Revert r110655, "Fix ARM hasFP() semantics. It should return true whenever FP

register is", it breaks a couple test-suite tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110701 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 63 insertions, 68 deletions

diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
index c8cc8706f6..ee1a82e737 100644
--- a/lib/Target/ARM/ARMBaseRegisterInfo.cpp
+++ b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
@@ -177,7 +177,7 @@ getReservedRegs(const MachineFunction &MF) const {
   Reserved.set(ARM::SP);
   Reserved.set(ARM::PC);
   Reserved.set(ARM::FPSCR);
-  if (hasFP(MF))
+  if (STI.isTargetDarwin() || hasFP(MF))
     Reserved.set(FramePtr);
   // Some targets reserve R9.
   if (STI.isR9Reserved())
@@ -194,7 +194,7 @@ bool ARMBaseRegisterInfo::isReservedReg(const MachineFunction &MF,
     return true;
   case ARM::R7:
   case ARM::R11:
-    if (FramePtr == Reg && hasFP(MF))
+    if (FramePtr == Reg && (STI.isTargetDarwin() || hasFP(MF)))
       return true;
     break;
   case ARM::R9:
@@ -511,7 +511,7 @@ ARMBaseRegisterInfo::getAllocationOrder(const TargetRegisterClass *RC,
       return std::make_pair(RC->allocation_order_begin(MF),
                             RC->allocation_order_end(MF));
 
-    if (!hasFP(MF)) {
+    if (!STI.isTargetDarwin() && !hasFP(MF)) {
       if (!STI.isR9Reserved())
         return std::make_pair(GPREven1,
                               GPREven1 + (sizeof(GPREven1)/sizeof(unsigned)));
@@ -540,7 +540,7 @@ ARMBaseRegisterInfo::getAllocationOrder(const TargetRegisterClass *RC,
       return std::make_pair(RC->allocation_order_begin(MF),
                             RC->allocation_order_end(MF));
 
-    if (!hasFP(MF)) {
+    if (!STI.isTargetDarwin() && !hasFP(MF)) {
       if (!STI.isR9Reserved())
         return std::make_pair(GPROdd1,
                               GPROdd1 + (sizeof(GPROdd1)/sizeof(unsigned)));
@@ -610,10 +610,6 @@ ARMBaseRegisterInfo::UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
 /// or if frame pointer elimination is disabled.
 ///
 bool ARMBaseRegisterInfo::hasFP(const MachineFunction &MF) const {
-  // Mac OS X requires FP not to be clobbered for backtracing purpose.
-  if (STI.isTargetDarwin())
-    return true;
-
   const MachineFrameInfo *MFI = MF.getFrameInfo();
   // Always eliminate non-leaf frame pointers.
   return ((DisableFramePointerElim(MF) && MFI->hasCalls()) ||
@@ -687,7 +683,6 @@ static unsigned estimateStackSize(MachineFunction &MF) {
 /// instructions will require a scratch register during their expansion later.
 unsigned
 ARMBaseRegisterInfo::estimateRSStackSizeLimit(MachineFunction &MF) const {
-  const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
   unsigned Limit = (1 << 12) - 1;
   for (MachineFunction::iterator BB = MF.begin(),E = MF.end(); BB != E; ++BB) {
     for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end();
@@ -713,10 +708,7 @@ ARMBaseRegisterInfo::estimateRSStackSizeLimit(MachineFunction &MF) const {
           Limit = std::min(Limit, ((1U << 8) - 1) * 4);
           break;
         case ARMII::AddrModeT2_i12:
-          // i12 supports only positive offset so these will be converted to
-          // i8 opcodes. See llvm::rewriteT2FrameIndex.
-          if (hasFP(MF) && AFI->hasStackFrame())
-            Limit = std::min(Limit, (1U << 8) - 1);
+          if (hasFP(MF)) Limit = std::min(Limit, (1U << 8) - 1);
           break;
         case ARMII::AddrMode6:
           // Addressing mode 6 (load/store) instructions can't encode an
@@ -868,9 +860,8 @@ ARMBaseRegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
   //        and which instructions will need a scratch register for them. Is it
   //        worth the effort and added fragility?
   bool BigStack =
-    (RS &&
-     (estimateStackSize(MF) + ((hasFP(MF) && AFI->hasStackFrame()) ? 4:0) >=
-      estimateRSStackSizeLimit(MF)))
+    (RS && (estimateStackSize(MF) + (hasFP(MF) ? 4:0) >=
+            estimateRSStackSizeLimit(MF)))
     || MFI->hasVarSizedObjects()
     || (MFI->adjustsStack() && !canSimplifyCallFramePseudos(MF));
 
