Fix a register scavenger crash when dealing with undefined subregs.
The LowerSubregs pass needs to preserve implicit def operands attached to
EXTRACT_SUBREG instructions when it replaces those instructions with copies.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107189 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LowerSubregs.cpp b/lib/CodeGen/LowerSubregs.cpp
index 78d8de4..2dfd07f 100644
--- a/lib/CodeGen/LowerSubregs.cpp
+++ b/lib/CodeGen/LowerSubregs.cpp
@@ -62,6 +62,7 @@
void TransferKillFlag(MachineInstr *MI, unsigned SrcReg,
const TargetRegisterInfo *TRI,
bool AddIfNotFound = false);
+ void TransferImplicitDefs(MachineInstr *MI);
};
char LowerSubregsInstructionPass::ID = 0;
@@ -104,6 +105,22 @@
}
}
+/// TransferImplicitDefs - MI is a pseudo-instruction, and the lowered
+/// replacement instructions immediately precede it. Copy any implicit-def
+/// operands from MI to the replacement instruction.
+void
+LowerSubregsInstructionPass::TransferImplicitDefs(MachineInstr *MI) {
+ MachineBasicBlock::iterator CopyMI = MI;
+ --CopyMI;
+
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg() || !MO.isImplicit() || MO.isUse())
+ continue;
+ CopyMI->addOperand(MachineOperand::CreateReg(MO.getReg(), true, true));
+ }
+}
+
bool LowerSubregsInstructionPass::LowerExtract(MachineInstr *MI) {
MachineBasicBlock *MBB = MI->getParent();
@@ -149,6 +166,7 @@
TransferDeadFlag(MI, DstReg, TRI);
if (MI->getOperand(1).isKill())
TransferKillFlag(MI, SuperReg, TRI, true);
+ TransferImplicitDefs(MI);
DEBUG({
MachineBasicBlock::iterator dMI = MI;
dbgs() << "subreg: " << *(--dMI);