ABI and API compatibility

The libgccjit developers strive for ABI and API backward-compatibility: programs built against libgccjit.so stand a good chance of running without recompilation against newer versions of libgccjit.so, and ought to recompile without modification against newer versions of libgccjit.h.

Note

The libgccjit++.h C++ API is more experimental, and less locked-down at this time.

API compatibility is achieved by extending the API rather than changing it. For ABI compatiblity, we avoid bumping the SONAME, and instead use symbol versioning to tag each symbol, so that a binary linked against libgccjit.so is tagged according to the symbols that it uses.

For example, gcc_jit_context_add_command_line_option() was added in LIBGCCJIT_ABI_1. If a client program uses it, this can be detected from metadata by using objdump:

$ objdump -p testsuite/jit/test-extra-options.c.exe | tail -n 8

Version References:
  required from libgccjit.so.0:
    0x00824161 0x00 04 LIBGCCJIT_ABI_1
    0x00824160 0x00 03 LIBGCCJIT_ABI_0
  required from libc.so.6:

You can see the symbol tags provided by libgccjit.so using objdump:

$ objdump -p libgccjit.so | less
[...snip...]
Version definitions:
1 0x01 0x0ff81f20 libgccjit.so.0
2 0x00 0x00824160 LIBGCCJIT_ABI_0
3 0x00 0x00824161 LIBGCCJIT_ABI_1
        LIBGCCJIT_ABI_0
[...snip...]

Programmatically checking version

Client code can programmatically check libgccjit version using:

int gcc_jit_version_major(void)

Return libgccjit major version. This is analogous to __GNUC__ in C code.

int gcc_jit_version_minor(void)

Return libgccjit minor version. This is analogous to __GNUC_MINOR__ in C code.

int gcc_jit_version_patchlevel(void)

Return libgccjit patchlevel version. This is analogous to __GNUC_PATCHLEVEL__ in C code.

Note

These entry points has been added with LIBGCCJIT_ABI_13 (see below).

ABI symbol tags

The initial release of libgccjit (in gcc 5.1) did not use symbol versioning.

Newer releases use the following tags.

LIBGCCJIT_ABI_0

All entrypoints in the initial release of libgccjit are tagged with LIBGCCJIT_ABI_0, to signify the transition to symbol versioning.

Binaries built against older copies of libgccjit.so should continue to work, with this being handled transparently by the linker (see this post)

LIBGCCJIT_ABI_1

LIBGCCJIT_ABI_1 covers the addition of gcc_jit_context_add_command_line_option()

LIBGCCJIT_ABI_2

LIBGCCJIT_ABI_2 covers the addition of gcc_jit_context_set_bool_allow_unreachable_blocks()

LIBGCCJIT_ABI_3

LIBGCCJIT_ABI_3 covers the addition of switch statements via API entrypoints:

• gcc_jit_block_end_with_switch()

• gcc_jit_case_as_object()

• gcc_jit_context_new_case()

LIBGCCJIT_ABI_4

LIBGCCJIT_ABI_4 covers the addition of timers via API entrypoints:

• gcc_jit_context_get_timer()

• gcc_jit_context_set_timer()

• gcc_jit_timer_new()

• gcc_jit_timer_release()

• gcc_jit_timer_push()

• gcc_jit_timer_pop()

• gcc_jit_timer_print()

LIBGCCJIT_ABI_5

LIBGCCJIT_ABI_5 covers the addition of gcc_jit_context_set_bool_use_external_driver()

LIBGCCJIT_ABI_6

LIBGCCJIT_ABI_6 covers the addition of gcc_jit_rvalue_set_bool_require_tail_call()

LIBGCCJIT_ABI_7

LIBGCCJIT_ABI_7 covers the addition of gcc_jit_type_get_aligned()

LIBGCCJIT_ABI_8

LIBGCCJIT_ABI_8 covers the addition of gcc_jit_type_get_vector()

LIBGCCJIT_ABI_9

LIBGCCJIT_ABI_9 covers the addition of gcc_jit_function_get_address()

LIBGCCJIT_ABI_10

LIBGCCJIT_ABI_10 covers the addition of gcc_jit_context_new_rvalue_from_vector()

LIBGCCJIT_ABI_11

LIBGCCJIT_ABI_11 covers the addition of gcc_jit_context_add_driver_option()