@@ -890,7 +881,9 @@ ARMBaseRegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
       ExtraCSSpill = true;
     }
 
-    if (hasFP(MF)) {
+    // Darwin ABI requires FP to point to the stack slot that contains the
+    // previous FP.
+    if (STI.isTargetDarwin() || hasFP(MF)) {
       MF.getRegInfo().setPhysRegUsed(FramePtr);
       NumGPRSpills++;
     }
@@ -983,7 +976,7 @@ unsigned ARMBaseRegisterInfo::getRARegister() const {
 
 unsigned 
 ARMBaseRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
-  if (hasFP(MF))
+  if (STI.isTargetDarwin() || hasFP(MF))
     return FramePtr;
   return ARM::SP;
 }
@@ -1553,8 +1546,7 @@ emitPrologue(MachineFunction &MF) const {
   // Otherwise, if this is not Darwin, all the callee-saved registers go
   // into spill area 1, including the FP in R11.  In either case, it is
   // now safe to emit this assignment.
-  bool HasFP = hasFP(MF);
-  if (HasFP) {
+  if (STI.isTargetDarwin() || hasFP(MF)) {
     unsigned ADDriOpc = !AFI->isThumbFunction() ? ARM::ADDri : ARM::t2ADDri;
     MachineInstrBuilder MIB =
       BuildMI(MBB, MBBI, dl, TII.get(ADDriOpc), FramePtr)
@@ -1573,7 +1565,7 @@ emitPrologue(MachineFunction &MF) const {
   unsigned DPRCSOffset  = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
   unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
   unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
-  if (HasFP)
+  if (STI.isTargetDarwin() || hasFP(MF))
     AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) +
                                 NumBytes);
   AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
@@ -1585,14 +1577,11 @@ emitPrologue(MachineFunction &MF) const {
   if (NumBytes) {
     // Adjust SP after all the callee-save spills.
     emitSPUpdate(isARM, MBB, MBBI, dl, TII, -NumBytes);
-    if (HasFP)
-      AFI->setShouldRestoreSPFromFP(true);
   }
 
   if (STI.isTargetELF() && hasFP(MF)) {
     MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
                              AFI->getFramePtrSpillOffset());
-    AFI->setShouldRestoreSPFromFP(true);
   }
 
   AFI->setGPRCalleeSavedArea1Size(GPRCS1Size);
@@ -1625,8 +1614,6 @@ emitPrologue(MachineFunction &MF) const {
       BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVtgpr2gpr), ARM::SP)
         .addReg(ARM::R4, RegState::Kill);
     }
-
-    AFI->setShouldRestoreSPFromFP(true);
   }
 }
 
@@ -1682,25 +1669,34 @@ emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const {
                  AFI->getGPRCalleeSavedArea2Size() +
                  AFI->getDPRCalleeSavedAreaSize());
 
