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| author | Tom de Vries <tom@codesourcery.com> | 2014-07-04 13:36:25 +0000 |
|---|---|---|
| committer | Tom de Vries <vries@gcc.gnu.org> | 2014-07-04 13:36:25 +0000 |
| commit | 34386e79b36040307ba65076cc09cb65ccfe1d66 (patch) | |
| tree | ef8a2fc7b51f7d2cd56f60438fa6119e5d604672 | |
| parent | 7973ca623ae0dda7e4843e618d8ccc7c31fa6328 (diff) | |
| download | gcc-34386e79b36040307ba65076cc09cb65ccfe1d66.zip gcc-34386e79b36040307ba65076cc09cb65ccfe1d66.tar.gz gcc-34386e79b36040307ba65076cc09cb65ccfe1d66.tar.bz2 | |
Improve documentation of earlyclobber
2014-07-04 Tom de Vries <tom@codesourcery.com>
* doc/md.texi (@subsection Constraint Modifier Characters): Clarify
combination of earlyclobber and read/write modifiers.
From-SVN: r212297
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/doc/md.texi | 5 |
2 files changed, 9 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index a9f5350..7637d26 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,5 +1,10 @@ 2014-07-04 Tom de Vries <tom@codesourcery.com> + * doc/md.texi (@subsection Constraint Modifier Characters): Clarify + combination of earlyclobber and read/write modifiers. + +2014-07-04 Tom de Vries <tom@codesourcery.com> + * config/aarch64/aarch64-simd.md (define_insn "vec_unpack_trunc_<mode>"): Fix constraint. diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index 539865e..fde67d7 100644 --- a/gcc/doc/md.texi +++ b/gcc/doc/md.texi @@ -1582,7 +1582,10 @@ alternatives of this form often allows GCC to produce better code when only some of the inputs can be affected by the earlyclobber. See, for example, the @samp{mulsi3} insn of the ARM@. -@samp{&} does not obviate the need to write @samp{=}. +Furthermore, if the @dfn{earlyclobber} operand is also read/write operand, then +that operand is modified only after it's used. + +@samp{&} does not obviate the need to write @samp{=} or @samp{+}. @cindex @samp{%} in constraint @item % |