* [PATCH] xtensa: Make register A0 allocable for the CALL0 ABI [not found] <faee7f9c-aef5-33e7-5f22-a52464ee4c35.ref@yahoo.co.jp> @ 2022-10-21 2:58 ` Takayuki 'January June' Suwa 2022-10-21 5:49 ` Max Filippov 0 siblings, 1 reply; 4+ messages in thread From: Takayuki 'January June' Suwa @ 2022-10-21 2:58 UTC (permalink / raw) To: GCC Patches; +Cc: Max Filippov This patch offers an additional allocable register by RA for the CALL0 ABI. > Register a0 holds the return address upon entry to a function, but > unlike the windowed register ABI, it is not reserved for this purpose > and may hold other values after the return address has been saved. - Xtensa ISA Reference Manual, 8.1.2 "CALL0 Register Usage and Stack Layout" [p.589] gcc/ChangeLog: * config/xtensa/xtensa.cc (xtensa_conditional_register_usage): Remove register A0 from FIXED_REGS if the CALL0 ABI. --- gcc/config/xtensa/xtensa.cc | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc index 950eb5a59be..f30725113dc 100644 --- a/gcc/config/xtensa/xtensa.cc +++ b/gcc/config/xtensa/xtensa.cc @@ -4970,6 +4970,13 @@ xtensa_conditional_register_usage (void) /* Remove hard FP register from the preferred reload registers set. */ CLEAR_HARD_REG_BIT (reg_class_contents[(int)RL_REGS], HARD_FRAME_POINTER_REGNUM); + + /* Register A0 holds the return address upon entry to a function + for the CALL0 ABI, but unlike the windowed register ABI, it is + not reserved for this purpose and may hold other values after + the return address has been saved. */ + if (!TARGET_WINDOWED_ABI) + fixed_regs[A0_REG] = 0; } /* Map hard register number to register class */ -- 2.30.2 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] xtensa: Make register A0 allocable for the CALL0 ABI 2022-10-21 2:58 ` [PATCH] xtensa: Make register A0 allocable for the CALL0 ABI Takayuki 'January June' Suwa @ 2022-10-21 5:49 ` Max Filippov 2022-10-21 22:46 ` [PATCH v2] " Takayuki 'January June' Suwa 0 siblings, 1 reply; 4+ messages in thread From: Max Filippov @ 2022-10-21 5:49 UTC (permalink / raw) To: Takayuki 'January June' Suwa; +Cc: GCC Patches Hi Suwa-san, On Thu, Oct 20, 2022 at 7:58 PM Takayuki 'January June' Suwa <jjsuwa_sys3175@yahoo.co.jp> wrote: > > This patch offers an additional allocable register by RA for the CALL0 > ABI. > > > Register a0 holds the return address upon entry to a function, but > > unlike the windowed register ABI, it is not reserved for this purpose > > and may hold other values after the return address has been saved. > - Xtensa ISA Reference Manual, > 8.1.2 "CALL0 Register Usage and Stack Layout" [p.589] > > gcc/ChangeLog: > > * config/xtensa/xtensa.cc (xtensa_conditional_register_usage): > Remove register A0 from FIXED_REGS if the CALL0 ABI. > --- > gcc/config/xtensa/xtensa.cc | 7 +++++++ > 1 file changed, 7 insertions(+) This change results in the following new regressions: FAIL: gcc.c-torture/execute/20040709-1.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions execution test FAIL: gcc.c-torture/execute/20040709-2.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions execution test FAIL: gcc.c-torture/execute/20190820-1.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions execution test FAIL: gcc.c-torture/execute/loop-15.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions execution test FAIL: gcc.dg/torture/pr101031.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions execution test FAIL: gcc.dg/torture/pr101972.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions execution test FAIL: gcc.dg/torture/pr99954.