[LivePhysRegs] Fix handling of return instructions.
See D42509 for the original version of this.
Basically, there are two significant changes to behavior here:
- addLiveOuts always adds all pristine registers (even if a block has
no successors).
- addLiveOuts and addLiveOutsNoPristines always add all callee-saved
registers for return blocks (including conditional return blocks).
I cleaned up the functions a bit to make it clear these properties hold.
Differential Revision: https://reviews.llvm.org/D42655
llvm-svn: 324422
diff --git a/llvm/lib/CodeGen/LivePhysRegs.cpp b/llvm/lib/CodeGen/LivePhysRegs.cpp
index f4b43a9..277212c 100644
--- a/llvm/lib/CodeGen/LivePhysRegs.cpp
+++ b/llvm/lib/CodeGen/LivePhysRegs.cpp
@@ -205,14 +205,18 @@
}
void LivePhysRegs::addLiveOutsNoPristines(const MachineBasicBlock &MBB) {
- if (!MBB.succ_empty()) {
- // To get the live-outs we simply merge the live-ins of all successors.
- for (const MachineBasicBlock *Succ : MBB.successors())
- addBlockLiveIns(*Succ);
- } else if (MBB.isReturnBlock()) {
- // For the return block: Add all callee saved registers that are saved and
- // restored (somewhere); This does not include callee saved registers that
- // are unused and hence not saved and restored; they are called pristine.
+ // To get the live-outs we simply merge the live-ins of all successors.
+ for (const MachineBasicBlock *Succ : MBB.successors())
+ addBlockLiveIns(*Succ);
+ if (MBB.isReturnBlock()) {
+ // Return blocks are a special case because we currently don't mark up
+ // return instructions completely: specifically, there is no explicit
+ // use for callee-saved registers. So we add all callee saved registers
+ // that are saved and restored (somewhere). This does not include
+ // callee saved registers that are unused and hence not saved and
+ // restored; they are called pristine.
+ // FIXME: PEI should add explicit markings to return instructions
+ // instead of implicitly handling them here.
const MachineFunction &MF = *MBB.getParent();
const MachineFrameInfo &MFI = MF.getFrameInfo();
if (MFI.isCalleeSavedInfoValid()) {
@@ -225,15 +229,8 @@
void LivePhysRegs::addLiveOuts(const MachineBasicBlock &MBB) {
const MachineFunction &MF = *MBB.getParent();
- if (!MBB.succ_empty()) {
- addPristines(MF);
- addLiveOutsNoPristines(MBB);
- } else if (MBB.isReturnBlock()) {
- // For the return block: Add all callee saved registers.
- const MachineFrameInfo &MFI = MF.getFrameInfo();
- if (MFI.isCalleeSavedInfoValid())
- addCalleeSavedRegs(*this, MF);
- }
+ addPristines(MF);
+ addLiveOutsNoPristines(MBB);
}
void LivePhysRegs::addLiveIns(const MachineBasicBlock &MBB) {