DejaGnu already has the requested feature as far as I can tell.
Rainer Orth wrote:
In the GCC testsuite, there's quite a number of tests (mostly in gcc/testsuite/gcc.target/i386, but also on powerpc and x86_64) that check if the host CPU supports some ISA extension at runtime and currently just exit (0) if that support is missing, producing a PASS result. That's not only highly confusing, but completely against the spirit of IEEE 1001.3. Some of those tests (rather some *-check.h headers that do the actual legwork of calling __cpuid or __builtin_cpu_supports) have provisions to print either PASSED or SKIPPED depending on the outcome of that test, but only in DEBUG mode.
These are problems with the GCC testsuite, not the DejaGnu framework.
It occured to me that it would be useful and reasonably simple to always prints these (or similarly stilyzed) comments and evaluate those from DejaGnu (respectively gcc-dg-prune). While there's already support for this for the compile step of a test (matching specific patterns and emitting e.g. ::unsupported::message which are then converted into an UNSUPPORTED result), the execution step only looks at the execution output to handle dg-output.
Looking at lib/dg.exp:dg-test, the execution step is performed by calling ${tool}_load, which is expected to produce a list of two elements, STATUS and OUTPUT. If STATUS is "pass", the framework can then further examine OUTPUT for expected execution results. If STATUS is "fail", the framework emits a verbose message reporting the state of the Tcl "errorCode" variable. Otherwise, STATUS is taken as the name of a test-reporting procedure and called.
The ${tool}_load (here probably "gcc_load") callback is supplied by the testsuite. All you should need to do is improve those tests to report a different status if the required ISA support is not available (maybe "exit (42)" instead of "exit (0)"?) and arrange for gcc_load to recognize that status and return a list {unsupported ""}, which will cause the execution test to be reported as UNSUPPORTED, which should be the correct status if it depends on CPU features lacking on the current machine.
-- Jacob
