[Bug fortran/29975] [meta-bugs] ICEs with CP2K

["jv244 at cam dot ac dot uk" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #112 from jv244 at cam dot ac dot uk  2007-06-20 20:25 -------
after the fix for PR 32140 gfortran compiles CP2K correctly on x86_64 using
'-O3 -ffast-math -ftree-vectorize -funroll-loops -march=native' . Thanks !

I've made a new tar file available that contains a more recent version of CP2K,
together with two benchmarks and a little script to run and test them as:

http://www.pci.unizh.ch/vandevondele/tmp/CP2K_gcc_2007_06.tgz

The timings of the benchmarks (against ifort 9.1 '-O1 -xT' on intel core2 duo)
are

gfortran:
> ./do_all
BENCH01 IS OK
BENCH01 WALL TIME [s] 267.27
BENCH02 IS OK
BENCH02 WALL TIME [s] 86.77

intel:
> ./do_all
BENCH01 IS OK
BENCH01 WALL TIME [s] 231.78
BENCH02 IS OK
BENCH02 WALL TIME [s] 77.84

this seems quite good (despite being 10-15% slower). For the first benchmark
most of the slowdown seems to be in one part of the code (core_hamiltonian),
for which gfortran is about 35% slower (I suspect the difference comes from one
subroutine ai_overlap_new).

There is one more issue, for which I will file a PR shortly. Compilation fails
with an out of memory error at '-O1 -fbounds-check'. This happens on an opteron
with 16Gb of RAM while compilation with e.g. '-O1' or '-O3' goes fine. Watching
top, the maximum virtual memory is about 3Gb (and somewhat more than 2Gb at
-O3).


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29975