Using and Porting GNU CC
The configuration file `
xm-machine.h' contains macro
definitions that describe the machine and system on which the compiler
is running, unlike the definitions in `
describe the machine for which the compiler is producing output. Most
of the values in `
xm-machine.h' are actually the same on all
machines that GNU CC runs on, so large parts of all configuration files
are identical. But there are some macros that vary:
TFmodefloating point numbers in memory with the word containing the sign bit at the lowest address; otherwise, define it to be zero.
This macro need not be defined if the ordering is the same as for multi-word integers.
TARGET_FLOAT_FORMATin Storage Layout for the alternatives and default.
charon the host machine.
shorton the host machine.
inton the host machine.
longon the host machine.
intbit fields, rather than other integral types, including
enum, as do most C compilers.
.exe') that must be mentioned explicitly when you run the program.
allocaimplemented in C. This version of
allocacan be found in the file `
alloca.c'; to use it, you must also alter the `
ALLOCA. (This is done automatically for the systems on which we know it is needed.)
If you do define this macro, you should probably do it as follows:
#ifndef __GNUC__ #define USE_C_ALLOCA #else #define alloca __builtin_alloca #endif
so that when the compiler is compiled with GNU CC it uses the more
vprintfis available on your system.
putenvis available on your system.
sys_siglist, and there is already a declaration of it in the system header files.
USE_PROTOTYPES' is not defined, it will be determined automatically whether your compiler supports prototypes by checking if `
__STDC__' is defined.
USE_PROTOTYPES' is defined to be 0, or the host compiler does not support prototypes, this macro has no effect.
gen_call_valuefunctions generated from the machine description file. If `
USE_PROTOTYPES' is defined to be 0, or the host compiler does not support prototypes, or `
NO_MD_PROTOTYPES' is defined, this macro has no effect. As soon as all of the machine descriptions are modified to have the appropriate number of arguments, this macro will be removed.
Some systems do provide this variable, but with a different name such
_sys_siglist. On these systems, you can define
sys_siglist as a macro which expands into the name actually
stab.h'. If `
USG' is defined, `
NO_STAB_H' is assumed.
In addition, configuration files for system V define
bcmp as aliases. Some files define
as a macro when compiled with GNU CC, in order to take advantage of the
benefit of GNU CC's built-in