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From: "deller at gmx dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/102162] Byte-wise access optimized away at -O1 and above
Date: Wed, 01 Sep 2021 21:29:26 +0000 [thread overview]
Message-ID: <bug-102162-4-W736hesmB2@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-102162-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102162
--- Comment #9 from deller at gmx dot de ---
On 9/1/21 11:25 PM, deller at gmx dot de wrote:
> The "ldh" loads only the first two bytes, and extends it into the upper 32bits
> with "extrw,s".
> So, only 16bits instead of 32bits are loaded from the address where "evil" is...
Forget this!
My testcase was wrong. Here is the correct testcase which then loads 32bits:
short evil;
int f_unaligned2(void)
{ return get_unaligned((unsigned long *)&evil); }
00000000 <f_unaligned2>:
0: 2b 60 00 00 addil L%0,dp,r1
4: 34 33 00 00 ldo 0(r1),r19
8: 44 3c 00 00 ldh 0(r1),ret0
c: d7 9c 0a 10 depw,z ret0,15,16,ret0
10: 0e 64 10 53 ldh 2(r19),r19
14: e8 40 c0 00 bv r0(rp)
18: 0b 93 02 5c or r19,ret0,ret0
next prev parent reply other threads:[~2021-09-01 21:29 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-01 16:52 [Bug tree-optimization/102162] New: " danglin at gcc dot gnu.org
2021-09-01 18:52 ` [Bug tree-optimization/102162] " danglin at gcc dot gnu.org
2021-09-01 20:14 ` arnd at linaro dot org
2021-09-01 20:52 ` deller at gmx dot de
2021-09-01 20:56 ` dave.anglin at bell dot net
2021-09-01 21:08 ` dave.anglin at bell dot net
2021-09-01 21:15 ` deller at gmx dot de
2021-09-01 21:19 ` dave.anglin at bell dot net
2021-09-01 21:25 ` deller at gmx dot de
2021-09-01 21:29 ` deller at gmx dot de [this message]
2021-09-01 21:48 ` pinskia at gcc dot gnu.org
2021-09-01 21:51 ` [Bug middle-end/102162] " pinskia at gcc dot gnu.org
2021-09-01 21:52 ` pinskia at gcc dot gnu.org
2021-09-01 22:35 ` dave.anglin at bell dot net
2021-09-01 22:46 ` dave.anglin at bell dot net
2021-09-01 22:56 ` pinskia at gcc dot gnu.org
2021-09-01 23:19 ` pinskia at gcc dot gnu.org
2021-09-01 23:21 ` pinskia at gcc dot gnu.org
2021-09-01 23:29 ` pinskia at gcc dot gnu.org
2021-09-01 23:45 ` pinskia at gcc dot gnu.org
2021-09-01 23:55 ` pinskia at gcc dot gnu.org
2021-09-02 0:02 ` dave.anglin at bell dot net
2021-09-02 0:19 ` pinskia at gcc dot gnu.org
2021-09-02 0:23 ` pinskia at gcc dot gnu.org
2021-09-02 0:47 ` dave.anglin at bell dot net
2021-09-02 0:49 ` pinskia at gcc dot gnu.org
2021-09-02 3:33 ` pinskia at gcc dot gnu.org
2021-09-02 7:12 ` rguenth at gcc dot gnu.org
2021-09-02 9:01 ` arnd at linaro dot org
2021-09-02 9:41 ` deller at gmx dot de
2021-09-02 9:52 ` pinskia at gcc dot gnu.org
2021-09-02 13:59 ` deller at gmx dot de
2021-09-02 14:00 ` deller at gmx dot de
2021-09-03 23:25 ` deller at gmx dot de
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