Implicit Calls to Library Routines

Here is an explanation of implicit calls to library routines.

DECLARE_LIBRARY_RENAMES

Macro

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.

void TARGET_INIT_LIBFUNCS (void)

Target Hook

This hook should declare additional library routines or rename existing ones, using the functions set_optab_libfunc and init_one_libfunc defined in optabs.c. init_optabs calls this macro after initializing all the normal library routines. The default is to do nothing. Most ports don't need to define this hook.

TARGET_FLOAT_LIB_COMPARE_RETURNS_BOOL (mode, comparison)

Macro

This macro should return true if 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.

US_SOFTWARE_GOFAST

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 TARGET_INIT_LIBFUNCS to 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_BOOL target hook must return false for SFmode and DFmode comparisons.

TARGET_EDOM

Macro

The value of EDOM on 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 EDOM into errno directly. Look in /usr/include/errno.h to find the value of EDOM on 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 matherr when there is an error, then you should leave TARGET_EDOM undefined so that matherr is used normally.

GEN_ERRNO_RTX

Macro

Define this macro as a C expression to create an rtl expression that refers to the global "variable" errno. (On certain systems, errno may not actually be a variable.) If you don't define this macro, a reasonable default is used.

TARGET_MEM_FUNCTIONS

Macro

Define this macro if GCC should generate calls to the ISO C (and System V) library functions memcpy, memmove and memset rather than the BSD functions bcopy and bzero.

TARGET_C99_FUNCTIONS

Macro

When this macro is nonzero, GCC will implicitly optimize sin calls into sinf and 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.

NEXT_OBJC_RUNTIME

Macro

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.