On Tue, Jan 31, 2023 at 9:43 AM Jakub Jelinek <ja...@redhat.com> wrote: > > On Tue, Jan 31, 2023 at 08:05:15AM +0100, Richard Biener via Gcc-patches > wrote: > > On Tue, Jan 31, 2023 at 4:39 AM Patrick Palka via Gcc-patches > > <gcc-patches@gcc.gnu.org> wrote: > > > > > > Many functions defined in our headers are declared 'static inline' which > > > is a vestige from when GCC's implementation language was C. But in C++ > > > the inline keyword is more than just a compiler hint, and is sufficient > > > to give the function the intended semantics. In fact declaring a > > > (namespace-scope) function both static and inline is a pessimization > > > since static effectively disables the intended definition merging > > > behavior that inline provides, and is also a source of (harmless) ODR > > > violations when a static inline function gets called from a non-static > > > inline one (such as tree_operand_length being called from > > > tree_operand_check). > > > > > > This patch mechanically fixes the vast majority of occurrences of this > > > anti-pattern throughout the compiler's headers via the command line > > > > > > echo gcc/*.h gcc/*/*.h | xargs sed -i 's/^static inline/inline/g' > > > > > > Besides fixing the ODR violations, this speeds up stage1 cc1plus by > > > about 2% and reduces the size of its text segment by 1.5MB. > > > > > > Bootstrapped and regtested on x86_64-pc-linux-gnu, would this be OK to > > > push now or wait for stage1? > > > > Speeding up and reducing the size of cc1plus improves on continued > > regression in this area. So I'd vote +1 to do this now, let's see what > > others > > think. > > I lean towards +1 too, but > 1) we should make sure we don't do that for installed headers with the > exception of headers meant for GCC plugins; in quick skimming I don't > see ginclude/ headers among the changed ones, but perhaps doing all > languages make install, then applying the patch, make and make install > again into another tree and compare all the headers in those tree > with the exception of paths with /plugin/include/ in it? > 2) we should make sure we don't introduce ODR violations through this, if > say 2 headers would define different static inline functions with the > same name (or even one static inline and another without that). > Don't know what would be best to catch that, get from the patch > list of changed functions and then search for it in readelf -wi output > using some script, or would LTO bootstrap detect that, or libabigail? > What I'm worried about is 2 different headers defining the same > function perhaps with different arguments/return values or content and > that we happen to never include the two headers in the same TU
Ah, didn't think of that - yes, I suppose it might be that LTO bootstrap would warn about those? > 3) we have also gcc/ada/gcc-interface/*.h with > ada.h:#define INLINE static inline > gigi.h:static inline unsigned HOST_WIDE_INT > gigi.h:static inline bool > gigi.h:static inline bool > gigi.h:static inline bool > gigi.h:static inline tree > gigi.h:static inline tree > gigi.h:static inline tree > gigi.h:static inline tree > gigi.h:static inline tree > gigi.h:static inline tree > gigi.h:static inline tree > gigi.h:static inline tree > gigi.h:static inline tree > gigi.h:static inline tree > I think we can defer that to Ada maintaners but we should tell them > about it > 4) there are some static inline also in > gcc/config/*/*.h (and some in gcc/common/*/*.h - though in that case > it is solely in installed header that shouldn't be changed) > avr/avr-protos.h:static inline unsigned > pru/pru-protos.h:static inline bool > rs6000/rs6000-internal.h:static inline bool > rs6000/rs6000-protos.h:static inline bool > s390/s390-builtins.h:static inline unsigned int > s390/s390-builtins.h:static inline unsigned int > s390/vecintrin.h:static inline int > The last one is an installed header, so I think we shouldn't touch > it, the rest should be considered. The above probably asks to split the patch up and separate gcc/*/*.h into individual patches? Richard. > > Jakub >
