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Local spiller kills a store if the folded restore is turned into a copy.

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But this is incorrect if the spilled value live range extends beyond the
current BB.
It is currently controlled by a temporary option -spiller-check-liveout.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28024 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2006-04-30 08:41:47 +00:00
parent 10a59ce701
commit 200370fb56
3 changed files with 21 additions and 10 deletions
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20
lib/CodeGen/VirtRegMap.cpp
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@@ -50,6 +50,10 @@ namespace {
clEnumVal(local, " local spiller"),
clEnumValEnd),
cl::init(local));
// TEMPORARY option to test a fix.
cl::opt<bool>
SpillerCheckLiveOut("spiller-check-liveout", cl::Hidden);
}
//===----------------------------------------------------------------------===//
@@ -81,7 +85,8 @@ void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int frameIndex) {
}
void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI,
unsigned OpNo, MachineInstr *NewMI) {
unsigned OpNo, MachineInstr *NewMI,
bool LiveOut) {
// Move previous memory references folded to new instruction.
MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(NewMI);
for (MI2VirtMapTy::iterator I = MI2VirtMap.lower_bound(OldMI),
@@ -96,6 +101,7 @@ void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI,
MRInfo = isRef;
} else {
MRInfo = OldMI->getOperand(OpNo).isUse() ? isModRef : isMod;
if (LiveOut) MRInfo = (ModRef)(MRInfo | isLiveOut);
}
// add new memory reference
@@ -727,10 +733,14 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
MaybeDeadStores.erase(MDSI);
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;
assert(!(MR & VirtRegMap::isRef) && "Can't be modref!");
// Don't nuke it if the value is needed in another block.
if (!SpillerCheckLiveOut || !(MR & VirtRegMap::isLiveOut)) {
DEBUG(std::cerr << " Killed store:\t" << *MDSI->second);
MBB.erase(MDSI->second);
MaybeDeadStores.erase(MDSI);
++NumDSE;
}
}
}