4 files changed, 28 insertions, 6 deletions

diff --git a/include/llvm/Target/TargetRegisterInfo.h b/include/llvm/Target/TargetRegisterInfo.h
index 65b60f7a93..212cc93401 100644
--- a/include/llvm/Target/TargetRegisterInfo.h
+++ b/include/llvm/Target/TargetRegisterInfo.h
@@ -587,6 +587,17 @@ public:
     return !hasFP(MF);
   }
 
+  /// canSimplifyCallFramePseudos - When possible, it's best to simplify the
+  /// call frame pseudo ops before doing frame index elimination. This is
+  /// possible only when frame index references between the pseudos won't
+  /// need adjusted for the call frame adjustments. Normally, that's true
+  /// if the function has a reserved call frame or a frame pointer. Some
+  /// targets (Thumb2, for example) may have more complicated criteria,
+  /// however, and can override this behavior.
+  virtual bool canSimplifyCallFramePseudos(MachineFunction &MF) const {
+    return hasReservedCallFrame(MF) || hasFP(MF);
+  }
+
   /// hasReservedSpillSlot - Return true if target has reserved a spill slot in
   /// the stack frame of the given function for the specified register. e.g. On
   /// x86, if the frame register is required, the first fixed stack object is
diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp
index 040259e15c..138e711030 100644
--- a/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/lib/CodeGen/PrologEpilogInserter.cpp
@@ -175,9 +175,10 @@ void PEI::calculateCallsInformation(MachineFunction &Fn) {
     MachineBasicBlock::iterator I = *i;
 
     // If call frames are not being included as part of the stack frame, and
-    // there is no dynamic allocation (therefore referencing frame slots off
-    // sp), leave the pseudo ops alone. We'll eliminate them later.
-    if (RegInfo->hasReservedCallFrame(Fn) || RegInfo->hasFP(Fn))
+    // the target doesn't indicate otherwise, remove the call frame pseudos
+    // here. The sub/add sp instruction pairs are still inserted, but we don't
+    // need to track the SP adjustment for frame index elimination.
+    if (RegInfo->canSimplifyCallFramePseudos(Fn))
       RegInfo->eliminateCallFramePseudoInstr(Fn, *I->getParent(), I);
   }
 }
diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
index 91e3550d07..e1c493ac63 100644
--- a/lib/Target/ARM/ARMBaseRegisterInfo.cpp
+++ b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
@@ -1085,6 +1085,16 @@ hasReservedCallFrame(MachineFunction &MF) const {
   return !MF.getFrameInfo()->hasVarSizedObjects();
 }
 
+// canSimplifyCallFramePseudos - If there is a reserved call frame, the
+// call frame pseudos can be simplified. Unlike most targets, having a FP
+// is not sufficient here since we still may reference some objects via SP
+// even when FP is available in Thumb2 mode.
+bool ARMBaseRegisterInfo::
+canSimplifyCallFramePseudos(MachineFunction &MF) const {
+  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+  return hasReservedCallFrame(MF) || (AFI->isThumb1OnlyFunction() && hasFP(MF));
+}
+
 static void
 emitSPUpdate(bool isARM,
              MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
@@ -1149,7 +1159,6 @@ ARMBaseRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
   MachineInstr &MI = *II;
   MachineBasicBlock &MBB = *MI.getParent();
   MachineFunction &MF = *MBB.getParent();
-  const MachineFrameInfo *MFI = MF.getFrameInfo();
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
   assert(!AFI->isThumb1OnlyFunction() &&
          "This eliminateFrameIndex does not support Thumb1!");
@@ -1160,12 +1169,12 @@ ARMBaseRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
   }
 
   int FrameIndex = MI.getOperand(i).getIndex();
-  int Offset = MFI->getObjectOffset(FrameIndex) + MFI->getStackSize() + SPAdj;
   unsigned FrameReg;
 
-  Offset = getFrameIndexReference(MF, FrameIndex, FrameReg);
+  int Offset = getFrameIndexReference(MF, FrameIndex, FrameReg);
   if (FrameReg != ARM::SP)
     SPAdj = 0;
+  Offset += SPAdj;
 
   // Modify MI as necessary to handle as much of 'Offset' as possible
   bool Done = false;
diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.h b/lib/Target/ARM/ARMBaseRegisterInfo.h
index 33ba21dcb8..64f6ff1cb3 100644
--- a/lib/Target/ARM/ARMBaseRegisterInfo.h
+++ b/lib/Target/ARM/ARMBaseRegisterInfo.h
@@ -138,6 +138,7 @@ public:
   virtual bool requiresFrameIndexScavenging(const MachineFunction &MF) const;
 
   virtual bool hasReservedCallFrame(MachineFunction &MF) const;
+  virtual bool canSimplifyCallFramePseudos(MachineFunction &MF) const;
 
   virtual void eliminateCallFramePseudoInstr(MachineFunction &MF,
                                              MachineBasicBlock &MBB,