On 03/14/2018 01:57 PM, H.J. Lu wrote: > On Wed, Mar 14, 2018 at 5:54 AM, Martin Liška <mli...@suse.cz> wrote: >> On 03/13/2018 04:23 PM, Jakub Jelinek wrote: >>> On Tue, Mar 13, 2018 at 04:19:21PM +0100, Martin Liška wrote: >>>>> Yes, see e.g. TARGET_LIBC_HAS_FUNCTION target hook, >>>>> where in particular linux_libc_has_function deals with various C >>>>> libraries. >>>>> Of course, in this case you need another target hook, that is dependent >>>>> both >>>>> on the target backend and C library. >>>>> >>>>> It would be nice to make the target hook a little bit more generic as >>>>> well, >>>>> e.g. pass it enum builtin_function and query if it is fast, slow or >>>>> unknown, or even some kind of cost, where the caller could ask for cost of >>>>> BUILT_IN_MEMCPY and BUILT_IN_MEMPCPY and decide based on the relative >>>>> costs. >>>> >>>> Let me start with simple return enum value of FAST,SLOW,UNKNOWN. I've >>>> added new hook >>>> definition to gcc/config/gnu-user.h that will point to >>>> gnu_libc_function_implementation. >>>> I would like to implement the function in gcc/targhooks.c, but I don't >>>> know how to >>>> make ifdef according to target? >>> >>> Put there just the default implementation (everything is UNKNOWN?). >>> >>>> One another issue is that built_in_function is enum defined in tree.h. >>>> Thus I'll replace the >>>> callback argument with int, that will be casted. One last issue: am I >>>> right that I'll have to define >>>> TARGET_LIBC_FUNCTION_IMPLEMENTATION in each config file (similar to >>>> no_c99_libc_has_function)? >>> >>> And define the i386/x86_64 glibc one in config/i386/*.h, check there >>> OPTION_GLIBC and only in that case return something other than UNKNOWN. >>> >>> And redefine TARGET_LIBC_FUNCTION_IMPLEMENTATION only in that case. >>> >>> Jakub >>> >> >> Hi. >> >> I'm sending V2 that can survive bootstrap and regression tests on both >> x86_64 and ppc64le. >> >> Martin > > diff --git a/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c > b/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c > index d82e2232d7b..91e1c87f83f 100644 > --- a/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c > +++ b/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c > @@ -62,7 +62,7 @@ main_test (void) > mempcpy (p + 5, s3, 1); > if (memcmp (p, "ABCDEFg", 8)) > abort (); > - mempcpy (p + 6, s1 + 1, l1); > + memcpy (p + 6, s1 + 1, l1); > if (memcmp (p, "ABCDEF2", 8)) > abort (); > } > > This is a mempcpy test. Why is mempcpy changed to memcpy? >
Because this mempcpy is not optimized out to memcpy and it then aborts. It's proper to leave here mempcpy I believe. Martin
