On Thu, May 4, 2023 at 2:10 AM Hans-Peter Nilsson via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > Ping again.
OK. > > From: Hans-Peter Nilsson <h...@axis.com> > > Date: Thu, 27 Apr 2023 01:55:24 +0200 > > > > > From: Hans-Peter Nilsson <h...@axis.com> > > > Date: Wed, 19 Apr 2023 18:59:14 +0200 > > [...] > > > > > So again: Approvers: pdf output reviewed. Ok to commit? > > > -- >8 -- > > > I was a bit surprised when my newly-added define_peephole2 didn't > > > match, but it was because it was expected to partially match the > > > generated output of a previous define_peephole2, which matched and > > > modified the last insn of a sequence to be matched. I had assumed > > > that the algorithm backed-up the size of the match-buffer, thereby > > > exposing newly created opportunities *with sufficient context* to all > > > define_peephole2's. While things can change in that direction, let's > > > start with documenting the current state. > > > > > > * doc/md.texi (define_peephole2): Document order of scanning. > > > --- > > > gcc/doc/md.texi | 9 +++++++++ > > > 1 file changed, 9 insertions(+) > > > > > > diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi > > > index 07bf8bdebffb..300d104d58ab 100644 > > > --- a/gcc/doc/md.texi > > > +++ b/gcc/doc/md.texi > > > @@ -9362,6 +9362,15 @@ If the preparation falls through (invokes neither > > > @code{DONE} nor > > > @code{FAIL}), then the @code{define_peephole2} uses the replacement > > > template. > > > > > > +Insns are scanned in forward order from beginning to end for each basic > > > +block. Matches are attempted in order of @code{define_peephole2} > > > +appearance in the @file{md} file. After a successful replacement, > > > +scanning for further opportunities for @code{define_peephole2}, resumes > > > +with the first generated replacement insn as the first insn to be > > > +matched against all @code{define_peephole2}. For the example above, > > > +after its successful replacement, the first insn that can be matched by > > > +a @code{define_peephole2} is @code{(set (match_dup 4) (match_dup 1))}. > > > + > > > @end ifset > > > @ifset INTERNALS > > > @node Insn Attributes > > > -- > > > 2.30.2 > > > > >