.. Copyright 2014-2015 David Malcolm <dmalcolm@redhat.com>
Copyright 2014-2015 Red Hat, Inc.
This is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see
<http://www.gnu.org/licenses/>.
Compilation contexts
====================
.. py:class:: gccjit.Context
The top-level of the API is the `gccjit.Context` class.
A `gccjit.Context` instance encapsulates the state of a compilation.
You can set up options on it, and add types, functions and code.
Invoking :py:meth:`gccjit.Context.compile` on it gives you a
:py:class:`gccjit.Result`.
.. py:method:: dump_to_file(path, update_locations)
.. py:method:: get_first_error()
.. py:method:: new_location(filename, line, column)
Make a :py:class:`gccjit.Location` representing a source location,
for use by the debugger::
loc = ctxt.new_location('web.js', 5, 0)
.. note::
You need to enable :py:data:`gccjit.BoolOption.DEBUGINFO` on the
context for these locations to actually be usable by the debugger::
ctxt.set_bool_option(gccjit.BoolOption.DEBUGINFO, True)
:rtype: :py:class:`gccjit.Location`
.. py:method:: new_global(Type type_, name, Location loc=None)
:rtype: :py:class:`gccjit.LValue`
.. py:method:: new_array_type(Type element_type, int num_elements, \
Location loc=None)
:rtype: :py:class:`gccjit.Type`
.. py:method:: new_field(Type type_, name, Location loc=None)
:rtype: :py:class:`gccjit.Field`
.. py:method:: new_struct(name, fields=None, Location loc=None)
:rtype: :py:class:`gccjit.Struct`
.. py:method:: new_union(name, fields=None, Location loc=None)
Construct a new "union" type.
:rtype: :py:class:`gccjit.Type`
:param field: The fields that make up the union
:type fields: A sequence of :py:class:`gccjit.Field`
:param loc: The source location, if any, or None
:type loc: :py:class:`gccjit.Location`
For example, to create the equivalent of:
.. code-block:: c
union u
{
int as_int;
float as_float;
};
you can use::
ctxt = gccjit.Context()
int_type = ctxt.get_type(gccjit.TypeKind.INT)
float_type = ctxt.get_type(gccjit.TypeKind.FLOAT)
as_int = ctxt.new_field(int_type, b'as_int')
as_float = ctxt.new_field(float_type, b'as_float')
u = ctxt.new_union(b'u', [as_int, as_float])
.. py:method:: new_function_ptr_type(return_type, param_types, loc=None, is_variadic=False)
:param return_type: The return type of the function
:type return_type: :py:class:`gccjit.Type`
:param param_types: The types of the parameters
:type param_types: A sequence of :py:class:`gccjit.Type`
:param loc: The source location, if any, or None
:type loc: :py:class:`gccjit.Location`
:param is_variadic: Is the function variadic (i.e. accepts a
variable number of arguments)
:type is_variadic: :py:class:`bool`
:rtype: :py:class:`gccjit.Type`
For example, to create the equivalent of:
.. code-block:: c
typedef void (*fn_ptr_type) (int, int int);
you can use::
>>> ctxt = gccjit.Context()
>>> void_type = ctxt.get_type(gccjit.TypeKind.VOID)
>>> int_type = ctxt.get_type(gccjit.TypeKind.INT)
>>> fn_ptr_type = ctxt.new_function_ptr_type (void_type,
[int_type,
int_type,
int_type])
>>> print(fn_ptr_type)
void (*) (int, int, int)
.. py:method:: new_param(Type type_, name, Location loc=None)
:rtype: :py:class:`gccjit.Param`
.. py:method:: new_function(kind, Type return_type, name, params, \
Location loc=None, \
is_variadic=False)
:rtype: :py:class:`gccjit.Function`
.. py:method:: get_builtin_function(name)
:rtype: :py:class:`gccjit.Function`
.. py:method:: zero(type_)
Given a :py:class:`gccjit.Type`, which must be a numeric type,
get the constant 0 as a :py:class:`gccjit.RValue` of that type.
