On Fri, May 21, 2021 at 3:19 PM Richard Biener <rguent...@suse.de> wrote: > > This adds support for the clang __builtin_shufflevector extension to > the C and C++ frontends. The builtin is lowered to VEC_PERM_EXPR. > Because VEC_PERM_EXPR does not support different sized vector inputs > or result or the special permute index of -1 (don't-care) > c_build_shufflevector applies lowering by widening inputs and output > to the widest vector, replacing -1 by a defined index and > subsetting the final vector if we produced a wider result than > desired. > > Code generation thus can be sub-optimal, followup patches will > aim to fix that by recovering from part of the missing features > during RTL expansion and by relaxing the constraints of the GIMPLE > IL with regard to VEC_PERM_EXPR. > > Bootstrapped on x86_64-unknown-linux-gnu, (re-)testing in progress. > > Honza - you've filed PR88601, can you point me to testcases that > exercise common uses so we can look at code generation quality > and where time is spent best in improving things? > > OK for trunk?
Updated patch with added documentation and the C++ testcases moved to g++.dg/ext/ Richard.
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