[ARM][LowOverheadLoops] Update liveness info
Recommitting e93e0d413f3a after reverting due to test failures, which
will hopefully now be fixed. Original commit message:
After expanding the pseudo instructions, update the liveness info.
We do this in a post-order traversal of the loop, including its
exit blocks and preheader(s).
Differential Revision: https://reviews.llvm.org/D72131
diff --git a/llvm/lib/CodeGen/LivePhysRegs.cpp b/llvm/lib/CodeGen/LivePhysRegs.cpp
index 7a5cffc..547970e 100644
--- a/llvm/lib/CodeGen/LivePhysRegs.cpp
+++ b/llvm/lib/CodeGen/LivePhysRegs.cpp
@@ -276,6 +276,7 @@
const MachineFunction &MF = *MBB.getParent();
const MachineRegisterInfo &MRI = MF.getRegInfo();
const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
+ const MachineFrameInfo &MFI = MF.getFrameInfo();
// We walk through the block backwards and start with the live outs.
LivePhysRegs LiveRegs;
@@ -294,6 +295,18 @@
assert(Register::isPhysicalRegister(Reg));
bool IsNotLive = LiveRegs.available(MRI, Reg);
+
+ // Special-case return instructions for cases when a return is not
+ // the last instruction in the block.
+ if (MI.isReturn() && MFI.isCalleeSavedInfoValid()) {
+ for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo()) {
+ if (Info.getReg() == Reg) {
+ IsNotLive = !Info.isRestored();
+ break;
+ }
+ }
+ }
+
MO->setIsDead(IsNotLive);
}