vendor/llvm/llvm-trunk-r300890

1 files changed, 37 insertions, 13 deletions

diff --git a/lib/Target/ARM/ARMFrameLowering.cpp b/lib/Target/ARM/ARMFrameLowering.cpp
index 37be22bed540..70dbe1bc5b95 100644
--- a/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/lib/Target/ARM/ARMFrameLowering.cpp
@@ -322,6 +322,18 @@ 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) {
+  // This is a conservative estimation: Assume the frame pointer being r7 and
+  // pc("r15") up to r8 getting spilled before (= 8 registers).
+  return -AFI.getArgRegsSaveSize() - (8 * 4);
+}
+
 void ARMFrameLowering::emitPrologue(MachineFunction &MF,
                                     MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator MBBI = MBB.begin();
@@ -432,8 +444,10 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF,
   unsigned DPRCSOffset = GPRCS2Offset - DPRGapSize - DPRCSSize;
   int FramePtrOffsetInPush = 0;
   if (HasFP) {
-    FramePtrOffsetInPush =
-        MFI.getObjectOffset(FramePtrSpillFI) + ArgRegsSaveSize;
+    int FPOffset = MFI.getObjectOffset(FramePtrSpillFI);
+    assert(getMaxFPOffset(*MF.getFunction(), *AFI) <= FPOffset &&
+           "Max FP estimation is wrong");
+    FramePtrOffsetInPush = FPOffset + ArgRegsSaveSize;
     AFI->setFramePtrSpillOffset(MFI.getObjectOffset(FramePtrSpillFI) +
                                 NumBytes);
   }
@@ -1700,6 +1714,14 @@ 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())
@@ -1707,15 +1729,20 @@ 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 += AFI->getArgumentStackSize();
+    EstimatedStackSize += MaxFixedOffset;
   }
   EstimatedStackSize += 16; // For possible paddings.
 
-  bool BigStack = EstimatedStackSize >= estimateRSStackSizeLimit(MF, this) ||
-                  MFI.hasVarSizedObjects() ||
-                  (MFI.adjustsStack() && !canSimplifyCallFramePseudos(MF));
+  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 ExtraCSSpill = false;
-  if (BigStack || !CanEliminateFrame || RegInfo->cannotEliminateFrame(MF)) {
+  if (BigFrameOffsets ||
+      !CanEliminateFrame || RegInfo->cannotEliminateFrame(MF)) {
     AFI->setHasStackFrame(true);
 
     if (HasFP) {
@@ -1899,7 +1926,7 @@ 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 (BigStack && !ExtraCSSpill) {
+    if (BigFrameOffsets && !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;
@@ -1958,7 +1985,7 @@ MachineBasicBlock::iterator ARMFrameLowering::eliminateCallFramePseudoInstr(
     // ADJCALLSTACKUP   -> add, sp, sp, amount
     MachineInstr &Old = *I;
     DebugLoc dl = Old.getDebugLoc();
-    unsigned Amount = Old.getOperand(0).getImm();
+    unsigned Amount = TII.getFrameSize(Old);
     if (Amount != 0) {
       // We need to keep the stack aligned properly.  To do this, we round the
       // amount of space needed for the outgoing arguments up to the next
@@ -1976,14 +2003,11 @@ MachineBasicBlock::iterator ARMFrameLowering::eliminateCallFramePseudoInstr(
       ARMCC::CondCodes Pred =
           (PIdx == -1) ? ARMCC::AL
                        : (ARMCC::CondCodes)Old.getOperand(PIdx).getImm();
+      unsigned PredReg = TII.getFramePred(Old);
       if (Opc == ARM::ADJCALLSTACKDOWN || Opc == ARM::tADJCALLSTACKDOWN) {
-        // Note: PredReg is operand 2 for ADJCALLSTACKDOWN.
-        unsigned PredReg = Old.getOperand(2).getReg();
         emitSPUpdate(isARM, MBB, I, dl, TII, -Amount, MachineInstr::NoFlags,
                      Pred, PredReg);
       } else {
-        // Note: PredReg is operand 3 for ADJCALLSTACKUP.
-        unsigned PredReg = Old.getOperand(3).getReg();
         assert(Opc == ARM::ADJCALLSTACKUP || Opc == ARM::tADJCALLSTACKUP);
         emitSPUpdate(isARM, MBB, I, dl, TII, Amount, MachineInstr::NoFlags,
                      Pred, PredReg);