On Tuesday 22 November 2005 11:45, Daniel Berlin wrote:
> > Another minor nit is performance. Judging by SPEC, LLVM has some
> > performance problems. It's very good for floating point (a 9%
> > advantage over GCC), but GCC has a 24% advantage over LLVM 1.2 in
> > integer code. I'm sure that is fixable and I only have data for an
> > old release of LLVM
>
> Uh, you are comparing 4 releases ago of LLVM, against the current
> release of gcc, and saying "It doesn't do as well".
>
Yes, that's why I said I needed more work. I ran with the latest release I
could find (LLVM 1.6). I'm not quite sure how to hook up the gfortran FE
to LLVM, so for SPECfp I could only run the C tests. Also, at -O3 LLVM
1.6 fails eon and perlbmk.
On x86 LLVM 1.6 still lags behind GCC in SPECint (7%) but the gap is
narrower, an excellent sign. For SPECfp, the difference is similar to
what it was with 1.2 (LLVM's score is 10% better).
Chris mentioned that the PPC backend is better. We wouldn't be using
LLVM's back end, so I guess this is not really a problem.
Processor: Intel(R) Pentium(R) 4 CPU 2.26GHz (2260.065 Mhz)
Memory: 1034832 kB
Cache: 512 KB
Before Compiler
Compiler: gcc version 3.4-llvm 20051104 (LLVM 1.6)
Peak flags: -O3 -Wl,-native-cbe
After Compiler
Compiler: gcc version 4.1.0 20051117 (experimental)
Peak flags: -O3
SPECint results for peak
Benchmark Before After % diff
164.gzip 550.30 659.84 + 19.90%
175.vpr 412.63 424.97 + 2.99%
176.gcc 726.04 759.82 + 4.65%
181.mcf 432.00 425.03 - 1.61%
186.crafty 507.09 680.06 + 34.11%
197.parser 557.70 610.13 + 9.40%
252.eon 0.00 575.67 INF
253.perlbmk 0.00 767.01 INF
254.gap 726.62 750.56 + 3.29%
255.vortex 1142.30 833.70 - 27.02%
256.bzip2 469.00 524.18 + 11.77%
300.twolf 488.30 532.43 + 9.04%
mean 573.20 614.47 + 7.20%
SPECfp result for peak
Benchmark Before After % diff
168.wupwise 0.00 662.55 INF
171.swim 0.00 496.77 INF
172.mgrid 0.00 445.58 INF
173.applu 0.00 598.96 INF
177.mesa 521.26 427.31 - 18.02%
178.galgel 0.00 351.39 INF
179.art 366.68 189.75 - 48.25%
183.equake 838.25 858.94 + 2.47%
187.facerec 0.00 359.06 INF
188.ammp 352.94 360.97 + 2.27%
189.lucas 0.00 507.08 INF
191.fma3d 0.00 408.12 INF
200.sixtrack 0.00 404.31 INF
301.apsi 0.00 439.52 INF
mean 487.64 440.16 - 9.74%
