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

1 files changed, 1 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index 25b73d9b845..84b202128e4 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -891,15 +891,7 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &Fn,
       InsideCallSequence = (I->getOpcode() == FrameSetupOpcode);
       SPAdj += TII.getSPAdjust(I);
 
-      MachineBasicBlock::iterator PrevI = BB->end();
-      if (I != BB->begin()) PrevI = std::prev(I);
-      TFI->eliminateCallFramePseudoInstr(Fn, *BB, I);
-
-      // Visit the instructions created by eliminateCallFramePseudoInstr().
-      if (PrevI == BB->end())
-        I = BB->begin();     // The replaced instr was the first in the block.
-      else
-        I = std::next(PrevI);
+      I = TFI->eliminateCallFramePseudoInstr(Fn, *BB, I);
       continue;
     }