[LLVM] [MC] Update frame layout & CFI generation to handle frames lar…

…ger than 2gb (#99263)

Rebase of #84114. I've only included the core changes to frame layout
calculation & CFI generation which sidesteps the regressions found after
merging #84114. Since these changes are a necessary precursor to the
overall fix and are themselves slightly beneficial as CFI is now
generated correctly, I think it is reasonable to merge this first step.

---

For very large stack frames, the offset from the stack pointer to a
local can be more than 2^31 which overflows various `int` offsets in the
frame lowering code.

This patch updates the frame lowering code to calculate the offsets as
64-bit values and fixes CFI to use the corrected sizes.

After this patch, additional work is needed to fix offset truncations in
each target's codegen.

(cherry picked from commit ca076f7)

llvm/include/llvm/CodeGen/MachineFrameInfo.h

@@ -251,7 +251,7 @@ class MachineFrameInfo {
   /// targets, this value is only used when generating debug info (via
   /// TargetRegisterInfo::getFrameIndexReference); when generating code, the
   /// corresponding adjustments are performed directly.
-  int OffsetAdjustment = 0;
+  int64_t OffsetAdjustment = 0;
 
   /// The prolog/epilog code inserter may process objects that require greater
   /// alignment than the default alignment the target provides.
@@ -280,7 +280,7 @@ class MachineFrameInfo {
   /// setup/destroy pseudo instructions (as defined in the TargetFrameInfo
   /// class).  This information is important for frame pointer elimination.
   /// It is only valid during and after prolog/epilog code insertion.
-  unsigned MaxCallFrameSize = ~0u;
+  uint64_t MaxCallFrameSize = ~UINT64_C(0);
 
   /// The number of bytes of callee saved registers that the target wants to
   /// report for the current function in the CodeView S_FRAMEPROC record.
@@ -593,10 +593,10 @@ class MachineFrameInfo {
   uint64_t estimateStackSize(const MachineFunction &MF) const;
 
   /// Return the correction for frame offsets.
-  int getOffsetAdjustment() const { return OffsetAdjustment; }
+  int64_t getOffsetAdjustment() const { return OffsetAdjustment; }
 
   /// Set the correction for frame offsets.
-  void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; }
+  void setOffsetAdjustment(int64_t Adj) { OffsetAdjustment = Adj; }
 
   /// Return the alignment in bytes that this function must be aligned to,
   /// which is greater than the default stack alignment provided by the target.
@@ -663,17 +663,17 @@ class MachineFrameInfo {
   /// CallFrameSetup/Destroy pseudo instructions are used by the target, and
   /// then only during or after prolog/epilog code insertion.
   ///
-  unsigned getMaxCallFrameSize() const {
+  uint64_t getMaxCallFrameSize() const {
     // TODO: Enable this assert when targets are fixed.
     //assert(isMaxCallFrameSizeComputed() && "MaxCallFrameSize not computed yet");
     if (!isMaxCallFrameSizeComputed())
       return 0;
     return MaxCallFrameSize;
   }
   bool isMaxCallFrameSizeComputed() const {
-    return MaxCallFrameSize != ~0u;
+    return MaxCallFrameSize != ~UINT64_C(0);
   }
-  void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; }
+  void setMaxCallFrameSize(uint64_t S) { MaxCallFrameSize = S; }
 
   /// Returns how many bytes of callee-saved registers the target pushed in the
   /// prologue. Only used for debug info.

llvm/include/llvm/CodeGen/TargetFrameLowering.h

@@ -51,7 +51,7 @@ class TargetFrameLowering {
   // Maps a callee saved register to a stack slot with a fixed offset.
   struct SpillSlot {
     unsigned Reg;
-    int Offset; // Offset relative to stack pointer on function entry.
+    int64_t Offset; // Offset relative to stack pointer on function entry.
   };
 
   struct DwarfFrameBase {
@@ -66,7 +66,7 @@ class TargetFrameLowering {
       // Used with FrameBaseKind::Register.
       unsigned Reg;
       // Used with FrameBaseKind::CFA.
-      int Offset;
+      int64_t Offset;
       struct WasmFrameBase WasmLoc;
     } Location;
   };

llvm/include/llvm/MC/MCAsmBackend.h

@@ -225,7 +225,7 @@ class MCAsmBackend {
   virtual void handleAssemblerFlag(MCAssemblerFlag Flag) {}
 
