[cfe-dev] clang target tests

[David Greene via cfe-dev]

I have a test that checks for specific asm sequences emitted by clang.
Unsurprisingly, the test fails if clang is built without support for the
target in question.

Unfortunately, I can't have the test emit LLVM IR because that won't
contain what I need to test.  I can't make it an LLVM test because I'm
testing the interaction of options to clang.

How does cmake/lit decide whether tests in test/CodeGen should be run or
not?  Take test/CodeGen/x86.c.  It's looking for register name specific
to an x86 target.  How does the testing infrastructure know not to run
this test if clang is built without support for x86?

                         -David