to
- /// improve the chance that subsequent instructions can use the reloaded
- /// value. This method returns the modified instruction.
+ /// it loads it into a register: PhysReg if that is an available physical
+ /// register, otherwise any physical register of the right class.
+ /// If register pressure is high, and it is possible, it tries to fold the
+ /// load of the virtual register into the instruction itself. It avoids
+ /// doing this if register pressure is low to improve the chance that
+ /// subsequent instructions can use the reloaded value. This method
+ /// returns the modified instruction.
///
MachineInstr *reloadVirtReg(MachineBasicBlock &MBB, MachineInstr *MI,
- unsigned OpNum, SmallSet<unsigned, 4> &RRegs);
+ unsigned OpNum, SmallSet<unsigned, 4> &RRegs,
+ unsigned PhysReg);
/// ComputeLocalLiveness - Computes liveness of registers within a basic
/// block, setting the killed/dead flags as appropriate.
return SS; // Already has space allocated?
// Allocate a new stack object for this spill location...
- int FrameIdx = MF->getFrameInfo()->CreateStackObject(RC->getSize(),
- RC->getAlignment(),true);
+ int FrameIdx = MF->getFrameInfo()->CreateSpillStackObject(RC->getSize(),
+ RC->getAlignment());
// Assign the slot...
StackSlotForVirtReg[VirtReg] = FrameIdx;
/// one of several ways: if the register is available in a physical register
/// already, it uses that physical register. If the value is not in a physical
/// register, and if there are physical registers available, it loads it into a
+/// register: PhysReg if that is an available physical register, otherwise any
/// register. If register pressure is high, and it is possible, it tries to
/// fold the load of the virtual register into the instruction itself. It
/// avoids doing this if register pressure is low to improve the chance that
-/// subsequent instructions can use the reloaded value. This method returns the
-/// modified instruction.
+/// subsequent instructions can use the reloaded value. This method returns
+/// the modified instruction.
///
MachineInstr *RALocal::reloadVirtReg(MachineBasicBlock &MBB, MachineInstr *MI,
unsigned OpNum,
- SmallSet<unsigned, 4> &ReloadedRegs) {
+ SmallSet<unsigned, 4> &ReloadedRegs,
+ unsigned PhysReg) {
unsigned VirtReg = MI->getOperand(OpNum).getReg();
// If the virtual register is already available, just update the instruction
// Otherwise, we need to fold it into the current instruction, or reload it.
// If we have registers available to hold the value, use them.
const TargetRegisterClass *RC = MF->getRegInfo().getRegClass(VirtReg);
- unsigned PhysReg = getFreeReg(RC);
+ // If we already have a PhysReg (this happens when the instruction is a
+ // reg-to-reg copy with a PhysReg destination) use that.
+ if (!PhysReg || !TargetRegisterInfo::isPhysicalRegister(PhysReg) ||
+ !isPhysRegAvailable(PhysReg))
+ PhysReg = getFreeReg(RC);
int FrameIndex = getStackSpaceFor(VirtReg, RC);
if (PhysReg) { // Register is available, allocate it!
errs() << '\n';
});
+ // Determine whether this is a copy instruction. The cases where the
+ // source or destination are phys regs are handled specially.
+ unsigned SrcCopyReg, DstCopyReg, SrcCopySubReg, DstCopySubReg;
+ bool isCopy = TII->isMoveInstr(*MI, SrcCopyReg, DstCopyReg,
+ SrcCopySubReg, DstCopySubReg);
+
// Loop over the implicit uses, making sure that they are at the head of the
// use order list, so they don't get reallocated.
if (TID.ImplicitUses) {
// here we are looking for only used operands (never def&use)
if (MO.isReg() && !MO.isDef() && MO.getReg() && !MO.isImplicit() &&
TargetRegisterInfo::isVirtualRegister(MO.getReg()))
- MI = reloadVirtReg(MBB, MI, i, ReloadedRegs);
+ MI = reloadVirtReg(MBB, MI, i, ReloadedRegs,
+ isCopy ? DstCopyReg : 0);
}
// If this instruction is the last user of this register, kill the
unsigned DestPhysReg;
// If DestVirtReg already has a value, use it.
- if (!(DestPhysReg = getVirt2PhysRegMapSlot(DestVirtReg)))
- DestPhysReg = getReg(MBB, MI, DestVirtReg);
+ if (!(DestPhysReg = getVirt2PhysRegMapSlot(DestVirtReg))) {
+ // If this is a copy, the source reg is a phys reg, and
+ // that reg is available, use that phys reg for DestPhysReg.
+ if (isCopy &&
+ TargetRegisterInfo::isPhysicalRegister(SrcCopyReg) &&
+ isPhysRegAvailable(SrcCopyReg)) {
+ DestPhysReg = SrcCopyReg;
+ assignVirtToPhysReg(DestVirtReg, DestPhysReg);
+ } else
+ DestPhysReg = getReg(MBB, MI, DestVirtReg);
+ }
MF->getRegInfo().setPhysRegUsed(DestPhysReg);
markVirtRegModified(DestVirtReg);
getVirtRegLastUse(DestVirtReg) = std::make_pair((MachineInstr*)0, 0);
// Finally, if this is a noop copy instruction, zap it. (Except that if
// the copy is dead, it must be kept to avoid messing up liveness info for
// the register scavenger. See pr4100.)
- unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
- if (TII->isMoveInstr(*MI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
- SrcReg == DstReg && DeadDefs.empty())
+ if (TII->isMoveInstr(*MI, SrcCopyReg, DstCopyReg,
+ SrcCopySubReg, DstCopySubReg) &&
+ SrcCopyReg == DstCopyReg && DeadDefs.empty())
MBB.erase(MI);
}
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