mirror of
git://gcc.gnu.org/git/gcc.git
synced 2025-03-21 21:01:34 +08:00
3d8e492088
record_reg_classes is often the hottest function when generating unoptimised output. It seems typical for over 60% of the instructions it handles to be moves, and of course moves tend to be the instructions with the longest constraint strings. Maybe we should avoid using move constraints to set costs in unoptimised output and instead use the "natural" class for the mode being moved. That's too invasive for stage 3 though. However, seeing so many moves means that we see many "failing" alternatives, usually because of '*' or because of hard registers in function call sequences. The frequency of alternatives that are detected as failures after the first operand tends again to be more than 60%. Previously we would continue to process the other operands of the alternative regardless. This patch instead adds a short-cut. As well as avoiding unnecessary work, it means that the alt_fail variable can be jump-threaded away. Tested on aach64-linux-gnu and x86_64-linux-gnu. It reduces compile time by about 1% on some tests with "-g -O0". gcc/ * ira-costs.c (record_reg_classes): Break from the inner loop early once alt_fail is known to be true. Update outer loop handling accordingly. From-SVN: r244446
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.