[RTEMS Project] #3767: Should all PPC BSPs build with -mstrict-align?
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trac at rtems.org
Thu Jul 18 19:00:23 UTC 2019
#3767: Should all PPC BSPs build with -mstrict-align?
--------------------------------+---------------------
Reporter: Michael Davidsaver | Owner: (none)
Type: defect | Status: new
Priority: normal | Milestone: 5.1
Component: arch/powerpc | Version: 5
Severity: normal | Resolution:
Keywords: | Blocked By:
Blocking: |
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Comment (by Michael Davidsaver):
I forgot to link to our analysis https://github.com/epics-base/epics-
base/issues/29
The effect can be seen by compiling:
{{{
#include <string.h>
void test_double(char *dest, double src)
{
memcpy(dest, &src, sizeof(src));
}
void test_int64(char *dest, long long src)
{
memcpy(dest, &src, sizeof(src));
}
}}}
eg.
{{{
powerpc-rtems4.10-gcc -mcpu=7400 -g -O3 -o copyme.o -c copyme.c &&
powerpc-rtems4.10-objdump -dS copyme.o
}}}
Then add -mstrict-align and see the difference.
I should also note that -mcpu=8540 (mvme3100) doesn't seem to need
-mstrict-align. Not sure if this is implied for this target.
--
Ticket URL: <http://devel.rtems.org/ticket/3767#comment:3>
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