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Diffstat (limited to 'gcc/doc/md.texi')
| -rw-r--r-- | gcc/doc/md.texi | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index 54ce9f5e315..01bcb59fe49 100644 --- a/gcc/doc/md.texi +++ b/gcc/doc/md.texi @@ -3063,7 +3063,9 @@ definitions. @deffn {MD Expression} define_register_constraint name regclass docstring All three arguments are string constants. @var{name} is the name of the constraint, as it will appear in -@code{match_operand} expressions. @var{regclass} can be either the +@code{match_operand} expressions. If @var{name} is a multi-letter +constraint its length shall be the same for all constraints starting +with the same letter. @var{regclass} can be either the name of the corresponding register class (@pxref{Register Classes}), or a C expression which evaluates to the appropriate register class. If it is an expression, it must have no side effects, and it cannot |