Attempt to fix the FreeBSD build, disable multiprocessing

Speculative quick fix based on clang-X86_64-freebsd output:

  File "/usr/local/lib/python2.6/multiprocessing/synchronize.py", line 33, in <module>
    " function, see issue 3770.")
ImportError: This platform lacks a functioning sem_open implementation, therefore, the required synchronization primitives needed will not function, see issue 3770.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193457 91177308-0d34-0410-b5e6-96231b3b80d8
llvm/test/Other/close-stderr.ll: Remove "XFAIL:win32". It reverts r173509.

"REQUIRES: shell" should cover if this failed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193458 91177308-0d34-0410-b5e6-96231b3b80d8
llvm/test/lit.cfg: Tighten conditions to enable 'native'.

I saw the case that 'native' was mis-enabled when x86_64-pc-win32 on x86_64-linux.

FIXME: Consider cases that target can be executed even if host_triple were different from target_triple.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193459 91177308-0d34-0410-b5e6-96231b3b80d8
Quick look-up for block in loop.

This patch implements quick look-up for block in loop by maintaining a hash set for blocks.
It improves the efficiency of loop analysis a lot, the biggest improvement could be 5-6%(458.sjeng).
Below are the compilation time for our benchmark in llc before & after the patch.

Benchmark	llc - trunk		llc - patched	
401.bzip2	0.339081	100.00%	0.329657	102.86%
403.gcc		19.853966	100.00%	19.605466	101.27%
429.mcf		0.049823	100.00%	0.048451	102.83%
433.milc	0.514898	100.00%	0.510217	100.92%
444.namd	1.109328	100.00%	1.103481	100.53%
445.gobmk	4.988028	100.00%	4.929114	101.20%
456.hmmer	0.843871	100.00%	0.825865	102.18%
458.sjeng	0.754238	100.00%	0.714095	105.62%
464.h264ref	2.9668		100.00%	2.90612		102.09%
471.omnetpp	4.556533	100.00%	4.511886	100.99%
bitmnp01	0.038168	100.00%	0.0357		106.91%
idctrn01	0.037745	100.00%	0.037332	101.11%
libquake2	3.78689		100.00%	3.76209		100.66%
libquake_	2.251525	100.00%	2.234104	100.78%
linpack		0.033159	100.00%	0.032788	101.13%
matrix01	0.045319	100.00%	0.043497	104.19%
nbench		0.333161	100.00%	0.329799	101.02%
tblook01	0.017863	100.00%	0.017666	101.12%
ttsprk01	0.054337	100.00%	0.053057	102.41%

Reviewer	: Andrew Trick <atrick@apple.com>, Hal Finkel <hfinkel@anl.gov>
Approver	: Andrew Trick <atrick@apple.com>
Test		: Pass make check-all & llvm test-suite


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193460 91177308-0d34-0410-b5e6-96231b3b80d8
lit: handle late multiprocessing errors gracefully

This should be a better fix for lit multiprocessing failures, replacing the
OpenBSD and FreeBSD workarounds in r193413 and r193457.

Reference: http://bugs.python.org/issue3770

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193463 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a referenced before assignment in r193463

Some versions of Python on the builders seem strict about this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193464 91177308-0d34-0410-b5e6-96231b3b80d8