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions execution test FAIL: g++.dg/coroutines/torture/co-yield-04-complex-local-state.C -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions execution test FAIL: g++.dg/coroutines/torture/local-var-05-awaitable.C -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions execution test -- Thanks. -- Max ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v2] xtensa: Make register A0 allocable for the CALL0 ABI 2022-10-21 5:49 ` Max Filippov @ 2022-10-21 22:46 ` Takayuki 'January June' Suwa 2022-10-22 7:26 ` Max Filippov 0 siblings, 1 reply; 4+ messages in thread From: Takayuki 'January June' Suwa @ 2022-10-21 22:46 UTC (permalink / raw) To: GCC Patches; +Cc: Max Filippov This patch offers an additional allocable register by RA for the CALL0 ABI. > Register a0 holds the return address upon entry to a function, but > unlike the windowed register ABI, it is not reserved for this purpose > and may hold other values after the return address has been saved. - Xtensa ISA Reference Manual, 8.1.2 "CALL0 Register Usage and Stack Layout" [p.589] gcc/ChangeLog: * config/xtensa/xtensa.cc (xtensa_conditional_register_usage): Remove register A0 from FIXED_REGS if the CALL0 ABI. (xtensa_expand_epilogue): Change to emit '(use (reg:SI A0_REG))' unconditionally after restoring callee-saved registers for sibling-call functions, in order to prevent misleading that register A0 is free to use. --- gcc/config/xtensa/xtensa.cc | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc index 950eb5a59be..94a98c25f8c 100644 --- a/gcc/config/xtensa/xtensa.cc +++ b/gcc/config/xtensa/xtensa.cc @@ -3471,15 +3471,14 @@ xtensa_expand_epilogue (bool sibcall_p) if (xtensa_call_save_reg(regno)) { rtx x = gen_rtx_PLUS (Pmode, stack_pointer_rtx, GEN_INT (offset)); - rtx reg; offset -= UNITS_PER_WORD; - emit_move_insn (reg = gen_rtx_REG (SImode, regno), + emit_move_insn (gen_rtx_REG (SImode, regno), gen_frame_mem (SImode, x)); - if (regno == A0_REG && sibcall_p) - emit_use (reg); } } + if (sibcall_p) + emit_use (gen_rtx_REG (SImode, A0_REG)); if (cfun->machine->current_frame_size > 0) { @@ -4970,6 +4969,13 @@ xtensa_conditional_register_usage (void) /* Remove hard FP register from the preferred reload registers set. */ CLEAR_HARD_REG_BIT (reg_class_contents[(int)RL_REGS], HARD_FRAME_POINTER_REGNUM); + + /* Register A0 holds the return address upon entry to a function + for the CALL0 ABI, but unlike the windowed register ABI, it is + not reserved for this purpose and may hold other values after + the return address has been saved. */ + if (!TARGET_WINDOWED_ABI) + fixed_regs[A0_REG] = 0; } /* Map hard register number to register class */ -- 2.30.2 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] xtensa: Make register A0 allocable for the CALL0 ABI 2022-10-21 22:46 ` [PATCH v2] " Takayuki 'January June' Suwa @ 2022-10-22 7:26 ` Max Filippov 0 siblings, 0 replies; 4+ messages in thread From: Max Filippov @ 2022-10-22 7:26 UTC (permalink / raw) To: Takayuki 'January June' Suwa; +Cc: GCC Patches On Fri, Oct 21, 2022 at 3:46 PM Takayuki 'January June' Suwa <jjsuwa_sys3175@yahoo.co.jp> wrote: > > This patch offers an additional allocable register by RA for the CALL0 > ABI. > > > Register a0 holds the return address upon entry to a function, but > > unlike the windowed register ABI, it is not reserved for this purpose > > and may hold other values after the return address has been saved. > - Xtensa ISA Reference Manual, > 8.1.2 "CALL0 Register Usage and Stack Layout" [p.589] > > gcc/ChangeLog: > > * config/xtensa/xtensa.cc (xtensa_conditional_register_usage): > Remove register A0 from FIXED_REGS if the CALL0 ABI. > (xtensa_expand_epilogue): Change to emit '(use (reg:SI A0_REG))' > unconditionally after restoring callee-saved registers for > sibling-call functions, in order to prevent misleading that > register A0 is free to use. > --- > gcc/config/xtensa/xtensa.cc | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) Regtested for target=xtensa-linux-uclibc, no new regressions. Committed to master. -- Thanks. -- Max ^ permalink raw reply [flat|nested] 4+ messages in thread
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[not found] <faee7f9c-aef5-33e7-5f22-a52464ee4c35.ref@yahoo.co.jp>
2022-10-21 2:58 ` [PATCH] xtensa: Make register A0 allocable for the CALL0 ABI Takayuki 'January June' Suwa
2022-10-21 5:49 ` Max Filippov
2022-10-21 22:46 ` [PATCH v2] " Takayuki 'January June' Suwa
2022-10-22 7:26 ` Max Filippov
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