[llvm-testresults] buildbot failure in lab.llvm.org on phase1 - sanity

[llvmlab-buildmaster at lab.llvm.org]

The Buildbot has detected a new failure on builder phase1 - sanity while building llvm.
Full details are available at:
 http://lab.llvm.org:8013/builders/phase1%20-%20sanity/builds/4923

Buildbot URL: http://lab.llvm.org:8013/

Buildslave for this Build: macpro1

Build Reason: scheduler
Build Source Stamp: 218702
Blamelist: dblaikie

BUILD FAILED: failed

sincerely,
 -The Buildbot


================================================================================

CHANGES:
Files:
 lib/CodeGen/AsmPrinter/DwarfDebug.cpp
 lib/CodeGen/AsmPrinter/DwarfDebug.h
 test/DebugInfo/gmlt.ll
On: http://10.1.1.2/svn/llvm-project
For: llvm
At: Tue 30 Sep 2014 14:40:33
Changed By: dblaikie
Comments: Disable the -gmlt optimization implemented in r218129 under Darwin due to issues with dsymutil.

r218129 omits DW_TAG_subprograms which have no inlined subroutines when
emitting -gmlt data. This makes -gmlt very low cost for -O0 builds.

Darwin's dsymutil reasonably considers a CU empty if it has no
subprograms (which occurs with the above optimization in -O0 programs
without any force_inline function calls) and drops the line table, CU,
and everything in this situation, making backtraces impossible.

Until dsymutil is modified to account for this, disable this
optimization on Darwin to preserve the desired functionality.
(see r218545, which should be reverted after this patch, for other
discussion/details)

Footnote:
In the long term, it doesn't look like this scheme (of simplified debug
info to describe inlining to enable backtracing) is tenable, it is far
too size inefficient for optimized code (the DW_TAG_inlined_subprograms,
even once compressed, are nearly twice as large as the line table
itself (also compressed)) and we'll be considering things like Cary's
two level line table proposal to encode all this information directly in
the line table.Properties: 




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