Re: [PATCH] c++: __builtin_shufflevector with value-dep expr [PR105353]

[Richard Biener via Gcc-patches]

> Am 23.04.2022 um 01:58 schrieb Marek Polacek via Gcc-patches 
> <gcc-patches@gcc.gnu.org>:
> 
> Here we issue an error from c_build_shufflevector while parsing a template
> because it got a TEMPLATE_PARM_INDEX, but this function expects INTEGER_CSTs
> (except the first two arguments).  It checks if any of the arguments are
> type-dependent, if so, we leave the processing for later, but it should
> also check value-dependency for the 3rd+ arguments, so as to avoid the
> problem above.
> 
> This is not a regression -- __builtin_shufflevector was introduced in
> GCC 12, but it looks safe enough.
> 
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

Fine with me.

Richard 

>    PR c++/105353
> 
> gcc/cp/ChangeLog:
> 
>    * typeck.cc (build_x_shufflevector): Use
>    instantiation_dependent_expression_p except for the first two
>    arguments.
> 
> gcc/testsuite/ChangeLog:
> 
>    * g++.dg/ext/builtin-shufflevector-3.C: New test.
> ---
> gcc/cp/typeck.cc                              |  4 +++-
> .../g++.dg/ext/builtin-shufflevector-3.C      | 23 +++++++++++++++++++
> 2 files changed, 26 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/g++.dg/ext/builtin-shufflevector-3.C
> 
> diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc
> index 26a7cb4b50d..0da6f2485d0 100644
> --- a/gcc/cp/typeck.cc
> +++ b/gcc/cp/typeck.cc
> @@ -6315,7 +6315,9 @@ build_x_shufflevector (location_t loc, vec<tree, va_gc> 
> *args,
>   if (processing_template_decl)
>     {
>       for (unsigned i = 0; i < args->length (); ++i)
> -    if (type_dependent_expression_p ((*args)[i]))
> +    if (i <= 1
> +        ? type_dependent_expression_p ((*args)[i])
> +        : instantiation_dependent_expression_p ((*args)[i]))
>      {
>        tree exp = build_min_nt_call_vec (NULL, args);
>        CALL_EXPR_IFN (exp) = IFN_SHUFFLEVECTOR;
> diff --git a/gcc/testsuite/g++.dg/ext/builtin-shufflevector-3.C 
> b/gcc/testsuite/g++.dg/ext/builtin-shufflevector-3.C
> new file mode 100644
> index 00000000000..0f3cbbee563
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/ext/builtin-shufflevector-3.C
> @@ -0,0 +1,23 @@
> +// PR c++/105353
> +// { dg-do compile { target c++17 } }
> +// { dg-additional-options "-Wno-psabi" }
> +
> +typedef unsigned char Simd128U8VectT __attribute__((__vector_size__(16)));
> +
> +template<int ShuffleIndex>
> +static inline Simd128U8VectT ShufFunc(Simd128U8VectT vect) noexcept {
> +    if constexpr(unsigned(ShuffleIndex) >= 16)
> +        return Simd128U8VectT { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
> 0 };
> +    else if constexpr(ShuffleIndex == 0)
> +        return vect;
> +    else
> +        return __builtin_shufflevector(vect, vect, ShuffleIndex, 
> ShuffleIndex + 1,
> +            ShuffleIndex + 2, ShuffleIndex + 3, ShuffleIndex + 4, 
> ShuffleIndex + 5,
> +            ShuffleIndex + 6, ShuffleIndex + 7, ShuffleIndex + 8, 
> ShuffleIndex + 9,
> +            ShuffleIndex + 10, ShuffleIndex + 11, ShuffleIndex + 12, 
> ShuffleIndex + 13,
> +            ShuffleIndex + 14, ShuffleIndex + 15);
> +}
> +
> +auto func1(Simd128U8VectT vect) noexcept {
> +    return ShufFunc<5>(vect);
> +}
> 
> base-commit: 7c21556daf385fe9ece37319f574776dd7d8ab1c
> -- 
> 2.35.1
>