#364: ptr_alignment 8 not honored, sparc 64bit broken
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Reporter: rurban | Owner:
Type: bug | Status: new
Priority: blocker | Milestone: 1.0
Component: core | Version: trunk
Severity: release | Keywords:
Lang: | Patch:
Platform: other |
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A strict 64bit cpu with a ptr_alignment 8 will break when reading frozen
pmc's because our alignment when writing our reading bytecode is
16/ptrsize and not 16.
Any 64bit big-endian cpu with strict alignment is broken without
'''-xmemalign=2i -xmemalign=2f -xmemalign=2s''' (the immediate workaround)
The goal should be to allow fast aligned code and to align as advertised
to 16, not 2 on 64-bit.
{{{
* First we should align to the foreign pbc ptrsize, not to the native
ptrsize.
* /sizeof (opcode_t) => /header->wordsize
* Then we should get rid of the "/" at all, and align absolutely to 16,
and not
* to 16/4 = 4 or 16/8 = 2.
* It is also broken in strict alignment 64bit CPU's. See
http://nopaste.snit.ch/15684
* 0x100000dec is an illegal alignment.
*/
#define ROUND_16(val) (((val) & 0xf) ? 16 - ((val) & 0xf) : 0)
#define ALIGN_16(st, cursor) \
(cursor) += ROUND_16((const char *)(cursor) - (const char
*)(st))/sizeof (opcode_t)
}}}
This requires a rewrite of all pbc writer alignment code
(no macro used, bad), and also of the pbc reader code which
is much simplier to fix.
{{{
t...@1 (l...@1) stopped in PF_fetch_integer at line 1076 in file "pf_items.c"
1076 ASSERT_ARGS(PF_fetch_integer)
(dbx) step
t...@1 (l...@1) stopped in PF_fetch_integer at line 1078 in file "pf_items.c"
1078 if (!pf || pf->fetch_iv == NULL)
(dbx) print *(*stream)
**stream = 4
(dbx) step
t...@1 (l...@1) stopped in PF_fetch_integer at line 1079 in file "pf_items.c"
1079 return *(*stream)++;
(dbx) print *(*stream)
**stream = 4
(dbx) step
t...@1 (l...@1) signal BUS (invalid address alignment) in PF_fetch_integer at
line 1079 in file "pf_items.c"
1079 return *(*stream)++;
(dbx) print *(*stream)
**stream = 35
(dbx) print *stream
*stream = 0x100000dec
}}}
'''0x100000dec''' is not properly aligned. It must be '''0x100000df0'''.
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/364>
Parrot <https://trac.parrot.org/parrot/>
Parrot Development
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