https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98971
--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> --- Created attachment 50133 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50133&action=edit Tentative patch As seen the flag -fpatchable-function-entry is properly marked as Optimization. However, it's the argument is parsed early and stored into the following tuple: ; How many NOP insns to place at each function entry by default Variable HOST_WIDE_INT function_entry_patch_area_size ; And how far the real asm entry point is into this area Variable HOST_WIDE_INT function_entry_patch_area_start That does not work with set_current_function where per-function arguments are restored. My tentative patch fixes that. The following examples works now: $ cat pr98971.c int testa7(void) { return 7; } int __attribute__((patchable_function_entry(10,5))) testa77(void) { return 77; } #pragma GCC optimize("patchable-function-entry=0,0") int testa_no(void) { return 1234; } $ cat pr98971-2.c int testa8(void) { return 8; } $ gcc pr98971.c -fPIC -fpatchable-function-entry=4,1 -flto -c $ gcc pr98971-2.c -fPIC -flto -c $ gcc pr98971.o pr98971-2.o -flto -shared -o x.so $ objdump -d x.so ... 0000000000000650 <frame_dummy>: 650: f3 0f 1e fa endbr64 654: e9 77 ff ff ff jmp 5d0 <register_tm_clones> 659: 90 nop 000000000000065a <testa7>: 65a: 90 nop 65b: 90 nop 65c: 90 nop 65d: 55 push %rbp 65e: 48 89 e5 mov %rsp,%rbp 661: b8 07 00 00 00 mov $0x7,%eax 666: 5d pop %rbp 667: c3 ret 668: 90 nop 669: 90 nop 66a: 90 nop 66b: 90 nop 66c: 90 nop 000000000000066d <testa77>: 66d: 90 nop 66e: 90 nop 66f: 90 nop 670: 90 nop 671: 90 nop 672: 55 push %rbp 673: 48 89 e5 mov %rsp,%rbp 676: b8 4d 00 00 00 mov $0x4d,%eax 67b: 5d pop %rbp 67c: c3 ret 000000000000067d <testa_no>: 67d: 55 push %rbp 67e: 48 89 e5 mov %rsp,%rbp 681: b8 d2 04 00 00 mov $0x4d2,%eax 686: 5d pop %rbp 687: c3 ret 0000000000000688 <testa8>: 688: 55 push %rbp 689: 48 89 e5 mov %rsp,%rbp 68c: b8 08 00 00 00 mov $0x8,%eax 691: 5d pop %rbp 692: c3 ret @Gabriel: Is it intended behavior?
