Changes in directory llvm/lib/CodeGen:
VirtRegMap.cpp updated: 1.78 -> 1.79
---
Log message:
Fixed some spiller bugs exposed by the recent two-address code changes. Now
there may be other def(s) apart from the use&def two-address operand. We need
to check if the register reuse for a use&def operand may conflicts with another
def. Provide a mean to recover from the conflict if it is detected when the
defs are processed later.
---
Diffs of the changes: (+53 -21)
VirtRegMap.cpp | 74 ++++++++++++++++++++++++++++++++++++++++-----------------
1 files changed, 53 insertions(+), 21 deletions(-)
Index: llvm/lib/CodeGen/VirtRegMap.cpp
diff -u llvm/lib/CodeGen/VirtRegMap.cpp:1.78
llvm/lib/CodeGen/VirtRegMap.cpp:1.79
--- llvm/lib/CodeGen/VirtRegMap.cpp:1.78 Wed Nov 1 17:18:32 2006
+++ llvm/lib/CodeGen/VirtRegMap.cpp Fri Nov 3 18:21:55 2006
@@ -394,8 +394,15 @@
class VISIBILITY_HIDDEN ReuseInfo {
MachineInstr &MI;
std::vector<ReusedOp> Reuses;
+ bool *PhysRegsClobbered;
public:
- ReuseInfo(MachineInstr &mi) : MI(mi) {}
+ ReuseInfo(MachineInstr &mi, const MRegisterInfo *mri) : MI(mi) {
+ PhysRegsClobbered = new bool[mri->getNumRegs()];
+ std::fill(PhysRegsClobbered, PhysRegsClobbered+mri->getNumRegs(), false);
+ }
+ ~ReuseInfo() {
+ delete[] PhysRegsClobbered;
+ }
bool hasReuses() const {
return !Reuses.empty();
@@ -414,6 +421,14 @@
Reuses.push_back(ReusedOp(OpNo, StackSlot, PhysRegReused,
AssignedPhysReg, VirtReg));
}
+
+ void markClobbered(unsigned PhysReg) {
+ PhysRegsClobbered[PhysReg] = true;
+ }
+
+ bool isClobbered(unsigned PhysReg) const {
+ return PhysRegsClobbered[PhysReg];
+ }
/// GetRegForReload - We are about to emit a reload into PhysReg. If there
/// is some other operand that is using the specified register, either pick
@@ -430,11 +445,7 @@
// register.
if (Op.PhysRegReused == PhysReg) {
// Yup, use the reload register that we didn't use before.
- unsigned NewReg = Op.AssignedPhysReg;
-
- // Remove the record for the previous reuse. We know it can never be
- // invalidated now.
- Reuses.erase(Reuses.begin()+ro);
+ unsigned NewReg = Op.AssignedPhysReg;
return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores);
} else {
// Otherwise, we might also have a problem if a previously reused
@@ -518,8 +529,19 @@
/// ReusedOperands - Keep track of operand reuse in case we need to undo
/// reuse.
- ReuseInfo ReusedOperands(MI);
-
+ ReuseInfo ReusedOperands(MI, MRI);
+
+ // Loop over all of the implicit defs, clearing them from our available
+ // sets.
+ const unsigned *ImpDef = TII->getImplicitDefs(MI.getOpcode());
+ if (ImpDef) {
+ for ( ; *ImpDef; ++ImpDef) {
+ PhysRegsUsed[*ImpDef] = true;
+ ReusedOperands.markClobbered(*ImpDef);
+ Spills.ClobberPhysReg(*ImpDef);
+ }
+ }
+
// Process all of the spilled uses and all non spilled reg references.
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI.getOperand(i);
@@ -530,6 +552,7 @@
// Ignore physregs for spilling, but remember that it is used by this
// function.
