https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=215819
--- Comment #3 from Mark Millard <mar...@dsl-only.net> --- (In reply to Mark Millard from comment #0) I found how to control the behavior based on the assembler notation @toc being missing vs. being present. If llvm should change is strongly tied to llvm's criteria for gcc compatibility relative to filling-in/defaulting omitted @toc's in the assembler notation. FreeBSD has the option of always being explicit with @toc in order to avoid differences in handling of omitted notation. So I've no clue if FreebSD wants to claim that a llvm change is a requirement for using clang as the powerpc64 system compiler. [The issue of the distinction is submittable to llvm either way.] Details. . . For: .section ".toc","aw" tmpstk.L: .tc tmpstk[TC],tmpstk . . . /* Set up the stack pointer */ ld %r1,tmpstk.L(%r2) using devel/powerpc64-gcc gets: # /usr/local/bin/powerpc64-unknown-freebsd12.0-gcc \ -c \ -x assembler-with-cpp \ -pipe \ locore64_simplified.S locore64_simplified.S: Assembler messages: locore64_simplified.S:80: Warning: assuming @toc on symbol and produces (with R_PPC64_TOC16_DS for .toc): # /usr/local/powerpc64-freebsd/bin/objdump -r locore64_simplified.o locore64_simplified.o: file format elf64-powerpc-freebsd RELOCATION RECORDS FOR [.text]: OFFSET TYPE VALUE 0000000000000028 R_PPC64_REL64 __tocbase+0x0000000000008000 0000000000000046 R_PPC64_TOC16_DS .toc RELOCATION RECORDS FOR [.toc]: OFFSET TYPE VALUE 0000000000000000 R_PPC64_ADDR64 tmpstk RELOCATION RECORDS FOR [.opd]: OFFSET TYPE VALUE 0000000000000000 R_PPC64_ADDR64 .__start 0000000000000008 R_PPC64_TOC *ABS* By contrast clang is silent (cross compiler used): # /usr/obj/powerpc64vtsc_clang_kernel/powerpc.powerpc64/usr/src/tmp/usr/bin/cc \ -target powerpc64-unknown-freebsd12.0 \ --sysroot=/usr/obj/powerpc64vtsc_clang_kernel/powerpc.powerpc64/usr/src/tmp \ -B/usr/obj/powerpc64vtsc_clang_kernel/powerpc.powerpc64/usr/src/tmp/usr/bin \ -c \ -x assembler-with-cpp \ -pipe \ locore64_simplified.S and produces code with R_PPC64_ADDR16_DS for the .toc instead: # /usr/local/powerpc64-freebsd/bin/objdump -r locore64_simplified.o | more locore64_simplified.o: file format elf64-powerpc-freebsd RELOCATION RECORDS FOR [.text]: OFFSET TYPE VALUE 0000000000000028 R_PPC64_REL64 __tocbase+0x0000000000008000 0000000000000046 R_PPC64_ADDR16_DS .toc RELOCATION RECORDS FOR [.toc]: OFFSET TYPE VALUE 0000000000000000 R_PPC64_ADDR64 tmpstk RELOCATION RECORDS FOR [.opd]: OFFSET TYPE VALUE 0000000000000000 R_PPC64_ADDR64 .__start 0000000000000008 R_PPC64_TOC *ABS* But for: .section ".toc","aw" tmpstk.L: .tc tmpstk[TC],tmpstk . . . /* Set up the stack pointer */ ld %r1,tmpstk.L@toc(%r2) (note the @toc notation) both compilers agree and use R_PPC64_TOC16_DS for the .toc: # /usr/local/bin/powerpc64-unknown-freebsd12.0-gcc \ -c \ -x assembler-with-cpp \ -pipe \ locore64_simplified.S # /usr/local/powerpc64-freebsd/bin/objdump -r locore64_simplified.o | more locore64_simplified.o: file format elf64-powerpc-freebsd RELOCATION RECORDS FOR [.text]: OFFSET TYPE VALUE 0000000000000028 R_PPC64_REL64 __tocbase+0x0000000000008000 0000000000000046 R_PPC64_TOC16_DS .toc RELOCATION RECORDS FOR [.toc]: OFFSET TYPE VALUE 0000000000000000 R_PPC64_ADDR64 tmpstk RELOCATION RECORDS FOR [.opd]: OFFSET TYPE VALUE 0000000000000000 R_PPC64_ADDR64 .