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From: Klaus.k.pedersen@nokia.com To: gcc-gnats@gcc.gnu.org Subject: target/5170: Supicious code in arm.md Date: Fri, 21 Dec 2001 06:56:00 -0000 [thread overview] Message-ID: <20011221145008.23546.qmail@sources.redhat.com> (raw) >Number: 5170 >Category: target >Synopsis: Supicious code in arm.md >Confidential: no >Severity: serious >Priority: medium >Responsible: unassigned >State: open >Class: sw-bug >Submitter-Id: net >Arrival-Date: Fri Dec 21 06:56:00 PST 2001 >Closed-Date: >Last-Modified: >Originator: Klaus Pedersen >Release: gcc version 3.1 20011203 (experimental) >Organization: >Environment: nice >Description: See also target/5107, investigated by Richard Earnshaw <rearnsha@arm.com> The arm.md file defines the split pattern (define_split [(set (match_operand:SI 0 "register_operand" "") (match_operand:SI 1 "const_int_operand" ""))] "TARGET_THUMB && CONST_OK_FOR_THUMB_LETTER (INTVAL (operands[1]), 'K')" [(set (match_dup 0) (match_dup 1)) (set (match_dup 0) (ashift:SI (match_dup 0) (match_dup 2)))] " { unsigned HOST_WIDE_INT val = INTVAL (operands[1]); unsigned HOST_WIDE_INT mask = 0xff; int i; for (i = 0; i < 25; i++) if ((val & (mask << i)) == val) break; if (i == 0) FAIL; operands[1] = GEN_INT (val >> i); operands[2] = GEN_INT (i); }" I think that there is a bug here: > for (i = 0; i < 25; i++) > if ((val & (mask << i)) == val) > break; > > if (i == 0) > FAIL; Consider "val = 0x55", which can be represented as 0x55 << 0, but calling the function with this value causes the function FAIL to be called. On the other hand, FAIL isn't called when passing the constant 0x101, which can't be represented, therefor I think that: > if (i == 0) > FAIL; should read: > if (i == 25) > FAIL; BR, Klaus Pedersen >How-To-Repeat: Well I have to admit it - I haven't been able to find code affected by this typo. So if it is redundant - it probably should be removed. >Fix: change if (i == 0) to if (i == 25) >Release-Note: >Audit-Trail: >Unformatted:
next reply other threads:[~2001-12-21 14:56 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2001-12-21 6:56 Klaus.k.pedersen [this message] 2002-01-04 9:46 Richard Earnshaw 2002-01-04 9:46 Richard Earnshaw 2002-01-22 3:04 pb 2002-01-23 11:16 Klaus Pedersen 2002-01-24 2:30 rearnsha 2002-03-15 9:18 rearnsha
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