attributes when making a declaration. This keyword is followed by an
attribute specification inside double parentheses. The following
attributes are currently defined for functions on all targets:
-@code{noreturn}, @code{returns_twice}, @code{noinline}, @code{always_inline},
-@code{flatten}, @code{pure}, @code{const}, @code{nothrow}, @code{sentinel},
-@code{format}, @code{format_arg}, @code{no_instrument_function},
-@code{section}, @code{constructor}, @code{destructor}, @code{used},
-@code{unused}, @code{deprecated}, @code{weak}, @code{malloc},
-@code{alias}, @code{warn_unused_result}, @code{nonnull},
-@code{gnu_inline} and @code{externally_visible}. Several other
-attributes are defined for functions on particular target systems. Other
-attributes, including @code{section} are supported for variables declarations
-(@pxref{Variable Attributes}) and for types (@pxref{Type Attributes}).
+@code{alloc_size}, @code{noreturn}, @code{returns_twice}, @code{noinline},
+@code{always_inline}, @code{flatten}, @code{pure}, @code{const},
+@code{nothrow}, @code{sentinel}, @code{format}, @code{format_arg},
+@code{no_instrument_function}, @code{section}, @code{constructor},
+@code{destructor}, @code{used}, @code{unused}, @code{deprecated},
+@code{weak}, @code{malloc}, @code{alias}, @code{warn_unused_result},
+@code{nonnull}, @code{gnu_inline} and @code{externally_visible},
+@code{hot}, @code{cold}.
+Several other attributes are defined for functions on particular target
+systems. Other attributes, including @code{section} are supported for
+variables declarations (@pxref{Variable Attributes}) and for types (@pxref{Type
+Attributes}).
You may also specify attributes with @samp{__} preceding and following
each keyword. This allows you to use them in header files without
Not all target machines support this attribute.
+@item alloc_size
+@cindex @code{alloc_size} attribute
+The @code{alloc_size} attribute is used to tell the compiler that the
+function return value points to memory, where the size is given by
+one or two of the functions parameters. GCC uses this
+information to improve the correctness of @code{__builtin_object_size}.
+
+The function parameter(s) denoting the allocated size are specified by
+one or two integer arguments supplied to the attribute. The allocated size
+is either the value of the single function argument specified or the product
+of the two function arguments specified. Argument numbering starts at
+one.
+
+For instance,
+
+@smallexample
+void* my_calloc(size_t, size_t) __attribute__((alloc_size(1,2)))
+void my_realloc(void* size_t) __attribute__((alloc_size(2)))
+@end smallexample
+
+declares that my_calloc will return memory of the size given by
+the product of parameter 1 and 2 and that my_realloc will return memory
+of the size given by parameter 2.
+
@item always_inline
@cindex @code{always_inline} function attribute
Generally, functions are not inlined unless optimization is specified.
@item gnu_inline
@cindex @code{gnu_inline} function attribute
-This attribute on an inline declaration results in the old GNU C89
-inline behavior even in the ISO C99 mode.
+This attribute should be used with a function which is also declared
+with the @code{inline} keyword. It directs GCC to treat the function
+as if it were defined in gnu89 mode even when compiling in C99 or
+gnu99 mode.
+
+If the function is declared @code{extern}, then this definition of the
+function is used only for inlining. In no case is the function
+compiled as a standalone function, not even if you take its address
+explicitly. Such an address becomes an external reference, as if you
+had only declared the function, and had not defined it. This has
+almost the effect of a macro. The way to use this is to put a
+function definition in a header file with this attribute, and put
+another copy of the function, without @code{extern}, in a library
+file. The definition in the header file will cause most calls to the
+function to be inlined. If any uses of the function remain, they will
+refer to the single copy in the library. Note that the two
+definitions of the functions need not be precisely the same, although
+if they do not have the same effect your program may behave oddly.
+
+If the function is neither @code{extern} nor @code{static}, then the
+function is compiled as a standalone function, as well as being
+inlined where possible.
+
+This is how GCC traditionally handled functions declared
+@code{inline}. Since ISO C99 specifies a different semantics for
+@code{inline}, this function attribute is provided as a transition
+measure and as a useful feature in its own right. This attribute is
+available in GCC 4.1.3 and later. It is available if either of the
+preprocessor macros @code{__GNUC_GNU_INLINE__} or
+@code{__GNUC_STDC_INLINE__} are defined. @xref{Inline,,An Inline
+Function is As Fast As a Macro}.
@cindex @code{flatten} function attribute
@item flatten
Controlling C Dialect}.
