[llvm-commits] CVS: llvm/lib/CodeGen/VirtRegMap.cpp
Chris Lattner
lattner at cs.uiuc.edu
Fri Feb 24 17:51:46 PST 2006
Changes in directory llvm/lib/CodeGen:
VirtRegMap.cpp updated: 1.55 -> 1.56
---
Log message:
Refactor some code from being inline to being out in a new class with methods.
This gets rid of two gotos, which is always nice, and also adds some comments.
No functionality change, this is just a refactor.
---
Diffs of the changes: (+97 -42)
VirtRegMap.cpp | 139 +++++++++++++++++++++++++++++++++++++++------------------
1 files changed, 97 insertions(+), 42 deletions(-)
Index: llvm/lib/CodeGen/VirtRegMap.cpp
diff -u llvm/lib/CodeGen/VirtRegMap.cpp:1.55 llvm/lib/CodeGen/VirtRegMap.cpp:1.56
--- llvm/lib/CodeGen/VirtRegMap.cpp:1.55 Fri Feb 3 21:27:39 2006
+++ llvm/lib/CodeGen/VirtRegMap.cpp Fri Feb 24 19:51:33 2006
@@ -269,6 +269,8 @@
return I->second >> 1; // Remove the CanClobber bit.
return 0;
}
+
+ const MRegisterInfo *getRegInfo() const { return MRI; }
/// addAvailable - Mark that the specified stack slot is available in the
/// specified physreg. If CanClobber is true, the physreg can be modified at
@@ -375,6 +377,88 @@
: Operand(o), StackSlot(ss), PhysRegReused(prr), AssignedPhysReg(apr),
VirtReg(vreg) {}
};
+
+ /// ReuseInfo - This maintains a collection of ReuseOp's for each operand that
+ /// is reused instead of reloaded.
+ class ReuseInfo {
+ MachineInstr &MI;
+ std::vector<ReusedOp> Reuses;
+ public:
+ ReuseInfo(MachineInstr &mi) : MI(mi) {}
+
+ bool hasReuses() const {
+ return !Reuses.empty();
+ }
+
+ /// addReuse - If we choose to reuse a virtual register that is already
+ /// available instead of reloading it, remember that we did so.
+ void addReuse(unsigned OpNo, unsigned StackSlot,
+ unsigned PhysRegReused, unsigned AssignedPhysReg,
+ unsigned VirtReg) {
+ // If the reload is to the assigned register anyway, no undo will be
+ // required.
+ if (PhysRegReused == AssignedPhysReg) return;
+
+ // Otherwise, remember this.
+ Reuses.push_back(ReusedOp(OpNo, StackSlot, PhysRegReused,
+ AssignedPhysReg, VirtReg));
+ }
+
+ /// GetRegForReload - We are about to emit a reload into PhysReg. If there
+ /// is some other operand that is using the specified register, either pick
+ /// a new register to use, or evict the previous reload and use this reg.
+ unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
+ AvailableSpills &Spills,
+ std::map<int, MachineInstr*> &MaybeDeadStores) {
+ if (Reuses.empty()) return PhysReg; // This is most often empty.
+
+ for (unsigned ro = 0, e = Reuses.size(); ro != e; ++ro) {
+ ReusedOp &Op = Reuses[ro];
+ // If we find some other reuse that was supposed to use this register
+ // exactly for its reload, we can change this reload to use ITS reload
+ // register.
+ if (Op.PhysRegReused == PhysReg) {
+ // Yup, use the reload register that we didn't use before.
+ return GetRegForReload(Op.AssignedPhysReg, MI,
+ Spills, MaybeDeadStores);
+ } else {
+ // Otherwise, we might also have a problem if a previously reused
+ // value aliases the new register. If so, codegen the previous reload
+ // and use this one.
+ unsigned PRRU = Op.PhysRegReused;
+ const MRegisterInfo *MRI = Spills.getRegInfo();
+ if (MRI->areAliases(PRRU, PhysReg)) {
+ // Okay, we found out that an alias of a reused register
+ // was used. This isn't good because it means we have
+ // to undo a previous reuse.
+ MachineBasicBlock *MBB = MI->getParent();
+ const TargetRegisterClass *AliasRC =
+ MBB->getParent()->getSSARegMap()->getRegClass(Op.VirtReg);
+ MRI->loadRegFromStackSlot(*MBB, MI, Op.AssignedPhysReg,
+ Op.StackSlot, AliasRC);
+ Spills.ClobberPhysReg(Op.AssignedPhysReg);
+ Spills.ClobberPhysReg(Op.PhysRegReused);
+
+ // Any stores to this stack slot are not dead anymore.
