https://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
--- Comment #33 from Vincent Lefèvre ---
(In reply to Niels Möller from comment #32)
> 4. I also wonder what happens if, for some reason, a constant invalid shift
> count is passed through all the way to code generation? Most architectures
> would
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
--- Comment #32 from Niels Möller ---
I've checked out the gcc sources, to see if I can understand how to move the
warning around. The example input I'm looking at now is
unsigned
shift_dead (unsigned x)
{
if (0)
return x >> 32;
else
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
Niels Möller changed:
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CC||nisse at lysator dot liu.se
--- Comment #3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
--- Comment #30 from joseph at codesourcery dot com ---
At the point where the then block starts being processed (and, thus,
warnings may be given) it wouldn't be known whether there are labels in
there or not; cf. the discussion in bug 68193 re
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
Eric Gallager changed:
What|Removed |Added
CC||joseph at codesourcery dot com
--- Commen
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
Andrew Pinski changed:
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CC||joshudson at gmail dot com
--- Comment #2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
Eric Gallager changed:
What|Removed |Added
Status|SUSPENDED |NEW
CC|
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
--- Comment #26 from Martin Sebor ---
*** Bug 79479 has been marked as a duplicate of this bug. ***
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
--- Comment #25 from Paul Eggert ---
I'd like this bug to be changed from SUSPENDED to CONFIRMED, given that it's
continuing to be a problem (e.g., bug#79479).
Also, I'd like to suggest what I hope is a simple fix. In 2006 Joseph wrote
"skip_eval
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
Andrew Pinski changed:
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CC||brooks at gcc dot gnu.org
--- Comment #24
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=4210
Andrew Pinski changed:
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CC||xzfcpw+gcc at gmail dot com
--- Comment #2
--- Comment #22 from manu at gcc dot gnu dot org 2010-07-06 17:28 ---
The way Clang gets this right is to perform some very-fast bitmap common
constant propagation in the FE. I personally think this would be helpful if
implemented correctly, even if it slows down the FE a little. But do
--- Comment #21 from manu at gcc dot gnu dot org 2010-07-06 17:24 ---
*** Bug 44842 has been marked as a duplicate of this bug. ***
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manu at gcc dot gnu dot org changed:
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--- Comment #20 from pinskia at gcc dot gnu dot org 2009-05-12 14:49
---
*** Bug 40114 has been marked as a duplicate of this bug. ***
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pinskia at gcc dot gnu dot org changed:
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--- Comment #19 from pinskia at gcc dot gnu dot org 2007-01-01 19:03
---
*** Bug 30343 has been marked as a duplicate of this bug. ***
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pinskia at gcc dot gnu dot org changed:
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--- Comment #18 from pinskia at gcc dot gnu dot org 2006-06-20 19:05
---
*** Bug 28106 has been marked as a duplicate of this bug. ***
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pinskia at gcc dot gnu dot org changed:
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--- Comment #17 from mattias at virtutech dot se 2006-03-02 09:22 ---
We have resorted to case-by-case workarounds, usually a cast which would have
been an identity operation had the condition been true. That is,
if (sizeof x == 8)
return x << 32 | x;
would have its second line
--- Comment #16 from bangerth at dealii dot org 2006-03-01 23:25 ---
> It does; I've used it to eliminate all these warnings in glibc's soft-fp
> code. Use statement expressions, i.e. surround the whole if body with ({
> }).
Ugh. Do we really want to advocate serious code obfuscatio
--- Comment #15 from joseph at codesourcery dot com 2006-03-01 23:22
---
Subject: Re: should not warning with dead code
On Wed, 1 Mar 2006, bangerth at dealii dot org wrote:
> c) doesn't work with code where the code guarded by the if(0) is more
>than a single statement.
It does
--- Comment #14 from bangerth at dealii dot org 2006-03-01 23:05 ---
But that's
a) clearly a kludge,
b) may not help in the future if our optimizers become more elaborate
c) doesn't work with code where the code guarded by the if(0) is more
than a single statement.
It would definitely
--- Comment #13 from joseph at codesourcery dot com 2006-03-01 23:01
---
Subject: Re: should not warning with dead code
A workaround is to use ? : and statement expressions instead of "if".
This way, the front-end setting of skip_evaluation disables these
warnings. (skip_evaluatio
--- Comment #12 from pinskia at gcc dot gnu dot org 2006-03-01 19:02
---
*** Bug 26516 has been marked as a duplicate of this bug. ***
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pinskia at gcc dot gnu dot org changed:
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