:rtype: :py:class:`gccjit.RValue`
.. py:method:: one(type_)
Given a :py:class:`gccjit.Type`, which must be a numeric type,
get the constant 1 as a :py:class:`gccjit.RValue` of that type.
:rtype: :py:class:`gccjit.RValue`
.. py:method:: new_rvalue_from_double(numeric_type, value)
Given a :py:class:`gccjit.Type`, which must be a numeric type,
get a floating-point constant as a :py:class:`gccjit.RValue` of
that type.
:rtype: :py:class:`gccjit.RValue`
.. py:method:: new_rvalue_from_int(type_, value)
Given a :py:class:`gccjit.Type`, which must be a numeric type,
get an integer constant as a :py:class:`gccjit.RValue` of
that type.
:rtype: :py:class:`gccjit.RValue`
.. py:method:: new_rvalue_from_ptr(pointer_type, value)
Given a :py:class:`gccjit.Type`, which must be a pointer type,
and an address, get a :py:class:`gccjit.RValue` representing
that address as a pointer of that type::
ptr = ctxt.new_rvalue_from_ptr(int_star, 0xDEADBEEF)
:rtype: :py:class:`gccjit.RValue`
.. py:method:: null(pointer_type)
Given a :py:class:`gccjit.Type`, which must be a pointer type,
get a :py:class:`gccjit.RValue` representing the `NULL` pointer
of that type::
ptr = ctxt.null(int_star)
:rtype: :py:class:`gccjit.RValue`
.. py:method:: new_string_literal(value)
Make a :py:class:`gccjit.RValue` for the given string literal
value (actually bytes)::
msg = ctxt.new_string_literal(b'hello world\n')
:param bytes value: the bytes of the string literal
:rtype: :py:class:`gccjit.RValue`
.. py:method:: new_unary_op(op, result_type, rvalue, loc=None)
Make a :py:class:`gccjit.RValue` for the given unary operation.
:param op: Which unary operation
:type op: :py:class:`gccjit.UnaryOp`
:param result_type: The type of the result
:type result_type: :py:class:`gccjit.Type`
:param rvalue: The input expression
:type rvalue: :py:class:`gccjit.RValue`
:param loc: The source location, if any, or None
:type loc: :py:class:`gccjit.Location`
:rtype: :py:class:`gccjit.RValue`
.. py:method:: new_binary_op(op, result_type, a, b, loc=None)
Make a :py:class:`gccjit.RValue` for the given binary operation.
:param op: Which binary operation
:type op: :py:class:`gccjit.BinaryOp`
:param result_type: The type of the result
:type result_type: :py:class:`gccjit.Type`
:param a: The first input expression
:type a: :py:class:`gccjit.RValue`
:param b: The second input expression
:type b: :py:class:`gccjit.RValue`
:param loc: The source location, if any, or None
:type loc: :py:class:`gccjit.Location`
:rtype: :py:class:`gccjit.RValue`
.. py:method:: new_comparison(op, a, b, loc=None)
Make a :py:class:`gccjit.RValue` of boolean type for the given
comparison.
