Originally I was to submit LRA at the very beginning of stage1 for
gcc4.9 as it was discussed on this summer GNU Tools Cauldron. After
some thinking, I've decided to submit LRA now but only switched on for
*x86/x86-64* target. The reasons for that are
o I am already pretty confident in LRA for this target with the
point of reliability, performance, code size, and compiler speed.
o I am confident that I can fix LRA bugs and pitfalls which might be
recognized and reported during stage2 and 3 of gcc4.8.
o Wider LRA testing for x86/x86-64 will make smoother a hard
transition of
other targets to LRA during gcc4.9 development.
During development of gcc4.9, I'd like to switch major targets to
LRA as it was planned before. I hope that all targets will be
switched for the next release after gcc4.9 (although it will be
dependent mostly on the target maintainers). When/if it is done,
reload and reload oriented machine-dependent code can be removed.
LRA project was reported on 2012 GNU Tools Cauldron
(http://gcc.gnu.org/wiki/cauldron2012). The presentation contains a
high-level description of LRA and the project status.
The following patches makes LRA working for x86/x86-64. Separately
patches mostly do nothing until the last patch switches on LRA for
x86/x86-64. Although compiler is bootstrapped after applying each
patch in given order, the division is only for review convenience.
Any comments and proposals are appreciated. Even if GCC community
decides that it is too late to submit it to gcc4.8, the earlier reviews
are always useful.
The patches were successfully bootstrapped and tested for x86/x86-64.