@item function_vector
-@cindex calling functions through the function vector on the H8/300 processors
+@cindex calling functions through the function vector on H8/300, M16C, and M32C processors
Use this attribute on the H8/300, H8/300H, and H8S to indicate that the specified
function should be called through the function vector. Calling a
function through the function vector will reduce code size, however;
You must use GAS and GLD from GNU binutils version 2.7 or later for
this attribute to work correctly.
+On M16C/M32C targets, the @code{function_vector} attribute declares a
+special page subroutine call function. Use of this attribute reduces
+the code size by 2 bytes for each call generated to the
+subroutine. The argument to the attribute is the vector number entry
+from the special page vector table which contains the 16 low-order
+bits of the subroutine's entry address. Each vector table has special
+page number (18 to 255) which are used in @code{jsrs} instruction.
+Jump addresses of the routines are generated by adding 0x0F0000 (in
+case of M16C targets) or 0xFF0000 (in case of M32C targets), to the 2
+byte addresses set in the vector table. Therefore you need to ensure
+that all the special page vector routines should get mapped within the
+address range 0x0F0000 to 0x0FFFFF (for M16C) and 0xFF0000 to 0xFFFFFF
+(for M32C).
+
+In the following example 2 bytes will be saved for each call to
+function @code{foo}.
+
+@smallexample
+void foo (void) __attribute__((function_vector(0x18)));
+void foo (void)
+@{
+@}
+
+void bar (void)
+@{
+ foo();
+@}
+@end smallexample
+
+If functions are defined in one file and are called in another file,
+then be sure to write this declaration in both files.
+
+This attribute is ignored for R8C target.
+
@item interrupt
@cindex interrupt handler functions
-Use this attribute on the ARM, AVR, C4x, CRX, M32C, M32R/D, MS1, and Xstormy16
-ports to indicate that the specified function is an interrupt handler.
-The compiler will generate function entry and exit sequences suitable
-for use in an interrupt handler when this attribute is present.
+Use this attribute on the ARM, AVR, C4x, CRX, M32C, M32R/D, m68k, MS1,
+and Xstormy16 ports to indicate that the specified function is an
+interrupt handler. The compiler will generate function entry and exit
+sequences suitable for use in an interrupt handler when this attribute
+is present.
-Note, interrupt handlers for the Blackfin, m68k, H8/300, H8/300H, H8S, and
+Note, interrupt handlers for the Blackfin, H8/300, H8/300H, H8S, and
SH processors can be specified via the @code{interrupt_handler} attribute.
Note, on the AVR, interrupts will be enabled inside the function.
will generate function entry and exit sequences suitable for use in an
interrupt handler when this attribute is present.
+@item interrupt_thread
+@cindex interrupt thread functions on fido
+Use this attribute on fido, a subarchitecture of the m68k, to indicate
+that the specified function is an interrupt handler that is designed
+to run as a thread. The compiler omits generate prologue/epilogue
+sequences and replaces the return instruction with a @code{sleep}
+instruction. This attribute is available only on fido.
+
@item kspisusp
@cindex User stack pointer in interrupts on the Blackfin
When used together with @code{interrupt_handler}, @code{exception_handler}
@xref{RS/6000 and PowerPC Options}, for more information on whether long
calls are necessary.
-@item long_call
+@item long_call/near/far
@cindex indirect calls on MIPS
-This attribute specifies how a particular function is called on MIPS@.
-The attribute overrides the @option{-mlong-calls} (@pxref{MIPS Options})
-command line switch. This attribute causes the compiler to always call
+These attributes specify how a particular function is called on MIPS@.
+The attributes override the @option{-mlong-calls} (@pxref{MIPS Options})
+command-line switch. The @code{long_call} and @code{far} attributes are
+synonyms, and cause the compiler to always call
the function by first loading its address into a register, and then using
-the contents of that register.
+the contents of that register. The @code{near} attribute has the opposite
+effect; it specifies that non-PIC calls should be made using the more
+efficient @code{jal} instruction.
@item malloc
@cindex @code{malloc} attribute
The attribute @code{pure} is not implemented in GCC versions earlier
than 2.96.
+@item hot
+@cindex @code{hot} function attribute
+The @code{hot} attribute is used to inform the compiler that a function is a
+hot spot of the compiled program. The function is optimized more aggressively
+and on many target it is placed into special subsection of the text section so
+all hot functions appears close together improving locality.
+
+When profile feedback is available, via @option{-fprofile-use}, hot functions
+are automatically detected and this attribute is ignored.
+
+The @code{hot} attribute is not implemented in GCC versions earlier than 4.3.