:param op: Which comparison
:type op: :py:class:`gccjit.Comparison`
:param a: The first input expression
:type a: :py:class:`gccjit.RValue`
:param b: The second input expression
:type b: :py:class:`gccjit.RValue`
:param loc: The source location, if any, or None
:type loc: :py:class:`gccjit.Location`
:rtype: :py:class:`gccjit.RValue`
.. py:method:: new_child_context(self)
:rtype: :py:class:`gccjit.Context`
.. py:method:: new_cast(RValue rvalue, Type type_, Location loc=None)
:rtype: :py:class:`gccjit.RValue`
.. py:method:: new_array_access(ptr, index, loc=None)
:param ptr: The pointer or array
:type ptr: :py:class:`gccjit.RValue`
:param index: The index within the array
:type index: :py:class:`gccjit.RValue`
:param loc: The source location, if any, or None
:type loc: :py:class:`gccjit.Location`
:rtype: :py:class:`gccjit.LValue`
.. py:method:: new_call(Function func, args, Location loc=None)
:rtype: :py:class:`gccjit.RValue`
.. py:method:: new_call_through_ptr(fn_ptr, args, loc=None)
:param fn_ptr: A function pointer
:type fn_ptr: :py:class:`gccjit.RValue`
:param args: The arguments to the function call
:type args: A sequence of :py:class:`gccjit.RValue`
:param loc: The source location, if any, or None
:type loc: :py:class:`gccjit.Location`
:rtype: :py:class:`gccjit.RValue`
For example, to create the equivalent of:
.. code-block:: c
typedef void (*fn_ptr_type) (int, int, int);
fn_ptr_type fn_ptr;
fn_ptr (a, b, c);
you can use::
block.add_eval (ctxt.new_call_through_ptr(fn_ptr, [a, b, c]))
Debugging
---------
.. py:method:: gccjit.Context.dump_reproducer_to_file(self, path)
Write C source code into `path` that can be compiled into a
self-contained executable (i.e. with libgccjit as the only
dependency).
The generated code will attempt to replay the API calls that have
been made into the given context, at the C level, eliminating any
dependency on Python or on client code or data.
This may be useful when debugging the library or client code, for
reducing a complicated recipe for reproducing a bug into a simpler
form.
Typically you need to supply :option:`-Wno-unused-variable` when
compiling the generated file (since the result of each API call is
assigned to a unique variable within the generated C source, and not
all are necessarily then used).
.. py:method:: gccjit.Context.set_logfile(self, f)
To help with debugging; enable ongoing logging of the context's
activity to the given file object.
For example, the following will enable logging to stderr::
ctxt.set_logfile(sys.stderr)
Examples of information logged include:
* API calls
* the various steps involved within compilation
* activity on any :py:class:`gccjit.Result` instances created by
the context
* activity within any child contexts
The precise format and kinds of information logged is subject
to change.
Unfortunately, doing so creates a leak of an underlying
:c:type:`FILE *` object.
There may a performance cost for logging.
Options
-------
String options
**************
.. py:method:: gccjit.Context.set_str_option(self, opt, val)
Set a string option of the context; see :py:class:`gccjit.StrOption`
for notes on the options and their meanings.
:param opt: Which option to set
:type opt: :py:class:`gccjit.StrOption`
:param str val: The new value
.. py:class:: gccjit.StrOption
.. py:data:: PROGNAME
The name of the program, for use as a prefix when printing error
messages to stderr. If `None`, or default, "libgccjit.so" is used.
Boolean options
***************
.. py:method:: gccjit.Context.set_bool_option(self, opt, val)
Set a boolean option of the context; see :py:class:`gccjit.BoolOption`
for notes on the options and their meanings.
:param opt: Which option to set
:type opt: :py:class:`gccjit.BoolOption`
:param str val: The new value
.. py:class:: gccjit.BoolOption
.. py:data:: DEBUGINFO
If true, :py:meth:`gccjit.Context.compile` will attempt to do the right
thing so that if you attach a debugger to the process, it will
be able to inspect variables and step through your code.
Note that you can't step through code unless you set up source
location information for the code (by creating and passing in
`gccjit.Location` instances).
.. py:data:: DUMP_INITIAL_TREE
If true, :py:meth:`gccjit.Context.compile` will dump its initial
"tree" representation of your code to stderr (before any
optimizations).
Here's some sample output (from the `square` example)::
<statement_list 0x7f4875a62cc0
type <void_type 0x7f4875a64bd0 VOID
align 8 symtab 0 alias set -1 canonical type 0x7f4875a64bd0
pointer_to_this <pointer_type 0x7f4875a64c78>>
side-effects head 0x7f4875a761e0 tail 0x7f4875a761f8 stmts 0x7f4875a62d20 0x7f4875a62d00
stmt <label_expr 0x7f4875a62d20 type <void_type 0x7f4875a64bd0>
side-effects
arg 0 <label_decl 0x7f4875a79080 entry type <void_type 0x7f4875a64bd0>
VOID file (null) line 0 col 0
align 1 context <function_decl 0x7f4875a77500 square>>>
stmt <return_expr 0x7f4875a62d00
type <integer_type 0x7f4875a645e8 public SI
size <integer_cst 0x7f4875a623a0 constant 32>
unit size <integer_cst 0x7f4875a623c0 constant 4>
align 32 symtab 0 alias set -1 canonical type 0x7f4875a645e8 precision 32 min <integer_cst 0x7f4875a62340 -2147483648> max <integer_cst 0x7f4875a62360 2147483647>
pointer_to_this <pointer_type 0x7f4875a6b348>>
side-effects
arg 0 <modify_expr 0x7f4875a72a78 type <integer_type 0x7f4875a645e8>
side-effects arg 0 <result_decl 0x7f4875a7a000 D.54>
arg 1 <mult_expr 0x7f4875a72a50 type <integer_type 0x7f4875a645e8>
arg 0 <parm_decl 0x7f4875a79000 i> arg 1 <parm_decl 0x7f4875a79000 i>>>>>
.. py:data:: DUMP_INITIAL_GIMPLE
If true, :py:meth:`gccjit.Context.compile` will dump the "gimple"
representation of your code to stderr, before any optimizations
are performed. The dump resembles C code::
square (signed int i)
{
signed int D.56;
entry:
D.56 = i * i;
return D.56;
}
.. py:data:: DUMP_GENERATED_CODE
If true, :py:meth:`gccjit.Context.compile` will dump the final
generated code to stderr, in the form of assembly language::
.file "fake.c"
.text
.globl square
.type square, @function
square:
.LFB0:
.cfi_startproc
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset 6, -16
movq %rsp, %rbp
.cfi_def_cfa_register 6
movl %edi, -4(%rbp)
.L2:
movl -4(%rbp), %eax
imull -4(%rbp), %eax
popq %rbp
.cfi_def_cfa 7, 8
ret
.cfi_endproc
.LFE0:
.size square, .-square
.ident "GCC: (GNU) 4.9.0 20131023 (Red Hat 0.1-%{gcc_release})"
.section .note.GNU-stack,"",@progbits
.. py:data:: DUMP_SUMMARY
If true, :py:meth:`gccjit.Context.compile` will print information to stderr
on the actions it is performing, followed by a profile showing
the time taken and memory usage of each phase.
.. py:data:: DUMP_EVERYTHING
If true, :py:meth:`gccjit.Context.compile` will dump copious
amount of information on what it's doing to various
files within a temporary directory. Use
:py:data:`gccjit.BoolOption.KEEP_INTERMEDIATES` (see below) to
see the results. The files are intended to be human-readable,
but the exact files and their formats are subject to change.
.. py:data:: SELFCHECK_GC
If true, libgccjit will aggressively run its garbage collector, to
shake out bugs (greatly slowing down the compile). This is likely
to only be of interest to developers *of* the library. It is
used when running the selftest suite.
.. py:data:: KEEP_INTERMEDIATES
If true, the gccjit.Context will not clean up intermediate files
written to the filesystem, and will display their location on stderr.
Integer options
***************
.. py:method:: gccjit.Context.set_int_option(seld, opt, val)
Set an integer option of the context; see :py:class:`gccjit.IntOption`
for notes on the options and their meanings.
:param opt: Which option to set
:type opt: :py:class:`gccjit.IntOption`
:param str val: The new value
.. py:class:: gccjit.IntOption
.. py:data:: OPTIMIZATION_LEVEL
How much to optimize the code.
Valid values are 0-3, corresponding to GCC's command-line options
-O0 through -O3.
The default value is 0 (unoptimized).