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| author | Richard Henderson <rth@redhat.com> | 2011-10-13 20:31:23 -0700 |
|---|---|---|
| committer | Richard Henderson <rth@gcc.gnu.org> | 2011-10-13 20:31:23 -0700 |
| commit | d7943c8b140b77226e40e32d10fcaf5dd786ef6a (patch) | |
| tree | 853fb9c2eda007bb7110b6aeb291f76f4011742d /gcc/doc | |
| parent | 5066ab2ee8ccdde331e871303cdfa7d44e461fcc (diff) | |
| download | gcc-d7943c8b140b77226e40e32d10fcaf5dd786ef6a.zip gcc-d7943c8b140b77226e40e32d10fcaf5dd786ef6a.tar.gz gcc-d7943c8b140b77226e40e32d10fcaf5dd786ef6a.tar.bz2 | |
Expand vector permutation with vec_perm and vec_perm_const.
From-SVN: r179958
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/md.texi | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index fe27210..68a5548 100644 --- a/gcc/doc/md.texi +++ b/gcc/doc/md.texi @@ -4041,6 +4041,12 @@ be computed modulo @math{2*@var{N}}. Note that if @code{rtx_equal_p(operand1, operand2)}, this can be implemented with just operand 1 and selector elements modulo @var{N}. +In order to make things easy for a number of targets, if there is no +@samp{vec_perm} pattern for mode @var{m}, but there is for mode @var{q} +where @var{q} is a vector of @code{QImode} of the same width as @var{m}, +the middle-end will lower the mode @var{m} @code{VEC_PERM_EXPR} to +mode @var{q}. + @cindex @code{vec_perm_const@var{m}} instruction pattern @item @samp{vec_perm_const@var{m}} Like @samp{vec_perm} except that the permutation is a compile-time |