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

This is the mail archive of the gcc-patches@gcc.gnu.orgmailing list for the GCC project.

• From: "Vladimir Yanovsky"
• To: "Richard Guenther"
• Cc: gcc-patches at gcc dot gnu dot org, vmakarov at redhat dot com, "Mircea Namolaru" , "Ayal Zaks" , "Vladimir Yanovsky"
• Date: Sat, 24 Feb 2007 10:46:25 -0500
• Subject: Re: [PATCH] Modulo-scheduling improvements. Missed initialization.
• Dkim-signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=HHde4Zt4siWYE790LM+a6apUqK6YQylJ0qjcS2rKNGelFC9BS8rbPwQddSvzCem4nniAs+sXpjwfMZ4ACZScRsSDV+GPrmEZQropC7dryKw1IDK4vq1AnROSPw3nFvgrMNg+zvpVOSH8oRJM0ks/1Id5R81j2y7/8QBDcVmoMzg=
• References: <48ee23ef0702220510r56d7ae84r18c23880f73110f4@mail.gmail.com> <84fc9c000702220517t2553d825nba85f3be95471c92@mail.gmail.com>

Thanks for the suggestion. Bootstrapped and regtested on powerpc64-suse-linux.Vladimir

Index: ddg.c

*** ddg.c (revision 121234) --- ddg.c (working copy) *************** find_nodes_on_paths (sbitmap result, ddg *** 975,981 **** } }

! answer = sbitmap_a_and_b_cg (result, reachable_from, reach_to); sbitmap_free (workset); sbitmap_free (reachable_from); sbitmap_free (reach_to); --- 978,985 ---- } }

! sbitmap_a_and_b (result, reachable_from, reach_to); ! answer = (sbitmap_last_set_bit (result) != -1); sbitmap_free (workset); sbitmap_free (reachable_from); sbitmap_free (reach_to);

On 2/22/07, Richard Guenther richard.guenther@gmail.com wrote:

On 2/22/07, Vladimir Yanovsky volodyan@gmail.com wrote:

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?

It looks like find_nodes_on_paths wants to use sbitmap_a_and_b instead of sbitmap_a_and_b_cg and check if any bit is set on the result (maybe we have a helper for that as well). But maybe it's not worth optimizing this.

Richard.

• Follow-Ups:
  • Re: [PATCH] Modulo-scheduling improvements. Missed initialization.
    * From: Ayal Zaks
• References:
  • [PATCH] Modulo-scheduling improvements. Missed initialization.
    * From: Vladimir Yanovsky
  • Re: [PATCH] Modulo-scheduling improvements. Missed initialization.
    * From: Richard Guenther