http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49543
--- Comment #5 from Alexander Carmeli
2011-06-27 20:15:37 UTC ---
That's a good point. I removed the const and g++ fails as well.
Therefore, the bug is in the C++ compiler too.
Consts can be promoted as well. Why promote the non-const expressio
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49543
--- Comment #3 from Alexander Carmeli
2011-06-27 18:40:25 UTC ---
Andrew,
You are correct about the standard not defining the result.
Similar behavior was fixed before (see bug 36300
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36300)
I think t
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49543
--- Comment #1 from Alexander Carmeli
2011-06-27 12:36:20 UTC ---
Created attachment 24607
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24607
Assembly code demonstrating incorrect cltq instruction placement
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49543
Summary: Cast move causes incorrect code and numerical results
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: middle-end
Assi
--- Comment #6 from acarmeli at mathworks dot com 2008-05-28 12:37 ---
Richard,
This is the root cause of the problem: I agree with you that an overflow can
occur and there is no way to guarantee the resulting value.
However, it must be a 32-bit value.
It cannot all of a sudden
--- Comment #14 from acarmeli at mathworks dot com 2008-05-28 12:25 ---
You are correct. But step 6 did not reveal that, and provided a correct s64
result. This result should have been carried over to step 7 to lead to a
correct result.
Otherwise, it will not be possible to get the
--- Comment #11 from acarmeli at mathworks dot com 2008-05-28 11:30 ---
I believe there is still a violation of the C standard when expression folding
folds this.
The attached file demonstrates this.
In step 7, we perform 4*3 in 32-bit and expect to get a 12 in a 64-bit.
It should be
--- Comment #10 from acarmeli at mathworks dot com 2008-05-28 11:21 ---
Created an attachment (id=15691)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15691&action=view)
Steps to reach numerically incorrect/impossible result
Compile: gcc bad_numeric.c
Builds up expressio
--- Comment #1 from acarmeli at mathworks dot com 2008-05-22 14:43 ---
Created an attachment (id=15671)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15671&action=view)
Wrong result if expression is inlined
At the bottom of the file there are:
- Instructions on how to
gnu dot org
ReportedBy: acarmeli at mathworks dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36300
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