//===-- llvm/Support/ARMWinEH.h - Windows on ARM EH Constants ---*- C++ -*-===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// #ifndef LLVM_SUPPORT_ARMWINEH_H #define LLVM_SUPPORT_ARMWINEH_H #include "llvm/ADT/ArrayRef.h" #include "llvm/Support/Endian.h" namespace llvm { namespace ARM { namespace WinEH { enum class RuntimeFunctionFlag { … }; enum class ReturnType { … }; /// RuntimeFunction - An entry in the table of procedure data (.pdata) /// /// This is ARM specific, but the Function Start RVA, Flag and /// ExceptionInformationRVA fields work identically for ARM64. /// /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 /// +---------------------------------------------------------------+ /// | Function Start RVA | /// +-------------------+-+-+-+-----+-+---+---------------------+---+ /// | Stack Adjust |C|L|R| Reg |H|Ret| Function Length |Flg| /// +-------------------+-+-+-+-----+-+---+---------------------+---+ /// /// Flag : 2-bit field with the following meanings: /// - 00 = packed unwind data not used; reamining bits point to .xdata record /// - 01 = packed unwind data /// - 10 = packed unwind data, function assumed to have no prologue; useful /// for function fragments that are discontiguous with the start of the /// function /// - 11 = reserved /// Function Length : 11-bit field providing the length of the entire function /// in bytes, divided by 2; if the function is greater than /// 4KB, a full .xdata record must be used instead /// Ret : 2-bit field indicating how the function returns /// - 00 = return via pop {pc} (the L bit must be set) /// - 01 = return via 16-bit branch /// - 10 = return via 32-bit branch /// - 11 = no epilogue; useful for function fragments that may only contain a /// prologue but the epilogue is elsewhere /// H : 1-bit flag indicating whether the function "homes" the integer parameter /// registers (r0-r3), allocating 16-bytes on the stack /// Reg : 3-bit field indicating the index of the last saved non-volatile /// register. If the R bit is set to 0, then only integer registers are /// saved (r4-rN, where N is 4 + Reg). If the R bit is set to 1, then /// only floating-point registers are being saved (d8-dN, where N is /// 8 + Reg). The special case of the R bit being set to 1 and Reg equal /// to 7 indicates that no registers are saved. /// R : 1-bit flag indicating whether the non-volatile registers are integer or /// floating-point. 0 indicates integer, 1 indicates floating-point. The /// special case of the R-flag being set and Reg being set to 7 indicates /// that no non-volatile registers are saved. /// L : 1-bit flag indicating whether the function saves/restores the link /// register (LR) /// C : 1-bit flag indicating whether the function includes extra instructions /// to setup a frame chain for fast walking. If this flag is set, r11 is /// implicitly added to the list of saved non-volatile integer registers. /// Stack Adjust : 10-bit field indicating the number of bytes of stack that are /// allocated for this function. Only values between 0x000 and /// 0x3f3 can be directly encoded. If the value is 0x3f4 or /// greater, then the low 4 bits have special meaning as follows: /// - Bit 0-1 /// indicate the number of words' of adjustment (1-4), minus 1 /// - Bit 2 /// indicates if the prologue combined adjustment into push /// - Bit 3 /// indicates if the epilogue combined adjustment into pop /// /// RESTRICTIONS: /// - IF C is SET: /// + L flag must be set since frame chaining requires r11 and lr /// + r11 must NOT be included in the set of registers described by Reg /// - IF Ret is 0: /// + L flag must be set // NOTE: RuntimeFunction is meant to be a simple class that provides raw access // to all fields in the structure. The accessor methods reflect the names of // the bitfields that they correspond to. Although some obvious simplifications // are possible via merging of methods, it would prevent the use of this class // to fully inspect the contents of the data structure which is particularly // useful for scenarios such as llvm-readobj to aid in testing. class RuntimeFunction { … }; /// PrologueFolding - pseudo-flag derived from Stack Adjust indicating that the /// prologue has stack adjustment combined into the push inline bool PrologueFolding(const RuntimeFunction &RF) { … } /// Epilogue - pseudo-flag derived from Stack Adjust indicating that the /// epilogue has stack adjustment combined into the pop inline bool EpilogueFolding(const RuntimeFunction &RF) { … } /// StackAdjustment - calculated stack adjustment in words. The stack /// adjustment should be determined via this function to account for the special /// handling the special encoding when the value is >= 0x3f4. inline uint16_t StackAdjustment(const RuntimeFunction &RF) { … } /// SavedRegisterMask - Utility function to calculate the set of saved general /// purpose (r0-r15) and VFP (d0-d31) registers. std::pair<uint16_t, uint32_t> SavedRegisterMask(const RuntimeFunction &RF, bool Prologue = true); /// RuntimeFunctionARM64 - An entry in the table of procedure data (.pdata) /// /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 /// +---------------------------------------------------------------+ /// | Function Start RVA | /// +-----------------+---+-+-------+-----+---------------------+---+ /// | Frame Size |CR |H| RegI |RegF | Function Length |Flg| /// +-----------------+---+-+-------+-----+---------------------+---+ /// /// See