Previous: profopt Testing, Up: Testsuites
The file compat.exp provides language-independent support for binary compatibility testing. It supports testing interoperability of two compilers that follow the same ABI, or of multiple sets of compiler options that should not affect binary compatibility. It is intended to be used for testsuites that complement ABI testsuites.
A test supported by this framework has three parts, each in a separate source file: a main program and two pieces that interact with each other to split up the functionality being tested.
Within each test, the main program and one functional piece are compiled by the GCC under test. The other piece can be compiled by an alternate compiler. If no alternate compiler is specified, then all three source files are all compiled by the GCC under test. It's also possible to specify a pair of lists of compiler options, one list for each compiler, so that each test will be compiled with each pair of options.
compat.exp defines default pairs of compiler options. These can be overridden by defining the environment variable COMPAT_OPTIONS as:
COMPAT_OPTIONS="[list [list {tst1} {alt1}] ...[list {tstn} {altn}]]"
where tsti and alti are lists of options, with tsti
used by the compiler under test and alti used by the alternate
compiler. For example, with
[list [list {-g -O0} {-O3}] [list {-fpic} {-fPIC -O2}]]
,
the test is first built with -g -O0
by the compiler under
test and with -O3
by the alternate compiler. The test is
built a second time using -fpic
by the compiler under test
and -fPIC -O2
by the alternate compiler.
An alternate compiler is specified by defining an environment
variable; for C++ define ALT_CXX_UNDER_TEST to be the full
pathname of an installed compiler. That will be written to the
site.exp file used by DejaGNU. The default is to build each
test with the compiler under test using the first of each pair of
compiler options from COMPAT_OPTIONS. When
ALT_CXX_UNDER_TEST is same
, each test is built using
the compiler under test but with combinations of the options from
COMPAT_OPTIONS.
To run only the C++ compatibility suite using the compiler under test and another version of GCC using specific compiler options, do the following from objdir/gcc:
rm site.exp make -k \ ALT_CXX_UNDER_TEST=${alt_prefix}/bin/g++ \ COMPAT_OPTIONS="lists as shown above" \ check-c++ \ RUNTESTFLAGS="compat.exp"
A test that fails when the source files are compiled with different compilers, but passes when the files are compiled with the same compiler, demonstrates incompatibility of the generated code or runtime support. A test that fails for the alternate compiler but passes for the compiler under test probably tests for a bug that was fixed in the compiler under test but is present in the alternate compiler.