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.. Copyright (C) 2014 Free Software Foundation, Inc.
Originally contributed by David Malcolm <dmalcolm@redhat.com>
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/>.
.. default-domain:: c
Expressions
===========
Rvalues
-------
.. type:: gcc_jit_rvalue
A :c:type:`gcc_jit_rvalue *` is an expression that can be computed.
It can be simple, e.g.:
* an integer value e.g. `0` or `42`
* a string literal e.g. `"Hello world"`
* a variable e.g. `i`. These are also lvalues (see below).
or compound e.g.:
* a unary expression e.g. `!cond`
* a binary expression e.g. `(a + b)`
* a function call e.g. `get_distance (&player_ship, &target)`
* etc.
Every rvalue has an associated type, and the API will check to ensure
that types match up correctly (otherwise the context will emit an error).
.. function:: gcc_jit_type *gcc_jit_rvalue_get_type (gcc_jit_rvalue *rvalue)
Get the type of this rvalue.
.. function:: gcc_jit_object *gcc_jit_rvalue_as_object (gcc_jit_rvalue *rvalue)
Upcast the given rvalue to be an object.
Simple expressions
******************
.. function:: gcc_jit_rvalue *\
gcc_jit_context_new_rvalue_from_int (gcc_jit_context *ctxt, \
gcc_jit_type *numeric_type, \
int value)
Given a numeric type (integer or floating point), build an rvalue for
the given constant :c:type:`int` value.
.. function:: gcc_jit_rvalue *\
gcc_jit_context_new_rvalue_from_long (gcc_jit_context *ctxt, \
gcc_jit_type *numeric_type, \
long value)
Given a numeric type (integer or floating point), build an rvalue for
the given constant :c:type:`long` value.
.. function:: gcc_jit_rvalue *gcc_jit_context_zero (gcc_jit_context *ctxt, \
gcc_jit_type *numeric_type)
Given a numeric type (integer or floating point), get the rvalue for
zero. Essentially this is just a shortcut for:
.. code-block:: c
gcc_jit_context_new_rvalue_from_int (ctxt, numeric_type, 0)
.. function:: gcc_jit_rvalue *gcc_jit_context_one (gcc_jit_context *ctxt, \
gcc_jit_type *numeric_type)
Given a numeric type (integer or floating point), get the rvalue for
zero. Essentially this is just a shortcut for:
.. code-block:: c
gcc_jit_context_new_rvalue_from_int (ctxt, numeric_type, 1)
.. function:: gcc_jit_rvalue *\
gcc_jit_context_new_rvalue_from_double (gcc_jit_context *ctxt, \
gcc_jit_type *numeric_type, \
double value)
Given a numeric type (integer or floating point), build an rvalue for
the given constant :c:type:`double` value.
.. function:: gcc_jit_rvalue *\
gcc_jit_context_new_rvalue_from_ptr (gcc_jit_context *ctxt, \
gcc_jit_type *pointer_type, \
void *value)
Given a pointer type, build an rvalue for the given address.
.. function:: gcc_jit_rvalue *gcc_jit_context_null (gcc_jit_context *ctxt, \
gcc_jit_type *pointer_type)
Given a pointer type, build an rvalue for ``NULL``. Essentially this
is just a shortcut for:
.. code-block:: c
gcc_jit_context_new_rvalue_from_ptr (ctxt, pointer_type, NULL)
.. function:: gcc_jit_rvalue *\
gcc_jit_context_new_string_literal (gcc_jit_context *ctxt, \
const char *value)
Generate an rvalue for the given NIL-terminated string, of type
:c:data:`GCC_JIT_TYPE_CONST_CHAR_PTR`.
Unary Operations
****************
.. function:: gcc_jit_rvalue * \
gcc_jit_context_new_unary_op (gcc_jit_context *ctxt, \
gcc_jit_location *loc, \
enum gcc_jit_unary_op op, \
gcc_jit_type *result_type, \
gcc_jit_rvalue *rvalue)
Build a unary operation out of an input rvalue.
.. type:: enum gcc_jit_unary_op
The available unary operations are:
========================================== ============
Unary Operation C equivalent
========================================== ============
:c:macro:`GCC_JIT_UNARY_OP_MINUS` `-(EXPR)`
:c:macro:`GCC_JIT_UNARY_OP_BITWISE_NEGATE` `~(EXPR)`
:c:macro:`GCC_JIT_UNARY_OP_LOGICAL_NEGATE` `!(EXPR)`
:c:macro:`GCC_JIT_UNARY_OP_ABS` `abs (EXPR)`
========================================== ============
.. c:macro:: GCC_JIT_UNARY_OP_MINUS
Negate an arithmetic value; analogous to:
.. code-block:: c
-(EXPR)
in C.
.. c:macro:: GCC_JIT_UNARY_OP_BITWISE_NEGATE
Bitwise negation of an integer value (one's complement); analogous
to:
.. code-block:: c
~(EXPR)
in C.
.. c:macro:: GCC_JIT_UNARY_OP_LOGICAL_NEGATE
Logical negation of an arithmetic or pointer value; analogous to:
.. code-block:: c
!(EXPR)
in C.
