text: /*===-- llvm-c/lto.h - LTO Public C Interface ---------------------*- C -*-===*\
  |*                                                                            *|
  |*                     The LLVM Compiler Infrastructure                       *|
  |*                                                                            *|
  |* This file is distributed under the University of Illinois Open Source      *|
  |* License. See LICENSE.TXT for details.                                      *|
  |*                                                                            *|
  |*===----------------------------------------------------------------------===*|
  |*                                                                            *|
  |* This header provides public interface to an abstract link time optimization*|
  |* library.  LLVM provides an implementation of this interface for use with   *|
  |* llvm bitcode files.                                                        *|
  |*                                                                            *|
  \*===----------------------------------------------------------------------===*/
  
  #ifndef LLVM_C_LTO_H
  #define LLVM_C_LTO_H
  
  #include <stddef.h>
  #include <sys/types.h>
  
  #ifndef __cplusplus
  #if !defined(_MSC_VER)
  #include <stdbool.h>
  typedef bool lto_bool_t;
  #else
  /* MSVC in particular does not have anything like _Bool or bool in C, but we can
     at least make sure the type is the same size.  The implementation side will
     use C++ bool. */
  typedef unsigned char lto_bool_t;
  #endif
  #else
  typedef bool lto_bool_t;
  #endif
  
  /**
   * @defgroup LLVMCLTO LTO
   * @ingroup LLVMC
   *
   * @{
   */
  
  #define LTO_API_VERSION 18
  /**
   * \since prior to LTO_API_VERSION=3
   */
  typedef enum {
      LTO_SYMBOL_ALIGNMENT_MASK              = 0x0000001F, /* log2 of alignment */
      LTO_SYMBOL_PERMISSIONS_MASK            = 0x000000E0,
      LTO_SYMBOL_PERMISSIONS_CODE            = 0x000000A0,
      LTO_SYMBOL_PERMISSIONS_DATA            = 0x000000C0,
      LTO_SYMBOL_PERMISSIONS_RODATA          = 0x00000080,
      LTO_SYMBOL_DEFINITION_MASK             = 0x00000700,
      LTO_SYMBOL_DEFINITION_REGULAR          = 0x00000100,
      LTO_SYMBOL_DEFINITION_TENTATIVE        = 0x00000200,
      LTO_SYMBOL_DEFINITION_WEAK             = 0x00000300,
      LTO_SYMBOL_DEFINITION_UNDEFINED        = 0x00000400,
      LTO_SYMBOL_DEFINITION_WEAKUNDEF        = 0x00000500,
      LTO_SYMBOL_SCOPE_MASK                  = 0x00003800,
      LTO_SYMBOL_SCOPE_INTERNAL              = 0x00000800,
      LTO_SYMBOL_SCOPE_HIDDEN                = 0x00001000,
      LTO_SYMBOL_SCOPE_PROTECTED             = 0x00002000,
      LTO_SYMBOL_SCOPE_DEFAULT               = 0x00001800,
      LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN = 0x00002800,
      LTO_SYMBOL_COMDAT                      = 0x00004000,
      LTO_SYMBOL_ALIAS                       = 0x00008000
  } lto_symbol_attributes;
  
  /**
   * \since prior to LTO_API_VERSION=3
   */
  typedef enum {
      LTO_DEBUG_MODEL_NONE         = 0,
      LTO_DEBUG_MODEL_DWARF        = 1
  } lto_debug_model;
  
  /**
   * \since prior to LTO_API_VERSION=3
   */
  typedef enum {
      LTO_CODEGEN_PIC_MODEL_STATIC         = 0,
      LTO_CODEGEN_PIC_MODEL_DYNAMIC        = 1,
      LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC = 2,
      LTO_CODEGEN_PIC_MODEL_DEFAULT        = 3
  } lto_codegen_model;
  
  /** opaque reference to a loaded object module */
  typedef struct LLVMOpaqueLTOModule *lto_module_t;
  
  /** opaque reference to a code generator */
  typedef struct LLVMOpaqueLTOCodeGenerator *lto_code_gen_t;
  
  /** opaque reference to a thin code generator */
  typedef struct LLVMOpaqueThinLTOCodeGenerator *thinlto_code_gen_t;
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * Returns a printable string.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern const char*
  lto_get_version(void);
  
  
  /**
   * Returns the last error string or NULL if last operation was successful.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern const char*
  lto_get_error_message(void);
  
  /**
   * Checks if a file is a loadable object file.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_bool_t
  lto_module_is_object_file(const char* path);
  
