https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81501
--- Comment #15 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by H.J. Lu <h...@gcc.gnu.org>: https://gcc.gnu.org/g:5cf1b9a03ec5b617af8c50c1e9c0d223083fd7f2 commit r16-3190-g5cf1b9a03ec5b617af8c50c1e9c0d223083fd7f2 Author: H.J. Lu <hjl.to...@gmail.com> Date: Fri Aug 19 11:50:41 2022 -0700 x86-64: Remove redundant TLS calls For TLS calls: 1. UNSPEC_TLS_GD: (parallel [ (set (reg:DI 0 ax) (call:DI (mem:QI (symbol_ref:DI ("__tls_get_addr"))) (const_int 0 [0]))) (unspec:DI [(symbol_ref:DI ("e") [flags 0x50]) (reg/f:DI 7 sp)] UNSPEC_TLS_GD) (clobber (reg:DI 5 di))]) 2. UNSPEC_TLS_LD_BASE: (parallel [ (set (reg:DI 0 ax) (call:DI (mem:QI (symbol_ref:DI ("__tls_get_addr"))) (const_int 0 [0]))) (unspec:DI [(reg/f:DI 7 sp)] UNSPEC_TLS_LD_BASE)]) 3. UNSPEC_TLSDESC: (parallel [ (set (reg/f:DI 104) (plus:DI (unspec:DI [ (symbol_ref:DI ("_TLS_MODULE_BASE_") [flags 0x10]) (reg:DI 114) (reg/f:DI 7 sp)] UNSPEC_TLSDESC) (const:DI (unspec:DI [ (symbol_ref:DI ("e") [flags 0x1a]) ] UNSPEC_DTPOFF)))) (clobber (reg:CC 17 flags))]) (parallel [ (set (reg:DI 101) (unspec:DI [(symbol_ref:DI ("e") [flags 0x50]) (reg:DI 112) (reg/f:DI 7 sp)] UNSPEC_TLSDESC)) (clobber (reg:CC 17 flags))]) they return the same value for the same input value. But multiple calls with the same input value may be generated for simple programs like: void a(long *); int b(void); void c(void); static __thread long e; long d(void) { a(&e); if (b()) c(); return e; } When compiled with -O2 -fPIC -mtls-dialect=gnu2, the following codes are generated: .type d, @function d: .LFB0: .cfi_startproc pushq %rbx .cfi_def_cfa_offset 16 .cfi_offset 3, -16 leaq e@TLSDESC(%rip), %rbx movq %rbx, %rax call *e@TLSCALL(%rax) addq %fs:0, %rax movq %rax, %rdi call a@PLT call b@PLT testl %eax, %eax jne .L8 movq %rbx, %rax call *e@TLSCALL(%rax) popq %rbx .cfi_remember_state .cfi_def_cfa_offset 8 movq %fs:(%rax), %rax ret .p2align 4,,10 .p2align 3 .L8: .cfi_restore_state call c@PLT movq %rbx, %rax call *e@TLSCALL(%rax) popq %rbx .cfi_def_cfa_offset 8 movq %fs:(%rax), %rax ret .cfi_endproc There are 3 "call *e@TLSCALL(%rax)". They all return the same value. Rename the remove_redundant_vector pass to the x86_cse pass, for 64bit, extend it to also remove redundant TLS calls to generate: d: .LFB0: .cfi_startproc pushq %rbx .cfi_def_cfa_offset 16 .cfi_offset 3, -16 leaq e@TLSDESC(%rip), %rax movq %fs:0, %rdi call *e@TLSCALL(%rax) addq %rax, %rdi movq %rax, %rbx call a@PLT call b@PLT testl %eax, %eax jne .L8 movq %fs:(%rbx), %rax popq %rbx .cfi_remember_state .cfi_def_cfa_offset 8 ret .p2align 4,,10 .p2align 3 .L8: .cfi_restore_state call c@PLT movq %fs:(%rbx), %rax popq %rbx .cfi_def_cfa_offset 8 ret .cfi_endproc with only one "call *e@TLSCALL(%rax)". This reduces the number of __tls_get_addr calls in libgcc.a by 72%: __tls_get_addr calls before after libgcc.a 868 243 gcc/ PR target/81501 * config/i386/i386-features.cc (x86_cse_kind): Add X86_CSE_TLS_GD, X86_CSE_TLS_LD_BASE and X86_CSE_TLSDESC. (redundant_load): Renamed to ... (redundant_pattern): This. (ix86_place_single_vector_set): Replace redundant_load with redundant_pattern. (replace_tls_call): New. (ix86_place_single_tls_call): Likewise. (pass_remove_redundant_vector_load): Renamed to ... (pass_x86_cse): This. Add val, def_insn, mode, scalar_mode, kind, x86_cse, candidate_gnu_tls_p, candidate_gnu2_tls_p and candidate_vector_p. (pass_x86_cse::candidate_gnu_tls_p): New. (pass_x86_cse::candidate_gnu2_tls_p): Likewise. (pass_x86_cse::candidate_vector_p): Likewise. (remove_redundant_vector_load): Renamed to ... (pass_x86_cse::x86_cse): This. Extend to remove redundant TLS calls. (make_pass_remove_redundant_vector_load): Renamed to ... (make_pass_x86_cse): This. * config/i386/i386-passes.def: Replace pass_remove_redundant_vector_load with pass_x86_cse. * config/i386/i386-protos.h (ix86_tls_get_addr): New. (make_pass_remove_redundant_vector_load): Renamed to ... (make_pass_x86_cse): This. * config/i386/i386.cc (ix86_tls_get_addr): Remove static. * config/i386/i386.h (machine_function): Add tls_descriptor_call_multiple_p. * config/i386/i386.md (tls64): New attribute. (@tls_global_dynamic_64_<mode>): Set tls_descriptor_call_multiple_p. (@tls_local_dynamic_base_64_<mode>): Likewise. (@tls_dynamic_gnu2_64_<mode>): Likewise. (*tls_global_dynamic_64_<mode>): Set tls64 attribute to gd. (*tls_local_dynamic_base_64_<mode>): Set tls64 attribute to ld_base. (*tls_dynamic_gnu2_lea_64_<mode>): Set tls64 attribute to lea. (*tls_dynamic_gnu2_call_64_<mode>): Set tls64 attribute to call. (*tls_dynamic_gnu2_combine_64_<mode>): Set tls64 attribute to combine. gcc/testsuite/ PR target/81501 * g++.target/i386/pr81501-1.C: New test. * gcc.target/i386/pr81501-1a.c: Likewise. * gcc.target/i386/pr81501-1b.c: Likewise. * gcc.target/i386/pr81501-2a.c: Likewise. * gcc.target/i386/pr81501-2b.c: Likewise. * gcc.target/i386/pr81501-3.c: Likewise. * gcc.target/i386/pr81501-4a.c: Likewise. * gcc.target/i386/pr81501-4b.c: Likewise. * gcc.target/i386/pr81501-5.c: Likewise. * gcc.target/i386/pr81501-6a.c: Likewise. * gcc.target/i386/pr81501-6b.c: Likewise. * gcc.target/i386/pr81501-7.c: Likewise. * gcc.target/i386/pr81501-8a.c: Likewise. * gcc.target/i386/pr81501-8b.c: Likewise. * gcc.target/i386/pr81501-9a.c: Likewise. * gcc.target/i386/pr81501-9b.c: Likewise. * gcc.target/i386/pr81501-10a.c: Likewise. * gcc.target/i386/pr81501-10b.c: Likewise. Signed-off-by: H.J. Lu <hjl.to...@gmail.com>
