Only erase virtregs with no uses left.
Also make sure registers aren't erased twice if the dead def mentions
the register twice.
This fixes PR12911.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157254 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp
index 4c2b0bf..434388b 100644
--- a/lib/CodeGen/LiveRangeEdit.cpp
+++ b/lib/CodeGen/LiveRangeEdit.cpp
@@ -220,6 +220,9 @@
DEBUG(dbgs() << "Deleting dead def " << Idx << '\t' << *MI);
+ // Collect virtual registers to be erased after MI is gone.
+ SmallVector<unsigned, 8> RegsToErase;
+
// Check for live intervals that may shrink
for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
MOE = MI->operands_end(); MOI != MOE; ++MOI) {
@@ -245,10 +248,8 @@
if (TheDelegate)
TheDelegate->LRE_WillShrinkVirtReg(LI.reg);
LI.removeValNo(VNI);
- if (LI.empty()) {
- ToShrink.remove(&LI);
- eraseVirtReg(Reg);
- }
+ if (LI.empty())
+ RegsToErase.push_back(Reg);
}
}
}
@@ -258,6 +259,16 @@
LIS.RemoveMachineInstrFromMaps(MI);
MI->eraseFromParent();
++NumDCEDeleted;
+
+ // Erase any virtregs that are now empty and unused. There may be <undef>
+ // uses around. Keep the empty live range in that case.
+ for (unsigned i = 0, e = RegsToErase.size(); i != e; ++i) {
+ unsigned Reg = RegsToErase[i];
+ if (LIS.hasInterval(Reg) && MRI.reg_nodbg_empty(Reg)) {
+ ToShrink.remove(&LIS.getInterval(Reg));
+ eraseVirtReg(Reg);
+ }
+ }
}
if (ToShrink.empty())