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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122218 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineVerifier.cpp b/lib/CodeGen/MachineVerifier.cpp
index 4025e29..d0f251e 100644
--- a/lib/CodeGen/MachineVerifier.cpp
+++ b/lib/CodeGen/MachineVerifier.cpp
@@ -1072,10 +1072,24 @@
<< 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';
+ }
}
}