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diff --git a/docs/TestingGuide.rst b/docs/TestingGuide.rst new file mode 100644 index 000000000..4edda6738 --- /dev/null +++ b/docs/TestingGuide.rst @@ -0,0 +1,66 @@ +======================================== +Compiler-rt Testing Infrastructure Guide +======================================== + +.. contents:: + :local: + +Overview +======== + +This document is the reference manual for the compiler-rt modifications to the +testing infrastructure. Documentation for the infrastructure itself can be found at +:ref:`llvm_testing_guide`. + +LLVM testing infrastructure organization +======================================== + +The compiler-rt testing infrastructure contains regression tests which are run +as part of the usual ``make check-all`` and are expected to always pass -- they +should be run before every commit. + +Quick start +=========== + +The regressions tests are in the "compiler-rt" module and are normally checked +out in the directory ``llvm/projects/compiler-rt/test``. Use ``make check-all`` +to run the regression tests after building compiler-rt. + +REQUIRES, XFAIL, etc. +--------------------- + +Sometimes it is necessary to restrict a test to a specific target or mark it as +an "expected fail" or XFAIL. This is normally achieved using ``REQUIRES:`` or +``XFAIL:`` with a substring of LLVM's default target triple. Unfortunately, the +behaviour of this is somewhat quirky in compiler-rt. There are two main +pitfalls to avoid. + +The first pitfall is that these directives perform a substring match on the +triple and as such ``XFAIL: mips`` affects more triples than expected. For +example, ``mips-linux-gnu``, ``mipsel-linux-gnu``, ``mips64-linux-gnu``, and +``mips64el-linux-gnu`` will all match a ``XFAIL: mips`` directive. Including a +trailing ``-`` such as in ``XFAIL: mips-`` can help to mitigate this quirk but +even that has issues as described below. + +The second pitfall is that the default target triple is often inappropriate for +compiler-rt tests since compiler-rt tests may be compiled for multiple targets. +For example, a typical build on an ``x86_64-linux-gnu`` host will often run the +tests for both x86_64 and i386. In this situation ``XFAIL: x86_64`` will mark +both the x86_64 and i386 tests as an expected failure while ``XFAIL: i386`` +will have no effect at all. + +To remedy both pitfalls, compiler-rt tests provide a feature string which can +be used to specify a single target. This string is of the form +``target-is-${arch}`` where ``${arch}}`` is one of the values from the +following lines of the CMake output:: + + -- Compiler-RT supported architectures: x86_64;i386 + -- Builtin supported architectures: i386;x86_64 + +So for example ``XFAIL: target-is-x86_64`` will mark a test as expected to fail +on x86_64 without also affecting the i386 test and ``XFAIL: target-is-i386`` +will mark a test as expected to fail on i386 even if the default target triple +is ``x86_64-linux-gnu``. Directives that use these ``target-is-${arch}`` string +require exact matches so ``XFAIL: target-is-mips``, +``XFAIL: target-is-mipsel``, ``XFAIL: target-is-mips64``, and +``XFAIL: target-is-mips64el`` all refer to different MIPS targets. |