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Re: [RFC C++ / PR51033 ] Handle __builtin_shuffle in constexpr properly in the C++ frontend.


On Mon, 18 Jun 2012, Ramana Radhakrishnan wrote:

This patch following on from the fix for turning on __builtin_shuffle
for c++ , enables folding of vec_perm_exprs in the front-end for
constexpr and constructor style values.

Hello,


I took a look, and the example I gave in
http://gcc.gnu.org/ml/gcc-patches/2012-06/msg01066.html
although it doesn't crash the compiler anymore, still fails to compile. I am not sure: were you just trying to remove the ICE, or actually support this use?


#include <x86intrin.h>
int main(){
  constexpr __m128d x={1.,2.};
  constexpr __m128i y={1,0};
  constexpr __m128d z=__builtin_shuffle(x,y);
}

$ g++ -std=gnu++11 m.cc
m.cc: In function 'int main()':
m.cc:5:23: error: '#'vec_perm_expr' not supported by dump_expr#<expression error>' is not a constant expression
constexpr __m128d z=__builtin_shuffle(x,y);
^


--
Marc Glisse


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