[Bug c/91664] Undefined reference linker errors when static linking archive with gcc target_clones function multi-versioning
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91664
Martin Liška changed:
What|Removed |Added
Status|ASSIGNED|WAITING
--- Comment #9 from Martin Liška ---
(In reply to Richard Biener from comment #7)
> The issue is that with a declaration like
>
> double fmv_test (double *dArray, int size) __attribute__ ((__target_clones__
> ("avx2","avx","sse4.1","sse2","default")));
>
> we're creating a resolver even if there's no definition of fmv_test visible.
> We shouldn't do that. We should only emit resolvers for definitions.
Are you sure we want to generate resolver only for definitions?
Similarly to normal declarations, it's linkers job to resolve symbols and
eventually print errors.
I don't see why the linker bails out when the archive is used.
[Bug c/91664] Undefined reference linker errors when static linking archive with gcc target_clones function multi-versioning
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91664 Martin Liška changed: What|Removed |Added Status|NEW |ASSIGNED Assignee|unassigned at gcc dot gnu.org |marxin at gcc dot gnu.org --- Comment #8 from Martin Liška --- I'll take a look.
[Bug c/91664] Undefined reference linker errors when static linking archive with gcc target_clones function multi-versioning
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91664
Richard Biener changed:
What|Removed |Added
Keywords||wrong-code
Status|WAITING |NEW
CC||marxin at gcc dot gnu.org
Known to fail||10.0, 8.3.1, 9.2.1
--- Comment #7 from Richard Biener ---
The issue is that with a declaration like
double fmv_test (double *dArray, int size) __attribute__ ((__target_clones__
("avx2","avx","sse4.1","sse2","default")));
we're creating a resolver even if there's no definition of fmv_test visible.
We shouldn't do that. We should only emit resolvers for definitions.
[Bug c/91664] Undefined reference linker errors when static linking archive with gcc target_clones function multi-versioning
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91664 --- Comment #6 from element at elementsofsound dot org --- I removed the internal_func() with the target_clones attribute, which caused the last number digit of the symbols for fmv_test clones to match up between object files, but errors still occur. I ran nm on the resulting archive and got the below output, which may provide a clue. Note that the fmv_test target clone functions have lower case 't' for local Text and don't end up in the archive index. I removed the target_clones attribute and fmv_test ends up being a global Text symbol (also pasted below), which builds fine: nm -s fmv-test.a Archive index: main in main.o fmv_test in main.o fmv_test.resolver in main.o fmv_normal_function in fmv-test.o fmv_test.resolver in fmv-test.o fmv_test in fmv-test.o main.o: U __cpu_indicator_init U __cpu_model i fmv_test U fmv_test.avx.1 U fmv_test.avx2.0 U fmv_test.default.4 W fmv_test.resolver U fmv_test.sse2.3 U fmv_test.sse4_1.2 U _GLOBAL_OFFSET_TABLE_ T main U malloc U memset fmv-test.o: U __cpu_indicator_init U __cpu_model 004d T fmv_normal_function i fmv_test 00a8 t fmv_test.avx.1 005b t fmv_test.avx2.0 t fmv_test.default.4 W fmv_test.resolver 0142 t fmv_test.sse2.3 00f5 t fmv_test.sse4_1.2 U _GLOBAL_OFFSET_TABLE_ This is when fmv_test is defined without target_clones attribute: Archive index: main in main.o fmv_test in fmv-test.o fmv_normal_function in fmv-test.o main.o: U fmv_test U _GLOBAL_OFFSET_TABLE_ T main U malloc U memset fmv-test.o: 004d T fmv_normal_function T fmv_test
[Bug c/91664] Undefined reference linker errors when static linking archive with gcc target_clones function multi-versioning
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91664 --- Comment #5 from element at elementsofsound dot org --- (In reply to Andrew Pinski from comment #3) > Maybe it is not clear but target_clones is only supposed to be on the > definition rather just declarations too. I'm not sure if I understood you exactly. The target_clones attribute is defined in the header file for the definition of the function (for use by other .c files). If I add it to the actual function, GCC complains, so I only have it on the definition. I think that is what you meant. One thing I have noticed is that when the .c files are compiled as individual object files, objdump shows that the number at the end of the symbols for the target clones do not match. However, when linking these object files with gcc they somehow are resolved. If instead they are placed in an archive, then they don't resolve. Not sure if this is related. It seems like this has something to do more with the linking than gcc compilation of the C code. So perhaps my lack of knowledge led me to file the bug for the wrong component? See below: objdump -t fmv-test.o | grep fmv_test l F .text 0062 fmv_test.default.9 0239 l F .text 0062 fmv_test.avx2.4 029b l F .text 0062 fmv_test.avx.5 02fd l F .text 0062 fmv_test.sse4_1.6 035f l F .text 0062 fmv_test.sse2.7 ld .text.fmv_test.resolver .text.fmv_test.resolver 03c1 g i .text 0080 internal_func._GLOBAL___fmv_test.ifunc wF .text.fmv_test.resolver0080 fmv_test.resolver g i .text.fmv_test.resolver0080 fmv_test objdump -t main.o | grep fmv_test ld .text.fmv_test.resolver .text.fmv_test.resolver g i .text.fmv_test.resolver0080 fmv_test wF .text.fmv_test.resolver0080 fmv_test.resolver *UND* fmv_test.avx2.0 *UND* fmv_test.avx.1 *UND* fmv_test.sse4_1.2 *UND* fmv_test.sse2.3 *UND* fmv_test.default.4
[Bug c/91664] Undefined reference linker errors when static linking archive with gcc target_clones function multi-versioning
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91664 --- Comment #4 from element at elementsofsound dot org --- (In reply to Andrew Pinski from comment #2) > Try this: > gcc -c fmv-test.c > gcc -c main.c > ar cr fmv-test.a main.o fmv-test.o > gcc -o fmv-test-borken fmv-test.a > > It might be because the way linker processes archives and most likely not a > bug. I tried changing the order of the .o files in the ar command as shown, but same errors occurred.
[Bug c/91664] Undefined reference linker errors when static linking archive with gcc target_clones function multi-versioning
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91664 --- Comment #3 from Andrew Pinski --- Maybe it is not clear but target_clones is only supposed to be on the definition rather just declarations too.
[Bug c/91664] Undefined reference linker errors when static linking archive with gcc target_clones function multi-versioning
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91664 Andrew Pinski changed: What|Removed |Added Status|UNCONFIRMED |WAITING Last reconfirmed||2019-09-05 Ever confirmed|0 |1 --- Comment #2 from Andrew Pinski --- Try this: gcc -c fmv-test.c gcc -c main.c ar cr fmv-test.a main.o fmv-test.o gcc -o fmv-test-borken fmv-test.a It might be because the way linker processes archives and most likely not a bug.
[Bug c/91664] Undefined reference linker errors when static linking archive with gcc target_clones function multi-versioning
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91664 --- Comment #1 from element at elementsofsound dot org --- Created attachment 46827 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46827=edit Preprocessed file for main.c
