[llvm-commits] CVS: llvm/lib/CodeGen/LiveIntervalAnalysis.cpp VirtRegMap.cpp VirtRegMap.h
Chris Lattner
lattner at cs.uiuc.edu
Fri Oct 1 16:15:49 PDT 2004
Changes in directory llvm/lib/CodeGen:
LiveIntervalAnalysis.cpp updated: 1.129 -> 1.130
VirtRegMap.cpp updated: 1.28 -> 1.29
VirtRegMap.h updated: 1.16 -> 1.17
---
Log message:
When a virtual register is folded into an instruction, keep track of whether
it was a use, def, or both. This allows us to be less pessimistic in our
analysis of them. In practice, this doesn't make a big difference, but it
doesn't hurt either.
---
Diffs of the changes: (+52 -27)
Index: llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
diff -u llvm/lib/CodeGen/LiveIntervalAnalysis.cpp:1.129 llvm/lib/CodeGen/LiveIntervalAnalysis.cpp:1.130
--- llvm/lib/CodeGen/LiveIntervalAnalysis.cpp:1.129 Fri Oct 1 14:01:39 2004
+++ llvm/lib/CodeGen/LiveIntervalAnalysis.cpp Fri Oct 1 18:15:35 2004
@@ -223,7 +223,7 @@
if (MachineInstr* fmi = mri_->foldMemoryOperand(mi, i, slot)) {
if (lv_)
lv_->instructionChanged(mi, fmi);
- vrm.virtFolded(li.reg, mi, fmi);
+ vrm.virtFolded(li.reg, mi, i, fmi);
mi2iMap_.erase(mi);
i2miMap_[index/InstrSlots::NUM] = fmi;
mi2iMap_[fmi] = index;
Index: llvm/lib/CodeGen/VirtRegMap.cpp
diff -u llvm/lib/CodeGen/VirtRegMap.cpp:1.28 llvm/lib/CodeGen/VirtRegMap.cpp:1.29
--- llvm/lib/CodeGen/VirtRegMap.cpp:1.28 Fri Oct 1 14:47:12 2004
+++ llvm/lib/CodeGen/VirtRegMap.cpp Fri Oct 1 18:15:36 2004
@@ -77,23 +77,26 @@
Virt2StackSlotMap[virtReg] = frameIndex;
}
-void VirtRegMap::virtFolded(unsigned virtReg,
- MachineInstr* oldMI,
- MachineInstr* newMI) {
- // move previous memory references folded to new instruction
- std::vector<MI2VirtMapTy::mapped_type> regs;
- for (MI2VirtMapTy::iterator I = MI2VirtMap.lower_bound(oldMI),
- E = MI2VirtMap.end(); I != E && I->first == oldMI; ) {
- regs.push_back(I->second);
+void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI,
+ unsigned OpNo, MachineInstr *NewMI) {
+ // Move previous memory references folded to new instruction.
+ MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(NewMI);
+ for (MI2VirtMapTy::iterator I = MI2VirtMap.lower_bound(OldMI),
+ E = MI2VirtMap.end(); I != E && I->first == OldMI; ) {
+ MI2VirtMap.insert(IP, std::make_pair(NewMI, I->second));
MI2VirtMap.erase(I++);
}
- MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(newMI);
- for (unsigned i = 0, e = regs.size(); i != e; ++i)
- MI2VirtMap.insert(IP, std::make_pair(newMI, regs[i]));
+ ModRef MRInfo;
+ if (!OldMI->getOperand(OpNo).isDef()) {
+ assert(OldMI->getOperand(OpNo).isUse() && "Operand is not use or def?");
+ MRInfo = isRef;
+ } else {
+ MRInfo = OldMI->getOperand(OpNo).isUse() ? isModRef : isMod;
+ }
// add new memory reference
- MI2VirtMap.insert(IP, std::make_pair(newMI, virtReg));
+ MI2VirtMap.insert(IP, std::make_pair(NewMI, std::make_pair(VirtReg, MRInfo)));
}
void VirtRegMap::print(std::ostream &OS) const {
@@ -433,18 +436,37 @@
// register
VirtRegMap::MI2VirtMapTy::const_iterator I, E;
for (tie(I, E) = VRM.getFoldedVirts(&MI); I != E; ++I) {
- DEBUG(std::cerr << "Folded vreg: " << I->second);
- if (VRM.hasStackSlot(I->second)) {
- int SS = VRM.getStackSlot(I->second);
+ DEBUG(std::cerr << "Folded vreg: " << I->second.first << " MR: "
+ << I->second.second);
+ unsigned VirtReg = I->second.first;
+ VirtRegMap::ModRef MR = I->second.second;
+ if (VRM.hasStackSlot(VirtReg)) {
+ int SS = VRM.getStackSlot(VirtReg);
DEBUG(std::cerr << " - StackSlot: " << SS << "\n");
- // Any stores to this stack slot are not dead anymore.