.. c:macro:: GCC_JIT_UNARY_OP_ABS
Absolute value of an arithmetic expression; analogous to:
.. code-block:: c
abs (EXPR)
in C.
Binary Operations
*****************
.. function:: gcc_jit_rvalue *gcc_jit_context_new_binary_op (gcc_jit_context *ctxt, \
gcc_jit_location *loc, \
enum gcc_jit_binary_op op, \
gcc_jit_type *result_type, \
gcc_jit_rvalue *a, gcc_jit_rvalue *b)
Build a binary operation out of two constituent rvalues.
.. type:: enum gcc_jit_binary_op
The available binary operations are:
======================================== ============
Binary Operation C equivalent
======================================== ============
:c:macro:`GCC_JIT_BINARY_OP_PLUS` `x + y`
:c:macro:`GCC_JIT_BINARY_OP_MINUS` `x - y`
:c:macro:`GCC_JIT_BINARY_OP_MULT` `x * y`
:c:macro:`GCC_JIT_BINARY_OP_DIVIDE` `x / y`
:c:macro:`GCC_JIT_BINARY_OP_MODULO` `x % y`
:c:macro:`GCC_JIT_BINARY_OP_BITWISE_AND` `x & y`
:c:macro:`GCC_JIT_BINARY_OP_BITWISE_XOR` `x ^ y`
:c:macro:`GCC_JIT_BINARY_OP_BITWISE_OR` `x | y`
:c:macro:`GCC_JIT_BINARY_OP_LOGICAL_AND` `x && y`
:c:macro:`GCC_JIT_BINARY_OP_LOGICAL_OR` `x || y`
:c:macro:`GCC_JIT_BINARY_OP_LSHIFT` `x << y`
:c:macro:`GCC_JIT_BINARY_OP_RSHIFT` `x >> y`
======================================== ============
.. c:macro:: GCC_JIT_BINARY_OP_PLUS
Addition of arithmetic values; analogous to:
.. code-block:: c
(EXPR_A) + (EXPR_B)
in C.
For pointer addition, use :c:func:`gcc_jit_context_new_array_access`.
.. c:macro:: GCC_JIT_BINARY_OP_MINUS`
Subtraction of arithmetic values; analogous to:
.. code-block:: c
(EXPR_A) - (EXPR_B)
in C.
.. c:macro:: GCC_JIT_BINARY_OP_MULT
Multiplication of a pair of arithmetic values; analogous to:
.. code-block:: c
(EXPR_A) * (EXPR_B)
in C.
.. c:macro:: GCC_JIT_BINARY_OP_DIVIDE
Quotient of division of arithmetic values; analogous to:
.. code-block:: c
(EXPR_A) / (EXPR_B)
in C.
The result type affects the kind of division: if the result type is
integer-based, then the result is truncated towards zero, whereas
a floating-point result type indicates floating-point division.
.. c:macro:: GCC_JIT_BINARY_OP_MODULO
Remainder of division of arithmetic values; analogous to:
.. code-block:: c
(EXPR_A) % (EXPR_B)
in C.
.. c:macro:: GCC_JIT_BINARY_OP_BITWISE_AND
Bitwise AND; analogous to:
.. code-block:: c
(EXPR_A) & (EXPR_B)
in C.
.. c:macro:: GCC_JIT_BINARY_OP_BITWISE_XOR
Bitwise exclusive OR; analogous to:
.. code-block:: c
(EXPR_A) ^ (EXPR_B)
in C.
.. c:macro:: GCC_JIT_BINARY_OP_BITWISE_OR
Bitwise inclusive OR; analogous to:
.. code-block:: c
(EXPR_A) | (EXPR_B)
in C.
.. c:macro:: GCC_JIT_BINARY_OP_LOGICAL_AND
Logical AND; analogous to:
.. code-block:: c
(EXPR_A) && (EXPR_B)
in C.
.. c:macro:: GCC_JIT_BINARY_OP_LOGICAL_OR
Logical OR; analogous to:
.. code-block:: c
(EXPR_A) || (EXPR_B)
in C.
.. c:macro:: GCC_JIT_BINARY_OP_LSHIFT
Left shift; analogous to:
.. code-block:: c
(EXPR_A) << (EXPR_B)
in C.
.. c:macro:: GCC_JIT_BINARY_OP_RSHIFT
Right shift; analogous to:
.. code-block:: c
(EXPR_A) >> (EXPR_B)
in C.
Comparisons
***********
.. function:: gcc_jit_rvalue *\
gcc_jit_context_new_comparison (gcc_jit_context *ctxt,\
gcc_jit_location *loc,\
enum gcc_jit_comparison op,\
gcc_jit_rvalue *a, gcc_jit_rvalue *b)
Build a boolean rvalue out of the comparison of two other rvalues.
