ff3227e77d
Users can specify the path a raw profile is written to by passing
-fprofile-instr-generate=<path>, but this functionality broke on Darwin
after __llvm_profile_filename was made weak [1], resulting in profiles
being written to "default.profraw" even when <path> is specified.
The situation is that instrumented programs provide a weak definition of
__llvm_profile_filename, which conflicts with a weak redefinition
provided by the profiling runtime.
The linker appears to pick the 'winning' definition arbitrarily: on
Darwin, it usually prefers the larger definition, which is probably why
the instrprof-override-filename.c test has been passing.
The fix is to move the runtime's definition into a separate object file
within the archive. This means that the linker won't "see" the runtime's
definition unless the user program has not provided one. I couldn't
think of a great way to test this other than to mimic the Darwin
failure: use -fprofile-instr-generate=<some-small-path>.
Testing: check-{clang,profile}, modified instrprof-override-filename.c.
[1] [Profile] deprecate __llvm_profile_override_default_filename
https://reviews.llvm.org/D22613
https://reviews.llvm.org/D22614
Differential Revision: https://reviews.llvm.org/D34797
llvm-svn: 306710
19 lines
679 B
C
19 lines
679 B
C
//===- InstrProfilingNameVar.c - profile name variable setup --------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "InstrProfiling.h"
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/* char __llvm_profile_filename[1]
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*
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* The runtime should only provide its own definition of this symbol when the
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* user has not specified one. Set this up by moving the runtime's copy of this
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* symbol to an object file within the archive.
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*/
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COMPILER_RT_WEAK char INSTR_PROF_PROFILE_NAME_VAR[1] = {0};
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