Vladimir Yanovsky - [PATCH] Modulo-scheduling improvements. Missed initialization. (original) (raw)

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• From: "Vladimir Yanovsky"
• To: gcc-patches at gcc dot gnu dot org
• Cc: vmakarov at redhat dot com, "Mircea Namolaru" , "Ayal Zaks" , "Vladimir Yanovsky"
• Date: Thu, 22 Feb 2007 08:10:48 -0500
• Subject: [PATCH] Modulo-scheduling improvements. Missed initialization.
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Hi all, I've encountered a bootstrap comparison failure building a 64bit mainline with "-fmodulo-sched" enabled on PowerPC 970 (OpenSuse 10.2) together with the "Modulo-scheduling improvements patches" sent for review on January 17: http://gcc.gnu.org/ml/gcc-patches/2007-01/msg01468.html http://gcc.gnu.org/ml/gcc-patches/2007-01/msg01470.html [Previously successfully tested the patches on SPU, x86 and PowerPC 970 (but with SLES 9 Linux).]

The reason for the failure was the missing initialization of sbitmap scc_nodes. This could cause in some cases the size of the possible schedule to be estimated incorrectly resulting in a loop to be not SMSed in one stage during the bootstrap and SMSed in another resulting in a comparison failure. Since this bug is not related to the scheduling itself, it couldn't result in an incorrect code. This bug is only exposed together with the "Modulo-scheduling improvements patches" mentioned above(any comments on them? thanks.) but can be applied independently.

Bootstrapped and regtested with "-fmodulo-sched" enabled on powerpc64-suse-linux.

ok for mainline?:ADDPATCH modulo-sched:

thanks, Vladimir

Index: ddg.c

*** ddg.c (revision 121234) --- ddg.c (working copy) *************** create_ddg_all_sccs (ddg_ptr g) *** 866,871 **** --- 868,874 ---- if (backarc->aux.count == IN_SCC) continue;

•   sbitmap_zero (scc_nodes);
   sbitmap_zero (from);
   sbitmap_zero (to);
   SET_BIT (from, dest->cuid);

Changelog: 2007-02-22 Vladimir Yanovsky yanov@il.ibm.com * ddg.c (create_ddg_all_sccs): fix missed initialization of scc_nodes

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    * From: Richard Guenther