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Don't assume that an instruction ending a register's live range always reads 

the register; it may be a dead def instead. Fixes PR8820.

llvm-svn: 122218
This commit is contained in:
Cameron Zwarich 2010-12-20 01:22:37 +00:00
parent 46b9efcad7
commit fc0c6b1ea9
1 changed files with 18 additions and 4 deletions
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22
llvm/lib/CodeGen/MachineVerifier.cpp
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@ -1072,10 +1072,24 @@ void MachineVerifier::verifyLiveIntervals() {
<< MBBStartIdx << '\n';
} else if (TargetRegisterInfo::isVirtualRegister(LI.reg) &&
!MI->readsVirtualRegister(LI.reg)) {
// FIXME: Should we require a kill flag?
report("Instruction killing live segment doesn't read register", MI);
I->print(*OS);
*OS << " in " << LI << '\n';
// A live range can end with either a redefinition, a kill flag on a
// use, or a dead flag on a def.
// FIXME: Should we check for each of these?
bool hasDeadDef = false;
for (MachineInstr::const_mop_iterator MOI = MI->operands_begin(),
MOE = MI->operands_end(); MOI != MOE; ++MOI) {
if (MOI->isReg() && MOI->isDef() && MOI->isDead()) {
hasDeadDef = true;
break;
}
}
if (!hasDeadDef) {
report("Instruction killing live segment neither defines nor reads "
"register", MI);
I->print(*OS);
*OS << " in " << LI << '\n';
}
}
}