Expressions¶

Rvalues¶

gcc_jit_rvalue¶

A 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).

gcc_jit_type *gcc_jit_rvalue_get_type(gcc_jit_rvalue *rvalue)¶: Get the type of this rvalue.

gcc_jit_object *gcc_jit_rvalue_as_object(gcc_jit_rvalue *rvalue)¶: Upcast the given rvalue to be an object.

Simple expressions¶

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 int value.

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 long value.

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:

gcc_jit_context_new_rvalue_from_int (ctxt, numeric_type, 0)

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 one. Essentially this is just a shortcut for:

gcc_jit_context_new_rvalue_from_int (ctxt, numeric_type, 1)

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 double value.

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.

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:

gcc_jit_context_new_rvalue_from_ptr (ctxt, pointer_type, NULL)

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 GCC_JIT_TYPE_CONST_CHAR_PTR.

The parameter value must be non-NULL. The call takes a copy of the underlying string, so it is valid to pass in a pointer to an on-stack buffer.

Vector expressions¶

gcc_jit_rvalue * gcc_jit_context_new_rvalue_from_vector(gcc_jit_context *ctxt, gcc_jit_location *loc, gcc_jit_type *vec_type, size_t num_elements, gcc_jit_rvalue **elements)¶

Build a vector rvalue from an array of elements.

“vec_type” should be a vector type, created using gcc_jit_type_get_vector().

“num_elements” should match that of the vector type.

This entrypoint was added in LIBGCCJIT_ABI_10; you can test for its presence using

#ifdef LIBGCCJIT_HAVE_gcc_jit_context_new_rvalue_from_vector

Unary Operations¶

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.

The parameter result_type must be a numeric type.

enum gcc_jit_unary_op¶

The available unary operations are:

Unary Operation	C equivalent
`GCC_JIT_UNARY_OP_MINUS`	-(EXPR)
`GCC_JIT_UNARY_OP_BITWISE_NEGATE`	~(EXPR)
`GCC_JIT_UNARY_OP_LOGICAL_NEGATE`	!(EXPR)
`GCC_JIT_UNARY_OP_ABS`	abs (EXPR)

GCC_JIT_UNARY_OP_MINUS¶

Negate an arithmetic value; analogous to:

-(EXPR)

in C.

GCC_JIT_UNARY_OP_BITWISE_NEGATE¶

Bitwise negation of an integer value (one’s complement); analogous to:

~(EXPR)

in C.

GCC_JIT_UNARY_OP_LOGICAL_NEGATE¶

Logical negation of an arithmetic or pointer value; analogous to:

!(EXPR)

in C.

GCC_JIT_UNARY_OP_ABS¶

Absolute value of an arithmetic expression; analogous to:

abs (EXPR)

in C.

Binary Operations¶

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.

The parameter result_type must be a numeric type.

enum gcc_jit_binary_op¶

The available binary operations are:

Binary Operation	C equivalent
`GCC_JIT_BINARY_OP_PLUS`	x + y
`GCC_JIT_BINARY_OP_MINUS`	x - y
`GCC_JIT_BINARY_OP_MULT`	x * y
`GCC_JIT_BINARY_OP_DIVIDE`	x / y
`GCC_JIT_BINARY_OP_MODULO`	x % y
`GCC_JIT_BINARY_OP_BITWISE_AND`	x & y
`GCC_JIT_BINARY_OP_BITWISE_XOR`	x ^ y
`GCC_JIT_BINARY_OP_BITWISE_OR`	x \| y
`GCC_JIT_BINARY_OP_LOGICAL_AND`	x && y
`GCC_JIT_BINARY_OP_LOGICAL_OR`	x \|\| y
`GCC_JIT_BINARY_OP_LSHIFT`	x << y
`GCC_JIT_BINARY_OP_RSHIFT`	x >> y

GCC_JIT_BINARY_OP_PLUS¶

Addition of arithmetic values; analogous to:

(EXPR_A) + (EXPR_B)

in C.

For pointer addition, use gcc_jit_context_new_array_access().

GCC_JIT_BINARY_OP_MINUS¶

Subtraction of arithmetic values; analogous to:

(EXPR_A) - (EXPR_B)

in C.

GCC_JIT_BINARY_OP_MULT¶

Multiplication of a pair of arithmetic values; analogous to:

(EXPR_A) * (EXPR_B)

in C.

GCC_JIT_BINARY_OP_DIVIDE¶

Quotient of division of arithmetic values; analogous to:

(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.

GCC_JIT_BINARY_OP_MODULO¶

Remainder of division of arithmetic values; analogous to:

(EXPR_A) % (EXPR_B)

in C.

GCC_JIT_BINARY_OP_BITWISE_AND¶

Bitwise AND; analogous to:

(EXPR_A) & (EXPR_B)

in C.

GCC_JIT_BINARY_OP_BITWISE_XOR¶

Bitwise exclusive OR; analogous to:

(EXPR_A) ^ (EXPR_B)

in C.

GCC_JIT_BINARY_OP_BITWISE_OR¶

Bitwise inclusive OR; analogous to:

(EXPR_A) | (EXPR_B)

in C.

GCC_JIT_BINARY_OP_LOGICAL_AND¶

Logical AND; analogous to:

(EXPR_A) && (EXPR_B)

in C.