- MaybeDeadStores.erase(SS);
+ // If this reference is not a use, any previous store is now dead.
+ // Otherwise, the store to this stack slot is not dead anymore.
+ std::map<int, MachineInstr*>::iterator MDSI = MaybeDeadStores.find(SS);
+ if (MDSI != MaybeDeadStores.end()) {
+ if (MR & VirtRegMap::isRef) // Previous store is not dead.
+ MaybeDeadStores.erase(SS);
+ else {
+ // If we get here, the store is dead, nuke it now.
+ assert(MR == VirtRegMap::isMod && "Can't be modref!");
+ MBB.erase(MDSI->second);
+ MaybeDeadStores.erase(MDSI);
+ ++NumDSE;
+ }
+ }
- std::map<int, unsigned>::iterator I = SpillSlotsAvailable.find(SS);
- if (I != SpillSlotsAvailable.end()) {
- PhysRegsAvailable.erase(I->second);
- SpillSlotsAvailable.erase(I);
+ // If the spill slot value is available, and this is a new definition of
+ // the value, the value is not available anymore.
+ if (MR & VirtRegMap::isMod) {
+ std::map<int, unsigned>::iterator It = SpillSlotsAvailable.find(SS);
+ if (It != SpillSlotsAvailable.end()) {
+ PhysRegsAvailable.erase(It->second);
+ SpillSlotsAvailable.erase(It);
+ }
}
} else {
DEBUG(std::cerr << ": No stack slot!\n");
Index: llvm/lib/CodeGen/VirtRegMap.h
diff -u llvm/lib/CodeGen/VirtRegMap.h:1.16 llvm/lib/CodeGen/VirtRegMap.h:1.17
--- llvm/lib/CodeGen/VirtRegMap.h:1.16 Thu Sep 30 19:35:07 2004
+++ llvm/lib/CodeGen/VirtRegMap.h Fri Oct 1 18:15:36 2004
@@ -26,7 +26,9 @@
class VirtRegMap {
public:
- typedef std::multimap<MachineInstr*, unsigned> MI2VirtMapTy;
+ enum ModRef { isRef = 1, isMod = 2, isModRef = 3 };
+ typedef std::multimap<MachineInstr*,
+ std::pair<unsigned, ModRef> > MI2VirtMapTy;
private:
MachineFunction &MF;
@@ -122,10 +124,11 @@
/// the specified stack slot
void assignVirt2StackSlot(unsigned virtReg, int frameIndex);
- /// @brief updates information about the specified virtual
- /// register's value folded into newMI machine instruction
- void virtFolded(unsigned virtReg, MachineInstr* oldMI,
- MachineInstr* newMI);
+ /// @brief Updates information about the specified virtual register's value
+ /// folded into newMI machine instruction. The OpNum argument indicates the
+ /// operand number of OldMI that is folded.
+ void virtFolded(unsigned VirtReg, MachineInstr *OldMI, unsigned OpNum,
+ MachineInstr *NewMI);
/// @brief returns the virtual registers' values folded in memory
/// operands of this instruction
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