1 files changed, 97 insertions, 75 deletions

diff --git a/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp b/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
index 6c3d247..679d3c4 100644
--- a/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
+++ b/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
@@ -203,7 +203,8 @@ private:
   void Reset();
 
   void EmitPersonalityFixup(StringRef Name);
-  void CollectUnwindOpcodes();
+  void FlushPendingOffset();
+  void FlushUnwindOpcodes(bool AllowCompactModel0);
 
   void SwitchToEHSection(const char *Prefix, unsigned Type, unsigned Flags,
                          SectionKind Kind, const MCSymbol &Fn);
@@ -220,13 +221,14 @@ private:
   MCSymbol *ExTab;
   MCSymbol *FnStart;
   const MCSymbol *Personality;
-  uint32_t VFPRegSave; // Register mask for {d31-d0}
-  uint32_t RegSave; // Register mask for {r15-r0}
-  int64_t SPOffset;
-  uint16_t FPReg;
-  int64_t FPOffset;
+  unsigned PersonalityIndex;
+  unsigned FPReg; // Frame pointer register
+  int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
+  int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
+  int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
   bool UsedFP;
   bool CantUnwind;
+  SmallVector<uint8_t, 64> Opcodes;
   UnwindOpcodeAssembler UnwindOpAsm;
 };
 } // end anonymous namespace
@@ -279,19 +281,18 @@ inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
 }
 
 void ARMELFStreamer::Reset() {
-  const MCRegisterInfo &MRI = getContext().getRegisterInfo();
-
   ExTab = NULL;
   FnStart = NULL;
   Personality = NULL;
-  VFPRegSave = 0;
-  RegSave = 0;
-  FPReg = MRI.getEncodingValue(ARM::SP);
+  PersonalityIndex = NUM_PERSONALITY_INDEX;
+  FPReg = ARM::SP;
   FPOffset = 0;
   SPOffset = 0;
+  PendingOffset = 0;
   UsedFP = false;
   CantUnwind = false;
 
+  Opcodes.clear();
   UnwindOpAsm.Reset();
 }
 
@@ -311,18 +312,6 @@ void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
                     MCFixup::getKindForSize(4, false)));
 }
 
-void ARMELFStreamer::CollectUnwindOpcodes() {
-  if (UsedFP) {
-    UnwindOpAsm.EmitSetFP(FPReg);
-    UnwindOpAsm.EmitSPOffset(-FPOffset);
-  } else {
-    UnwindOpAsm.EmitSPOffset(SPOffset);
-  }
-  UnwindOpAsm.EmitVFPRegSave(VFPRegSave);
-  UnwindOpAsm.EmitRegSave(RegSave);
-  UnwindOpAsm.Finalize();
-}
-
 void ARMELFStreamer::EmitFnStart() {
   assert(FnStart == 0);
   FnStart = getContext().CreateTempSymbol();
@@ -333,27 +322,12 @@ void ARMELFStreamer::EmitFnEnd() {
   assert(FnStart && ".fnstart must preceeds .fnend");
 
   // Emit unwind opcodes if there is no .handlerdata directive
-  if (!ExTab && !CantUnwind) {
-    CollectUnwindOpcodes();
-
-    unsigned PersonalityIndex = UnwindOpAsm.getPersonalityIndex();
-    if (PersonalityIndex == AEABI_UNWIND_CPP_PR1 ||
-        PersonalityIndex == AEABI_UNWIND_CPP_PR2) {
-      // For the __aeabi_unwind_cpp_pr1 and __aeabi_unwind_cpp_pr2, we have to
-      // emit the unwind opcodes in the corresponding ".ARM.extab" section, and
-      // then emit a reference to these unwind opcodes in the second word of
-      // the exception index table entry.
-      SwitchToExTabSection(*FnStart);
-      ExTab = getContext().CreateTempSymbol();
-      EmitLabel(ExTab);
-      EmitBytes(UnwindOpAsm.data(), 0);
-    }
-  }
+  if (!ExTab && !CantUnwind)
+    FlushUnwindOpcodes(true);
 
   // Emit the exception index table entry
   SwitchToExIdxSection(*FnStart);
 
-  unsigned PersonalityIndex = UnwindOpAsm.getPersonalityIndex();
   if (PersonalityIndex < NUM_PERSONALITY_INDEX)
     EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
 
@@ -379,11 +353,15 @@ void ARMELFStreamer::EmitFnEnd() {
     // opcodes should always be 4 bytes.
     assert(PersonalityIndex == AEABI_UNWIND_CPP_PR0 &&
            "Compact model must use __aeabi_cpp_unwind_pr0 as personality");
-    assert(UnwindOpAsm.size() == 4u &&
+    assert(Opcodes.size() == 4u &&
            "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be equal to 4");
-    EmitBytes(UnwindOpAsm.data(), 0);
+    EmitBytes(StringRef(reinterpret_cast<const char*>(Opcodes.data()),
+                        Opcodes.size()), 0);
   }
 
+  // Switch to the section containing FnStart
+  SwitchSection(&FnStart->getSection());
+
   // Clean exception handling frame information
   Reset();
 }
@@ -392,7 +370,34 @@ void ARMELFStreamer::EmitCantUnwind() {
   CantUnwind = true;
 }
 