+
+@item cold
+@cindex @code{cold} function attribute
+The @code{cold} attribute is used to inform the compiler that a function is
+unlikely executed. The function is optimized for size rather than speed and on
+many targets it is placed into special subsection of the text section so all
+cold functions appears close together improving code locality of non-cold parts
+of program. The paths leading to call of cold functions within code are marked
+as unlikely by the branch prediction mechanism. It is thus useful to mark
+functions used to handle unlikely conditions, such as @code{perror}, as cold to
+improve optimization of hot functions that do call marked functions in rare
+occasions.
+
+When profile feedback is available, via @option{-fprofile-use}, hot functions
+are automatically detected and this attribute is ignored.
+
+The @code{hot} attribute is not implemented in GCC versions earlier than 4.3.
+
@item regparm (@var{number})
@cindex @code{regparm} attribute
@cindex functions that are passed arguments in registers on the 386
into their callers with the option @option{-finline-functions}.
GCC implements three different semantics of declaring a function
-inline. One is available with @option{-std=gnu89} or when @code{gnu_inline}
-attribute is present on all inline declarations, another when
-@option{-std=c99} or @option{-std=gnu99}, and the third is used when
-compiling C++.
+inline. One is available with @option{-std=gnu89} or
+@option{-fgnu89-inline} or when @code{gnu_inline} attribute is present
+on all inline declarations, another when @option{-std=c99} or
+@option{-std=gnu99} (without @option{-fgnu89-inline}), and the third
+is used when compiling C++.
To declare a function inline, use the @code{inline} keyword in its
declaration, like this:
@findex gamma
@findex gammaf
@findex gammal
+@findex gamma_r
+@findex gammaf_r
+@findex gammal_r
@findex gettext
@findex hypot
@findex hypotf
@findex lgamma
@findex lgammaf
@findex lgammal
+@findex lgamma_r
+@findex lgammaf_r
+@findex lgammal_r
@findex llabs
@findex llrint
@findex llrintf
@findex lroundf
@findex lroundl
@findex malloc
+@findex memchr
@findex memcmp
@findex memcpy
@findex mempcpy
@findex signbit
@findex signbitf
@findex signbitl
+@findex signbitd32
+@findex signbitd64
+@findex signbitd128
@findex significand
@findex significandf
@findex significandl
@code{_exit}, @code{alloca}, @code{bcmp}, @code{bzero},
@code{dcgettext}, @code{dgettext}, @code{dremf}, @code{dreml},
@code{drem}, @code{exp10f}, @code{exp10l}, @code{exp10}, @code{ffsll},
-@code{ffsl}, @code{ffs}, @code{fprintf_unlocked}, @code{fputs_unlocked},
-@code{gammaf}, @code{gammal}, @code{gamma}, @code{gettext},
+@code{ffsl}, @code{ffs}, @code{fprintf_unlocked},
+@code{fputs_unlocked}, @code{gammaf}, @code{gammal}, @code{gamma},
+@code{gammaf_r}, @code{gammal_r}, @code{gamma_r}, @code{gettext},
@code{index}, @code{isascii}, @code{j0f}, @code{j0l}, @code{j0},
@code{j1f}, @code{j1l}, @code{j1}, @code{jnf}, @code{jnl}, @code{jn},
-@code{mempcpy}, @code{pow10f}, @code{pow10l}, @code{pow10},
-@code{printf_unlocked}, @code{rindex}, @code{scalbf}, @code{scalbl},
-@code{scalb}, @code{signbit}, @code{signbitf}, @code{signbitl},
-@code{significandf}, @code{significandl}, @code{significand},
-@code{sincosf}, @code{sincosl}, @code{sincos}, @code{stpcpy},
-@code{stpncpy}, @code{strcasecmp}, @code{strdup}, @code{strfmon},
-@code{strncasecmp}, @code{strndup}, @code{toascii}, @code{y0f},
-@code{y0l}, @code{y0}, @code{y1f}, @code{y1l}, @code{y1}, @code{ynf},
-@code{ynl} and @code{yn}
+@code{lgammaf_r}, @code{lgammal_r}, @code{lgamma_r}, @code{mempcpy},
+@code{pow10f}, @code{pow10l}, @code{pow10}, @code{printf_unlocked},
+@code{rindex}, @code{scalbf}, @code{scalbl}, @code{scalb},
+@code{signbit}, @code{signbitf}, @code{signbitl}, @code{signbitd32},
+@code{signbitd64}, @code{signbitd128}, @code{significandf},
+@code{significandl}, @code{significand}, @code{sincosf},
+@code{sincosl}, @code{sincos}, @code{stpcpy}, @code{stpncpy},
+@code{strcasecmp}, @code{strdup}, @code{strfmon}, @code{strncasecmp},
+@code{strndup}, @code{toascii}, @code{y0f}, @code{y0l}, @code{y0},
+@code{y1f}, @code{y1l}, @code{y1}, @code{ynf}, @code{ynl} and
+@code{yn}
may be handled as built-in functions.
