ppc64 clang LNT buildbot / reference_output / test failures

[Will Schmidt]

Hi All, 

I've been continuing to poke at the ppc64-elf-linux LNT/clang buildbot,
and think I now understand part of whats causing the current failures,
but am not sure how to properly resolve.

A number of the tests indicate FAILED, with output such as:

	/home/clangbuild/clang-ppc64-1/test-suite/DiffOutput.sh
	"/home/clangbuild/clang-ppc64-1/tests/nt/build/sample-0/tools/fpcmp  -r
0.002" simple alti.stepfft 
	******************** TEST (simple) 'alti.stepfft' FAILED! ********************
	Execution Context Diff:
	/home/clangbuild/clang-ppc64-1/tests/nt/build/sample-0/tools/fpcmp: FP Comparison failed, not a numeric difference between 'e' and 'f'


In this and most(?) of the other failure cases, there is no attempt to build or run
the native version of the testcase.   The result comparison is occurring between the
output of testcase.simple and the contents of test-suite/default.reference_output
which contains "exit 0".   This is in contrast to when we are running the test-suite by
hand, and seeing both .native and .simple versions of each test.

On the surface, this seems to be related to USE_REFERENCE_OUTPUT=1 (set by lnt/nt.py ),
but a local hack to set that to zero is not sufficient.  Nor is resetting
USE_REFERENCE_OUTPUT:=0 in Makefile.programs.

...  ideas ? 

Thanks, 
-Will