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Diffstat (limited to 'gcc/doc/extend.texi')
| -rw-r--r-- | gcc/doc/extend.texi | 38 |
1 files changed, 16 insertions, 22 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index 79b0a88..05c7797 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -4631,30 +4631,24 @@ The first step in using these extensions is to provide the necessary data types. This should be done using an appropriate @code{typedef}: @smallexample -typedef int v4si __attribute__ ((mode(V4SI))); +typedef int v4si __attribute__ ((vector_size (16))); @end smallexample -The base type @code{int} is effectively ignored by the compiler, the -actual properties of the new type @code{v4si} are defined by the -@code{__attribute__}. It defines the machine mode to be used; for vector -types these have the form @code{V@var{n}@var{B}}; @var{n} should be the -number of elements in the vector, and @var{B} should be the base mode of the -individual elements. The following can be used as base modes: +The @code{int} type specifies the base type, while the attribute specifies +the vector size for the variable, measured in bytes. For example, the +declaration above causes the compiler to set the mode for the @code{v4si} +type to be 16 bytes wide and divided into @code{int} sized units. For +a 32-bit @code{int} this means a vector of 4 units of 4 bytes, and the +corresponding mode of @code{foo} will be @acronym{V4SI}. -@table @code -@item QI -An integer that is as wide as the smallest addressable unit, usually 8 bits. -@item HI -An integer, twice as wide as a QI mode integer, usually 16 bits. -@item SI -An integer, four times as wide as a QI mode integer, usually 32 bits. -@item DI -An integer, eight times as wide as a QI mode integer, usually 64 bits. -@item SF -A floating point value, as wide as a SI mode integer, usually 32 bits. -@item DF -A floating point value, as wide as a DI mode integer, usually 64 bits. -@end table +The @code{vector_size} attribute is only applicable to integral and +float scalars, although arrays, pointers, and function return values +are allowed in conjunction with this construct. + +All the basic integer types can be used as base types, both as signed +and as unsigned: @code{char}, @code{short}, @code{int}, @code{long}, +@code{long long}. In addition, @code{float} and @code{double} can be +used to build floating-point vector types. Specifying a combination that is not valid for the current architecture will cause GCC to synthesize the instructions using a narrower mode. @@ -4673,7 +4667,7 @@ added to the corresponding 4 elements in @var{b} and the resulting vector will be stored in @var{c}. @smallexample -typedef int v4si __attribute__ ((mode(V4SI))); +typedef int v4si __attribute__ ((vector_size (16))); v4si a, b, c; |