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Fix for PR1831: if all defs of an interval are re-materializable, then it's a preferred spill candiate.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44644 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2007-12-06 00:01:56 +00:00
parent bdcb726fca
commit 5ef3a04b54
4 changed files with 58 additions and 8 deletions
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38
lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -607,12 +607,16 @@ LiveInterval LiveIntervals::createInterval(unsigned reg) {
/// isReMaterializable - Returns true if the definition MI of the specified
/// val# of the specified interval is re-materializable.
bool LiveIntervals::isReMaterializable(const LiveInterval &li,
const VNInfo *ValNo, MachineInstr *MI) {
const VNInfo *ValNo, MachineInstr *MI,
bool &isLoad) {
if (DisableReMat)
return false;
if (tii_->isTriviallyReMaterializable(MI))
isLoad = false;
if (tii_->isTriviallyReMaterializable(MI)) {
isLoad = MI->getInstrDescriptor()->Flags & M_LOAD_FLAG;
return true;
}
int FrameIdx = 0;
if (!tii_->isLoadFromStackSlot(MI, FrameIdx) ||
@ -621,6 +625,7 @@ bool LiveIntervals::isReMaterializable(const LiveInterval &li,
// This is a load from fixed stack slot. It can be rematerialized unless it's
// re-defined by a two-address instruction.
isLoad = true;
for (LiveInterval::const_vni_iterator i = li.vni_begin(), e = li.vni_end();
i != e; ++i) {
const VNInfo *VNI = *i;
@ -631,8 +636,32 @@ bool LiveIntervals::isReMaterializable(const LiveInterval &li,
continue; // Dead val#.
MachineInstr *DefMI = (DefIdx == ~0u)
? NULL : getInstructionFromIndex(DefIdx);
if (DefMI && DefMI->isRegReDefinedByTwoAddr(li.reg))
if (DefMI && DefMI->isRegReDefinedByTwoAddr(li.reg)) {
isLoad = false;
return false;
}
}
return true;
}
/// isReMaterializable - Returns true if every definition of MI of every
/// val# of the specified interval is re-materializable.
bool LiveIntervals::isReMaterializable(const LiveInterval &li, bool &isLoad) {
isLoad = false;
for (LiveInterval::const_vni_iterator i = li.vni_begin(), e = li.vni_end();
i != e; ++i) {
const VNInfo *VNI = *i;
unsigned DefIdx = VNI->def;
if (DefIdx == ~1U)
continue; // Dead val#.
// Is the def for the val# rematerializable?
if (DefIdx == ~0u)
return false;
MachineInstr *ReMatDefMI = getInstructionFromIndex(DefIdx);
bool DefIsLoad = false;
if (!ReMatDefMI || !isReMaterializable(li, VNI, ReMatDefMI, DefIsLoad))
return false;
isLoad |= DefIsLoad;
}
return true;
}
@ -1225,7 +1254,8 @@ addIntervalsForSpills(const LiveInterval &li,
// Is the def for the val# rematerializable?
MachineInstr *ReMatDefMI = (DefIdx == ~0u)
? 0 : getInstructionFromIndex(DefIdx);
if (ReMatDefMI && isReMaterializable(li, VNI, ReMatDefMI)) {
bool dummy;
if (ReMatDefMI && isReMaterializable(li, VNI, ReMatDefMI, dummy)) {
// Remember how to remat the def of this val#.
ReMatOrigDefs[VN] = ReMatDefMI;
// Original def may be modified so we have to make a copy here. vrm must