openblas on sandybridge is unstable

[ViralBShah]

This was originally reported in #1013, and is now tracked in here.

$ make test-lapack
    JULIA test/lapack
     * lapack
assertion failed: norm(-(*(l,u),ref(a,p,:)))<Eps
 in load at util.jl:234
 in load at util.jl:246
 in runtests at ./runtests.jl:3
 in include at boot.jl:197
 in process_options at client.jl:172
 in _start at client.jl:214
at /Users/viral/julia-clang/test/lapack.jl:4
 in load at util.jl:257
 in runtests at ./runtests.jl:3
 in include at boot.jl:197
 in process_options at client.jl:172
 in _start at client.jl:214
at ./runtests.jl:48
 in include at boot.jl:197
 in process_options at client.jl:172
 in _start at client.jl:214
make[1]: *** [lapack] Error 1
make: *** [test-lapack] Error 2

Compiling openblas with TARGET=NEHALEM or USE_THREAD=0 seems to address it.

OpenMathLib/OpenBLAS#125

[ViralBShah]

Cc @xianyi
Cc @nolta

[ViralBShah]

From @nolta

This is not just a problem with clang. The lapack test also fails on my sandybridge ubuntu 10.04 box, for both gcc 4.4.3 and 4.7.1.

[ViralBShah]

openblas 0.2.3 should fix this. Works in the develop branch for me.

[ViralBShah]

Fixed in commit 926c073