[Bug middle-end/49699] Aligned load on unaligned address

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49699

Andrew Pinski  changed:

   What|Removed |Added

   Last reconfirmed|2011-07-11 09:24:48 |2021-9-1
   Keywords||wrong-code

--- Comment #6 from Andrew Pinski  ---
What is interesting is clang gets it wrong too.

[Bug middle-end/49699] Aligned load on unaligned address

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49699

--- Comment #4 from H.J. Lu hjl.tools at gmail dot com 2011-07-12 14:05:08 
UTC ---
(In reply to comment #2)
 
 Very old issue.  The aligned attribute cannot be reliably used to decrease
 alignment.

Can we issue a warning for things like this?

[Bug middle-end/49699] Aligned load on unaligned address

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49699

--- Comment #5 from H.J. Lu hjl.tools at gmail dot com 2011-07-12 14:06:08 
UTC ---
(In reply to comment #3)
 I think you'd need to make it packed as well, but then it depends on gcc
 version which alignment the aggregate actually has.

This issue came from

http://sourceware.org/bugzilla/show_bug.cgi?id=12872

[Bug middle-end/49699] Aligned load on unaligned address

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49699

Richard Guenther rguenth at gcc dot gnu.org changed:

   What|Removed |Added

 Status|UNCONFIRMED |NEW
   Last reconfirmed||2011.07.11 09:24:48
 Ever Confirmed|0   |1

--- Comment #2 from Richard Guenther rguenth at gcc dot gnu.org 2011-07-11 
09:24:48 UTC ---
Confirmed.

The issue is that alignment info in FIELD_DECLs is broken.  I think that
in this case get_inner_reference simply chooses to tell the caller that
V4SF mode is to be used for the access and that's all it gets.

Very old issue.  The aligned attribute cannot be reliably used to decrease
alignment.

[Bug middle-end/49699] Aligned load on unaligned address

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49699

Jakub Jelinek jakub at gcc dot gnu.org changed:

   What|Removed |Added

 CC||jakub at gcc dot gnu.org

--- Comment #3 from Jakub Jelinek jakub at gcc dot gnu.org 2011-07-11 
09:47:27 UTC ---
I think you'd need to make it packed as well, but then it depends on gcc
version which alignment the aggregate actually has.

[Bug middle-end/49699] Aligned load on unaligned address

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49699

H.J. Lu hjl.tools at gmail dot com changed:

   What|Removed |Added

  Component|target  |middle-end

--- Comment #1 from H.J. Lu hjl.tools at gmail dot com 2011-07-11 03:13:16 
UTC ---
It looks like a middle-end bug.