On Thu, Jun 1, 2017 at 11:59 AM, Zoltán Herczeg <hzmes...@freemail.hu> wrote: >> > I would simply use the PCRE version number to detect jit_exec at compile >> > time: >> > >> > #if (PCRE_MAJOR > 8 || (PCRE_MAJOR == 8 && PCRE_MINOR >= 32)) >> > #define PCRE_JIT_EXEC_AVAILABLE >> > #endif >> That'll only work if pcre isn't compiled with --disable-jit, if it is >> even on the latest svn trunk linking against it results in: >> libgit.a(grep.o): In function `pcre1match': >> /home/avar/g/git/grep.c:411: undefined reference to `pcre_jit_exec' >> If you look at pcre_jit_compile.c the whole structure of the file is: >> #if defined SUPPORT_JIT >> [...] >> #define SLJIT_CONFIG_AUTO 1 /* ...and other macros */ >> int >> PRIV(jit_exec)(const PUBL(extra) *extra_data, const pcre_uchar *subject, >> [...] >> #else /* SUPPORT_JIT */ >> [... no definition of pcre_jit_exec ...] >> #endif >> I.e. the pcre_jit_exec symbol won't be in the library, and thus >> linking to it fails, so I need a macro accessible from pcre.h that >> tells me whether it's going to be there, calling pcre_config() will be >> too late. > > Oh... we have dummy functions for jit stack management, but jit_exec is > missing from. This is a bug and bad news. Perhaps defining a weak symbol > could help, but might be not portable enough. Falling back to pcre_exec is > also an option.
I'm a total noob when it comes to any workarounds in the linker to mitigate this, but googling around any weak symbol mitigation seems very compiler/toolchain specific. I'm probably better off just providing my own compile-time flag for "did you compile your PCRE with JIT support?". > Are the SLJIT macros visible outside? That is also something which shouldn't > be :( It's not. I was mistaken about that, that ifdef is always false regardless of whether I compile with JIT or not, I just screwed up in my testing and sent the E-Mail too quickly. If I save away the include directory between --disable-jit and --enable-jit it's exactly the same, i.e. there's no way to tell from a macro whether pcre_exec_jit is compiled into the library. -- ## List details at https://lists.exim.org/mailman/listinfo/pcre-dev
