diff options
| author | vries <vries@138bc75d-0d04-0410-961f-82ee72b054a4> | 2014-07-04 13:36:25 +0000 |
|---|---|---|
| committer | vries <vries@138bc75d-0d04-0410-961f-82ee72b054a4> | 2014-07-04 13:36:25 +0000 |
| commit | 9a9ee0201749bd0da2889d655bb2f70778f80f1d (patch) | |
| tree | ef8a2fc7b51f7d2cd56f60438fa6119e5d604672 /gcc | |
| parent | c0a0cc5e5dbea99fb50d522c7a4ae13e4a5cdd5b (diff) | |
| download | gcc-9a9ee0201749bd0da2889d655bb2f70778f80f1d.tar.gz | |
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.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@212297 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'gcc')
| -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 a9f535079b3..7637d263554 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 539865ea3da..fde67d7a01e 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 % |