  
  /**
   * Checks if a file is a loadable object compiled for requested target.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_bool_t
  lto_module_is_object_file_for_target(const char* path,
                                       const char* target_triple_prefix);
  
  
  /**
   * Checks if a buffer is a loadable object file.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_bool_t
  lto_module_is_object_file_in_memory(const void* mem, size_t length);
  
  
  /**
   * Checks if a buffer is a loadable object compiled for requested target.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_bool_t
  lto_module_is_object_file_in_memory_for_target(const void* mem, size_t length,
                                                const char* target_triple_prefix);
  
  
  /**
   * Loads an object file from disk.
   * Returns NULL on error (check lto_get_error_message() for details).
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_module_t
  lto_module_create(const char* path);
  
  
  /**
   * Loads an object file from memory.
   * Returns NULL on error (check lto_get_error_message() for details).
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_module_t
  lto_module_create_from_memory(const void* mem, size_t length);
  
  /**
   * Loads an object file from memory with an extra path argument.
   * Returns NULL on error (check lto_get_error_message() for details).
   *
   * \since LTO_API_VERSION=9
   */
  extern lto_module_t
  lto_module_create_from_memory_with_path(const void* mem, size_t length,
                                          const char *path);
  
  /**
   * \brief Loads an object file in its own context.
   *
   * Loads an object file in its own LLVMContext.  This function call is
   * thread-safe.  However, modules created this way should not be merged into an
   * lto_code_gen_t using \a lto_codegen_add_module().
   *
   * Returns NULL on error (check lto_get_error_message() for details).
   *
   * \since LTO_API_VERSION=11
   */
  extern lto_module_t
  lto_module_create_in_local_context(const void *mem, size_t length,
                                     const char *path);
  
  /**
   * \brief Loads an object file in the codegen context.
   *
   * Loads an object file into the same context as \c cg.  The module is safe to
   * add using \a lto_codegen_add_module().
   *
   * Returns NULL on error (check lto_get_error_message() for details).
   *
   * \since LTO_API_VERSION=11
   */
  extern lto_module_t
  lto_module_create_in_codegen_context(const void *mem, size_t length,
                                       const char *path, lto_code_gen_t cg);
  
  /**
   * Loads an object file from disk. The seek point of fd is not preserved.
   * Returns NULL on error (check lto_get_error_message() for details).
   *
   * \since LTO_API_VERSION=5
   */
  extern lto_module_t
  lto_module_create_from_fd(int fd, const char *path, size_t file_size);
  
  /**
   * Loads an object file from disk. The seek point of fd is not preserved.
   * Returns NULL on error (check lto_get_error_message() for details).
   *
   * \since LTO_API_VERSION=5
   */
  extern lto_module_t
  lto_module_create_from_fd_at_offset(int fd, const char *path, size_t file_size,
                                      size_t map_size, off_t offset);
  
  /**
   * Frees all memory internally allocated by the module.
   * Upon return the lto_module_t is no longer valid.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern void
  lto_module_dispose(lto_module_t mod);
  
  /**
   * Returns triple string which the object module was compiled under.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern const char*
  lto_module_get_target_triple(lto_module_t mod);
  
  /**
   * Sets triple string with which the object will be codegened.
   *
   * \since LTO_API_VERSION=4
   */
  extern void
  lto_module_set_target_triple(lto_module_t mod, const char *triple);
  
  
  /**
   * Returns the number of symbols in the object module.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern unsigned int
  lto_module_get_num_symbols(lto_module_t mod);
  
  
  /**
   * Returns the name of the ith symbol in the object module.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern const char*
  lto_module_get_symbol_name(lto_module_t mod, unsigned int index);
  
  
  /**
   * Returns the attributes of the ith symbol in the object module.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_symbol_attributes
  lto_module_get_symbol_attribute(lto_module_t mod, unsigned int index);
  
  
  /**
   * Returns the module's linker options.
   *
   * The linker options may consist of multiple flags. It is the linker's
   * responsibility to split the flags using a platform-specific mechanism.
   *
   * \since LTO_API_VERSION=16
   */
  extern const char*
  lto_module_get_linkeropts(lto_module_t mod);
  
  
  /**
   * Diagnostic severity.
   *
   * \since LTO_API_VERSION=7
   */
  typedef enum {
    LTO_DS_ERROR = 0,
    LTO_DS_WARNING = 1,
    LTO_DS_REMARK = 3, // Added in LTO_API_VERSION=10.
    LTO_DS_NOTE = 2
  } lto_codegen_diagnostic_severity_t;
  
