From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 8272D385828D; Thu, 19 Oct 2023 12:02:30 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 8272D385828D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1697716950; bh=vpXXPNcaOyPeHRI191H4ChevDuv1W+o5NrJxZEN8YAk=; h=From:To:Subject:Date:In-Reply-To:References:From; b=mqV9rCHUfrvUJs27H7H8Y+LwplVg7gy+SQwYmYOhwnpntmKYOWrgk2EGkKN60oybt 68RT4W/2ktTqqGaQCxcvWqdTjg5Z2RTAhQwR+O2L6LWhHwtsCf9MgBj8VgtPtFI7ra PnIRPGGGPB/KVqUaIdkzKbsINN1qsr41fXdWXIr4= From: "rguenther at suse dot de" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/111720] RISC-V: Ugly codegen in RVV Date: Thu, 19 Oct 2023 12:02:30 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Version: 14.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: rguenther at suse dot de X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 List-Id: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111720 --- Comment #22 from rguenther at suse dot de --- On Thu, 19 Oct 2023, juzhe.zhong at rivai dot ai wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111720 >=20 > --- Comment #21 from JuzheZhong --- > (In reply to rguenther@suse.de from comment #20) > > On Thu, 19 Oct 2023, juzhe.zhong at rivai dot ai wrote: > >=20 > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111720 > > >=20 > > > --- Comment #19 from JuzheZhong --- > > > (In reply to Richard Biener from comment #18) > > > > With RVV you have intrinsic calls in GIMPLE so nothing to optimize: > > > >=20 > > > > vbool8_t fn () > > > > { > > > > vbool8_t vmask; > > > > vuint8m1_t vand_m; > > > > vuint8m1_t varr; > > > > uint8_t arr[32]; > > > >=20 > > > > [local count: 1073741824]: > > > > arr =3D > > > > "\x01\x02\x07\x01\x03\x04\x05\x03\x01\x00\x01\x02\x04\x04\t\t\x01\x= 02\x07\x01 > > > > \x03\x04\x05\x03\x01\x00\x01\x02\x04\x04\t\t"; > > > > varr_3 =3D __riscv_vle8_v_u8m1 (&arr, 32); [return slot optimizat= ion] > > > > vand_m_4 =3D __riscv_vand_vx_u8m1 (varr_3, 1, 32); [return slot o= ptimization] > > > > vmask_5 =3D __riscv_vreinterpret_v_u8m1_b8 (vand_m_4); [return sl= ot > > > > optimization] > > > > =3D vmask_5; > > > > arr =3D{v} {CLOBBER(eol)}; > > > > return ; > > > >=20 > > > > and on RTL I see lots of UNSPECs, RTL opts cannot do anything with = those. > > > >=20 > > > > This is what Andrew said already. > > >=20 > > > Ok. I wonder why this issue is gone when I change it into: > > >=20 > > > arr as static > > >=20 > > > https://godbolt.org/z/Tdoshdfr6 > >=20 > > Because the stacik initialization isn't required then. >=20 > I have experiment with a simplifed pattern: >=20 >=20 > (insn 14 13 15 2 (set (reg/v:RVVM1QI 134 [ varr ]) > (if_then_else:RVVM1QI (unspec:RVVMF8BI [ > (const_vector:RVVMF8BI repeat [ > (const_int 1 [0x1]) > ]) > (reg:DI 143) > (const_int 2 [0x2]) repeated x2 > (const_int 0 [0]) > (reg:SI 66 vl) > (reg:SI 67 vtype) > ] UNSPEC_VPREDICATE) > (mem:RVVM1QI (reg:DI 142) [0 S[16, 16] A8]) > (const_vector:RVVM1QI repeat [ > (const_int 0 [0]) > ]))) "rvv.c":5:23 1476 {*pred_movrvvm1qi} > (nil)) > (insn 15 14 16 2 (set (reg:DI 144) > (const_int 32 [0x20])) "rvv.c":6:5 206 {*movdi_64bit} > (nil)) > (insn 16 15 0 2 (set (mem:RVVM1QI (reg/v/f:DI 135 [ out ]) [0 S[16, 16] = A8]) > (if_then_else:RVVM1QI (unspec:RVVMF8BI [ > (const_vector:RVVMF8BI repeat [ > (const_int 1 [0x1]) > ]) > (reg:DI 144) > (const_int 0 [0]) > (reg:SI 66 vl) > (reg:SI 67 vtype) > ] UNSPEC_VPREDICATE) > (reg/v:RVVM1QI 134 [ varr ]) > (mem:RVVM1QI (reg/v/f:DI 135 [ out ]) [0 S[16, 16] A8]))) > "rvv.c":6:5 1592 {pred_storervvm1qi} > (nil)) >=20 > You can see there is only one UNSPEC now. Still has redundant stack > transferring. >=20 > Is it because the pattern too complicated? It's because it has an UNSPEC in it - that makes it have target specific (unknown to the middle-end) behavior so nothing can be optimized here. Specifically passes likely refuse to replace MEM operands in such a construct.=