* [Bug target/20102] Incorrect floating point code generated when assigning to "packed" structure
2005-02-20 17:21 [Bug c/20102] New: Incorrect floating point code generated when assigning to "packed" structure oakad at yahoo dot com
@ 2005-02-20 18:50 ` pinskia at gcc dot gnu dot org
2005-02-20 19:44 ` pinskia at gcc dot gnu dot org
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From: pinskia at gcc dot gnu dot org @ 2005-02-20 18:50 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-02-20 13:34 -------
lfs f2, 395(r1) //p.v3 - incorrect misaligned load (throws exception)
Yes but the OS/kernel is supposed to handle the exception as any other OS on PPC would.
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* [Bug target/20102] Incorrect floating point code generated when assigning to "packed" structure
2005-02-20 17:21 [Bug c/20102] New: Incorrect floating point code generated when assigning to "packed" structure oakad at yahoo dot com
2005-02-20 18:50 ` [Bug target/20102] " pinskia at gcc dot gnu dot org
@ 2005-02-20 19:44 ` pinskia at gcc dot gnu dot org
2005-02-21 10:47 ` oakad at yahoo dot com
` (7 subsequent siblings)
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From: pinskia at gcc dot gnu dot org @ 2005-02-20 19:44 UTC (permalink / raw)
To: gcc-bugs
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* [Bug target/20102] Incorrect floating point code generated when assigning to "packed" structure
2005-02-20 17:21 [Bug c/20102] New: Incorrect floating point code generated when assigning to "packed" structure oakad at yahoo dot com
2005-02-20 18:50 ` [Bug target/20102] " pinskia at gcc dot gnu dot org
2005-02-20 19:44 ` pinskia at gcc dot gnu dot org
@ 2005-02-21 10:47 ` oakad at yahoo dot com
2005-02-21 10:57 ` pinskia at gcc dot gnu dot org
` (6 subsequent siblings)
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From: oakad at yahoo dot com @ 2005-02-21 10:47 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From oakad at yahoo dot com 2005-02-20 21:16 -------
Three points:
1. Handling of this case shall be consistent. When dealing with global
variables compiler emits byte by byte copy code. With automatic variables,
compiler emits single lfs/stfs.
2. I believe that PPC architecture explicitly forbids unaligned floating loads
and stores.
3. The whole point in my code sniplet is to accelerate some communication
protocol. Exception handler invocation is obviously out of question.
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* [Bug target/20102] Incorrect floating point code generated when assigning to "packed" structure
2005-02-20 17:21 [Bug c/20102] New: Incorrect floating point code generated when assigning to "packed" structure oakad at yahoo dot com
` (2 preceding siblings ...)
2005-02-21 10:47 ` oakad at yahoo dot com
@ 2005-02-21 10:57 ` pinskia at gcc dot gnu dot org
2005-02-21 19:50 ` oakad at yahoo dot com
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From: pinskia at gcc dot gnu dot org @ 2005-02-21 10:57 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-02-20 21:24 -------
(In reply to comment #2)
> 2. I believe that PPC architecture explicitly forbids unaligned floating loads
> and stores.
Wrong. The PPC architecutures says that it will most likely to produce an unalignment exception but
IIRC all unalignment exceptions have to be handled.
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* [Bug target/20102] Incorrect floating point code generated when assigning to "packed" structure
2005-02-20 17:21 [Bug c/20102] New: Incorrect floating point code generated when assigning to "packed" structure oakad at yahoo dot com
` (3 preceding siblings ...)
2005-02-21 10:57 ` pinskia at gcc dot gnu dot org
@ 2005-02-21 19:50 ` oakad at yahoo dot com
2005-08-23 1:31 ` amodra at bigpond dot net dot au
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From: oakad at yahoo dot com @ 2005-02-21 19:50 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From oakad at yahoo dot com 2005-02-21 10:39 -------
I would like to notice that the issue only arises with packed structs, which
are mostly found in places where exception handling is undesirable. Non-packed
structs are always aligned anyway.
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* [Bug target/20102] Incorrect floating point code generated when assigning to "packed" structure
2005-02-20 17:21 [Bug c/20102] New: Incorrect floating point code generated when assigning to "packed" structure oakad at yahoo dot com
` (4 preceding siblings ...)
2005-02-21 19:50 ` oakad at yahoo dot com
@ 2005-08-23 1:31 ` amodra at bigpond dot net dot au
2005-08-23 10:40 ` oakad at yahoo dot com
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From: amodra at bigpond dot net dot au @ 2005-08-23 1:31 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From amodra at bigpond dot net dot au 2005-08-23 01:20 -------
Using -mstrict-align will avoid the unaligned accesses, I haven't looked into
why there is a difference between the global and auto var..
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* [Bug target/20102] Incorrect floating point code generated when assigning to "packed" structure
2005-02-20 17:21 [Bug c/20102] New: Incorrect floating point code generated when assigning to "packed" structure oakad at yahoo dot com
` (5 preceding siblings ...)
2005-08-23 1:31 ` amodra at bigpond dot net dot au
@ 2005-08-23 10:40 ` oakad at yahoo dot com
2005-08-24 1:51 ` amodra at bigpond dot net dot au
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From: oakad at yahoo dot com @ 2005-08-23 10:40 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From oakad at yahoo dot com 2005-08-23 10:27 -------
I was dealing with packed structs in this case. Are you sure that
-mstrict-align will not break packing? And I'm talking of both inter- and
intra-struct packing, as in packed array of packed structs.
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* [Bug target/20102] Incorrect floating point code generated when assigning to "packed" structure
2005-02-20 17:21 [Bug c/20102] New: Incorrect floating point code generated when assigning to "packed" structure oakad at yahoo dot com
` (6 preceding siblings ...)
2005-08-23 10:40 ` oakad at yahoo dot com
@ 2005-08-24 1:51 ` amodra at bigpond dot net dot au
2005-08-24 6:47 ` amodra at bigpond dot net dot au
2005-08-25 5:24 ` pinskia at gcc dot gnu dot org
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From: amodra at bigpond dot net dot au @ 2005-08-24 1:51 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From amodra at bigpond dot net dot au 2005-08-24 00:44 -------
-mstrict-align should not affect aggregate layout.
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* [Bug target/20102] Incorrect floating point code generated when assigning to "packed" structure
2005-02-20 17:21 [Bug c/20102] New: Incorrect floating point code generated when assigning to "packed" structure oakad at yahoo dot com
` (7 preceding siblings ...)
2005-08-24 1:51 ` amodra at bigpond dot net dot au
@ 2005-08-24 6:47 ` amodra at bigpond dot net dot au
2005-08-25 5:24 ` pinskia at gcc dot gnu dot org
9 siblings, 0 replies; 11+ messages in thread
From: amodra at bigpond dot net dot au @ 2005-08-24 6:47 UTC (permalink / raw)
To: gcc-bugs
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* [Bug target/20102] Incorrect floating point code generated when assigning to "packed" structure
2005-02-20 17:21 [Bug c/20102] New: Incorrect floating point code generated when assigning to "packed" structure oakad at yahoo dot com
` (8 preceding siblings ...)
2005-08-24 6:47 ` amodra at bigpond dot net dot au
@ 2005-08-25 5:24 ` pinskia at gcc dot gnu dot org
9 siblings, 0 replies; 11+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-08-25 5:24 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-08-25 03:26 -------
-mstrict-align means don't produce loads which have unaligned loads.
--
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