Re: optimization/8541: Alpha architecture: Wrong code with -O1 and higher (Regression from 2.95)

[Christoph Ludwig <cludwig@cdc.informatik.tu-darmstadt.de>]

The following reply was made to PR optimization/8541; it has been noted by GNATS.

From: Christoph Ludwig <cludwig@cdc.informatik.tu-darmstadt.de>
To: Falk Hueffner <falk.hueffner@student.uni-tuebingen.de>
Cc: gcc-gnats@gcc.gnu.org
Subject: Re: optimization/8541: Alpha architecture: Wrong code with -O1 and higher (Regression from 2.95)
Date: Tue, 12 Nov 2002 14:00:57 +0100

 On Tue, Nov 12, 2002 at 01:01:25PM +0100, Falk Hueffner wrote:
 > 
 >   // a1 * RADIX + a0 = quot * b + RV
 >   inline udigit
 >   divide (udigit & quot, udigit a1, udigit a0, udigit b)
 >   {
 >     udigit a[2] = { a0, a1 };
 >     return mpn_divrem_1(&quot, 0, a, 2, b);
 >   }
 > 
 > [...]
 >     udigit accum_l, accum_h, temp_h, temp_l, carry;
 > [...]
 >       accum_h = divide(carry, 0, accum_h, pp);
 > 
 > It seems to me that mpn_divrem_1 might write 2 words to carry,
 > clobbering random stack memory. Are you sure it doesn't?
 
 Oops! I added a few further tests, and it seems, you are right.
 I was looking for the error in the wrong corner of the library. :-(
 
 My apologies for the unnecessary noise on the gcc bug mailing
 list. How do I withdraw a bug report or request it to be closed?
 
 Regards
 
 Christoph
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