PhysRegsUsed[MO.getReg()] = true;
+ ReusedOperands.markClobbered(MO.getReg());
continue;
}
@@ -541,6 +564,8 @@
// This virtual register was assigned a physreg!
unsigned Phys = VRM.getPhys(VirtReg);
PhysRegsUsed[Phys] = true;
+ if (MO.isDef())
+ ReusedOperands.markClobbered(Phys);
MI.getOperand(i).setReg(Phys);
continue;
}
@@ -567,8 +592,10 @@
MI.getOperand(ti).isReg() &&
MI.getOperand(ti).getReg() == VirtReg) {
// Okay, we have a two address operand. We can reuse this physreg as
- // long as we are allowed to clobber the value.
- CanReuse = Spills.canClobberPhysReg(StackSlot);
+ // long as we are allowed to clobber the value and there is an
earlier
+ // def that has already clobbered the physreg.
+ CanReuse = Spills.canClobberPhysReg(StackSlot) &&
+ !ReusedOperands.isClobbered(PhysReg);
}
if (CanReuse) {
@@ -595,6 +622,9 @@
// we can get at R0 or its alias.
ReusedOperands.addReuse(i, StackSlot, PhysReg,
VRM.getPhys(VirtReg), VirtReg);
+ if (ti != -1)
+ // Only mark it clobbered if this is a use&def operand.
+ ReusedOperands.markClobbered(PhysReg);
++NumReused;
continue;
}
@@ -629,6 +659,7 @@
<< VirtReg
<< " instead of reloading into same physreg.\n");
MI.getOperand(i).setReg(PhysReg);
+ ReusedOperands.markClobbered(PhysReg);
++NumReused;
continue;
}
@@ -637,6 +668,7 @@
MBB.getParent()->getSSARegMap()->getRegClass(VirtReg);
PhysRegsUsed[DesignatedReg] = true;
+ ReusedOperands.markClobbered(DesignatedReg);
MRI->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC);
// This invalidates DesignatedReg.
@@ -664,6 +696,7 @@
Spills, MaybeDeadStores);
PhysRegsUsed[PhysReg] = true;
+ ReusedOperands.markClobbered(PhysReg);
MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
// This invalidates PhysReg.
Spills.ClobberPhysReg(PhysReg);
@@ -676,16 +709,6 @@
DEBUG(std::cerr << '\t' << *prior(MII));
}
- // Loop over all of the implicit defs, clearing them from our available
- // sets.
- const unsigned *ImpDef = TII->getImplicitDefs(MI.getOpcode());
- if (ImpDef) {
- for ( ; *ImpDef; ++ImpDef) {
- PhysRegsUsed[*ImpDef] = true;
- Spills.ClobberPhysReg(*ImpDef);
- }
- }
-
DEBUG(std::cerr << '\t' << MI);
// If we have folded references to memory operands, make sure we clear all
@@ -798,6 +821,7 @@
// If it's not a no-op copy, it clobbers the value in the destreg.
Spills.ClobberPhysReg(VirtReg);
+ ReusedOperands.markClobbered(VirtReg);
// Check to see if this instruction is a load from a stack slot into
// a register. If so, this provides the stack slot value in the reg.
@@ -824,10 +848,18 @@
int TiedOp = TII->findTiedToSrcOperand(MI.getOpcode(), i);
if (TiedOp != -1)
PhysReg = MI.getOperand(TiedOp).getReg();
- else
+ else {
PhysReg = VRM.getPhys(VirtReg);
+ if (ReusedOperands.isClobbered(PhysReg)) {
+ // Another def has taken the assigned physreg. It must have been a
+ // use&def which got it due to reuse. Undo the reuse!
+ PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
+ Spills, MaybeDeadStores);
+ }
+ }
PhysRegsUsed[PhysReg] = true;
+ ReusedOperands.markClobbered(PhysReg);
MRI->storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
DEBUG(std::cerr << "Store:\t" << *next(MII));
MI.getOperand(i).setReg(PhysReg);
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