[Bug rtl-optimization/89676] [7/8/9 Regression] Redundant moves for long long shift on 32bit x86
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89676 --- Comment #9 from Vladimir Makarov --- Author: vmakarov Date: Mon Mar 25 21:14:40 2019 New Revision: 269924 URL: https://gcc.gnu.org/viewcvs?rev=269924=gcc=rev Log: 2019-03-25 Vladimir Makarov PR rtl-optimization/89676 * lra-constraints.c (curr_insn_transform): Do match reload for early clobbers when the match was successful only for different registers. Modified: trunk/gcc/ChangeLog trunk/gcc/lra-constraints.c
[Bug rtl-optimization/89676] [7/8/9 Regression] Redundant moves for long long shift on 32bit x86
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89676 --- Comment #8 from Vladimir Makarov --- Author: vmakarov Date: Fri Mar 22 16:59:21 2019 New Revision: 269878 URL: https://gcc.gnu.org/viewcvs?rev=269878=gcc=rev Log: 2019-03-22 Vladimir Makarov PR rtl-optimization/89676 * lra-constraints.c (curr_insn_transform): Do match reload for early clobbers even if the match was successful. 2019-03-22 Vladimir Makarov PR rtl-optimization/89676 * gcc.target/i386/pr89676.c: New. Added: trunk/gcc/testsuite/gcc.target/i386/pr89676.c Modified: trunk/gcc/ChangeLog trunk/gcc/lra-constraints.c trunk/gcc/testsuite/ChangeLog
[Bug rtl-optimization/89676] [7/8/9 Regression] Redundant moves for long long shift on 32bit x86
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89676 --- Comment #7 from Vladimir Makarov --- (In reply to Jakub Jelinek from comment #6) > > That said, if you can handle it in the RA, it could handle even those > variable shift cases better (just make sure it doesn't overlap ecx, but > otherwise allow the same reg as the first input). I believe it should be fixed in RA. It is a common case: earlyclobber output with a matched input. Currently they are conflicting and this results in worse code generation. Building conflict is now pretty complicated in LRA. My idea is to reload and use one reload register for the output and input even if their allocations satisfy such constraints. Actually, it is also good with LRA design to reflect RA decisions in RTL as much as possible.
[Bug rtl-optimization/89676] [7/8/9 Regression] Redundant moves for long long shift on 32bit x86
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89676 --- Comment #6 from Jakub Jelinek --- I wonder if in this case the instruction couldn't replace the current = 0n Ic constraints e.g. with =r, 0n,0n I,c because if the shift count is constant, then I don't see the point of early-clobber, if the two inputs are n and I, then there are no input registers (arguably that should have been folded earlier), if one input is 0 and the other one is I, then the earlyclobber doesn't make much sense either, the first input is equal to the output and there is no other input. It is just the variable shift count where the count is in %cl register and there we must make sure that the destination register will not overlap %cl even when doing stuff like: unsigned long long x; ... x = x << (char) x; That said, if you can handle it in the RA, it could handle even those variable shift cases better (just make sure it doesn't overlap ecx, but otherwise allow the same reg as the first input).
[Bug rtl-optimization/89676] [7/8/9 Regression] Redundant moves for long long shift on 32bit x86
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89676 --- Comment #5 from Vladimir Makarov --- I am working on it. It is a non-trivial problem. We should somehow exclude creation of conflicts in lra-lives.c for an early clobber matched with an input. I hope to fix it this week.
[Bug rtl-optimization/89676] [7/8/9 Regression] Redundant moves for long long shift on 32bit x86
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89676 --- Comment #4 from Jakub Jelinek --- The above commit fixed PR86979 instead.
[Bug rtl-optimization/89676] [7/8/9 Regression] Redundant moves for long long shift on 32bit x86
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89676 --- Comment #3 from Andrey Belevantsev --- Author: abel Date: Mon Mar 18 07:51:06 2019 New Revision: 269751 URL: https://gcc.gnu.org/viewcvs?rev=269751=gcc=rev Log: PR middle-end/89676 * sel-sched.c (compute_av_set_at_bb_end): When we have an ineligible successor, use NULL as its av set. Modified: trunk/gcc/ChangeLog trunk/gcc/sel-sched.c
[Bug rtl-optimization/89676] [7/8/9 Regression] Redundant moves for long long shift on 32bit x86
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89676 Jakub Jelinek changed: What|Removed |Added Priority|P3 |P2 Target Milestone|--- |7.5 Summary|Redundant moves for long|[7/8/9 Regression] |long shift on 32bit x86 |Redundant moves for long ||long shift on 32bit x86 --- Comment #2 from Jakub Jelinek --- Started with r244942 (at least with -O2 -m32 -fomit-frame-pointer), before that we emitted foo: movl4(%esp), %eax movl8(%esp), %edx shldl $3, %eax, %edx sall$3, %eax ret