https://docs.microsoft.com/en-us/cpp/build/arm64-exception-handling /// for the full reference for this struct. class RuntimeFunctionARM64 { … }; /// ExceptionDataRecord - An entry in the table of exception data (.xdata) /// /// The format on ARM is: /// /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 /// +-------+---------+-+-+-+---+-----------------------------------+ /// | C Wrd | Epi Cnt |F|E|X|Ver| Function Length | /// +-------+--------+'-'-'-'---'---+-------------------------------+ /// | Reserved |Ex. Code Words| (Extended Epilogue Count) | /// +-------+--------+--------------+-------------------------------+ /// /// The format on ARM64 is: /// /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 /// +---------+---------+-+-+---+-----------------------------------+ /// | C Wrd | Epi Cnt |E|X|Ver| Function Length | /// +---------+------+--'-'-'---'---+-------------------------------+ /// | Reserved |Ex. Code Words| (Extended Epilogue Count) | /// +-------+--------+--------------+-------------------------------+ /// /// Function Length : 18-bit field indicating the total length of the function /// in bytes divided by 2. If a function is larger than /// 512KB, then multiple pdata and xdata records must be used. /// Vers : 2-bit field describing the version of the remaining structure. Only /// version 0 is currently defined (values 1-3 are not permitted). /// X : 1-bit field indicating the presence of exception data /// E : 1-bit field indicating that the single epilogue is packed into the /// header /// F : 1-bit field indicating that the record describes a function fragment /// (implies that no prologue is present, and prologue processing should be /// skipped) (ARM only) /// Epilogue Count : 5-bit field that differs in meaning based on the E field. /// /// If E is set, then this field specifies the index of the /// first unwind code describing the (only) epilogue. /// /// Otherwise, this field indicates the number of exception /// scopes. If more than 31 scopes exist, then this field and /// the Code Words field must both be set to 0 to indicate that /// an extension word is required. /// Code Words : 4-bit (5-bit on ARM64) field that specifies the number of /// 32-bit words needed to contain all the unwind codes. If more /// than 15 words (31 words on ARM64) are required, then this field /// and the Epilogue Count field must both be set to 0 to indicate /// that an extension word is required. /// Extended Epilogue Count, Extended Code Words : /// Valid only if Epilog Count and Code Words are both /// set to 0. Provides an 8-bit extended code word /// count and 16-bits for epilogue count /// /// The epilogue scope format on ARM is: /// /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 /// +----------------+------+---+---+-------------------------------+ /// | Ep Start Idx | Cond |Res| Epilogue Start Offset | /// +----------------+------+---+-----------------------------------+ /// /// The epilogue scope format on ARM64 is: /// /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 /// +-------------------+-------+---+-------------------------------+ /// | Ep Start Idx | Res | Epilogue Start Offset | /// +-------------------+-------+-----------------------------------+ /// /// If the E bit is unset in the header, the header is followed by a series of /// epilogue scopes, which are sorted by their offset. /// /// Epilogue Start Offset: 18-bit field encoding the offset of epilogue relative /// to the start of the function in bytes divided by two /// Res : 2-bit field reserved for future expansion (must be set to 0) /// Condition : (ARM only) 4-bit field providing the condition under which the /// epilogue is executed. Unconditional epilogues should set this /// field to 0xe. Epilogues must be entirely conditional or /// unconditional, and in Thumb-2 mode. The epilogue begins with /// the first instruction after the IT opcode. /// Epilogue Start Index : 8-bit field indicating the byte index of the first /// unwind code describing the epilogue /// /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 /// +---------------+---------------+---------------+---------------+ /// | Unwind Code 3 | Unwind Code 2 | Unwind Code 1 | Unwind Code 0 | /// +---------------+---------------+---------------+---------------+ /// /// Following the epilogue scopes, the byte code describing the unwinding /// follows. This is padded to align up to word alignment. Bytes are stored in /// little endian. /// /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 /// +---------------------------------------------------------------+ /// | Exception Handler RVA (requires X = 1) | /// +---------------------------------------------------------------+ /// | (possibly followed by data required for exception handler) | /// +---------------------------------------------------------------+ /// /// If the X bit is set in the header, the unwind byte code is followed by the /// exception handler information. This constants of one Exception Handler RVA /// which is the address to the exception handler, followed immediately by the /// variable length data associated with the exception handler. /// struct EpilogueScope { … }; struct ExceptionDataRecord; inline size_t HeaderWords(const ExceptionDataRecord &XR); struct ExceptionDataRecord { … }; inline size_t HeaderWords(const ExceptionDataRecord &XR) { … } } } } #endif
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