[cfe-dev] compilation time 3.5 vs 3.6

[Milian Wolff]

On Thursday 22 January 2015 17:31:37 mobi phil wrote:
> > Did you build 3.6 with assertions?
> > 
> >   --enable-assertions     Compile with assertion checks enabled (default
> > 
> > is YES)
> 
> oops, sorry... intuitively I made the wrong assumption that
> --enable-optimize would turn off assertions code
> 
> build with --disable-assertions, still the on system clang 3.5 beats :
> 
> system clang: 2,66s user 0,14s system 99% cpu 2,826 total
> Release/bin/clang (git pulled latest): 3,04s user 0,13s system 98% cpu
> 3,206 total
> 
> Release+Asserts/bin/clang: 3,97s user 0,15s system 99% cpu 4,146 total
> 
> indeed I had also  --enable-shared active
> 
> rebuilt all and now I have:
> Release/bin/clang  2,93s user 0,15s system 99% cpu 3,101 total versus
> system clang: 2,66s user 0,14s system 99% cpu 2,826 total
> 
> made another test and built clang with /usr/bin/clang
> CC=/usr/bin/clang CXX=/usr/bin/clang++ /g/llvm.git/configure
>  --enable-optimized    --disable-assertions
> 
> got a little closer,  2,94s user 0,13s system 99% cpu 3,090 total  but
> still not the total 2.82

Just a naive guess from me: Could it be due the Clang 3.5 provided by your 
distributor having been built with GCC, and not with clang 3.5? What happens 
if you also built it with the GCC provided by the distributor?

Bye
-- 
Milian Wolff
mail at milianw.de
http://milianw.de