From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Mon, 27 Jun 2011 15:00:36 +0000 (+0000)
Subject: Track live-out physical registers in MachineDCE.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=f27229ee5ad121247b9c79e7605b19fccf781d8d;p=oota-llvm.git

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 fdc1d914214..6de6c0cb81b 100644
--- a/lib/CodeGen/DeadMachineInstructionElim.cpp
+++ b/lib/CodeGen/DeadMachineInstructionElim.cpp
@@ -110,9 +110,14 @@ bool DeadMachineInstructionElim::runOnMachineFunction(MachineFunction &MF) {
           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.