On Wed, Nov 12, 2014 at 7:08 PM, Vladimir Makarov <vmaka...@redhat.com> wrote: > After submitting LRA rematerialization patch, I got a lot of > feedback. Some people reported performance degradation and pointed me > out the most important problem which looks like > > p0 <- p1 + p2 p0 <- p1 + p2 > spilled_pseudo <- p0 spilled_pseudo <- p0 > > ... some code => > > p3 <- spilled_pseudo p3 <- p1 + p2 > > The first 2 insns were not removed and the second one became a dead > store. It was hard to fix as LRA (and reload pass) does mostly local > transformations (in BB or EBB). It could be fixed in BB or EBB. But > some important cases (e.g. the code between is a loop) still will be > missed and will result in the same problem. To fix this in right way, > we needed to update the global live info. > > A recent Intel project on reuse of pic register came to problems > which need a global live analysis too in LRA to fix them. For > rematerialization, it is a matter of better code generation but for > reuse of pic register project it is a matter of correct code > generation. > > So the last two weeks I worked on global live analysis in LRA and > submitted the patch 3 days ago. The rematerialization patch here is > mostly the same I sent month ago. I added only small changes to adapt > it to global live analysis and fix some tests failures I found on > ppc64. > > The patch with live analysis generates smaller and a better code > than before. Last time I reported only 1% SPECFP2000 improvement on > ARM. Now I see about 0.4% SPECFP2000 improvement on x86-64 too. > > So I've committed the rematerialization patch to the trunk as rev. 217458. > > As I wrote its initial version of rematerialziation. Other > people and me proposed several ideas how to improve it in the future. > > 2014-11-12 Vladimir Makarov <vmaka...@redhat.com> > > * common.opt (flra-remat): New. > * opts.c (default_options_table): Add entry for flra_remat. > * timevar_def (TV_LRA_REMAT): New. > * doc/invoke.texi (-flra-remat): Add description of the new > option. > * doc/passes.texi (-flra-remat): Remove lra-equivs.c and > lra-saves.c. Add lra-remat.c. > * Makefile.in (OBJS): Add lra-remat.o. > * lra-remat.c: New file. > * lra.c: Add info about the rematerialization pass in the top > comment. > (collect_non_operand_hard_regs, add_regs_to_insn_regno_info): > Process unallocatable regs too. > (lra_constraint_new_insn_uid_start): Remove. > (lra): Add code for calling rematerialization sub-pass. > * lra-int.h (lra_constraint_new_insn_uid_start): Remove. > (lra_constrain_insn, lra_remat): New prototypes. > (lra_eliminate_regs_1): Add parameter. > * lra-lives.c (make_hard_regno_born, make_hard_regno_dead): > Process unallocatable hard regs too. > (process_bb_lives): Ditto. > * lra-spills.c (remove_pseudos): Add argument to > lra_eliminate_regs_1 call. > * lra-eliminations.c (lra_eliminate_regs_1): Add parameter. Use it > for sp offset calculation. > (lra_eliminate_regs): Add argument for lra_eliminate_regs_1 call. > (eliminate_regs_in_insn): Add parameter. Use it for sp offset > calculation. > (process_insn_for_elimination): Add argument for > eliminate_regs_in_insn call. > * lra-constraints.c (get_equiv_with_elimination): Add argument > for lra_eliminate_regs_1 call. > (process_addr_reg): Add parameter. Use it. > (process_address_1): Ditto. Add argument for process_addr_reg > call. > (process_address): Ditto. > (curr_insn_transform): Add parameter. Use it. Add argument for > process_address calls. > (lra_constrain_insn): New function. > (lra_constraints): Add argument for curr_insn_transform call. >
Unfortunately, it breaks bootstrap on Linux/ia32: https://gcc.gnu.org/ml/gcc-regression/2014-11/msg00288.html ../../../src-trunk/libgcc/config/libbid/bid_round.c: In function â__bid_round128_19_38â: ../../../src-trunk/libgcc/config/libbid/bid_round.c:391:1: internal compiler error: Segmentation fault } ^ /export/gnu/import/git/gcc-test-ia32corei7/bld/./gcc/xgcc -B/export/gnu/import/git/gcc-test-ia32corei7/bld/./gcc/ -B/usr/5.0.0/i686-linux/bin/ -B/usr/5.0.0/i686-linux/lib/ -isystem /usr/5.0.0/i686-linux/include -isystem /usr/5.0.0/i686-linux/sys-include -g -O2 -O2 -g -O2 -DIN_GCC -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -isystem ./include -fpic -mlong-double-80 -g -DIN_LIBGCC2 -fbuilding-libgcc -fno-stack-protector -fpic -mlong-double-80 -I. -I. -I../.././gcc -I../../../src-trunk/libgcc -I../../../src-trunk/libgcc/. -I../../../src-trunk/libgcc/../gcc -I../../../src-trunk/libgcc/../include -I../../../src-trunk/libgcc/config/libbid -DENABLE_DECIMAL_BID_FORMAT -DHAVE_CC_TLS -DUSE_TLS -o bid128.o -MT bid128.o -MD -MP -MF bid128.dep -c ../../../src-trunk/libgcc/config/libbid/bid128.c Please submit a full bug report, with preprocessed source if appropriate. See <http://gcc.gnu.org/bugs.html> for instructions. make[6]: *** [bid_round.o] Error 1 when configured with --with-arch=corei7 --with-cpu=corei7 --prefix=/usr/5.0.0 --enable-clocale=gnu --with-system-zlib --enable-shared --with-demangler-in-ld i686-linux --with-fpmath=sse --enable-languages=c,c++,fortran,java,lto,objc H.J. -- H.J.
