From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id BFB2C3858401; Thu,  1 Jun 2023 10:35:55 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org BFB2C3858401
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1685615755;
	bh=pHOBd2hdOAr84iwEYZDaJ9QuLHAPYH3TATLYPtwqqv8=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=NH7XvPWJ36Sp1RZdYZOLT2elnM1+PJUoziWvdMVyzgkmpu4hP4oArfY9s8IGEBEZ/
	 VpPdcY4att9gr5sKoFhB8x1FRgOUM5UlfIeq590juKDMmnLxUFycTGddfKnClcu4Cc
	 fu4s5uYkcji0Q4vZyaRcZrhv/TVF5QrA/BBzugRM=
From: "maxim.blinov at imgtec dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/109989] RISC-V: Missing sign extension with int to float
 conversion with 64bit soft floats
Date: Thu, 01 Jun 2023 10:35:51 +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: 13.1.0
X-Bugzilla-Keywords: ABI, wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: maxim.blinov at imgtec dot com
X-Bugzilla-Status: UNCONFIRMED
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: cc
Message-ID: <bug-109989-4-VoeP6d76xv@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109989-4@http.gcc.gnu.org/bugzilla/>
References: <bug-109989-4@http.gcc.gnu.org/bugzilla/>
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: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109989

Maxim Blinov <maxim.blinov at imgtec dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |maxim.blinov at imgtec dot=
 com

--- Comment #1 from Maxim Blinov <maxim.blinov at imgtec dot com> ---
Hi all,

I bisected the failure to commit

3496ca4e656, "RISC-V: Add runtime invariant support".

GCC seems to treat the x array (`x[2]`) as a 2 integer vector, and loads it
into a DI mode register. However after the patch it neglects to honour the =
fact
that we only really want the lower 32 bits (which corresponds to `x[0]`) wh=
en
passing it as an argument to `__floatsisf`.

Before the commit, we generate

(insn 12 11 13 2 (set (reg:DI 10 a0)
        (sign_extend:DI (subreg:SI (reg:DI 77) 0))) "../a.c":16:10 116
{extendsidi2}
     (expr_list:REG_DEAD (reg:DI 77)
        (nil)))

After the commit, we generate

(insn 12 11 13 2 (set (reg:SI 10 a0)
        (subreg:SI (reg:DI 77) 0)) "../a.c":16:10 178 {*movsi_internal}
     (expr_list:REG_DEAD (reg:DI 77)
        (nil)))

which consequently gets removed as a useless instruction during the lra pas=
s.=