On Wed, Jul 12, 2017 at 05:06:22PM +0100, Daniel P. Berrange wrote:
Currently any mockable functions are marked with attributes noinline, noclone and weak. This prevents the compiler from optimizing away the impl of these functions. It has an unfortunate side effect with the libtool convenience libraries, if executables directly link to them. For example virlockd, virlogd both link to libvirt_util.la When this is done, the linker does not consider weak symbols as being undefined, so it never copies them into the final executable. In this new approach, we stop annotating the headers entirely. Instead we create a weak function alias in the source. int fooImpl(void) { ..the real code.. } int foo(void) __attribute__((noinline, noclone, weak, alias("fooImpl")) If any functions in the same file call "foo", this prevents the optimizer from inlining any part of fooImpl. When linking to the libtool convenience static library, we also get all the symbols present. Finally the test suite can just directly define a 'foo' function in its source, removing the need to use LD_PRELOAD (though removal of LD_PRELOADS is left for a future patch).
What are you using for tag navigation? With this macro-defined functions I cannot easily jump to them (the main reason why I don't like macros defining functions). I would very much prefer if ATTRIBUTE_MOCKABLE just took a parameter like this: #define ATTRIBUTE_MOCKABLE(func) __attribute__((noinline, noclone, weak, alias(#func "Impl")) (written by hand, don't take mu word for it working out of the box) and the original function would be left untouched. Also, this fails on OS X [1] and I don't really see why: util/vircommand.c:988:1: error: only weak aliases are supported on darwin VIR_MOCKABLE(void, ^ ./internal.h:252:60: note: expanded from macro 'VIR_MOCKABLE' ret name(__VA_ARGS__) __attribute__((noinline, weak, __alias__(#name "Impl"))); \ ^ 1 error generated. make[3]: *** [util/libvirt_util_la-vircommand.lo] Error 1 make[3]: *** Waiting for unfinished jobs.... [1] https://travis-ci.org/nertpinx/libvirt/jobs/253136004
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