All these functions have corresponding versions
prefixed with @code{__builtin_}, which may be used even in strict C89
@code{isgraph}, @code{islower}, @code{isprint}, @code{ispunct},
@code{isspace}, @code{isupper}, @code{isxdigit}, @code{tolower},
@code{toupper}, @code{labs}, @code{ldexp}, @code{log10}, @code{log},
-@code{malloc}, @code{memcmp}, @code{memcpy}, @code{memset}, @code{modf},
-@code{pow}, @code{printf}, @code{putchar}, @code{puts}, @code{scanf},
-@code{sinh}, @code{sin}, @code{snprintf}, @code{sprintf}, @code{sqrt},
-@code{sscanf}, @code{strcat}, @code{strchr}, @code{strcmp},
-@code{strcpy}, @code{strcspn}, @code{strlen}, @code{strncat},
-@code{strncmp}, @code{strncpy}, @code{strpbrk}, @code{strrchr},
-@code{strspn}, @code{strstr}, @code{tanh}, @code{tan}, @code{vfprintf},
-@code{vprintf} and @code{vsprintf}
+@code{malloc}, @code{memchr}, @code{memcmp}, @code{memcpy},
+@code{memset}, @code{modf}, @code{pow}, @code{printf}, @code{putchar},
+@code{puts}, @code{scanf}, @code{sinh}, @code{sin}, @code{snprintf},
+@code{sprintf}, @code{sqrt}, @code{sscanf}, @code{strcat},
+@code{strchr}, @code{strcmp}, @code{strcpy}, @code{strcspn},
+@code{strlen}, @code{strncat}, @code{strncmp}, @code{strncpy},
+@code{strpbrk}, @code{strrchr}, @code{strspn}, @code{strstr},
+@code{tanh}, @code{tan}, @code{vfprintf}, @code{vprintf} and @code{vsprintf}
are all recognized as built-in functions unless
@option{-fno-builtin} is specified (or @option{-fno-builtin-@var{function}}
is specified for an individual function). All of these functions have
v8hi __builtin_ia32_pabsw128 (v8hi)
@end smallexample
+The following built-in functions are available when @option{-msse4.1} is
+used. All of them generate the machine instruction that is part of the
+name.
+
+@smallexample
+v2df __builtin_ia32_blendpd (v2df, v2df, const int)
+v4sf __builtin_ia32_blendps (v4sf, v4sf, const int)
+v2df __builtin_ia32_blendvpd (v2df, v2df, v2df)
+v4sf __builtin_ia32_blendvps (v4sf, v4sf, v4sf)
+v2df __builtin_ia32_dppd (__v2df, __v2df, const int)
+v4sf __builtin_ia32_dpps (v4sf, v4sf, const int)
+v4sf __builtin_ia32_insertps128 (v4sf, v4sf, const int)
+v2di __builtin_ia32_movntdqa (v2di *);
+v16qi __builtin_ia32_mpsadbw128 (v16qi, v16qi, const int)
+v8hi __builtin_ia32_packusdw128 (v4si, v4si)
+v16qi __builtin_ia32_pblendvb128 (v16qi, v16qi, v16qi)
+v8hi __builtin_ia32_pblendw128 (v8hi, v8hi, const int)
+v2di __builtin_ia32_pcmpeqq (v2di, v2di)
+v8hi __builtin_ia32_phminposuw128 (v8hi)
+v16qi __builtin_ia32_pmaxsb128 (v16qi, v16qi)
+v4si __builtin_ia32_pmaxsd128 (v4si, v4si)
+v4si __builtin_ia32_pmaxud128 (v4si, v4si)
+v8hi __builtin_ia32_pmaxuw128 (v8hi, v8hi)
+v16qi __builtin_ia32_pminsb128 (v16qi, v16qi)
+v4si __builtin_ia32_pminsd128 (v4si, v4si)
+v4si __builtin_ia32_pminud128 (v4si, v4si)
+v8hi __builtin_ia32_pminuw128 (v8hi, v8hi)
+v4si __builtin_ia32_pmovsxbd128 (v16qi)
+v2di __builtin_ia32_pmovsxbq128 (v16qi)
+v8hi __builtin_ia32_pmovsxbw128 (v16qi)
+v2di __builtin_ia32_pmovsxdq128 (v4si)
+v4si __builtin_ia32_pmovsxwd128 (v8hi)
+v2di __builtin_ia32_pmovsxwq128 (v8hi)
+v4si __builtin_ia32_pmovzxbd128 (v16qi)
+v2di __builtin_ia32_pmovzxbq128 (v16qi)
+v8hi __builtin_ia32_pmovzxbw128 (v16qi)
+v2di __builtin_ia32_pmovzxdq128 (v4si)
+v4si __builtin_ia32_pmovzxwd128 (v8hi)
+v2di __builtin_ia32_pmovzxwq128 (v8hi)
+v2di __builtin_ia32_pmuldq128 (v4si, v4si)
+v4si __builtin_ia32_pmulld128 (v4si, v4si)
+int __builtin_ia32_ptestc128 (v2di, v2di)
+int __builtin_ia32_ptestnzc128 (v2di, v2di)
+int __builtin_ia32_ptestz128 (v2di, v2di)
+v2df __builtin_ia32_roundpd (v2df, const int)
+v4sf __builtin_ia32_roundps (v4sf, const int)
+v2df __builtin_ia32_roundsd (v2df, v2df, const int)
+v4sf __builtin_ia32_roundss (v4sf, v4sf, const int)
+@end smallexample
+
+The following built-in functions are available when @option{-msse4.1} is
+used.