LIBGCCJIT_ABI_12

LIBGCCJIT_ABI_12 covers the addition of gcc_jit_context_new_bitfield()

LIBGCCJIT_ABI_13

LIBGCCJIT_ABI_13 covers the addition of version functions via API entrypoints:

• gcc_jit_version_major()

• gcc_jit_version_minor()

• gcc_jit_version_patchlevel()

LIBGCCJIT_ABI_14

LIBGCCJIT_ABI_14 covers the addition of gcc_jit_global_set_initializer()

LIBGCCJIT_ABI_15

LIBGCCJIT_ABI_15 covers the addition of API entrypoints for directly embedding assembler instructions:

• gcc_jit_block_add_extended_asm()

• gcc_jit_block_end_with_extended_asm_goto()

• gcc_jit_extended_asm_as_object()

• gcc_jit_extended_asm_set_volatile_flag()

• gcc_jit_extended_asm_set_inline_flag()

• gcc_jit_extended_asm_add_output_operand()

• gcc_jit_extended_asm_add_input_operand()

• gcc_jit_extended_asm_add_clobber()

• gcc_jit_context_add_top_level_asm()

LIBGCCJIT_ABI_16

LIBGCCJIT_ABI_16 covers the addition of reflection functions via API entrypoints:

• gcc_jit_function_get_return_type()

• gcc_jit_function_get_param_count()

• gcc_jit_type_dyncast_array()

• gcc_jit_type_is_bool()

• gcc_jit_type_is_integral()

• gcc_jit_type_is_pointer()

• gcc_jit_type_is_struct()

• gcc_jit_type_dyncast_vector()

• gcc_jit_type_unqualified()

• gcc_jit_type_dyncast_function_ptr_type()

• gcc_jit_function_type_get_return_type()

• gcc_jit_function_type_get_param_count()

• gcc_jit_function_type_get_param_type()

• gcc_jit_vector_type_get_num_units()

• gcc_jit_vector_type_get_element_type()

• gcc_jit_struct_get_field()

• gcc_jit_struct_get_field_count()

LIBGCCJIT_ABI_17

LIBGCCJIT_ABI_17 covers the addition of an API entrypoint to set the thread-local storage model of a variable:

• gcc_jit_lvalue_set_tls_model()

LIBGCCJIT_ABI_18

LIBGCCJIT_ABI_18 covers the addition of an API entrypoint to set the link section of a variable:

• gcc_jit_lvalue_set_link_section()

LIBGCCJIT_ABI_19

LIBGCCJIT_ABI_19 covers the addition of API entrypoints to set the initial value of a global with an rvalue and to use constructors:

• gcc_jit_context_new_array_constructor()

• gcc_jit_context_new_struct_constructor()

• gcc_jit_context_new_union_constructor()

• gcc_jit_global_set_initializer_rvalue()

LIBGCCJIT_ABI_20

LIBGCCJIT_ABI_20 covers the addition of sized integer types, including 128-bit integers and helper functions for types:

• gcc_jit_compatible_types()

• gcc_jit_type_get_size()

• GCC_JIT_TYPE_UINT8_T

• GCC_JIT_TYPE_UINT16_T

• GCC_JIT_TYPE_UINT32_T

• GCC_JIT_TYPE_UINT64_T

• GCC_JIT_TYPE_UINT128_T

• GCC_JIT_TYPE_INT8_T

• GCC_JIT_TYPE_INT16_T

• GCC_JIT_TYPE_INT32_T

• GCC_JIT_TYPE_INT64_T

• GCC_JIT_TYPE_INT128_T

LIBGCCJIT_ABI_21

LIBGCCJIT_ABI_21 covers the addition of an API entrypoint to bitcast a value from one type to another:

• gcc_jit_context_new_bitcast()

LIBGCCJIT_ABI_22

LIBGCCJIT_ABI_22 covers the addition of an API entrypoint to set the register name of a variable:

• gcc_jit_lvalue_set_register_name()

LIBGCCJIT_ABI_23

LIBGCCJIT_ABI_23 covers the addition of an API entrypoint to hide stderr logs:

• gcc_jit_context_set_bool_print_errors_to_stderr()

LIBGCCJIT_ABI_24

LIBGCCJIT_ABI_24 covers the addition of functions to get and set the alignment of a variable:

• gcc_jit_lvalue_set_alignment()

• gcc_jit_lvalue_get_alignment()