   /// Generate the compact unwind encoding for the CFI instructions.
-  virtual uint32_t generateCompactUnwindEncoding(const MCDwarfFrameInfo *FI,
+  virtual uint64_t generateCompactUnwindEncoding(const MCDwarfFrameInfo *FI,
                                                  const MCContext *Ctxt) const {
     return 0;
   }

llvm/include/llvm/MC/MCDwarf.h

@@ -509,11 +509,11 @@ class MCCFIInstruction {
   union {
     struct {
       unsigned Register;
-      int Offset;
+      int64_t Offset;
     } RI;
     struct {
       unsigned Register;
-      int Offset;
+      int64_t Offset;
       unsigned AddressSpace;
     } RIA;
     struct {
@@ -527,7 +527,7 @@ class MCCFIInstruction {
   std::vector<char> Values;
   std::string Comment;
 
-  MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int O, SMLoc Loc,
+  MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int64_t O, SMLoc Loc,
                    StringRef V = "", StringRef Comment = "")
       : Label(L), Operation(Op), Loc(Loc), Values(V.begin(), V.end()),
         Comment(Comment) {
@@ -539,7 +539,7 @@ class MCCFIInstruction {
     assert(Op == OpRegister);
     U.RR = {R1, R2};
   }
-  MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int O, unsigned AS,
+  MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int64_t O, unsigned AS,
                    SMLoc Loc)
       : Label(L), Operation(Op), Loc(Loc) {
     assert(Op == OpLLVMDefAspaceCfa);
@@ -555,30 +555,30 @@ class MCCFIInstruction {
 public:
   /// .cfi_def_cfa defines a rule for computing CFA as: take address from
   /// Register and add Offset to it.
-  static MCCFIInstruction cfiDefCfa(MCSymbol *L, unsigned Register, int Offset,
-                                    SMLoc Loc = {}) {
+  static MCCFIInstruction cfiDefCfa(MCSymbol *L, unsigned Register,
+                                    int64_t Offset, SMLoc Loc = {}) {
     return MCCFIInstruction(OpDefCfa, L, Register, Offset, Loc);
   }
 
   /// .cfi_def_cfa_register modifies a rule for computing CFA. From now
   /// on Register will be used instead of the old one. Offset remains the same.
   static MCCFIInstruction createDefCfaRegister(MCSymbol *L, unsigned Register,
                                                SMLoc Loc = {}) {
-    return MCCFIInstruction(OpDefCfaRegister, L, Register, 0, Loc);
+    return MCCFIInstruction(OpDefCfaRegister, L, Register, INT64_C(0), Loc);
   }
 
   /// .cfi_def_cfa_offset modifies a rule for computing CFA. Register
   /// remains the same, but offset is new. Note that it is the absolute offset
   /// that will be added to a defined register to the compute CFA address.
-  static MCCFIInstruction cfiDefCfaOffset(MCSymbol *L, int Offset,
+  static MCCFIInstruction cfiDefCfaOffset(MCSymbol *L, int64_t Offset,
                                           SMLoc Loc = {}) {
     return MCCFIInstruction(OpDefCfaOffset, L, 0, Offset, Loc);
   }
 
   /// .cfi_adjust_cfa_offset Same as .cfi_def_cfa_offset, but
   /// Offset is a relative value that is added/subtracted from the previous
   /// offset.
-  static MCCFIInstruction createAdjustCfaOffset(MCSymbol *L, int Adjustment,
+  static MCCFIInstruction createAdjustCfaOffset(MCSymbol *L, int64_t Adjustment,
                                                 SMLoc Loc = {}) {
     return MCCFIInstruction(OpAdjustCfaOffset, L, 0, Adjustment, Loc);
   }
@@ -588,7 +588,7 @@ class MCCFIInstruction {
   /// be the result of evaluating the DWARF operation expression
   /// `DW_OP_constu AS; DW_OP_aspace_bregx R, B` as a location description.
   static MCCFIInstruction createLLVMDefAspaceCfa(MCSymbol *L, unsigned Register,
-                                                 int Offset,
+                                                 int64_t Offset,
                                                  unsigned AddressSpace,
                                                  SMLoc Loc) {
     return MCCFIInstruction(OpLLVMDefAspaceCfa, L, Register, Offset,
@@ -598,15 +598,15 @@ class MCCFIInstruction {
   /// .cfi_offset Previous value of Register is saved at offset Offset
   /// from CFA.
   static MCCFIInstruction createOffset(MCSymbol *L, unsigned Register,
-                                       int Offset, SMLoc Loc = {}) {
+                                       int64_t Offset, SMLoc Loc = {}) {
     return MCCFIInstruction(OpOffset, L, Register, Offset, Loc);
   }
 
   /// .cfi_rel_offset Previous value of Register is saved at offset
   /// Offset from the current CFA register. This is transformed to .cfi_offset
   /// using the known displacement of the CFA register from the CFA.
   static MCCFIInstruction createRelOffset(MCSymbol *L, unsigned Register,
-                                          int Offset, SMLoc Loc = {}) {
+                                          int64_t Offset, SMLoc Loc = {}) {
     return MCCFIInstruction(OpRelOffset, L, Register, Offset, Loc);
   }
 
@@ -619,44 +619,44 @@ class MCCFIInstruction {
 
   /// .cfi_window_save SPARC register window is saved.
   static MCCFIInstruction createWindowSave(MCSymbol *L, SMLoc Loc = {}) {
-    return MCCFIInstruction(OpWindowSave, L, 0, 0, Loc);
+    return MCCFIInstruction(OpWindowSave, L, 0, INT64_C(0), Loc);
   }
 
   /// .cfi_negate_ra_state AArch64 negate RA state.
   static MCCFIInstruction createNegateRAState(MCSymbol *L, SMLoc Loc = {}) {
-    return MCCFIInstruction(OpNegateRAState, L, 0, 0, Loc);
+    return MCCFIInstruction(OpNegateRAState, L, 0, INT64_C(0), Loc);
   }
 
   /// .cfi_restore says that the rule for Register is now the same as it
   /// was at the beginning of the function, after all initial instructions added
   /// by .cfi_startproc were executed.
   static MCCFIInstruction createRestore(MCSymbol *L, unsigned Register,
                                         SMLoc Loc = {}) {
-    return MCCFIInstruction(OpRestore, L, Register, 0, Loc);
+    return MCCFIInstruction(OpRestore, L, Register, INT64_C(0), Loc);
   }
 
   /// .cfi_undefined From now on the previous value of Register can't be
   /// restored anymore.
   static MCCFIInstruction createUndefined(MCSymbol *L, unsigned Register,
                                           SMLoc Loc = {}) {
-    return MCCFIInstruction(OpUndefined, L, Register, 0, Loc);
+    return MCCFIInstruction(OpUndefined, L, Register, INT64_C(0), Loc);
   }
 
   /// .cfi_same_value Current value of Register is the same as in the
   /// previous frame. I.e., no restoration is needed.
   static MCCFIInstruction createSameValue(MCSymbol *L, unsigned Register,
                                           SMLoc Loc = {}) {
-    return MCCFIInstruction(OpSameValue, L, Register, 0, Loc);
+    return MCCFIInstruction(OpSameValue, L, Register, INT64_C(0), Loc);
   }
 
   /// .cfi_remember_state Save all current rules for all registers.
   static MCCFIInstruction createRememberState(MCSymbol *L, SMLoc Loc = {}) {
-    return MCCFIInstruction(OpRememberState, L, 0, 0, Loc);
+    return MCCFIInstruction(OpRememberState, L, 0, INT64_C(0), Loc);
   }
 
   /// .cfi_restore_state Restore the previously saved state.
   static MCCFIInstruction createRestoreState(MCSymbol *L, SMLoc Loc = {}) {
-    return MCCFIInstruction(OpRestoreState, L, 0, 0, Loc);
+    return MCCFIInstruction(OpRestoreState, L, 0, INT64_C(0), Loc);
   }
 
   /// .cfi_escape Allows the user to add arbitrary bytes to the unwind
@@ -667,7 +667,7 @@ class MCCFIInstruction {
   }
 
   /// A special wrapper for .cfi_escape that indicates GNU_ARGS_SIZE
-  static MCCFIInstruction createGnuArgsSize(MCSymbol *L, int Size,
+  static MCCFIInstruction createGnuArgsSize(MCSymbol *L, int64_t Size,
                                             SMLoc Loc = {}) {
     return MCCFIInstruction(OpGnuArgsSize, L, 0, Size, Loc);
   }
@@ -702,7 +702,7 @@ class MCCFIInstruction {
     return U.RIA.AddressSpace;
   }
 