-    // Reset SP based on frame pointer only if the stack frame extends beyond
-    // frame pointer stack slot or target is ELF and the function has FP.
-    if (AFI->shouldRestoreSPFromFP()) {
+    // Darwin ABI requires FP to point to the stack slot that contains the
+    // previous FP.
+    bool HasFP = hasFP(MF);
+    if ((STI.isTargetDarwin() && NumBytes) || HasFP) {
       NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
-      if (NumBytes) {
-        if (isARM)
-          emitARMRegPlusImmediate(MBB, MBBI, dl, ARM::SP, FramePtr, -NumBytes,
-                                  ARMCC::AL, 0, TII);
-        else
-          emitT2RegPlusImmediate(MBB, MBBI, dl, ARM::SP, FramePtr, -NumBytes,
-                                 ARMCC::AL, 0, TII);
-      } else {
-        // Thumb2 or ARM.
-        if (isARM)
-          BuildMI(MBB, MBBI, dl, TII.get(ARM::MOVr), ARM::SP)
-            .addReg(FramePtr).addImm((unsigned)ARMCC::AL).addReg(0).addReg(0);
-        else
-          BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVgpr2gpr), ARM::SP)
-            .addReg(FramePtr);
+      // Reset SP based on frame pointer only if the stack frame extends beyond
+      // frame pointer stack slot or target is ELF and the function has FP.
+      if (HasFP ||
+          AFI->getGPRCalleeSavedArea2Size() ||
+          AFI->getDPRCalleeSavedAreaSize()  ||
+          AFI->getDPRCalleeSavedAreaOffset()) {
+        if (NumBytes) {
+          if (isARM)
+            emitARMRegPlusImmediate(MBB, MBBI, dl, ARM::SP, FramePtr, -NumBytes,
+                                    ARMCC::AL, 0, TII);
+          else
+            emitT2RegPlusImmediate(MBB, MBBI, dl, ARM::SP, FramePtr, -NumBytes,
+                                    ARMCC::AL, 0, TII);
+        } else {
+          // Thumb2 or ARM.
+          if (isARM)
+            BuildMI(MBB, MBBI, dl, TII.get(ARM::MOVr), ARM::SP)
+              .addReg(FramePtr)
+              .addImm((unsigned)ARMCC::AL).addReg(0).addReg(0);
+          else
+            BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVgpr2gpr), ARM::SP)
+              .addReg(FramePtr);
+        }
       }
     } else if (NumBytes)
       emitSPUpdate(isARM, MBB, MBBI, dl, TII, NumBytes);
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index c3d60ad9e6..db550b1c42 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -742,15 +742,14 @@ Sched::Preference ARMTargetLowering::getSchedulingPreference(SDNode *N) const {
 unsigned
 ARMTargetLowering::getRegPressureLimit(const TargetRegisterClass *RC,
                                        MachineFunction &MF) const {
+  unsigned FPDiff = RegInfo->hasFP(MF) ? 1 : 0;
   switch (RC->getID()) {
   default:
     return 0;
   case ARM::tGPRRegClassID:
-    return RegInfo->hasFP(MF) ? 4 : 5;
-  case ARM::GPRRegClassID: {
-    unsigned FP = RegInfo->hasFP(MF) ? 1 : 0;
-    return 10 - FP - (Subtarget->isR9Reserved() ? 1 : 0);
-  }
+    return 5 - FPDiff;
+  case ARM::GPRRegClassID:
+    return 10 - FPDiff - (Subtarget->isR9Reserved() ? 1 : 0);
   case ARM::SPRRegClassID:  // Currently not used as 'rep' register class.
   case ARM::DPRRegClassID:
     return 32 - 10;
diff --git a/lib/Target/ARM/ARMMachineFunctionInfo.h b/lib/Target/ARM/ARMMachineFunctionInfo.h
index 514c26b4da..7e57a1ca55 100644
--- a/lib/Target/ARM/ARMMachineFunctionInfo.h
+++ b/lib/Target/ARM/ARMMachineFunctionInfo.h
@@ -43,10 +43,6 @@ class ARMFunctionInfo : public MachineFunctionInfo {
   /// processFunctionBeforeCalleeSavedScan().
   bool HasStackFrame;
 
