diff options
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/md.texi | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index ac10a0ad03c..1e22b88f608 100644 --- a/gcc/doc/md.texi +++ b/gcc/doc/md.texi @@ -5291,12 +5291,13 @@ are the first two operands, and both are @code{mem:BLK}s with an address in mode @code{Pmode}. The number of bytes to move is the third operand, in mode @var{m}. -Usually, you specify @code{word_mode} for @var{m}. However, if you can +Usually, you specify @code{Pmode} for @var{m}. However, if you can generate better code knowing the range of valid lengths is smaller than -those representable in a full word, you should provide a pattern with a +those representable in a full Pmode pointer, you should provide +a pattern with a mode corresponding to the range of values you can handle efficiently (e.g., @code{QImode} for values in the range 0--127; note we avoid numbers -that appear negative) and also a pattern with @code{word_mode}. +that appear negative) and also a pattern with @code{Pmode}. The fourth operand is the known shared alignment of the source and destination, in the form of a @code{const_int} rtx. Thus, if the |