-void ARMELFStreamer::EmitHandlerData() {
+void ARMELFStreamer::FlushPendingOffset() {
+  if (PendingOffset != 0) {
+    UnwindOpAsm.EmitSPOffset(-PendingOffset);
+    PendingOffset = 0;
+  }
+}
+
+void ARMELFStreamer::FlushUnwindOpcodes(bool AllowCompactModel0) {
+  // Emit the unwind opcode to restore $sp.
+  if (UsedFP) {
+    const MCRegisterInfo &MRI = getContext().getRegisterInfo();
+    int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
+    UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
+    UnwindOpAsm.EmitSetSP(MRI.getEncodingValue(FPReg));
+  } else {
+    FlushPendingOffset();
+  }
+
+  // Finalize the unwind opcode sequence
+  UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
+
+  // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
+  // section.  Thus, we don't have to create an entry in the .ARM.extab
+  // section.
+  if (AllowCompactModel0 && PersonalityIndex == AEABI_UNWIND_CPP_PR0)
+    return;
+
+  // Switch to .ARM.extab section.
   SwitchToExTabSection(*FnStart);
 
   // Create .ARM.extab label for offset in .ARM.exidx
@@ -400,19 +405,23 @@ void ARMELFStreamer::EmitHandlerData() {
   ExTab = getContext().CreateTempSymbol();
   EmitLabel(ExTab);
 
-  // Emit Personality
-  assert(Personality && ".personality directive must preceed .handlerdata");
-
-  const MCSymbolRefExpr *PersonalityRef =
-    MCSymbolRefExpr::Create(Personality,
-                            MCSymbolRefExpr::VK_ARM_PREL31,
-                            getContext());
+  // Emit personality
+  if (Personality) {
+    const MCSymbolRefExpr *PersonalityRef =
+      MCSymbolRefExpr::Create(Personality,
+                              MCSymbolRefExpr::VK_ARM_PREL31,
+                              getContext());
 
-  EmitValue(PersonalityRef, 4, 0);
+    EmitValue(PersonalityRef, 4, 0);
+  }
 
   // Emit unwind opcodes
-  CollectUnwindOpcodes();
-  EmitBytes(UnwindOpAsm.data(), 0);
+  EmitBytes(StringRef(reinterpret_cast<const char *>(Opcodes.data()),
+                      Opcodes.size()), 0);
+}
+
+void ARMELFStreamer::EmitHandlerData() {
+  FlushUnwindOpcodes(false);
 }
 
 void ARMELFStreamer::EmitPersonality(const MCSymbol *Per) {
@@ -423,42 +432,55 @@ void ARMELFStreamer::EmitPersonality(const MCSymbol *Per) {
 void ARMELFStreamer::EmitSetFP(unsigned NewFPReg,
                                unsigned NewSPReg,
                                int64_t Offset) {
-  assert(SPOffset == 0 &&
-         "Current implementation assumes .setfp precedes .pad");
-
-  const MCRegisterInfo &MRI = getContext().getRegisterInfo();
-
-  uint16_t NewFPRegEncVal = MRI.getEncodingValue(NewFPReg);
-#ifndef NDEBUG
-  uint16_t NewSPRegEncVal = MRI.getEncodingValue(NewSPReg);
-#endif
-
-  assert((NewSPReg == ARM::SP || NewSPRegEncVal == FPReg) &&
+  assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
          "the operand of .setfp directive should be either $sp or $fp");
 
   UsedFP = true;
-  FPReg = NewFPRegEncVal;
-  FPOffset = Offset;
+  FPReg = NewFPReg;
+
+  if (NewSPReg == ARM::SP)
+    FPOffset = SPOffset + Offset;
+  else
+    FPOffset += Offset;
 }
 
 void ARMELFStreamer::EmitPad(int64_t Offset) {
-  SPOffset += Offset;
+  // Track the change of the $sp offset
+  SPOffset -= Offset;
+
+  // To squash multiple .pad directives, we should delay the unwind opcode
+  // until the .save, .vsave, .handlerdata, or .fnend directives.
+  PendingOffset -= Offset;
 }
 
 void ARMELFStreamer::EmitRegSave(const SmallVectorImpl<unsigned> &RegList,
                                  bool IsVector) {
+  // Collect the registers in the register list
+  unsigned Count = 0;
+  uint32_t Mask = 0;
   const MCRegisterInfo &MRI = getContext().getRegisterInfo();
-
-#ifndef NDEBUG
-  unsigned Max = IsVector ? 32 : 16;
-#endif
-  uint32_t &RegMask = IsVector ? VFPRegSave : RegSave;
-
   for (size_t i = 0; i < RegList.size(); ++i) {
     unsigned Reg = MRI.getEncodingValue(RegList[i]);
-    assert(Reg < Max && "Register encoded value out of range");
-    RegMask |= 1u << Reg;
+    assert(Reg < (IsVector ? 32U : 16U) && "Register out of range");
+    unsigned Bit = (1u << Reg);
+    if ((Mask & Bit) == 0) {
+      Mask |= Bit;
+      ++Count;
+    }
   }
+
+  // Track the change the $sp offset: For the .save directive, the
+  // corresponding push instruction will decrease the $sp by (4 * Count).
+  // For the .vsave directive, the corresponding vpush instruction will
+  // decrease $sp by (8 * Count).
+  SPOffset -= Count * (IsVector ? 8 : 4);
+
+  // Emit the opcode
+  FlushPendingOffset();
+  if (IsVector)
+    UnwindOpAsm.EmitVFPRegSave(Mask);
+  else
+    UnwindOpAsm.EmitRegSave(Mask);
 }
 
 namespace llvm {