  /**
   * Diagnostic handler type.
   * \p severity defines the severity.
   * \p diag is the actual diagnostic.
   * The diagnostic is not prefixed by any of severity keyword, e.g., 'error: '.
   * \p ctxt is used to pass the context set with the diagnostic handler.
   *
   * \since LTO_API_VERSION=7
   */
  typedef void (*lto_diagnostic_handler_t)(
      lto_codegen_diagnostic_severity_t severity, const char *diag, void *ctxt);
  
  /**
   * Set a diagnostic handler and the related context (void *).
   * This is more general than lto_get_error_message, as the diagnostic handler
   * can be called at anytime within lto.
   *
   * \since LTO_API_VERSION=7
   */
  extern void lto_codegen_set_diagnostic_handler(lto_code_gen_t,
                                                 lto_diagnostic_handler_t,
                                                 void *);
  
  /**
   * Instantiates a code generator.
   * Returns NULL on error (check lto_get_error_message() for details).
   *
   * All modules added using \a lto_codegen_add_module() must have been created
   * in the same context as the codegen.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_code_gen_t
  lto_codegen_create(void);
  
  /**
   * \brief Instantiate a code generator in its own context.
   *
   * Instantiates a code generator in its own context.  Modules added via \a
   * lto_codegen_add_module() must have all been created in the same context,
   * using \a lto_module_create_in_codegen_context().
   *
   * \since LTO_API_VERSION=11
   */
  extern lto_code_gen_t
  lto_codegen_create_in_local_context(void);
  
  /**
   * Frees all code generator and all memory it internally allocated.
   * Upon return the lto_code_gen_t is no longer valid.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern void
  lto_codegen_dispose(lto_code_gen_t);
  
  /**
   * Add an object module to the set of modules for which code will be generated.
   * Returns true on error (check lto_get_error_message() for details).
   *
   * \c cg and \c mod must both be in the same context.  See \a
   * lto_codegen_create_in_local_context() and \a
   * lto_module_create_in_codegen_context().
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_bool_t
  lto_codegen_add_module(lto_code_gen_t cg, lto_module_t mod);
  
  /**
   * Sets the object module for code generation. This will transfer the ownership
   * of the module to the code generator.
   *
   * \c cg and \c mod must both be in the same context.
   *
   * \since LTO_API_VERSION=13
   */
  extern void
  lto_codegen_set_module(lto_code_gen_t cg, lto_module_t mod);
  
  /**
   * Sets if debug info should be generated.
   * Returns true on error (check lto_get_error_message() for details).
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_bool_t
  lto_codegen_set_debug_model(lto_code_gen_t cg, lto_debug_model);
  
  
  /**
   * Sets which PIC code model to generated.
   * Returns true on error (check lto_get_error_message() for details).
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern lto_bool_t
  lto_codegen_set_pic_model(lto_code_gen_t cg, lto_codegen_model);
  
  
  /**
   * Sets the cpu to generate code for.
   *
   * \since LTO_API_VERSION=4
   */
  extern void
  lto_codegen_set_cpu(lto_code_gen_t cg, const char *cpu);
  
  
  /**
   * Sets the location of the assembler tool to run. If not set, libLTO
   * will use gcc to invoke the assembler.
   *
   * \since LTO_API_VERSION=3
   */
  extern void
  lto_codegen_set_assembler_path(lto_code_gen_t cg, const char* path);
  
  /**
   * Sets extra arguments that libLTO should pass to the assembler.
   *
   * \since LTO_API_VERSION=4
   */
  extern void
  lto_codegen_set_assembler_args(lto_code_gen_t cg, const char **args,
                                 int nargs);
  
  /**
   * Adds to a list of all global symbols that must exist in the final generated
   * code. If a function is not listed there, it might be inlined into every usage
   * and optimized away.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern void
  lto_codegen_add_must_preserve_symbol(lto_code_gen_t cg, const char* symbol);
  
  /**
   * Writes a new object file at the specified path that contains the
   * merged contents of all modules added so far.
   * Returns true on error (check lto_get_error_message() for details).
   *
   * \since LTO_API_VERSION=5
   */
  extern lto_bool_t
  lto_codegen_write_merged_modules(lto_code_gen_t cg, const char* path);
  
  /**
   * Generates code for all added modules into one native object file.
   * This calls lto_codegen_optimize then lto_codegen_compile_optimized.
   *
   * On success returns a pointer to a generated mach-o/ELF buffer and
   * length set to the buffer size.  The buffer is owned by the
   * lto_code_gen_t and will be freed when lto_codegen_dispose()
   * is called, or lto_codegen_compile() is called again.
   * On failure, returns NULL (check lto_get_error_message() for details).
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern const void*
  lto_codegen_compile(lto_code_gen_t cg, size_t* length);
  
