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If the source of a move is in spill slot, the reload may be folded to essentially a load from stack slot. It's ok to mark the stack slot value as available for reuse. But it should not be clobbered since the destination of the move is live.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41109 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-08-15 20:20:34 +00:00
parent ae5115dd44
commit 90a43c3ae3
1 changed files with 19 additions and 13 deletions
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32
lib/CodeGen/VirtRegMap.cpp
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@ -320,7 +320,7 @@ public:
ModifyStackSlotOrReMat(SlotOrReMat);
PhysRegsAvailable.insert(std::make_pair(Reg, SlotOrReMat));
SpillSlotsOrReMatsAvailable[SlotOrReMat] = (Reg << 1) | (unsigned)CanClobber;
SpillSlotsOrReMatsAvailable[SlotOrReMat]= (Reg << 1) | (unsigned)CanClobber;
if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
DOUT << "Remembering RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1;
@ -333,7 +333,8 @@ public:
/// value of the specified stackslot register if it desires. The specified
/// stack slot must be available in a physreg for this query to make sense.
bool canClobberPhysReg(int SlotOrReMat) const {
assert(SpillSlotsOrReMatsAvailable.count(SlotOrReMat) && "Value not available!");
assert(SpillSlotsOrReMatsAvailable.count(SlotOrReMat) &&
"Value not available!");
return SpillSlotsOrReMatsAvailable.find(SlotOrReMat)->second & 1;
}
@ -347,9 +348,9 @@ public:
/// it and any of its aliases.
void ClobberPhysReg(unsigned PhysReg);
/// ModifyStackSlotOrReMat - This method is called when the value in a stack slot
/// changes. This removes information about which register the previous value
/// for this slot lives in (as the previous value is dead now).
/// ModifyStackSlotOrReMat - This method is called when the value in a stack
/// slot changes. This removes information about which register the previous
/// value for this slot lives in (as the previous value is dead now).
void ModifyStackSlotOrReMat(int SlotOrReMat);
};
}
@ -409,11 +410,12 @@ void AvailableSpills::ClobberPhysReg(unsigned PhysReg) {
ClobberPhysRegOnly(PhysReg);
}
/// ModifyStackSlotOrReMat - This method is called when the value in a stack slot
/// changes. This removes information about which register the previous value
/// for this slot lives in (as the previous value is dead now).
/// ModifyStackSlotOrReMat - This method is called when the value in a stack
/// slot changes. This removes information about which register the previous
/// value for this slot lives in (as the previous value is dead now).
void AvailableSpills::ModifyStackSlotOrReMat(int SlotOrReMat) {
std::map<int, unsigned>::iterator It = SpillSlotsOrReMatsAvailable.find(SlotOrReMat);
std::map<int, unsigned>::iterator It =
SpillSlotsOrReMatsAvailable.find(SlotOrReMat);
if (It == SpillSlotsOrReMatsAvailable.end()) return;
unsigned Reg = It->second >> 1;
SpillSlotsOrReMatsAvailable.erase(It);
@ -557,8 +559,8 @@ namespace {
ReusedOp(unsigned o, unsigned ss, unsigned prr, unsigned apr,
unsigned vreg)
: Operand(o), StackSlotOrReMat(ss), PhysRegReused(prr), AssignedPhysReg(apr),
VirtReg(vreg) {}
: Operand(o), StackSlotOrReMat(ss), PhysRegReused(prr),
AssignedPhysReg(apr), VirtReg(vreg) {}
};
/// ReuseInfo - This maintains a collection of ReuseOp's for each operand that
@ -976,6 +978,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
// If we have folded references to memory operands, make sure we clear all
// physical registers that may contain the value of the spilled virtual
// register
SmallSet<int, 1> FoldedSS;
for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
DOUT << "Folded vreg: " << I->second.first << " MR: "
<< I->second.second;
@ -986,6 +989,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
continue;
}
int SS = VRM.getStackSlot(VirtReg);
FoldedSS.insert(SS);
DOUT << " - StackSlot: " << SS << "\n";
// If this folded instruction is just a use, check to see if it's a
@ -1093,9 +1097,11 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
int FrameIdx;
if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) {
assert(DestReg == VirtReg && "Unknown load situation!");
// If it is a folded reference, then it's not safe to clobber.
bool Folded = FoldedSS.count(FrameIdx);
// Otherwise, if it wasn't available, remember that it is now!
Spills.addAvailable(FrameIdx, &MI, DestReg);
Spills.addAvailable(FrameIdx, &MI, DestReg, !Folded);
goto ProcessNextInst;
}