+
+@table @code
+@item v4sf __builtin_ia32_vec_set_v4sf (v4sf, float, const int)
+Generates the @code{insertps} machine instruction.
+@item int __builtin_ia32_vec_ext_v16qi (v16qi, const int)
+Generates the @code{pextrb} machine instruction.
+@item v16qi __builtin_ia32_vec_set_v16qi (v16qi, int, const int)
+Generates the @code{pinsrb} machine instruction.
+@item v4si __builtin_ia32_vec_set_v4si (v4si, int, const int)
+Generates the @code{pinsrd} machine instruction.
+@item v2di __builtin_ia32_vec_set_v2di (v2di, long long, const int)
+Generates the @code{pinsrq} machine instruction in 64bit mode.
+@end table
+
+The following built-in functions are changed to generate new SSE4.1
+instructions when @option{-msse4.1} is used.
+
+@table @code
+@item float __builtin_ia32_vec_ext_v4sf (v4sf, const int)
+Generates the @code{extractps} machine instruction.
+@item int __builtin_ia32_vec_ext_v4si (v4si, const int)
+Generates the @code{pextrd} machine instruction.
+@item long long __builtin_ia32_vec_ext_v2di (v2di, const int)
+Generates the @code{pextrq} machine instruction in 64bit mode.
+@end table
+
+The following built-in functions are available when @option{-msse4.2} is
+used. All of them generate the machine instruction that is part of the
+name.
+
+@smallexample
+v16qi __builtin_ia32_pcmpestrm128 (v16qi, int, v16qi, int, const int)
+int __builtin_ia32_pcmpestri128 (v16qi, int, v16qi, int, const int)
+int __builtin_ia32_pcmpestria128 (v16qi, int, v16qi, int, const int)
+int __builtin_ia32_pcmpestric128 (v16qi, int, v16qi, int, const int)
+int __builtin_ia32_pcmpestrio128 (v16qi, int, v16qi, int, const int)
+int __builtin_ia32_pcmpestris128 (v16qi, int, v16qi, int, const int)
+int __builtin_ia32_pcmpestriz128 (v16qi, int, v16qi, int, const int)
+v16qi __builtin_ia32_pcmpistrm128 (v16qi, v16qi, const int)
+int __builtin_ia32_pcmpistri128 (v16qi, v16qi, const int)
+int __builtin_ia32_pcmpistria128 (v16qi, v16qi, const int)
+int __builtin_ia32_pcmpistric128 (v16qi, v16qi, const int)
+int __builtin_ia32_pcmpistrio128 (v16qi, v16qi, const int)
+int __builtin_ia32_pcmpistris128 (v16qi, v16qi, const int)
+int __builtin_ia32_pcmpistriz128 (v16qi, v16qi, const int)
+__v2di __builtin_ia32_pcmpgtq (__v2di, __v2di)
+@end smallexample
+
+The following built-in functions are available when @option{-msse4.2} is
+used.
+
+@table @code
+unsigned int __builtin_ia32_crc32qi (unsigned int, unsigned char)
+Generates the @code{crc32b} machine instruction.
+unsigned int __builtin_ia32_crc32hi (unsigned int, unsigned short)
+Generates the @code{crc32w} machine instruction.
+unsigned int __builtin_ia32_crc32si (unsigned int, unsigned int)
+Generates the @code{crc32l} machine instruction.
+unsigned long long __builtin_ia32_crc32di (unsigned int, unsigned long long)
+@end table
+
+The following built-in functions are changed to generate new SSE4.2
+instructions when @option{-msse4.2} is used.
+
+@table @code
+int __builtin_popcount (unsigned int)
+Generates the @code{popcntl} machine instruction.