  /**
   * Generates code for all added modules into one native object file.
   * This calls lto_codegen_optimize then lto_codegen_compile_optimized (instead
   * of returning a generated mach-o/ELF buffer, it writes to a file).
   *
   * The name of the file is written to name. Returns true on error.
   *
   * \since LTO_API_VERSION=5
   */
  extern lto_bool_t
  lto_codegen_compile_to_file(lto_code_gen_t cg, const char** name);
  
  /**
   * Runs optimization for the merged module. Returns true on error.
   *
   * \since LTO_API_VERSION=12
   */
  extern lto_bool_t
  lto_codegen_optimize(lto_code_gen_t cg);
  
  /**
   * Generates code for the optimized merged module into one native object file.
   * It will not run any IR optimizations on the merged module.
   *
   * On success returns a pointer to a generated mach-o/ELF buffer and length set
   * to the buffer size.  The buffer is owned by the lto_code_gen_t and will be
   * freed when lto_codegen_dispose() is called, or
   * lto_codegen_compile_optimized() is called again. On failure, returns NULL
   * (check lto_get_error_message() for details).
   *
   * \since LTO_API_VERSION=12
   */
  extern const void*
  lto_codegen_compile_optimized(lto_code_gen_t cg, size_t* length);
  
  /**
   * Returns the runtime API version.
   *
   * \since LTO_API_VERSION=12
   */
  extern unsigned int
  lto_api_version(void);
  
  /**
   * Sets options to help debug codegen bugs.
   *
   * \since prior to LTO_API_VERSION=3
   */
  extern void
  lto_codegen_debug_options(lto_code_gen_t cg, const char *);
  
  /**
   * Initializes LLVM disassemblers.
   * FIXME: This doesn't really belong here.
   *
   * \since LTO_API_VERSION=5
   */
  extern void
  lto_initialize_disassembler(void);
  
  /**
   * Sets if we should run internalize pass during optimization and code
   * generation.
   *
   * \since LTO_API_VERSION=14
   */
  extern void
  lto_codegen_set_should_internalize(lto_code_gen_t cg,
                                     lto_bool_t ShouldInternalize);
  
  /**
   * \brief Set whether to embed uselists in bitcode.
   *
   * Sets whether \a lto_codegen_write_merged_modules() should embed uselists in
   * output bitcode.  This should be turned on for all -save-temps output.
   *
   * \since LTO_API_VERSION=15
   */
  extern void
  lto_codegen_set_should_embed_uselists(lto_code_gen_t cg,
                                        lto_bool_t ShouldEmbedUselists);
  
  /**
   * @}
   * @defgroup LLVMCTLTO ThinLTO
   * @ingroup LLVMC
   *
   * @{
   */
  
  /**
   * Type to wrap a single object returned by ThinLTO.
   *
   * \since LTO_API_VERSION=18
   */
  typedef struct {
    void *Buffer;
    size_t Size;
  } LTOObjectBuffer;
  
  /**
   * Instantiates a ThinLTO code generator.
   * Returns NULL on error (check lto_get_error_message() for details).
   *
   *
   * The ThinLTOCodeGenerator is not intended to be reuse for multiple
   * compilation: the model is that the client adds modules to the generator and
   * ask to perform the ThinLTO optimizations / codegen, and finally destroys the
   * codegenerator.
   *
   * \since LTO_API_VERSION=18
   */
  extern thinlto_code_gen_t thinlto_create_codegen(void);
  
  /**
   * Frees the generator and all memory it internally allocated.
   * Upon return the thinlto_code_gen_t is no longer valid.
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_dispose(thinlto_code_gen_t cg);
  
  /**
   * Add a module to a ThinLTO code generator. Identifier has to be unique among
   * all the modules in a code generator. The data buffer stays owned by the
   * client, and is expected to be available for the entire lifetime of the
   * thinlto_code_gen_t it is added to.
   *
   * On failure, returns NULL (check lto_get_error_message() for details).
   *
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_add_module(thinlto_code_gen_t cg,
                                         const char *identifier, const char *data,
                                         int length);
  
  /**
   * Optimize and codegen all the modules added to the codegenerator using
   * ThinLTO. Resulting objects are accessible using thinlto_module_get_object().
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_process(thinlto_code_gen_t cg);
  
