Explain code coverage with Lit in docs/SourceBasedCodeCoverage.rst
The documentation for code coverage in clang/docs/SourceBasedCodeCoverage.rst omits a couple of crucial steps when using it with Lit.
This patch should fix that.
Differential revision: https://reviews.llvm.org/D140730
diff --git a/clang/docs/SourceBasedCodeCoverage.rst b/clang/docs/SourceBasedCodeCoverage.rst
index 5f4bcf8..f92e8d8 100644
--- a/clang/docs/SourceBasedCodeCoverage.rst
+++ b/clang/docs/SourceBasedCodeCoverage.rst
@@ -127,6 +127,11 @@
other platforms by passing the ``-runtime-counter-relocation`` option to the
backend during compilation.
+For a program such as the :doc:`Lit <CommandGuide/lit>` testing tool which
+invokes other programs, it may be necessary to set ``LLVM_PROFILE_FILE`` for
+each invocation. The pattern strings "%p" or "%Nm" may help to avoid
+corruption due to concurrency.
+
.. code-block:: console
% clang++ -fprofile-instr-generate -fcoverage-mapping -mllvm -runtime-counter-relocation foo.cc -o foo
@@ -143,6 +148,9 @@
# Step 3(a): Index the raw profile.
% llvm-profdata merge -sparse foo.profraw -o foo.profdata
+For an example of merging multiple profiles created by testing,
+see the LLVM `coverage build script <https://github.com/llvm/llvm-zorg/blob/main/zorg/jenkins/jobs/jobs/llvm-coverage>`_.
+
There are multiple different ways to render coverage reports. The simplest
option is to generate a line-oriented report:
