gcc-4.0.0-prerelease: -O0 build time higher than -O1?

[Rene Rebe]

Hi all,

I'm just doing the first benchmarking with the 4.0.0 pre release 
(20050319) and just noticed that -O0 build time is not always the 
fastest. (In contrast to what the changes suggest: "When compiling 
without optimizations (-O0), the C++ frontend is much faster than in any 
previous versions of GCC. ..." - Or is it just that previous versions 
have already been way slower ...)

One of the tests is Richard Guenther's tramp3d and the -O0 build time is 
_significantly_ higher than with -O1: (user + system)

    CXX used: g++ (4.0.0) -O0 -march=i386
tramp3d-v3
   Building ... 63.85 + 2.02
   Running ... 76.71 + 0.11

    CXX used: g++ (4.0.0) -O1 -march=i386
tramp3d-v3
   Building ... 49.62 + 0.98
   Running ... 12.82 + 0.11

    CXX used: g++ (4.0.0) -O2 -march=i386
tramp3d-v3
   Building ... 66.33 + 1.05
   Running ... 13.55 + 0.12

Most probably due to -O1 eliminates much more of the template stuff and 
needs to generate far less code?

Currently my athlon is busy crunching all the optimization permutations 
I want to get numbers for - and then 3.4.3 results are build up for 
comparision ... I hope to have a full set available tomorrow ...

Yours,

-- 
René Rebe - Rubensstr. 64 - 12157 Berlin (Europe / Germany)
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