Here is an explanation of implicit calls to library routines.
This macro, if defined, should expand to a piece of C code that will get expanded when compiling functions for libgcc.a. It can be used to provide alternate names for GCC's internal library functions if there are ABI-mandated names that the compiler should provide.
This hook should declare additional library routines or rename existing ones, using the functions
init_one_libfuncdefined in optabs.c.
init_optabscalls this macro after initializing all the normal library routines.
The default is to do nothing. Most ports don't need to define this hook.
This macro should return
trueif the library routine that implements the floating point comparison operator comparison in mode mode will return a boolean, and false if it will return a tristate.
GCC's own floating point libraries return tristates from the comparison operators, so the default returns false always. Most ports don't need to define this macro.
This macro should evaluate to
trueif the integer comparison functions (like
__cmpdi2) return 0 to indicate that the first operand is smaller than the second, 1 to indicate that they are equal, and 2 to indicate that the first operand is greater than the second. If this macro evaluates to
falsethe comparison functions return −1, 0, and 1 instead of 0, 1, and 2. If the target uses the routines in libgcc.a, you do not need to define this macro.
Define this macro if your system C library uses the US Software GOFAST library to provide floating point emulation.
In addition to defining this macro, your architecture must set
gofast_maybe_init_libfuncs, or else call that function from its version of that hook. It is defined in config/gofast.h, which must be included by your architecture's cpu.c file. See sparc/sparc.c for an example.
If this macro is defined, the
TARGET_FLOAT_LIB_COMPARE_RETURNS_BOOLtarget hook must return false for
The value of
EDOMon the target machine, as a C integer constant expression. If you don't define this macro, GCC does not attempt to deposit the value of
errnodirectly. Look in /usr/include/errno.h to find the value of
EDOMon your system.
If you do not define
TARGET_EDOM, then compiled code reports domain errors by calling the library function and letting it report the error. If mathematical functions on your system use
matherrwhen there is an error, then you should leave
TARGET_EDOMundefined so that
matherris used normally.
Define this macro as a C expression to create an rtl expression that refers to the global “variable”
errno. (On certain systems,
errnomay not actually be a variable.) If you don't define this macro, a reasonable default is used.
When this macro is nonzero, GCC will implicitly optimize
sinfand similarly for other functions defined by C99 standard. The default is nonzero that should be proper value for most modern systems, however number of existing systems lacks support for these functions in the runtime so they needs this macro to be redefined to 0.
Define this macro to generate code for Objective-C message sending using the calling convention of the NeXT system. This calling convention involves passing the object, the selector and the method arguments all at once to the method-lookup library function.
The default calling convention passes just the object and the selector to the lookup function, which returns a pointer to the method.