Miscellaneous clean-ups based on Evan's feedback:

- Cleaned up how the prologue-epilogue inserter loops over the instructions.
- Instead of restarting the processing of an instruction if we remove an
  implicit kill, just update the end iterator and make sure that the iterator
  isn't incremented.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47870 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 52 insertions, 42 deletions

diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp
index d14d710..4a00ea0 100644
--- a/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/lib/CodeGen/PrologEpilogInserter.cpp
@@ -517,53 +517,63 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) {
     for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
       MachineInstr *MI = I;
 
-      if (I->getOpcode() == FrameSetupOpcode ||
-          I->getOpcode() == FrameDestroyOpcode) {
-        // Remember how much SP has been adjustment to create the call frame.
-        int Size = I->getOperand(0).getImm();
-        if ((!StackGrowsDown && I->getOpcode() == FrameSetupOpcode) ||
-            (StackGrowsDown && I->getOpcode() == FrameDestroyOpcode))
-          Size = -Size;
-        SPAdj += Size;
-        MachineBasicBlock::iterator PrevI = prior(I);
-        TRI.eliminateCallFramePseudoInstr(Fn, *BB, I);
-        // Visit the instructions created by eliminateCallFramePseudoInstr().
-        I = next(PrevI);
-        MI = NULL;
-      } else if (I->getOpcode() == TargetInstrInfo::DECLARE) {
+      if (I->getOpcode() == TargetInstrInfo::DECLARE) {
         // Ignore it.
         ++I;
-      } else {
-        bool DoIncr = true;
-
-        for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
-          if (MI->getOperand(i).isFrameIndex()) {
-            // Some instructions (e.g. inline asm instructions) can have
-            // multiple frame indices and/or cause eliminateFrameIndex to insert
-            // more than one instruction. We need the register scavenger to go
-            // through all of these instructions so that it can update its
-            // register information. We keep the iterator at the point before
-            // insertion so that we can revisit them in full.
-            bool AtBeginning = (I == BB->begin());
-            if (!AtBeginning) --I;
-
-            // If this instruction has a FrameIndex operand, we need to use that
-            // target machine register info object to eliminate it.
-            TRI.eliminateFrameIndex(MI, SPAdj, RS);
-
-            // Reset the iterator if we were at the beginning of the BB.
-            if (AtBeginning) {
-              I = BB->begin();
-              DoIncr = false;
-            }
-
-            MI = 0;
-            break;
-          }
+	continue;
+      }
+
+      if (I->getOpcode() == FrameSetupOpcode ||
+          I->getOpcode() == FrameDestroyOpcode) {
+        // Remember how much SP has been adjusted to create the call
+        // frame.
+	int Size = I->getOperand(0).getImm();
+
+	if ((!StackGrowsDown && I->getOpcode() == FrameSetupOpcode) ||
+	    (StackGrowsDown && I->getOpcode() == FrameDestroyOpcode))
+	  Size = -Size;
 
-        if (DoIncr) ++I;
+	SPAdj += Size;
+
+	MachineBasicBlock::iterator PrevI = prior(I);
+	TRI.eliminateCallFramePseudoInstr(Fn, *BB, I);
+
+	// Visit the instructions created by eliminateCallFramePseudoInstr().
+	I = next(PrevI);
+	continue;
       }
 
+      bool DoIncr = true;
+
+      for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
+	if (MI->getOperand(i).isFrameIndex()) {
+	  // Some instructions (e.g. inline asm instructions) can have
+	  // multiple frame indices and/or cause eliminateFrameIndex
+	  // to insert more than one instruction. We need the register
+	  // scavenger to go through all of these instructions so that
+	  // it can update its register information. We keep the
+	  // iterator at the point before insertion so that we can
+	  // revisit them in full.
+	  bool AtBeginning = (I == BB->begin());
+	  if (!AtBeginning) --I;
+
+	  // If this instruction has a FrameIndex operand, we need to
+	  // use that target machine register info object to eliminate
+	  // it.
+	  TRI.eliminateFrameIndex(MI, SPAdj, RS);
+
+	  // Reset the iterator if we were at the beginning of the BB.
+	  if (AtBeginning) {
+	    I = BB->begin();
+	    DoIncr = false;
+	  }
+
+	  MI = 0;
+	  break;
+	}
+
+      if (DoIncr) ++I;
+
       // Update register states.
       if (RS && MI) RS->forward(MI);
     }