  /**
   * Returns the number of object files produced by the ThinLTO CodeGenerator.
   *
   * It usually matches the number of input files, but this is not a guarantee of
   * the API and may change in future implementation, so the client should not
   * assume it.
   *
   * \since LTO_API_VERSION=18
   */
  extern unsigned int thinlto_module_get_num_objects(thinlto_code_gen_t cg);
  
  /**
   * Returns a reference to the ith object file produced by the ThinLTO
   * CodeGenerator.
   *
   * Client should use \p thinlto_module_get_num_objects() to get the number of
   * available objects.
   *
   * \since LTO_API_VERSION=18
   */
  extern LTOObjectBuffer thinlto_module_get_object(thinlto_code_gen_t cg,
                                                   unsigned int index);
  
  /**
   * Sets which PIC code model to generate.
   * Returns true on error (check lto_get_error_message() for details).
   *
   * \since LTO_API_VERSION=18
   */
  extern lto_bool_t thinlto_codegen_set_pic_model(thinlto_code_gen_t cg,
                                                  lto_codegen_model);
  
  /**
   * @}
   * @defgroup LLVMCTLTO_CACHING ThinLTO Cache Control
   * @ingroup LLVMCTLTO
   *
   * These entry points control the ThinLTO cache. The cache is intended to
   * support incremental build, and thus needs to be persistent accross build.
   * The client enabled the cache by supplying a path to an existing directory.
   * The code generator will use this to store objects files that may be reused
   * during a subsequent build.
   * To avoid filling the disk space, a few knobs are provided:
   *  - The pruning interval limit the frequency at which the garbage collector
   *    will try to scan the cache directory to prune it from expired entries.
   *    Setting to -1 disable the pruning (default).
   *  - The pruning expiration time indicates to the garbage collector how old an
   *    entry needs to be to be removed.
   *  - Finally, the garbage collector can be instructed to prune the cache till
   *    the occupied space goes below a threshold.
   * @{
   */
  
  /**
   * Sets the path to a directory to use as a cache storage for incremental build.
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_set_cache_dir(thinlto_code_gen_t cg,
                                            const char *cache_dir);
  
  /**
   * Sets the cache pruning interval (in seconds). A negative value disable the
   * pruning (default).
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_set_cache_pruning_interval(thinlto_code_gen_t cg,
                                                         int interval);
  
  /**
   * Sets the maximum cache size that can be persistent across build, in terms of
   * percentage of the available space on the the disk. Set to 100 to indicate
   * no limit, 50 to indicate that the cache size will not be left over half the
   * available space. A value over 100 will be reduced to 100.
   *
   * The formula looks like:
   *  AvailableSpace = FreeSpace + ExistingCacheSize
   *  NewCacheSize = AvailableSpace * P/100
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_set_final_cache_size_relative_to_available_space(
      thinlto_code_gen_t cg, unsigned percentage);
  
  /**
   * Sets the expiration (in seconds) for an entry in the cache.
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_set_cache_entry_expiration(thinlto_code_gen_t cg,
                                                         unsigned expiration);
  
  /**
   * @}
   */
  
  /**
   * Sets the path to a directory to use as a storage for temporary bitcode files.
   * The intention is to make the bitcode files available for debugging at various
   * stage of the pipeline.
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_set_savetemps_dir(thinlto_code_gen_t cg,
                                                const char *save_temps_dir);
  
  /**
   * Sets the cpu to generate code for.
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_set_cpu(thinlto_code_gen_t cg, const char *cpu);
  
  /**
   * Parse -mllvm style debug options.
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_debug_options(const char *const *options, int number);
  
  /**
   * Test if a module has support for ThinLTO linking.
   *
   * \since LTO_API_VERSION=18
   */
  extern lto_bool_t lto_module_is_thinlto(lto_module_t mod);
  
  /**
   * Adds a symbol to the list of global symbols that must exist in the final
   * generated code. If a function is not listed there, it might be inlined into
   * every usage and optimized away. For every single module, the functions
   * referenced from code outside of the ThinLTO modules need to be added here.
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_add_must_preserve_symbol(thinlto_code_gen_t cg,
                                                       const char *name,
                                                       int length);
  
  /**
   * Adds a symbol to the list of global symbols that are cross-referenced between
   * ThinLTO files. If the ThinLTO CodeGenerator can ensure that every
   * references from a ThinLTO module to this symbol is optimized away, then
   * the symbol can be discarded.
   *
   * \since LTO_API_VERSION=18
   */
  extern void thinlto_codegen_add_cross_referenced_symbol(thinlto_code_gen_t cg,
                                                          const char *name,
                                                          int length);
  
  #ifdef __cplusplus
  }
  #endif
  
  /**
   * @}
   */
  
  #endif
  