Message ID | 2203c450-66c4-f100-2fc1-ab7e45cc008f@yahoo.co.jp |
---|---|
State | New |
Headers | show |
Series | xtensa: Make instruction cost estimation for size more accurate | expand |
On Mon, Jan 9, 2023 at 7:34 PM Takayuki 'January June' Suwa <jjsuwa_sys3175@yahoo.co.jp> wrote: > > Until now, we applied COSTS_N_INSNS() (multiplying by 4) after dividing > the instruction length by 3, so we couldn't express the difference less > than modulo 3 in insn cost for size (e.g. 11 Bytes and 12 bytes cost the > same). > > This patch fixes that. > > ;; 2 bytes > addi.n a2, a2, -1 ; cost 3 > > ;; 3 bytes > addmi a2, a2, 1024 ; cost 4 > > ;; 4 bytes > movi.n a3, 80 ; cost 5 > bnez.n a2, a3, .L4 > > ;; 5 bytes > srli a2, a3, 1 ; cost 7 > add.n a2, a2, a2 > > ;; 6 bytes > ssai 8 ; cost 8 > src a4, a2, a3 > > :: 3 + 4 bytes > l32r a2, .L5 ; cost 9 > > ;; 11 bytes ; cost 15 > ;; 12 bytes ; cost 16 > > gcc/ChangeLog: > > * config/xtensa/xtensa.cc (xtensa_insn_cost): > Let insn cost for size be obtained by applying COSTS_N_INSNS() > to instruction length and then dividing by 3. > --- > gcc/config/xtensa/xtensa.cc | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) Regtested for target=xtensa-linux-uclibc, no new regressions. Committed to master.
diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc index a1f184950ae..6cf6b35399a 100644 --- a/gcc/config/xtensa/xtensa.cc +++ b/gcc/config/xtensa/xtensa.cc @@ -4519,13 +4519,15 @@ xtensa_insn_cost (rtx_insn *insn, bool speed) { if (!(recog_memoized (insn) < 0)) { - int len = get_attr_length (insn), n = (len + 2) / 3; + int len = get_attr_length (insn); if (len == 0) return COSTS_N_INSNS (0); if (speed) /* For speed cost. */ { + int n = (len + 2) / 3; + /* "L32R" may be particular slow (implementation-dependent). */ if (xtensa_is_insn_L32R_p (insn)) return COSTS_N_INSNS (1 + xtensa_extra_l32r_costs); @@ -4572,10 +4574,11 @@ xtensa_insn_cost (rtx_insn *insn, bool speed) { /* "L32R" itself plus constant in litpool. */ if (xtensa_is_insn_L32R_p (insn)) - return COSTS_N_INSNS (2) + 1; + len = 3 + 4; - /* Consider ".n" short instructions. */ - return COSTS_N_INSNS (n) - (n * 3 - len); + /* Consider fractional instruction length (for example, ".n" + short instructions or "L32R" litpool constants. */ + return (COSTS_N_INSNS (len) + 1) / 3; } } }