Teach live intervals to not crash on dead livein regs
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23206 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 0f43c1b..bac4b70 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -131,10 +131,10 @@
for (MachineFunction::livein_iterator I = fn.livein_begin(),
E = fn.livein_end(); I != E; ++I) {
handlePhysicalRegisterDef(Entry, Entry->begin(),
- getOrCreateInterval(I->first), 0, 0);
+ getOrCreateInterval(I->first), 0, 0, true);
for (const unsigned* AS = mri_->getAliasSet(I->first); *AS; ++AS)
handlePhysicalRegisterDef(Entry, Entry->begin(),
- getOrCreateInterval(*AS), 0, 0);
+ getOrCreateInterval(*AS), 0, 0, true);
}
}
@@ -478,7 +478,8 @@
void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock *MBB,
MachineBasicBlock::iterator mi,
LiveInterval& interval,
- unsigned SrcReg, unsigned DestReg)
+ unsigned SrcReg, unsigned DestReg,
+ bool isLiveIn)
{
// A physical register cannot be live across basic block, so its
// lifetime must end somewhere in its defining basic block.
@@ -501,9 +502,7 @@
// If it is not dead on definition, it must be killed by a
// subsequent instruction. Hence its interval is:
// [defSlot(def), useSlot(kill)+1)
- while (true) {
- ++mi;
- assert(mi != MBB->end() && "physreg was not killed in defining block!");
+ while (++mi != MBB->end()) {
baseIndex += InstrSlots::NUM;
if (lv_->KillsRegister(mi, interval.reg)) {
DEBUG(std::cerr << " killed");
@@ -511,6 +510,12 @@
goto exit;
}
}
+
+ // The only case we should have a dead physreg here without a killing or
+ // instruction where we know it's dead is if it is live-in to the function
+ // and never used.
+ assert(isLiveIn && "physreg was not killed in defining block!");
+ end = getDefIndex(start) + 1; // It's dead.
exit:
assert(start < end && "did not find end of interval?");