GCC_JIT_BINARY_OP_LOGICAL_OR¶

Logical OR; analogous to:

(EXPR_A) || (EXPR_B)

in C.

GCC_JIT_BINARY_OP_LSHIFT¶

Left shift; analogous to:

(EXPR_A) << (EXPR_B)

in C.

GCC_JIT_BINARY_OP_RSHIFT¶

Right shift; analogous to:

(EXPR_A) >> (EXPR_B)

in C.

Comparisons¶

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.

enum gcc_jit_comparison¶

Comparison	C equivalent
`GCC_JIT_COMPARISON_EQ`	x == y
`GCC_JIT_COMPARISON_NE`	x != y
`GCC_JIT_COMPARISON_LT`	x < y
`GCC_JIT_COMPARISON_LE`	x <= y
`GCC_JIT_COMPARISON_GT`	x > y
`GCC_JIT_COMPARISON_GE`	x >= y

Function calls¶

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

gcc_jit_context_new_call() merely builds a 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 gcc_jit_block_add_eval():

/* Add "(void)printf (arg0, arg1);".  */
gcc_jit_block_add_eval (
  block, NULL,
  gcc_jit_context_new_call (
    ctxt,
    NULL,
    printf_func,
    2, args));

gcc_jit_rvalue * gcc_jit_context_new_call_through_ptr(gcc_jit_context *ctxt, gcc_jit_location *loc, gcc_jit_rvalue *fn_ptr, int numargs, gcc_jit_rvalue **args)¶: Given an rvalue of function pointer type (e.g. from gcc_jit_context_new_function_ptr_type()), and the given table of argument rvalues, construct a call to the function pointer, with the result as an rvalue.

Note

The same caveat as for gcc_jit_context_new_call() applies.

void gcc_jit_rvalue_set_bool_require_tail_call(gcc_jit_rvalue *call, int require_tail_call)¶

Given an gcc_jit_rvalue * for a call created through gcc_jit_context_new_call() or gcc_jit_context_new_call_through_ptr(), mark/clear the call as needing tail-call optimization. The optimizer will attempt to optimize the call into a jump instruction; if it is unable to do do, an error will be emitted.

This may be useful when implementing functions that use the continuation-passing style (e.g. for functional programming languages), in which every function “returns” by calling a “continuation” function pointer. This call must be guaranteed to be implemented as a jump, otherwise the program could consume an arbitrary amount of stack space as it executed.

This entrypoint was added in LIBGCCJIT_ABI_6; you can test for its presence using

#ifdef LIBGCCJIT_HAVE_gcc_jit_rvalue_set_bool_require_tail_call

Function pointers¶

Function pointers can be obtained:

from a gcc_jit_function using gcc_jit_function_get_address(), or

from an existing function using gcc_jit_context_new_rvalue_from_ptr(), using a function pointer type obtained using gcc_jit_context_new_function_ptr_type().

Type-coercion¶

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¶

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.

gcc_jit_object * gcc_jit_lvalue_as_object(gcc_jit_lvalue *lvalue)¶: Upcast an lvalue to be an object.

gcc_jit_rvalue * gcc_jit_lvalue_as_rvalue(gcc_jit_lvalue *lvalue)¶: Upcast an lvalue to be an rvalue.

gcc_jit_rvalue * gcc_jit_lvalue_get_address(gcc_jit_lvalue *lvalue, gcc_jit_location *loc)¶

Take the address of an lvalue; analogous to:

&(EXPR)

in C.

Global variables¶

gcc_jit_lvalue * gcc_jit_context_new_global(gcc_jit_context *ctxt, gcc_jit_location *loc, enum gcc_jit_global_kind kind, gcc_jit_type *type, const char *name)¶

Add a new global variable of the given type and name to the context.

The parameter type must be non-void.

The parameter name must be non-NULL. The call takes a copy of the underlying string, so it is valid to pass in a pointer to an on-stack buffer.

The “kind” parameter determines the visibility of the “global” outside of the gcc_jit_result:

enum gcc_jit_global_kind¶

GCC_JIT_GLOBAL_EXPORTED¶: Global is defined by the client code and is visible by name outside of this JIT context via gcc_jit_result_get_global() (and this value is required for the global to be accessible via that entrypoint).

GCC_JIT_GLOBAL_INTERNAL¶: Global is defined by the client code, but is invisible outside of it. Analogous to a “static” global within a .c file. Specifically, the variable will only be visible within this context and within child contexts.

GCC_JIT_GLOBAL_IMPORTED¶: Global is not defined by the client code; we’re merely referring to it. Analogous to using an “extern” global from a header file.

Working with pointers, structs and unions¶

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:

*(EXPR)

in C.

Field access is provided separately for both lvalues and rvalues.

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:

(EXPR).field = ...;

in C.

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:

(EXPR).field

in C.

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:

(EXPR)->field

in C, itself equivalent to (*EXPR).FIELD.

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:

PTR[INDEX]

in C (or, indeed, to PTR + INDEX).

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Expressions¶

Rvalues¶

Simple expressions¶

Vector expressions¶

Unary Operations¶

Binary Operations¶

Comparisons¶

Function calls¶

Function pointers¶

Type-coercion¶

Lvalues¶

Global variables¶

Working with pointers, structs and unions¶