__start 0000000000000008 R_PPC64_TOC *ABS* # /usr/obj/powerpc64vtsc_clang_kernel/powerpc.powerpc64/usr/src/tmp/usr/bin/cc \ -target powerpc64-unknown-freebsd12.0 \ --sysroot=/usr/obj/powerpc64vtsc_clang_kernel/powerpc.powerpc64/usr/src/tmp \ -B/usr/obj/powerpc64vtsc_clang_kernel/powerpc.powerpc64/usr/src/tmp/usr/bin \ -c \ -x assembler-with-cpp \ -pipe \ locore64_simplified.S # /usr/local/powerpc64-freebsd/bin/objdump -r locore64_simplified.o | more locore64_simplified.o: file format elf64-powerpc-freebsd RELOCATION RECORDS FOR [.text]: OFFSET TYPE VALUE 0000000000000028 R_PPC64_REL64 __tocbase+0x0000000000008000 0000000000000046 R_PPC64_TOC16_DS .toc RELOCATION RECORDS FOR [.toc]: OFFSET TYPE VALUE 0000000000000000 R_PPC64_ADDR64 tmpstk RELOCATION RECORDS FOR [.opd]: OFFSET TYPE VALUE 0000000000000000 R_PPC64_ADDR64 .__start 0000000000000008 R_PPC64_TOC *ABS* I omitted "-f -gdwarf-2" to simplify things but with such clang complains about: locore64_simplified.S:36:2: warning: DWARF2 only supports one section per compilation unit .section ".toc","aw" ^ locore64_simplified.S:47:2: warning: DWARF2 only supports one section per compilation unit .section ".opd","aw" ^ (buildkernel gets such messages.) I expect I can simplify the .S code more than I have so far but I figured I'd report the discovery of the choice FreeBSD needs to make for powerpc64 for if llvm changes are to be required vs. not. The following should be a list of the places that adding @toc usage would fix things: # grep "@toc[^b]" /root/sys_typescripts/typescript_make_powerpc64vtsc_nodebug_incl_clang_xtoolchain_kernel-amd64-host-2017-01-03:23:48:41 | more /usr/src/sys/powerpc/aim/locore64.S:102: Warning: assuming @toc on symbol /usr/src/sys/powerpc/aim/trap_subr64.S:320: Warning: assuming @toc on symbol /usr/src/sys/powerpc/aim/trap_subr64.S:797: Warning: assuming @toc on symbol /usr/src/sys/powerpc/ofw/ofwcall64.S:104: Warning: assuming @toc on symbol /usr/src/sys/powerpc/ofw/ofwcall64.S:108: Warning: assuming @toc on symbol /usr/src/sys/powerpc/ofw/ofwcall64.S:116: Warning: assuming @toc on symbol /usr/src/sys/powerpc/ofw/ofwcall64.S:226: Warning: assuming @toc on symbol /usr/src/sys/powerpc/ofw/ofwcall64.S:228: Warning: assuming @toc on symbol /usr/src/sys/powerpc/ofw/ofwcall64.S:235: Warning: assuming @toc on symbol /usr/src/sys/powerpc/powerpc/swtch64.S:153: Warning: assuming @toc on symbol -- You are receiving this mail because: You are the assignee for the bug. _______________________________________________ freebsd-toolchain@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-toolchain To unsubscribe, send any mail to "freebsd-toolchain-unsubscr...@freebsd.org"