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If a rematerializable def is not deleted, i.e. it is also spilled, check if the

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spilled value is available for reuse.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41067 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-08-14 05:42:54 +00:00
parent 430a7b0c94
commit dc6be19859
1 changed files with 20 additions and 11 deletions
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31
lib/CodeGen/VirtRegMap.cpp
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@ -744,10 +744,19 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
bool DoReMat = VRM.isReMaterialized(VirtReg);
int SSorRMId = DoReMat
? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
unsigned PhysReg;
int ReuseSlot = SSorRMId;
// Check to see if this stack slot is available.
if ((PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId))) {
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
if (!PhysReg && DoReMat) {
// This use is rematerializable. But perhaps the value is available in
// stack if the definition is not deleted. If so, check if we can
// reuse the value.
ReuseSlot = VRM.getStackSlot(VirtReg);
if (ReuseSlot != VirtRegMap::NO_STACK_SLOT)
PhysReg = Spills.getSpillSlotOrReMatPhysReg(ReuseSlot);
}
if (PhysReg) {
// This spilled operand might be part of a two-address operand. If this
// is the case, then changing it will necessarily require changing the
// def part of the instruction as well. However, in some cases, we
@ -761,16 +770,16 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
// Okay, we have a two address operand. We can reuse this physreg as
// long as we are allowed to clobber the value and there isn't an
// earlier def that has already clobbered the physreg.
CanReuse = Spills.canClobberPhysReg(SSorRMId) &&
CanReuse = Spills.canClobberPhysReg(ReuseSlot) &&
!ReusedOperands.isClobbered(PhysReg);
}
if (CanReuse) {
// If this stack slot value is already available, reuse it!
if (SSorRMId > VirtRegMap::MAX_STACK_SLOT)
DOUT << "Reusing RM#" << SSorRMId-VirtRegMap::MAX_STACK_SLOT-1;
if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
else
DOUT << "Reusing SS#" << SSorRMId;
DOUT << "Reusing SS#" << ReuseSlot;
DOUT << " from physreg "
<< MRI->getName(PhysReg) << " for vreg"
<< VirtReg <<" instead of reloading into physreg "
@ -791,7 +800,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
// or R0 and R1 might not be compatible with each other. In this
// case, we actually insert a reload for V1 in R1, ensuring that
// we can get at R0 or its alias.
ReusedOperands.addReuse(i, SSorRMId, PhysReg,
ReusedOperands.addReuse(i, ReuseSlot, PhysReg,
VRM.getPhys(VirtReg), VirtReg);
if (ti != -1)
// Only mark it clobbered if this is a use&def operand.
@ -825,10 +834,10 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
// incoming, we don't need to inserted a dead copy.
if (DesignatedReg == PhysReg) {
// If this stack slot value is already available, reuse it!
if (SSorRMId > VirtRegMap::MAX_STACK_SLOT)
DOUT << "Reusing RM#" << SSorRMId-VirtRegMap::MAX_STACK_SLOT-1;
if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
else
DOUT << "Reusing SS#" << SSorRMId;
DOUT << "Reusing SS#" << ReuseSlot;
DOUT << " from physreg " << MRI->getName(PhysReg) << " for vreg"
<< VirtReg
<< " instead of reloading into same physreg.\n";
@ -849,7 +858,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
// This invalidates DesignatedReg.
Spills.ClobberPhysReg(DesignatedReg);
Spills.addAvailable(SSorRMId, &MI, DesignatedReg);
Spills.addAvailable(ReuseSlot, &MI, DesignatedReg);
MI.getOperand(i).setReg(DesignatedReg);
DOUT << '\t' << *prior(MII);
++NumReused;