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* [Bug target/33431]  New: [SH4] performance regression between 3.4.6 and 4.x
@ 2007-09-14  9:56 nbkolchin at gmail dot com
  2007-09-14 11:46 ` [Bug target/33431] " kkojima at gcc dot gnu dot org
                   ` (9 more replies)
  0 siblings, 10 replies; 11+ messages in thread
From: nbkolchin at gmail dot com @ 2007-09-14  9:56 UTC (permalink / raw)
  To: gcc-bugs

I've found serious performance regression between GCC version 3.4.6 and
4.2/4.3.

SciMark2 Numeric Benchmark, see http://math.nist.gov/scimark
================================================================
           GCC: 3.4.6   4.2.1   4.3.0 (20070907)
     Composite:  6.05    5.01    4.82
           FFT:  4.90    4.15    4.21
           SOR: 10.10    8.36    7.64
    MonteCarlo:  3.68    3.06    3.04
Sparse matmult:  5.45    4.45    4.03
            LU:  6.10    5.03    5.18
================================================================

BYTEmark* Native Mode Benchmark ver. 2 (10/95)
================================================================
             GCC:      3.4.6      4.2.1  4.3.0 (20070907)
    NUMERIC SORT:     35.459       32.2      29.327
     STRING SORT:     0.5943    0.57604      0.8603
        BITFIELD: 1.0585e+07  9.269e+06  9.4138e+06
    FP EMULATION:     4.4944     4.6012       5.364
         FOURIER:     272.28     241.34      259.12
      ASSIGNMENT:    0.35997    0.38373     0.39683
            IDEA:     124.11     95.057      100.07
         HUFFMAN:     45.593     52.083      56.391
      NEURAL NET:    0.36153    0.30922     0.31348
LU DECOMPOSITION:     11.331     9.4938       8.255
================================================================

The "real world application" has 20%-200% performance regression with GCC 4.x.

All tests were compiled with this arguments:
 -O3 -ffast-math -fomit-frame-pointer -funroll-loops -ftracer
 -funit-at-a-time
 -m4 -ml

This arguments were tuned for the best results under 3.4.6. I've played with
various settings under 4.x, but can't achieve any performance improvement.

I can rerun them with any key combination you want.

This tests compilable under Linux can be downloaded from:
- scimark: http://oktetlabs.ru/~snob/scimark.tgz
- nbench: http://oktetlabs.ru/~snob/nbench.tgz

I can attach this files to bugreport if this is acceptable and will not pollute
bugzilla.

Our target hardware has SH7750 processor running in little endian mode under
RTEMS. Unfortunetaly there is no way to boot linux there.

Can I ask you to run this tests under linux-sh? At least scimark one.

After lurking inside backend sources, I found that m4 has several variants in
GCC 4.x: m4-100, m4-200, etc. I've tried to compile this tests with m4-200
switch, but it looks like m4-200 enforces big-endian.

Backend sources show, that there is a lot of work going on SH4 GCC part.

I also wrote simple stupid tests to compare code generation between different
compiler versions (I can mail/attach them to you, but they are really stupid)
to
understand what can cause such performance regression. But generated assembler
is really different across versions. I can found only two obvious things:
- GCC4 has a much more aggressive inline and loop unrolling. (-funroll-loops
  was dropped from compiler arguments with no positive result)
- GCC4 has different command scheduling, which probably leads to performance
  regression.


-- 
           Summary: [SH4] performance regression between 3.4.6 and 4.x
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: nbkolchin at gmail dot com
 GCC build triplet: x86_64-unknown-linux-gnu
  GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: sh-unknown-rtemself


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33431


^ permalink raw reply	[flat|nested] 11+ messages in thread
end of thread, other threads:[~2009-09-23  0:39 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2007-09-14  9:56 [Bug target/33431] New: [SH4] performance regression between 3.4.6 and 4.x nbkolchin at gmail dot com
2007-09-14 11:46 ` [Bug target/33431] " kkojima at gcc dot gnu dot org
2007-09-14 16:11 ` nbkolchin at gmail dot com
2007-09-14 22:10 ` kkojima at gcc dot gnu dot org
2007-09-15 12:13 ` nbkolchin at gmail dot com
2007-09-17 10:30 ` andrew dot stubbs at st dot com
2007-09-17 10:30 ` [Bug target/33431] New: " Andrew STUBBS
2009-03-31 16:05 ` [Bug target/33431] [4.3/4.4/4.5 Regression] " jsm28 at gcc dot gnu dot org
2009-03-31 19:01 ` jakub at gcc dot gnu dot org
2009-08-04 12:37 ` rguenth at gcc dot gnu dot org
2009-09-23  0:39 ` kkojima at gcc dot gnu dot org

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