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Diffstat (limited to 'clang')
| -rw-r--r-- | clang/docs/LanguageExtensions.html | 79 |
1 files changed, 29 insertions, 50 deletions
diff --git a/clang/docs/LanguageExtensions.html b/clang/docs/LanguageExtensions.html index e9f409ace9c..1a8ff953adf 100644 --- a/clang/docs/LanguageExtensions.html +++ b/clang/docs/LanguageExtensions.html @@ -24,7 +24,6 @@ td { <li><a href="#overloading-in-c">Function Overloading in C</a></li> <li><a href="#builtins">Builtin Functions</a> <ul> - <li><a href="#__builtin_overload">__builtin_overload</a></li> <li><a href="#__builtin_shufflevector">__builtin_shufflevector</a></li> </ul> </li> @@ -148,75 +147,55 @@ functions are implemented directly in terms of <a href="#vectors">extended vector support</a> instead of builtins, in order to reduce the number of builtins that we need to implement.</p> - <!-- ======================================================================= --> -<h3 id="__builtin_overload">__builtin_overload</h3> +<h3 id="__builtin_shufflevector">__builtin_shufflevector</h3> <!-- ======================================================================= --> -<p><tt>__builtin_overload</tt> is used to implement type-generic "overloaded" -functions in C. This builtin is used to implement the <tt><tgmath.h></tt> -header file, but is intended to be usable for a broad variety of other similar -situations, like the <tt><altivec.h></tt> header. -<b>In the future, we intend to eliminate <tt>__builtin_overload</tt> in favor of <a href="#overloading-in-c">function overloading in C</a>, which provides a better solution for type-generic "overloaded" functions.</b> +<p><tt>__builtin_shufflevector</tt> is used to expression generic vector +permutation/shuffle/swizzle operations. This builtin is also very important for +the implementation of various target-specific header files like +<tt><xmmintrin.h></tt>. </p> <p><b>Syntax:</b></p> <pre> -__builtin_overload(FnNameStr, PromotionRuleStr, NumArgs, arg1, arg2, ... - overloadcandidate1, overloadcandidate2, ...) +__builtin_shufflevector(vec1, vec2, index1, index2, ...) </pre> <p><b>Examples:</b></p> <pre> -#define sin(x) \ - (__builtin_overload("sin", "tgmath", 1, x, sinf, sin, sinl, - csinf, csin, csinl)(x)) -#define fma(x,y,z) \ - (__builtin_overload("fma", "tgmath", 3, x, y, z, fmaf, fma, fmal)(x,y,z)) -#define ldexp(x, y) \ - (__builtin_overload("ldexp", "tgmath1", 2, x, 0, ldexpf, ldexp, ldexpl)(x,y)) -</pre> + // Identity operation - return 4-element vector V1. + __builtin_shufflevector(V1, V1, 0, 1, 2, 3) -<p><b>Description:</b></p> + // "Splat" element 0 of V1 into a 4-element result. + __builtin_shufflevector(V1, V1, 0, 0, 0, 0) -<p>The first argument to __builtin_overload is a string that is the name of the -"function" being implemented. This is used to produce diagnostics that make -sense to the user. For example, if you accidentally pass a pointer argument to -"sin" in GCC, it emits 6 errors about incompatible types. This name allows -Clang to diagnose the error in a way the user can understand. -</p> + // Reverse 4-element vector V1. + __builtin_shufflevector(V1, V1, 3, 2, 1, 0) -<p>The second argument is a string that indicates a set of promotion rules to -apply to the arguments before prototype matching occurs. The currently -supported rules are:</p> - -<dl> - <dt>tgmath</dt> - <dd>Follow the rules of C99 7.22 to determine a single common type, and use it - for every argument.</dd> - <dt>tgmath1</dt> - <dd>Follow the rules of C99 7.22 to determine a single common type of just the - first argument (e.g. treat ints as doubles).</dd> -</dl> - -<p>The third argument is an integer that specifies the arity of the function - being overloaded. After this are N expression arguments which are promoted - according to the rules specified by the promotion rule string.</p> - -<p>The final arguments are functions or function pointers with different - signatures. __builtin_overload will match and evaluate to the first function - pointer whose signature is compatible and does not cause value truncation of - any arguments to the function.</p> + // Concatenate every other element of 4-element vectors V1 and V2. + __builtin_shufflevector(V1, V2, 0, 2, 4, 6) + // Concatenate every other element of 8-element vectors V1 and V2. + __builtin_shufflevector(V1, V2, 0, 2, 4, 6, 8, 10, 12, 14) +</pre> -<!-- ======================================================================= --> -<h3 id="__builtin_shufflevector">__builtin_shufflevector</h3> -<!-- ======================================================================= --> +<p><b>Description:</b></p> -<p>todo describe me.</p> +<p>The first two arguments to __builtin_shufflevector are vectors that have the +same element type. The remaining arguments are a list of integers that specify +the elements indices of the first two vectors that should be extracted and +returned in a new vector. These element indices are numbered sequentially +starting with the first vector, continuing into the second vector. Thus, if +vec1 is a 4-element vector, index 5 would refer to the second element of vec2. +</p> +<p>The result of __builtin_shufflevector is a vector +with the same element type as vec1/vec2 but that has an element count equal to +the number of indices specified. +</p> </div> </body> |