+ MaybeDeadStores.erase(Op.StackSlot);
+
+ MI->SetMachineOperandReg(Op.Operand, Op.AssignedPhysReg);
+
+ Spills.addAvailable(Op.StackSlot, Op.AssignedPhysReg);
+ ++NumLoads;
+ DEBUG(MachineBasicBlock::iterator MII = MI;
+ std::cerr << '\t' << *prior(MII));
+
+ DEBUG(std::cerr << "Reuse undone!\n");
+ Reuses.erase(Reuses.begin()+ro);
+ --NumReused;
+ return PhysReg;
+ }
+ }
+ }
+ return PhysReg;
+ }
+ };
}
@@ -388,8 +472,6 @@
// that we can choose to reuse the physregs instead of emitting reloads.
AvailableSpills Spills(MRI, TII);
- std::vector<ReusedOp> ReusedOperands;
-
// DefAndUseVReg - When we see a def&use operand that is spilled, keep track
// of it. ".first" is the machine operand index (should always be 0 for now),
// and ".second" is the virtual register that is spilled.
@@ -405,12 +487,18 @@
bool *PhysRegsUsed = MBB.getParent()->getUsedPhysregs();
+ if (MBB.getBasicBlock()->getName() == "endif.3.i")
+ std::cerr << "HERE\n";
+
for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
MII != E; ) {
MachineInstr &MI = *MII;
MachineBasicBlock::iterator NextMII = MII; ++NextMII;
- ReusedOperands.clear();
+ /// ReusedOperands - Keep track of operand reuse in case we need to undo
+ /// reuse.
+ ReuseInfo ReusedOperands(MI);
+
DefAndUseVReg.clear();
// Process all of the spilled uses and all non spilled reg references.
@@ -480,8 +568,8 @@
// 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.push_back(ReusedOp(i, StackSlot, PhysReg,
- VRM.getPhys(VirtReg), VirtReg));
+ ReusedOperands.addReuse(i, StackSlot, PhysReg,
+ VRM.getPhys(VirtReg), VirtReg);
++NumReused;
continue;
}
@@ -492,47 +580,14 @@
const TargetRegisterClass* RC =
MBB.getParent()->getSSARegMap()->getRegClass(VirtReg);
- RecheckRegister:
// Note that, if we reused a register for a previous operand, the
// register we want to reload into might not actually be
// available. If this occurs, use the register indicated by the
// reuser.
- if (!ReusedOperands.empty()) // This is most often empty.
- for (unsigned ro = 0, e = ReusedOperands.size(); ro != e; ++ro)
- if (ReusedOperands[ro].PhysRegReused == PhysReg) {
- // Yup, use the reload register that we didn't use before.
- PhysReg = ReusedOperands[ro].AssignedPhysReg;
- goto RecheckRegister;
- } else {
- ReusedOp &Op = ReusedOperands[ro];
- unsigned PRRU = Op.PhysRegReused;
- if (MRI->areAliases(PRRU, PhysReg)) {
- // Okay, we found out that an alias of a reused register
- // was used. This isn't good because it means we have
- // to undo a previous reuse.
- const TargetRegisterClass *AliasRC =
- MBB.getParent()->getSSARegMap()->getRegClass(Op.VirtReg);
- MRI->loadRegFromStackSlot(MBB, &MI, Op.AssignedPhysReg,
- Op.StackSlot, AliasRC);
- Spills.ClobberPhysReg(Op.AssignedPhysReg);
- Spills.ClobberPhysReg(Op.PhysRegReused);
-
- // Any stores to this stack slot are not dead anymore.
- MaybeDeadStores.erase(Op.StackSlot);
-
- MI.SetMachineOperandReg(Op.Operand, Op.AssignedPhysReg);
-
- Spills.addAvailable(Op.StackSlot, Op.AssignedPhysReg);
- ++NumLoads;
- DEBUG(std::cerr << '\t' << *prior(MII));
-
- DEBUG(std::cerr << "Reuse undone!\n");
- ReusedOperands.erase(ReusedOperands.begin()+ro);
- --NumReused;
- goto ContinueReload;
- }
- }
- ContinueReload:
+ if (ReusedOperands.hasReuses())
+ PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
+ Spills, MaybeDeadStores);
+
PhysRegsUsed[PhysReg] = true;
MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
// This invalidates PhysReg.
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