[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41868 Segher Boessenkool changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|---

[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41868 Segher Boessenkool changed: What|Removed |Added Status|NEW |ASSIGNED CC|

[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41868 Andrew Pinski pinskia at gcc dot gnu.org changed: What|Removed |Added Status|ASSIGNED|NEW

[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41868 --- Comment #8 from Andrew Pinski pinskia at gcc dot gnu.org 2011-11-29 23:18:32 UTC --- No longer working on this.

[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

--- Comment #7 from siarhei dot siamashka at gmail dot com 2009-11-03 20:09 --- Thanks a lot for checking this. And sorry about the confusion caused by attributing slowness of the testcase to the microcoded stuff (which turned out to be not the case) without proper checking this first.

[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

--- Comment #2 from pinskia at gcc dot gnu dot org 2009-11-02 16:51 --- Simple patch which I am testing right now: Index: gcc/gcc/config/rs6000/rs6000.md === --- gcc/gcc/config/rs6000/rs6000.md (revision 153680) +++

[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

--- Comment #3 from pinskia at gcc dot gnu dot org 2009-11-02 16:56 --- Actually the warning is incorrect at least according to the PPU book 4. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41868

[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

--- Comment #4 from pinskia at gcc dot gnu dot org 2009-11-02 17:05 --- In fact changing the the addic. into addic/cmpwi does not improve the speed of the code: With the change: [apin...@dhcp-10-98-10-216 local]$ time ./a.out 56.316u 0.084s 0:57.09 98.7%0+0k 0+0io 0pf+0w Without:

[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

--- Comment #5 from pinskia at gcc dot gnu dot org 2009-11-02 17:08 --- In fact doing the following diff to the -Os assembly: --- t5.Os.s 2009-11-02 23:18:52.0 +0900 +++ t5.Os.dot.s 2009-11-02 23:20:19.0 +0900 @@ -29,9 +29,9 @@ x: .L4: bl y .L3: -

[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

--- Comment #6 from pinskia at gcc dot gnu dot org 2009-11-02 17:10 --- So in conclusion, addic. is not microcoded and the warning is incorrect but still -Os is faster than -O2. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41868

[Bug target/41868] cell microcode instruction (addic.) is generated for a trivial loop with -O2 optimizations, hurting performance badly

--- Comment #1 from siarhei dot siamashka at gmail dot com 2009-10-29 15:21 --- -O2: 0010 .x: 10: 2c 23 00 00 cmpdi r3,0 14: 7c 08 02 a6 mflrr0 18: f8 01 00 10 std r0,16(r1) 1c: f8 21 ff 81 stdur1,-128(r1) 20: 41 82 00 1c