+int __builtin_popcountl (unsigned long)
+Generates the @code{popcntl} or @code{popcntq} machine instruction,
+depending on the size of @code{unsigned long}.
+int __builtin_popcountll (unsigned long long)
+Generates the @code{popcntq} machine instruction.
+@end table
+
The following built-in functions are available when @option{-msse4a} is used.
@smallexample
The MIPS DSP Application-Specific Extension (ASE) includes new
instructions that are designed to improve the performance of DSP and
media applications. It provides instructions that operate on packed
-8-bit integer data, Q15 fractional data and Q31 fractional data.
+8-bit/16-bit integer data, Q7, Q15 and Q31 fractional data.
GCC supports MIPS DSP operations using both the generic
vector extensions (@pxref{Vector Extensions}) and a collection of
MIPS-specific built-in functions. Both kinds of support are
enabled by the @option{-mdsp} command-line option.
+Revision 2 of the ASE was introduced in the second half of 2006.
+This revision adds extra instructions to the original ASE, but is
+otherwise backwards-compatible with it. You can select revision 2
+using the command-line option @option{-mdspr2}; this option implies
+@option{-mdsp}.
+
At present, GCC only provides support for operations on 32-bit
vectors. The vector type associated with 8-bit integer data is
-usually called @code{v4i8} and the vector type associated with Q15 is
-usually called @code{v2q15}. They can be defined in C as follows:
+usually called @code{v4i8}, the vector type associated with Q7
+is usually called @code{v4q7}, the vector type associated with 16-bit
+integer data is usually called @code{v2i16}, and the vector type
+associated with Q15 is usually called @code{v2q15}. They can be
+defined in C as follows:
@smallexample
-typedef char v4i8 __attribute__ ((vector_size(4)));
+typedef signed char v4i8 __attribute__ ((vector_size(4)));
+typedef signed char v4q7 __attribute__ ((vector_size(4)));
+typedef short v2i16 __attribute__ ((vector_size(4)));
typedef short v2q15 __attribute__ ((vector_size(4)));
@end smallexample
-@code{v4i8} and @code{v2q15} values are initialized in the same way as
-aggregates. For example:
+@code{v4i8}, @code{v4q7}, @code{v2i16} and @code{v2q15} values are
+initialized in the same way as aggregates. For example:
@smallexample
v4i8 a = @{1, 2, 3, 4@};
set the lowest byte of @code{a} to @code{1} on little-endian targets
and @code{4} on big-endian targets.
-@emph{Note:} Q15 and Q31 values must be initialized with their integer
+@emph{Note:} Q7, Q15 and Q31 values must be initialized with their integer
representation. As shown in this example, the integer representation
-of a Q15 value can be obtained by multiplying the fractional value by
+of a Q7 value can be obtained by multiplying the fractional value by
+@code{0x1.0p7}. The equivalent for Q15 values is to multiply by
@code{0x1.0p15}. The equivalent for Q31 values is to multiply by
@code{0x1.0p31}.
@item @code{c - d} @tab @code{subq.ph}
@end multitable
+The table below lists the @code{v2i16} operation for which
+hardware support exists for the DSP ASE REV 2. @code{e} and @code{f} are
+@code{v2i16} values.
+
+@multitable @columnfractions .50 .50
+@item C code @tab MIPS instruction
+@item @code{e * f} @tab @code{mul.ph}
+@end multitable
+
It is easier to describe the DSP built-in functions if we first define
the following types:
@smallexample
typedef int q31;
typedef int i32;
+typedef unsigned int ui32;
typedef long long a64;
@end smallexample
immediate parameters are listed as follows.
@smallexample
+imm0_3: 0 to 3.
imm0_7: 0 to 7.
imm0_15: 0 to 15.
imm0_31: 0 to 31.
i32 __builtin_mips_bposge32 (void)
@end smallexample
+The following built-in functions map directly to a particular MIPS DSP REV 2
+instruction. Please refer to the architecture specification
+for details on what each instruction does.
