diff options
| author | Takayuki 'January June' Suwa <jjsuwa_sys3175@yahoo.co.jp> | 2022-10-22 07:46:13 +0900 |
|---|---|---|
| committer | Max Filippov <jcmvbkbc@gmail.com> | 2022-10-22 00:23:02 -0700 |
| commit | e0927d7ddca154b1a5151da698e205593cb8912e (patch) | |
| tree | 3d3ed9ce0c0c552d6c5899acc81d698840f7ecdd /gcc/config | |
| parent | 1043971957af092e265cc4553b2382398d7308ae (diff) | |
| download | gcc-e0927d7ddca154b1a5151da698e205593cb8912e.zip gcc-e0927d7ddca154b1a5151da698e205593cb8912e.tar.gz gcc-e0927d7ddca154b1a5151da698e205593cb8912e.tar.bz2 | |
xtensa: Make register A0 allocable for the CALL0 ABI
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.
Diffstat (limited to 'gcc/config')
| -rw-r--r-- | gcc/config/xtensa/xtensa.cc | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc index 950eb5a..94a98c2 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 */ |