1 files changed, 8 insertions, 41 deletions

diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.cpp b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
index 2703af7d73b..3b1c843f035 100644
--- a/llvm/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
@@ -322,24 +322,6 @@ static void emitAligningInstructions(MachineFunction &MF, ARMFunctionInfo *AFI,
   }
 }
 
-/// We need the offset of the frame pointer relative to other MachineFrameInfo
-/// offsets which are encoded relative to SP at function begin.
-/// See also emitPrologue() for how the FP is set up.
-/// Unfortunately we cannot determine this value in determineCalleeSaves() yet
-/// as assignCalleeSavedSpillSlots() hasn't run at this point. Instead we use
-/// this to produce a conservative estimate that we check in an assert() later.
-static int getMaxFPOffset(const Function &F, const ARMFunctionInfo &AFI) {
-  // We may end up saving a lot of registers that are higher numbered than the
-  // r7 used for FP in thumb.
-  if (F.hasFnAttribute("interrupt") ||
-      F.getCallingConv() == CallingConv::CXX_FAST_TLS)
-    return -AFI.getArgRegsSaveSize() - (8 * 4);
-
-  // Usually it is just the link register and the FP itself (and in rare cases
-  // r12?) saved to reach FP.
-  return -AFI.getArgRegsSaveSize() - 12;
-}
-
 void ARMFrameLowering::emitPrologue(MachineFunction &MF,
                                     MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator MBBI = MBB.begin();
@@ -450,10 +432,8 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF,
   unsigned DPRCSOffset = GPRCS2Offset - DPRGapSize - DPRCSSize;
   int FramePtrOffsetInPush = 0;
   if (HasFP) {
-    int FPOffset = MFI.getObjectOffset(FramePtrSpillFI);
-    assert(getMaxFPOffset(*MF.getFunction(), *AFI) <= FPOffset &&
-           "Max FP estimation is wrong");
-    FramePtrOffsetInPush = FPOffset + ArgRegsSaveSize;
+    FramePtrOffsetInPush =
+        MFI.getObjectOffset(FramePtrSpillFI) + ArgRegsSaveSize;
     AFI->setFramePtrSpillOffset(MFI.getObjectOffset(FramePtrSpillFI) +
                                 NumBytes);
   }
@@ -1720,14 +1700,6 @@ void ARMFrameLowering::determineCalleeSaves(MachineFunction &MF,
   //        worth the effort and added fragility?
   unsigned EstimatedStackSize =
       MFI.estimateStackSize(MF) + 4 * (NumGPRSpills + NumFPRSpills);
-
-  // Determine biggest (positive) SP offset in MachineFrameInfo.
-  int MaxFixedOffset = 0;
-  for (int I = MFI.getObjectIndexBegin(); I < 0; ++I) {
-    int MaxObjectOffset = MFI.getObjectOffset(I) + MFI.getObjectSize(I);
-    MaxFixedOffset = std::max(MaxFixedOffset, MaxObjectOffset);
-  }
-
   bool HasFP = hasFP(MF);
   if (HasFP) {
     if (AFI->hasStackFrame())
@@ -1735,20 +1707,15 @@ void ARMFrameLowering::determineCalleeSaves(MachineFunction &MF,
   } else {
     // If FP is not used, SP will be used to access arguments, so count the
     // size of arguments into the estimation.
-    EstimatedStackSize += MaxFixedOffset;
+    EstimatedStackSize += AFI->getArgumentStackSize();
   }
   EstimatedStackSize += 16; // For possible paddings.
 
-  unsigned EstimatedRSStackSizeLimit = estimateRSStackSizeLimit(MF, this);
-  int MaxFPOffset = getMaxFPOffset(*MF.getFunction(), *AFI);
-  bool BigFrameOffsets = EstimatedStackSize >= EstimatedRSStackSizeLimit ||
-    MFI.hasVarSizedObjects() ||
-    (MFI.adjustsStack() && !canSimplifyCallFramePseudos(MF)) ||
-    // For large argument stacks fp relative addressed may overflow.
-    (HasFP && (MaxFixedOffset - MaxFPOffset) >= (int)EstimatedRSStackSizeLimit);
+  bool BigStack = EstimatedStackSize >= estimateRSStackSizeLimit(MF, this) ||
+                  MFI.hasVarSizedObjects() ||
+                  (MFI.adjustsStack() && !canSimplifyCallFramePseudos(MF));
   bool ExtraCSSpill = false;
-  if (BigFrameOffsets ||
-      !CanEliminateFrame || RegInfo->cannotEliminateFrame(MF)) {
+  if (BigStack || !CanEliminateFrame || RegInfo->cannotEliminateFrame(MF)) {
     AFI->setHasStackFrame(true);
 
     if (HasFP) {
@@ -1932,7 +1899,7 @@ void ARMFrameLowering::determineCalleeSaves(MachineFunction &MF,
     // callee-saved register or reserve a special spill slot to facilitate
     // register scavenging. Thumb1 needs a spill slot for stack pointer
     // adjustments also, even when the frame itself is small.
-    if (BigFrameOffsets && !ExtraCSSpill) {
+    if (BigStack && !ExtraCSSpill) {
       // If any non-reserved CS register isn't spilled, just spill one or two
       // extra. That should take care of it!
       unsigned NumExtras = TargetAlign / 4;