+
+@smallexample
+v4q7 __builtin_mips_absq_s_qb (v4q7);
+v2i16 __builtin_mips_addu_ph (v2i16, v2i16);
+v2i16 __builtin_mips_addu_s_ph (v2i16, v2i16);
+v4i8 __builtin_mips_adduh_qb (v4i8, v4i8);
+v4i8 __builtin_mips_adduh_r_qb (v4i8, v4i8);
+i32 __builtin_mips_append (i32, i32, imm0_31);
+i32 __builtin_mips_balign (i32, i32, imm0_3);
+i32 __builtin_mips_cmpgdu_eq_qb (v4i8, v4i8);
+i32 __builtin_mips_cmpgdu_lt_qb (v4i8, v4i8);
+i32 __builtin_mips_cmpgdu_le_qb (v4i8, v4i8);
+a64 __builtin_mips_dpa_w_ph (a64, v2i16, v2i16);
+a64 __builtin_mips_dps_w_ph (a64, v2i16, v2i16);
+a64 __builtin_mips_madd (a64, i32, i32);
+a64 __builtin_mips_maddu (a64, ui32, ui32);
+a64 __builtin_mips_msub (a64, i32, i32);
+a64 __builtin_mips_msubu (a64, ui32, ui32);
+v2i16 __builtin_mips_mul_ph (v2i16, v2i16);
+v2i16 __builtin_mips_mul_s_ph (v2i16, v2i16);
+q31 __builtin_mips_mulq_rs_w (q31, q31);
+v2q15 __builtin_mips_mulq_s_ph (v2q15, v2q15);
+q31 __builtin_mips_mulq_s_w (q31, q31);
+a64 __builtin_mips_mulsa_w_ph (a64, v2i16, v2i16);
+a64 __builtin_mips_mult (i32, i32);
+a64 __builtin_mips_multu (ui32, ui32);
+v4i8 __builtin_mips_precr_qb_ph (v2i16, v2i16);
+v2i16 __builtin_mips_precr_sra_ph_w (i32, i32, imm0_31);
+v2i16 __builtin_mips_precr_sra_r_ph_w (i32, i32, imm0_31);
+i32 __builtin_mips_prepend (i32, i32, imm0_31);
+v4i8 __builtin_mips_shra_qb (v4i8, imm0_7);
+v4i8 __builtin_mips_shra_r_qb (v4i8, imm0_7);
+v4i8 __builtin_mips_shra_qb (v4i8, i32);
+v4i8 __builtin_mips_shra_r_qb (v4i8, i32);
+v2i16 __builtin_mips_shrl_ph (v2i16, imm0_15);
+v2i16 __builtin_mips_shrl_ph (v2i16, i32);
+v2i16 __builtin_mips_subu_ph (v2i16, v2i16);
+v2i16 __builtin_mips_subu_s_ph (v2i16, v2i16);
+v4i8 __builtin_mips_subuh_qb (v4i8, v4i8);
+v4i8 __builtin_mips_subuh_r_qb (v4i8, v4i8);
+v2q15 __builtin_mips_addqh_ph (v2q15, v2q15);
+v2q15 __builtin_mips_addqh_r_ph (v2q15, v2q15);
+q31 __builtin_mips_addqh_w (q31, q31);
+q31 __builtin_mips_addqh_r_w (q31, q31);
+v2q15 __builtin_mips_subqh_ph (v2q15, v2q15);
+v2q15 __builtin_mips_subqh_r_ph (v2q15, v2q15);
+q31 __builtin_mips_subqh_w (q31, q31);
+q31 __builtin_mips_subqh_r_w (q31, q31);
+a64 __builtin_mips_dpax_w_ph (a64, v2i16, v2i16);
+a64 __builtin_mips_dpsx_w_ph (a64, v2i16, v2i16);
+a64 __builtin_mips_dpaqx_s_w_ph (a64, v2q15, v2q15);
+a64 __builtin_mips_dpaqx_sa_w_ph (a64, v2q15, v2q15);
+a64 __builtin_mips_dpsqx_s_w_ph (a64, v2q15, v2q15);
+a64 __builtin_mips_dpsqx_sa_w_ph (a64, v2q15, v2q15);
+@end smallexample
+
+
@node MIPS Paired-Single Support
@subsection MIPS Paired-Single Support
method denoted by a @samp{->*} or @samp{.*} expression.
* C++ Attributes:: Variable, function, and type attributes for C++ only.
* Namespace Association:: Strong using-directives for namespace association.
+* Type Traits:: Compiler support for type traits
* Java Exceptions:: Tweaking exception handling to work with Java.
* Deprecated Features:: Things will disappear from g++.
* Backwards Compatibility:: Compatibilities with earlier definitions of C++.
@}
@end smallexample
+@node Type Traits
+@section Type Traits
+
+The C++ front-end implements syntactic extensions that allow to
+determine at compile time various characteristics of a type (or of a
+pair of types).
+
+@table @code
+@item __has_nothrow_assign (type)
+If @code{type} is const qualified or is a reference type then the trait is
+false. Otherwise if @code{__has_trivial_assign (type)} is true then the trait
+is true, else if @code{type} is a cv class or union type with copy assignment
+operators that are known not to throw an exception then the trait is true,
+else it is false. Requires: @code{type} shall be a complete type, an array
+type of unknown bound, or is a @code{void} type.
