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From: David Mosberger <davidm@hpl.hp.com> To: gcc-gnats@gcc.gnu.org Cc: davidm@hpl.hp.com Subject: c/5420: bad code generated with gcc3.1/ia64 Date: Thu, 17 Jan 2002 18:56:00 -0000 [thread overview] Message-ID: <200201180252.g0I2qOh29734@wailua.hpl.hp.com> (raw) >Number: 5420 >Category: c >Synopsis: bad code generated with gcc3.1/ia64 >Confidential: no >Severity: serious >Priority: medium >Responsible: unassigned >State: open >Class: wrong-code >Submitter-Id: net >Arrival-Date: Thu Jan 17 18:56:00 PST 2002 >Closed-Date: >Last-Modified: >Originator: David Mosberger >Release: 3.1 20020117 (experimental) >Organization: HP Labs >Environment: System: Linux wailua.hpl.hp.com 2.4.17 #2 SMP Thu Jan 17 13:53:26 PST 2002 ia64 unknown Architecture: ia64 ia64, Linux, ia64 host: ia64-hp-linux-gnu build: ia64-hp-linux-gnu target: ia64-hp-linux-gnu configured with: ../gcc/configure --prefix=/opt/gcc3.1 --host=ia64-hp-linux : (reconfigured) >Description: On the attached test program, gcc generates bad code with an optimization level of -O2. -O works fine. >How-To-Repeat: $ gcc -O2 test.c $ ./a.out ./a.out dev=1220 dev=1220 This is wrong. The correct output should be: dev=800 dev=810 >Fix: The workaround is to drop the optimization level to -O. <-- test.c --><-- test.c --><-- test.c --><-- test.c --> typedef struct { unsigned short value; } kdev_t; #define mk_kdev(major, minor) ((kdev_t) { (((major) << 8) + (minor)) } ) #define SD_MAJOR(i) (!(i) ? 8 : 65-1+(i)) #define MKDEV_SD_PARTITION(i) mk_kdev(SD_MAJOR((i) >> 8), (i)) int main (int argc, char **argv) { int idx; for (idx = 0; idx < 2; ++idx) printf ("dev=%x\n", MKDEV_SD_PARTITION((idx) << 4).value); } >Release-Note: >Audit-Trail: >Unformatted:
next reply other threads:[~2002-01-18 2:56 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2002-01-17 18:56 David Mosberger [this message] 2002-02-06 5:25 jakub 2002-02-22 20:38 rodrigc
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