X86FrameLowering: No need to mark FP as live-in everywhere

The frame pointer (when used as frame pointer) is a reserved register.
We do not track liveness of reserved registers and hence do not need to
add them to the basic block livein lists.

llvm-svn: 304274

1 files changed, 2 insertions, 7 deletions

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 331e56976db..328a8030460 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -1062,6 +1062,8 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
   }
 
   if (HasFP) {
+    assert(MF.getRegInfo().isReserved(MachineFramePtr) && "FP reserved");
+
     // Calculate required stack adjustment.
     uint64_t FrameSize = StackSize - SlotSize;
     // If required, include space for extra hidden slot for stashing base pointer.
@@ -1124,13 +1126,6 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
                                     nullptr, DwarfFramePtr));
       }
     }
-
-    // Mark the FramePtr as live-in in every block. Don't do this again for
-    // funclet prologues.
-    if (!IsFunclet) {
-      for (MachineBasicBlock &EveryMBB : MF)
-        EveryMBB.addLiveIn(MachineFramePtr);
-    }
   } else {
     assert(!IsFunclet && "funclets without FPs not yet implemented");
     NumBytes = StackSize - X86FI->getCalleeSavedFrameSize();