Change eliminateCallFramePseudoInstr() to return an iterator

This will become necessary in a subsequent change to make this method
merge adjacent stack adjustments, i.e. it might erase the previous
and/or next instruction.

It also greatly simplifies the calls to this function from Prolog-
EpilogInserter. Previously, that had a bunch of logic to resume iteration
after the call; now it just continues with the returned iterator.

Note that this changes the behaviour of PEI a little. Previously,
it attempted to re-visit the new instruction created by
eliminateCallFramePseudoInstr(). That code was added in r36625,
but I can't see any reason for it: the new instructions will obviously
not be pseudo instructions, they will not have FrameIndex operands,
and we have already accounted for the stack adjustment.

Differential Revision: http://reviews.llvm.org/D18627

llvm-svn: 265036

2 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/Target/Lanai/LanaiFrameLowering.cpp b/llvm/lib/Target/Lanai/LanaiFrameLowering.cpp
index da54f6e75c4..e7fd030b9b0 100644
--- a/llvm/lib/Target/Lanai/LanaiFrameLowering.cpp
+++ b/llvm/lib/Target/Lanai/LanaiFrameLowering.cpp
@@ -139,11 +139,11 @@ void LanaiFrameLowering::emitPrologue(MachineFunction &MF,
     replaceAdjDynAllocPseudo(MF);
 }
 
-void LanaiFrameLowering::eliminateCallFramePseudoInstr(
+MachineBasicBlock::iterator LanaiFrameLowering::eliminateCallFramePseudoInstr(
     MachineFunction &MF, MachineBasicBlock &MBB,
     MachineBasicBlock::iterator I) const {
   // Discard ADJCALLSTACKDOWN, ADJCALLSTACKUP instructions.
-  MBB.erase(I);
+  return MBB.erase(I);
 }
 
 // The function epilogue should not depend on the current stack pointer!
diff --git a/llvm/lib/Target/Lanai/LanaiFrameLowering.h b/llvm/lib/Target/Lanai/LanaiFrameLowering.h
index 2027da9e35a..808a96638c0 100644
--- a/llvm/lib/Target/Lanai/LanaiFrameLowering.h
+++ b/llvm/lib/Target/Lanai/LanaiFrameLowering.h
@@ -42,7 +42,7 @@ public:
   void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
   void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
 
-  void
+  MachineBasicBlock::iterator
   eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
                                 MachineBasicBlock::iterator I) const override;