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* [Bug c/54951] New: Incorrect pointer handling on 32K boundary
@ 2012-10-17 14:37 m.galante at centrosistemi dot it
2012-10-18 2:15 ` [Bug target/54951] " dj at redhat dot com
2012-12-09 2:12 ` pinskia at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: m.galante at centrosistemi dot it @ 2012-10-17 14:37 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54951
Bug #: 54951
Summary: Incorrect pointer handling on 32K boundary
Classification: Unclassified
Product: gcc
Version: 4.7.2
Status: UNCONFIRMED
Severity: critical
Priority: P3
Component: c
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: m.galante@centrosistemi.it
Created attachment 28460
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28460
Simple test case to reproduce the bug
m32c-elf-gcc (GCC) 4.7.2 hosted on Windows XP.
The attached "run.bat" batch compiles and runs a simple program that adds a
constant value (COUNT) to a pointer (0x10000) and prints the result.
The first result (a) is calculated by adding COUNT to the pointer, the second
result (b) is calculated by incrementing the pointer COUNT times.
When COUNT is 0x7FFF the result is correct for both a and b (0x17FFF).
When COUNT is 0x8000 the result is incorrect for a (0x8000) but correct for b
(0x18000).
When COUNT is 0xFFFF the result is incorrect for a (0xFFFF) but correct for b
(0x1FFFF) when compiled with -O0, and incorrect for both a and b (0xFFFF) when
compiled with -O1.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/54951] Incorrect pointer handling on 32K boundary
2012-10-17 14:37 [Bug c/54951] New: Incorrect pointer handling on 32K boundary m.galante at centrosistemi dot it
@ 2012-10-18 2:15 ` dj at redhat dot com
2012-12-09 2:12 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: dj at redhat dot com @ 2012-10-18 2:15 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54951
DJ Delorie <dj at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |dj at redhat dot com
--- Comment #1 from DJ Delorie <dj at redhat dot com> 2012-10-18 02:14:48 UTC ---
This is, unfortunately, the expected behavior for m32c. The m32c has 20-bit
pointers but 16-bit math operations, so size_t is 16 bits resulting in many
pointer math operations being truncated to 16 bits. So, a COUNT of 0xFFFF may
be interpreted as -1 instead of 65536, etc.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/54951] Incorrect pointer handling on 32K boundary
2012-10-17 14:37 [Bug c/54951] New: Incorrect pointer handling on 32K boundary m.galante at centrosistemi dot it
2012-10-18 2:15 ` [Bug target/54951] " dj at redhat dot com
@ 2012-12-09 2:12 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2012-12-09 2:12 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54951
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|critical |normal
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2012-12-09 2:12 UTC | newest]
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2012-10-17 14:37 [Bug c/54951] New: Incorrect pointer handling on 32K boundary m.galante at centrosistemi dot it
2012-10-18 2:15 ` [Bug target/54951] " dj at redhat dot com
2012-12-09 2:12 ` pinskia at gcc dot gnu.org
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