Compiler-rt Testing Infrastructure Guide

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.