.. type:: enum gcc_jit_comparison
======================================= ============
Comparison C equivalent
======================================= ============
:c:macro:`GCC_JIT_COMPARISON_EQ` `x == y`
:c:macro:`GCC_JIT_COMPARISON_NE` `x != y`
:c:macro:`GCC_JIT_COMPARISON_LT` `x < y`
:c:macro:`GCC_JIT_COMPARISON_LE` `x <= y`
:c:macro:`GCC_JIT_COMPARISON_GT` `x > y`
:c:macro:`GCC_JIT_COMPARISON_GE` `x >= y`
======================================= ============
Function calls
**************
.. function:: gcc_jit_rvalue *\
gcc_jit_context_new_call (gcc_jit_context *ctxt,\
gcc_jit_location *loc,\
gcc_jit_function *func,\
int numargs , gcc_jit_rvalue **args)
Given a function and the given table of argument rvalues, construct a
call to the function, with the result as an rvalue.
.. note::
:c:func:`gcc_jit_context_new_call` merely builds a
:c:type:`gcc_jit_rvalue` i.e. an expression that can be evaluated,
perhaps as part of a more complicated expression.
The call *won't* happen unless you add a statement to a function
that evaluates the expression.
For example, if you want to call a function and discard the result
(or to call a function with ``void`` return type), use
:c:func:`gcc_jit_block_add_eval`:
.. code-block:: c
/* Add "(void)printf (arg0, arg1);". */
gcc_jit_block_add_eval (
block, NULL,
gcc_jit_context_new_call (
ctxt,
NULL,
printf_func,
2, args));
Type-coercion
*************
.. function:: gcc_jit_rvalue *\
gcc_jit_context_new_cast (gcc_jit_context *ctxt,\
gcc_jit_location *loc,\
gcc_jit_rvalue *rvalue,\
gcc_jit_type *type)
Given an rvalue of T, construct another rvalue of another type.
Currently only a limited set of conversions are possible:
* int <-> float
* int <-> bool
* P* <-> Q*, for pointer types P and Q
Lvalues
-------
.. type:: gcc_jit_lvalue
An lvalue is something that can of the *left*-hand side of an assignment:
a storage area (such as a variable). It is also usable as an rvalue,
where the rvalue is computed by reading from the storage area.
.. function:: gcc_jit_object *\
gcc_jit_lvalue_as_object (gcc_jit_lvalue *lvalue)
Upcast an lvalue to be an object.
.. function:: gcc_jit_rvalue *\
gcc_jit_lvalue_as_rvalue (gcc_jit_lvalue *lvalue)
Upcast an lvalue to be an rvalue.
.. function:: gcc_jit_rvalue *\
gcc_jit_lvalue_get_address (gcc_jit_lvalue *lvalue,\
gcc_jit_location *loc)
Take the address of an lvalue; analogous to:
.. code-block:: c
&(EXPR)
in C.
Global variables
****************
.. function:: gcc_jit_lvalue *\
gcc_jit_context_new_global (gcc_jit_context *ctxt,\
gcc_jit_location *loc,\
gcc_jit_type *type,\
const char *name)
Add a new global variable of the given type and name to the context.
Working with pointers, structs and unions
-----------------------------------------
.. function:: gcc_jit_lvalue *\
gcc_jit_rvalue_dereference (gcc_jit_rvalue *rvalue,\
gcc_jit_location *loc)
Given an rvalue of pointer type ``T *``, dereferencing the pointer,
getting an lvalue of type ``T``. Analogous to:
.. code-block:: c
*(EXPR)
in C.
Field access is provided separately for both lvalues and rvalues.
.. function:: gcc_jit_lvalue *\
gcc_jit_lvalue_access_field (gcc_jit_lvalue *struct_,\
gcc_jit_location *loc,\
gcc_jit_field *field)
Given an lvalue of struct or union type, access the given field,
getting an lvalue of the field's type. Analogous to:
.. code-block:: c
(EXPR).field = ...;
in C.
.. function:: gcc_jit_rvalue *\
gcc_jit_rvalue_access_field (gcc_jit_rvalue *struct_,\
gcc_jit_location *loc,\
gcc_jit_field *field)
Given an rvalue of struct or union type, access the given field
as an rvalue. Analogous to:
.. code-block:: c
(EXPR).field
in C.
.. function:: gcc_jit_lvalue *\
gcc_jit_rvalue_dereference_field (gcc_jit_rvalue *ptr,\
gcc_jit_location *loc,\
gcc_jit_field *field)
Given an rvalue of pointer type ``T *`` where T is of struct or union
type, access the given field as an lvalue. Analogous to:
.. code-block:: c
(EXPR)->field
in C, itself equivalent to ``(*EXPR).FIELD``.
.. function:: gcc_jit_lvalue *\
gcc_jit_context_new_array_access (gcc_jit_context *ctxt,\
gcc_jit_location *loc,\
gcc_jit_rvalue *ptr,\
gcc_jit_rvalue *index)
Given an rvalue of pointer type ``T *``, get at the element `T` at
the given index, using standard C array indexing rules i.e. each
increment of ``index`` corresponds to ``sizeof(T)`` bytes.
Analogous to:
.. code-block:: c
PTR[INDEX]
in C (or, indeed, to ``PTR + INDEX``).
|