+
+@item __has_nothrow_copy (type)
+If @code{__has_trivial_copy (type)} is true then the trait is true, else if
+@code{type} is a cv class or union type with copy constructors that
+are known not to throw an exception then the trait is true, else it is false.
+Requires: @code{type} shall be a complete type, an array type of
+unknown bound, or is a @code{void} type.
+
+@item __has_nothrow_constructor (type)
+If @code{__has_trivial_constructor (type)} is true then the trait is
+true, else if @code{type} is a cv class or union type (or array
+thereof) with a default constructor that is known not to throw an
+exception then the trait is true, else it is false. Requires:
+@code{type} shall be a complete type, an array type of unknown bound,
+or is a @code{void} type.
+
+@item __has_trivial_assign (type)
+If @code{type} is const qualified or is a reference type then the trait is
+false. Otherwise if @code{__is_pod (type)} is true then the trait is
+true, else if @code{type} is a cv class or union type with a trivial
+copy assignment ([class.copy]) then the trait is true, else it is
+false. Requires: @code{type} shall be a complete type, an array type
+of unknown bound, or is a @code{void} type.
+
+@item __has_trivial_copy (type)
+If @code{__is_pod (type)} is true or @code{type} is a reference type
+then the trait is true, else if @code{type} is a cv class or union type
+with a trivial copy constructor ([class.copy]) then the trait
+is true, else it is false. Requires: @code{type} shall be a complete
+type, an array type of unknown bound, or is a @code{void} type.
+
+@item __has_trivial_constructor (type)
+If @code{__is_pod (type)} is true then the trait is true, else if
+@code{type} is a cv class or union type (or array thereof) with a
+trivial default constructor ([class.ctor]) then the trait is true,
+else it is false. Requires: @code{type} shall be a complete type, an
+array type of unknown bound, or is a @code{void} type.
+
+@item __has_trivial_destructor (type)
+If @code{__is_pod (type)} is true or @code{type} is a reference type then
+the trait is true, else if @code{type} is a cv class or union type (or
+array thereof) with a trivial destructor ([class.dtor]) then the trait
+is true, else it is false. Requires: @code{type} shall be a complete
+type, an array type of unknown bound, or is a @code{void} type.
+
+@item __has_virtual_destructor (type)
+If @code{type} is a class type with a virtual destructor
+([class.dtor]) then the trait is true, else it is false. Requires:
+@code{type} shall be a complete type, an array type of unknown bound,
+or is a @code{void} type.
+
+@item __is_abstract (type)
+If @code{type} is an abstract class ([class.abstract]) then the trait
+is true, else it is false. Requires: @code{type} shall be a complete
+type, an array type of unknown bound, or is a @code{void} type.
+
+@item __is_base_of (base_type, derived_type)
+If @code{base_type} is a base class of @code{derived_type}
+([class.derived]) then the trait is true, otherwise it is false.
+Top-level cv qualifications of @code{base_type} and
+@code{derived_type} are ignored. For the purposes of this trait, a
+class type is considered is own base. Requires: if @code{__is_class
+(base_type)} and @code{__is_class (derived_type)} are true and
+@code{base_type} and @code{derived_type} are not the same type
+(disregarding cv-qualifiers), @code{derived_type} shall be a complete
+type. Diagnostic is produced if this requirement is not met.
+
+@item __is_class (type)
+If @code{type} is a cv class type, and not a union type
+([basic.compound]) the the trait is true, else it is false.
+
+@item __is_empty (type)
+If @code{__is_class (type)} is false then the trait is false.
+Otherwise @code{type} is considered empty if and only if: @code{type}
+has no non-static data members, or all non-static data members, if
+any, are bit-fields of lenght 0, and @code{type} has no virtual
+members, and @code{type} has no virtual base classes, and @code{type}
+has no base classes @code{base_type} for which
+@code{__is_empty (base_type)} is false. Requires: @code{type} shall
+be a complete type, an array type of unknown bound, or is a
+@code{void} type.
+
+@item __is_enum (type)
+If @code{type} is a cv enumeration type ([basic.compound]) the the trait is
+true, else it is false.
+
+@item __is_pod (type)
+If @code{type} is a cv POD type ([basic.types]) then the trait is true,
+else it is false. Requires: @code{type} shall be a complete type,
+an array type of unknown bound, or is a @code{void} type.
+
+@item __is_polymorphic (type)
+If @code{type} is a polymorphic class ([class.virtual]) then the trait
+is true, else it is false. Requires: @code{type} shall be a complete
+type, an array type of unknown bound, or is a @code{void} type.
+
+@item __is_union (type)
+If @code{type} is a cv union type ([basic.compound]) the the trait is
+true, else it is false.
+
+@end table
+
@node Java Exceptions
@section Java Exceptions
projects / gcc.git / blobdiff