-  int getOffset() const {
+  int64_t getOffset() const {
     if (Operation == OpLLVMDefAspaceCfa)
       return U.RIA.Offset;
     assert(Operation == OpDefCfa || Operation == OpOffset ||
@@ -736,7 +736,7 @@ struct MCDwarfFrameInfo {
   unsigned CurrentCfaRegister = 0;
   unsigned PersonalityEncoding = 0;
   unsigned LsdaEncoding = 0;
-  uint32_t CompactUnwindEncoding = 0;
+  uint64_t CompactUnwindEncoding = 0;
   bool IsSignalFrame = false;
   bool IsSimple = false;
   unsigned RAReg = static_cast<unsigned>(INT_MAX);

llvm/lib/CodeGen/CFIInstrInserter.cpp

@@ -68,9 +68,9 @@ class CFIInstrInserter : public MachineFunctionPass {
   struct MBBCFAInfo {
     MachineBasicBlock *MBB;
     /// Value of cfa offset valid at basic block entry.
-    int IncomingCFAOffset = -1;
+    int64_t IncomingCFAOffset = -1;
     /// Value of cfa offset valid at basic block exit.
-    int OutgoingCFAOffset = -1;
+    int64_t OutgoingCFAOffset = -1;
     /// Value of cfa register valid at basic block entry.
     unsigned IncomingCFARegister = 0;
     /// Value of cfa register valid at basic block exit.
@@ -120,7 +120,7 @@ class CFIInstrInserter : public MachineFunctionPass {
   /// Return the cfa offset value that should be set at the beginning of a MBB
   /// if needed. The negated value is needed when creating CFI instructions that
   /// set absolute offset.
-  int getCorrectCFAOffset(MachineBasicBlock *MBB) {
+  int64_t getCorrectCFAOffset(MachineBasicBlock *MBB) {
     return MBBVector[MBB->getNumber()].IncomingCFAOffset;
   }
 
@@ -175,7 +175,7 @@ void CFIInstrInserter::calculateCFAInfo(MachineFunction &MF) {
 
 void CFIInstrInserter::calculateOutgoingCFAInfo(MBBCFAInfo &MBBInfo) {
   // Outgoing cfa offset set by the block.
-  int SetOffset = MBBInfo.IncomingCFAOffset;
+  int64_t SetOffset = MBBInfo.IncomingCFAOffset;
   // Outgoing cfa register set by the block.
   unsigned SetRegister = MBBInfo.IncomingCFARegister;
   MachineFunction *MF = MBBInfo.MBB->getParent();
@@ -188,7 +188,7 @@ void CFIInstrInserter::calculateOutgoingCFAInfo(MBBCFAInfo &MBBInfo) {
   for (MachineInstr &MI : *MBBInfo.MBB) {
     if (MI.isCFIInstruction()) {
       std::optional<unsigned> CSRReg;
-      std::optional<int> CSROffset;
+      std::optional<int64_t> CSROffset;
       unsigned CFIIndex = MI.getOperand(0).getCFIIndex();
       const MCCFIInstruction &CFI = Instrs[CFIIndex];
       switch (CFI.getOperation()) {

llvm/lib/CodeGen/MachineFrameInfo.cpp

@@ -197,7 +197,7 @@ void MachineFrameInfo::computeMaxCallFrameSize(
     for (MachineInstr &MI : MBB) {
       unsigned Opcode = MI.getOpcode();
       if (Opcode == FrameSetupOpcode || Opcode == FrameDestroyOpcode) {
-        unsigned Size = TII.getFrameSize(MI);
+        uint64_t Size = TII.getFrameSize(MI);
         MaxCallFrameSize = std::max(MaxCallFrameSize, Size);
         if (FrameSDOps != nullptr)
           FrameSDOps->push_back(&MI);

llvm/lib/CodeGen/PrologEpilogInserter.cpp

@@ -366,8 +366,8 @@ void PEI::calculateCallFrameInfo(MachineFunction &MF) {
     return;
 
   // (Re-)Compute the MaxCallFrameSize.
-  [[maybe_unused]] uint32_t MaxCFSIn =
-      MFI.isMaxCallFrameSizeComputed() ? MFI.getMaxCallFrameSize() : UINT32_MAX;
+  [[maybe_unused]] uint64_t MaxCFSIn =
+      MFI.isMaxCallFrameSizeComputed() ? MFI.getMaxCallFrameSize() : UINT64_MAX;
   std::vector<MachineBasicBlock::iterator> FrameSDOps;
   MFI.computeMaxCallFrameSize(MF, &FrameSDOps);
   assert(MFI.getMaxCallFrameSize() <= MaxCFSIn &&

llvm/lib/MC/MCDwarf.cpp

@@ -1299,8 +1299,8 @@ static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
 namespace {
 
 class FrameEmitterImpl {
-  int CFAOffset = 0;
-  int InitialCFAOffset = 0;
+  int64_t CFAOffset = 0;
+  int64_t InitialCFAOffset = 0;
   bool IsEH;
   MCObjectStreamer &Streamer;
 
