Track live-out physical registers in MachineDCE.
Patch by Sanjoy Das!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133910 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/DeadMachineInstructionElim.cpp b/lib/CodeGen/DeadMachineInstructionElim.cpp
index fdc1d91..6de6c0c 100644
--- a/lib/CodeGen/DeadMachineInstructionElim.cpp
+++ b/lib/CodeGen/DeadMachineInstructionElim.cpp
@@ -110,9 +110,14 @@
LivePhysRegs.set(Reg);
}
- // FIXME: Add live-ins from sucessors to LivePhysRegs. Normally, physregs
- // are not live across blocks, but some targets (x86) can have flags live
- // out of a block.
+ // Add live-ins from sucessors to LivePhysRegs. Normally, physregs are not
+ // live across blocks, but some targets (x86) can have flags live out of a
+ // block.
+ for (MachineBasicBlock::succ_iterator S = MBB->succ_begin(),
+ E = MBB->succ_end(); S != E; S++)
+ for (MachineBasicBlock::livein_iterator LI = (*S)->livein_begin();
+ LI != (*S)->livein_end(); LI++)
+ LivePhysRegs.set(*LI);
// Now scan the instructions and delete dead ones, tracking physreg
// liveness as we go.