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A value defined by an implicit_def can be liven to a use BB. This is unfortunate. But register allocator still has to add it to the live-in set of the use BB.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72889 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2009-06-04 20:28:22 +00:00
parent cd0c4ac7fb
commit 550aacb978
1 changed files with 18 additions and 0 deletions
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18
lib/CodeGen/RegAllocLinearScan.cpp
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@ -542,6 +542,24 @@ void RALinScan::linearScan()
// Ignore splited live intervals.
if (!isPhys && vrm_->getPreSplitReg(cur.reg))
continue;
// A register defined by an implicit_def can be liveout the def BB and livein
// to a use BB. Add it to the livein set of the use BB's.
if (!isPhys && cur.empty()) {
if (MachineInstr *DefMI = mri_->getVRegDef(cur.reg)) {
assert(DefMI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF);
MachineBasicBlock *DefMBB = DefMI->getParent();
SmallPtrSet<MachineBasicBlock*, 4> Seen;
Seen.insert(DefMBB);
for (MachineRegisterInfo::reg_iterator ri = mri_->reg_begin(cur.reg),
re = mri_->reg_end(); ri != re; ++ri) {
MachineInstr *UseMI = &*ri;
MachineBasicBlock *UseMBB = UseMI->getParent();
if (Seen.insert(UseMBB))
UseMBB->addLiveIn(Reg);
}
}
}
for (LiveInterval::Ranges::const_iterator I = cur.begin(), E = cur.end();
I != E; ++I) {
const LiveRange &LR = *I;