https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78529
--- Comment #3 from prathamesh3492 at gcc dot gnu.org --- Created attachment 40183 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40183&action=edit revert part of r242745 for strcat, strcat_chk, strncat, strncat_chk Hi, Unfortunately I haven't been able to reproduce the issue on aarch64-none-elf with (almost) identical configure opts with make-check, and neither did it get caught by our validation matrix. I would be grateful for suggestions on how to build strcat-chk.c standalone. It seems it depends on lib/chk.c and possibly other files ? I tried a few approaches but none of them worked :/ Regarding the code-gen difference "cmp x0, x0", I have verified that is not caused by my patch. The same can be reproduced with the following test-case before r242745. char *f(char *dest, char *src) { if (__builtin_strcpy (dest + 5, src) != (dest + 5)) __builtin_abort (); } -O2 shows following assembly for aarch64-none-elf: f: add x2, x0, 5 stp x29, x30, [sp, -16]! mov x0, x2 add x29, sp, 0 bl strcpy cmp x0, x0 bne .L5 ldp x29, x30, [sp], 16 ret This seems to start after "pro_and_epilogue" pass, which probably realizes strcpy returns 1st arg. The dump of the pass contains the following insn: (insn 13 36 14 2 (set (reg:CC 66 cc) (compare:CC (reg/f:DI 0 x0 [orig:73 _1 ] [73]) (reg:DI 0 x0))) "foo2.c":3 393 {cmpdi} (nil)) Full dump: http://pastebin.com/sUmg09SK Apparently, this is also observed on x86_64-unknown-linux-gnu: f: .LFB0: .cfi_startproc leaq 5(%rdi), %rdx subq $8, %rsp .cfi_def_cfa_offset 16 movq %rdx, %rdi call strcpy cmpq %rax, %rax jne .L5 addq $8, %rsp .cfi_remember_state .cfi_def_cfa_offset 8 ret The reason it started showing up this for strcat/strcat_chk is because r242745 changed attribute of BUILT_IN_STRCAT_CHK and BUILT_IN_STRCAT from ATTR_NOTHROW_NONNULL_LEAF to ATTR_RET1_NOTHROW_NONNULL_LEAF, which is same as for strcpy. Could you check if reverting that change (attached patch), doesn't cause the issue ? Thanks, Prathamesh