@@ -1414,7 +1414,7 @@ void FrameEmitterImpl::emitCFIInstruction(const MCCFIInstruction &Instr) {
     if (!IsEH)
       Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
 
-    int Offset = Instr.getOffset();
+    int64_t Offset = Instr.getOffset();
     if (IsRelative)
       Offset -= CFAOffset;
     Offset = Offset / dataAlignmentFactor;

llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp

@@ -599,7 +599,7 @@ class DarwinAArch64AsmBackend : public AArch64AsmBackend {
   }
 
   /// Generate the compact unwind encoding from the CFI directives.
-  uint32_t generateCompactUnwindEncoding(const MCDwarfFrameInfo *FI,
+  uint64_t generateCompactUnwindEncoding(const MCDwarfFrameInfo *FI,
                                          const MCContext *Ctxt) const override {
     ArrayRef<MCCFIInstruction> Instrs = FI->Instructions;
     if (Instrs.empty())
@@ -609,10 +609,10 @@ class DarwinAArch64AsmBackend : public AArch64AsmBackend {
       return CU::UNWIND_ARM64_MODE_DWARF;
 
     bool HasFP = false;
-    unsigned StackSize = 0;
+    uint64_t StackSize = 0;
 
-    uint32_t CompactUnwindEncoding = 0;
-    int CurOffset = 0;
+    uint64_t CompactUnwindEncoding = 0;
+    int64_t CurOffset = 0;
     for (size_t i = 0, e = Instrs.size(); i != e; ++i) {
       const MCCFIInstruction &Inst = Instrs[i];
 

llvm/lib/Target/ARM/ARMFrameLowering.cpp

@@ -1166,7 +1166,7 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF,
         if (STI.splitFramePushPop(MF)) {
           unsigned DwarfReg = MRI->getDwarfRegNum(
               Reg == ARM::R12 ? ARM::RA_AUTH_CODE : Reg, true);
-          unsigned Offset = MFI.getObjectOffset(FI);
+          int64_t Offset = MFI.getObjectOffset(FI);
           unsigned CFIIndex = MF.addFrameInst(
               MCCFIInstruction::createOffset(nullptr, DwarfReg, Offset));
           BuildMI(MBB, Pos, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
@@ -1188,7 +1188,7 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF,
       if ((Reg >= ARM::D0 && Reg <= ARM::D31) &&
           (Reg < ARM::D8 || Reg >= ARM::D8 + AFI->getNumAlignedDPRCS2Regs())) {
         unsigned DwarfReg = MRI->getDwarfRegNum(Reg, true);
-        unsigned Offset = MFI.getObjectOffset(FI);
+        int64_t Offset = MFI.getObjectOffset(FI);
         unsigned CFIIndex = MF.addFrameInst(
             MCCFIInstruction::createOffset(nullptr, DwarfReg, Offset));
         BuildMI(MBB, Pos, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))

llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp

@@ -1146,7 +1146,7 @@ enum CompactUnwindEncodings {
 /// instructions. If the CFI instructions describe a frame that cannot be
 /// encoded in compact unwind, the method returns UNWIND_ARM_MODE_DWARF which
 /// tells the runtime to fallback and unwind using dwarf.
-uint32_t ARMAsmBackendDarwin::generateCompactUnwindEncoding(
+uint64_t ARMAsmBackendDarwin::generateCompactUnwindEncoding(
     const MCDwarfFrameInfo *FI, const MCContext *Ctxt) const {
   DEBUG_WITH_TYPE("compact-unwind", llvm::dbgs() << "generateCU()\n");
   // Only armv7k uses CFI based unwinding.

llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackendDarwin.h

@@ -34,7 +34,7 @@ class ARMAsmBackendDarwin : public ARMAsmBackend {
         /*Is64Bit=*/false, cantFail(MachO::getCPUType(TT)), Subtype);
   }
 
-  uint32_t generateCompactUnwindEncoding(const MCDwarfFrameInfo *FI,
+  uint64_t generateCompactUnwindEncoding(const MCDwarfFrameInfo *FI,
                                          const MCContext *Ctxt) const override;
 };
 } // end namespace llvm