-  /// RestoreSPFromFP - True if epilogue should restore SP from FP. Set by
-  /// emitPrologue.
-  bool RestoreSPFromFP;
-
   /// LRSpilledForFarJump - True if the LR register has been for spilled to
   /// enable far jump.
   bool LRSpilledForFarJump;
@@ -99,7 +95,7 @@ public:
   ARMFunctionInfo() :
     isThumb(false),
     hasThumb2(false),
-    VarArgsRegSaveSize(0), HasStackFrame(false), RestoreSPFromFP(false),
+    VarArgsRegSaveSize(0), HasStackFrame(false),
     LRSpilledForFarJump(false),
     FramePtrSpillOffset(0), GPRCS1Offset(0), GPRCS2Offset(0), DPRCSOffset(0),
     GPRCS1Size(0), GPRCS2Size(0), DPRCSSize(0),
@@ -110,7 +106,7 @@ public:
   explicit ARMFunctionInfo(MachineFunction &MF) :
     isThumb(MF.getTarget().getSubtarget<ARMSubtarget>().isThumb()),
     hasThumb2(MF.getTarget().getSubtarget<ARMSubtarget>().hasThumb2()),
-    VarArgsRegSaveSize(0), HasStackFrame(false), RestoreSPFromFP(false),
+    VarArgsRegSaveSize(0), HasStackFrame(false),
     LRSpilledForFarJump(false),
     FramePtrSpillOffset(0), GPRCS1Offset(0), GPRCS2Offset(0), DPRCSOffset(0),
     GPRCS1Size(0), GPRCS2Size(0), DPRCSSize(0),
@@ -129,9 +125,6 @@ public:
   bool hasStackFrame() const { return HasStackFrame; }
   void setHasStackFrame(bool s) { HasStackFrame = s; }
 
-  bool shouldRestoreSPFromFP() const { return RestoreSPFromFP; }
-  void setShouldRestoreSPFromFP(bool s) { RestoreSPFromFP = s; }
-
   bool isLRSpilledForFarJump() const { return LRSpilledForFarJump; }
   void setLRIsSpilledForFarJump(bool s) { LRSpilledForFarJump = s; }
 
diff --git a/lib/Target/ARM/ARMRegisterInfo.td b/lib/Target/ARM/ARMRegisterInfo.td
index 2b72739c30..5e17175b97 100644
--- a/lib/Target/ARM/ARMRegisterInfo.td
+++ b/lib/Target/ARM/ARMRegisterInfo.td
@@ -294,7 +294,8 @@ def GPR : RegisterClass<"ARM", [i32], 32, [R0, R1, R2, R3, R4, R5, R6,
 
       if (Subtarget.isThumb1Only()) {
         I = THUMB_GPR_AO + (sizeof(THUMB_GPR_AO)/sizeof(unsigned));
-        return RI->hasFP(MF) ? I-1 : I;
+        // Mac OS X requires FP not to be clobbered for backtracing purpose.
+        return (Subtarget.isTargetDarwin() || RI->hasFP(MF)) ? I-1 : I;
       }
 
       if (Subtarget.isTargetDarwin()) {
@@ -311,7 +312,8 @@ def GPR : RegisterClass<"ARM", [i32], 32, [R0, R1, R2, R3, R4, R5, R6,
           I = ARM_GPR_AO_1 + (sizeof(ARM_GPR_AO_1)/sizeof(unsigned));
       }
 
