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LLVM uses profiling data that's deliberately similar to GCC, but has a very different way of exporting that data. LLVM calls llvm_gcov_init() once per module, and provides a couple of callbacks that we can use to ask for more data. We care about the "writeout" callback, which in turn calls back into compiler-rt/this module to dump all the gathered coverage data to disk: llvm_gcda_start_file() llvm_gcda_emit_function() llvm_gcda_emit_arcs() llvm_gcda_emit_function() llvm_gcda_emit_arcs() [... repeats for each function ...] llvm_gcda_summary_info() llvm_gcda_end_file() This design is much more stateless and unstructured than gcc's, and is intended to run at process exit. This forces us to keep some local state about which module we're dealing with at the moment. On the other hand, it also means we don't depend as much on how LLVM represents profiling data internally. See LLVM's lib/Transforms/Instrumentation/GCOVProfiling.cpp for more details on how this works, particularly GCOVProfiler::emitProfileArcs(), GCOVProfiler::insertCounterWriteout(), and GCOVProfiler::insertFlush(). [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20190417225328.208129-1-trong@android.com Signed-off-by: Greg Hackmann <ghackmann@android.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Tri Vo <trong@android.com> Co-developed-by: Nick Desaulniers <ndesaulniers@google.com> Co-developed-by: Tri Vo <trong@android.com> Tested-by: Trilok Soni <tsoni@quicinc.com> Tested-by: Prasad Sodagudi <psodagud@quicinc.com> Tested-by: Tri Vo <trong@android.com> Tested-by: Daniel Mentz <danielmentz@google.com> Tested-by: Petri Gynther <pgynther@google.com> Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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arch | ||
block | ||
certs | ||
crypto | ||
Documentation | ||
drivers | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
LICENSES | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | ||
.cocciconfig | ||
.get_maintainer.ignore | ||
.gitattributes | ||
.gitignore | ||
.mailmap | ||
COPYING | ||
CREDITS | ||
Kbuild | ||
Kconfig | ||
MAINTAINERS | ||
Makefile | ||
README |
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.