Fix PR6300.
A virtual register can be used before it is defined in the same MBB if the MBB
is part of a loop. Teach the implicit-def pass about this case.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96279 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ProcessImplicitDefs.cpp b/lib/CodeGen/ProcessImplicitDefs.cpp
index e3df2e4..d7179b3 100644
--- a/lib/CodeGen/ProcessImplicitDefs.cpp
+++ b/lib/CodeGen/ProcessImplicitDefs.cpp
@@ -205,10 +205,9 @@
// Process each use instruction once.
for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(Reg),
UE = mri_->use_end(); UI != UE; ++UI) {
- MachineInstr *RMI = &*UI;
- MachineBasicBlock *RMBB = RMI->getParent();
- if (RMBB == MBB)
+ if (UI.getOperand().isUndef())
continue;
+ MachineInstr *RMI = &*UI;
if (ModInsts.insert(RMI))
RUses.push_back(RMI);
}