-      return RI->hasFP(MF) ? I-1 : I;
+      // Mac OS X requires FP not to be clobbered for backtracing purpose.
+      return (Subtarget.isTargetDarwin() || RI->hasFP(MF)) ? I-1 : I;
     }
   }];
 }
@@ -401,7 +403,8 @@ def rGPR : RegisterClass<"ARM", [i32], 32, [R0, R1, R2, R3, R4, R5, R6,
 
       if (Subtarget.isThumb1Only()) {
         I = THUMB_rGPRAO + (sizeof(THUMB_rGPRAO)/sizeof(unsigned));
-        return RI->hasFP(MF) ? I-1 : I;
+        // Mac OS X requires FP not to be clobbered for backtracing purpose.
+        return (Subtarget.isTargetDarwin() || RI->hasFP(MF)) ? I-1 : I;
       }
 
       if (Subtarget.isTargetDarwin()) {
@@ -418,7 +421,8 @@ def rGPR : RegisterClass<"ARM", [i32], 32, [R0, R1, R2, R3, R4, R5, R6,
           I = ARM_rGPRAO_1 + (sizeof(ARM_rGPRAO_1)/sizeof(unsigned));
       }
 
-      return RI->hasFP(MF) ? I-1 : I;
+      // Mac OS X requires FP not to be clobbered for backtracing purpose.
+      return (Subtarget.isTargetDarwin() || RI->hasFP(MF)) ? I-1 : I;
     }
   }];
 }
@@ -445,9 +449,11 @@ def tGPR : RegisterClass<"ARM", [i32], 32, [R0, R1, R2, R3, R4, R5, R6, R7]> {
     tGPRClass::allocation_order_end(const MachineFunction &MF) const {
       const TargetMachine &TM = MF.getTarget();
       const TargetRegisterInfo *RI = TM.getRegisterInfo();
+      const ARMSubtarget &Subtarget = TM.getSubtarget<ARMSubtarget>();
       tGPRClass::iterator I =
         THUMB_tGPR_AO + (sizeof(THUMB_tGPR_AO)/sizeof(unsigned));
-      return RI->hasFP(MF) ? I-1 : I;
+      // Mac OS X requires FP not to be clobbered for backtracing purpose.
+      return (Subtarget.isTargetDarwin() || RI->hasFP(MF)) ? I-1 : I;
     }
   }];
 }
diff --git a/lib/Target/ARM/Thumb1RegisterInfo.cpp b/lib/Target/ARM/Thumb1RegisterInfo.cpp
index 50328e3760..9ae3145389 100644
--- a/lib/Target/ARM/Thumb1RegisterInfo.cpp
+++ b/lib/Target/ARM/Thumb1RegisterInfo.cpp
@@ -742,11 +742,11 @@ void Thumb1RegisterInfo::emitPrologue(MachineFunction &MF) const {
       dl = MBBI->getDebugLoc();
   }
 
-  // Adjust FP so it point to the stack slot that contains the previous FP.
-  if (hasFP(MF)) {
+  // Darwin ABI requires FP to point to the stack slot that contains the
+  // previous FP.
+  if (STI.isTargetDarwin() || hasFP(MF)) {
     BuildMI(MBB, MBBI, dl, TII.get(ARM::tADDrSPi), FramePtr)
       .addFrameIndex(FramePtrSpillFI).addImm(0);
-    AFI->setShouldRestoreSPFromFP(true);
   }
 
   // Determine starting offsets of spill areas.
@@ -764,9 +764,10 @@ void Thumb1RegisterInfo::emitPrologue(MachineFunction &MF) const {
     emitSPUpdate(MBB, MBBI, TII, dl, *this, -NumBytes);
   }
 
-  if (STI.isTargetELF() && hasFP(MF))
+  if (STI.isTargetELF() && hasFP(MF)) {
     MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
                              AFI->getFramePtrSpillOffset());
+  }
 
   AFI->setGPRCalleeSavedArea1Size(GPRCS1Size);
   AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
@@ -827,7 +828,7 @@ void Thumb1RegisterInfo::emitEpilogue(MachineFunction &MF,
                  AFI->getGPRCalleeSavedArea2Size() +
                  AFI->getDPRCalleeSavedAreaSize());
 
-    if (AFI->shouldRestoreSPFromFP()) {
+    if (hasFP(MF)) {
       NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
       // Reset SP based on frame pointer only if the stack frame extends beyond
       // frame pointer stack slot or target is ELF and the function has FP.