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make sure all programs are 8-byte aligned

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* libguile/objcodes.c (OBJCODE_COOKIE): Bump objcode cookie, as we added
  to struct scm_objcode.
* libguile/objcodes.h (struct scm_objcode): Add a uint32 after metalen
  and before base, so that if the structure has 8-byte alignment, base
  will have 8-byte alignment too. (Before, base was 12 bytes from the
  start of the structure, now it's 16 bytes.)

* libguile/vm-engine.h (ASSERT_ALIGNED_PROCEDURE): Add a check that can
  be turned on with VM_ENABLE_PARANOID_ASSERTIONS.
  (CACHE_PROGRAM): Call ASSERT_ALIGNED_PROCEDURE.

* libguile/vm-i-system.c (long-local-ref): Add a missing semicolon.

* libguile/vm.c (really_make_boot_program): Rework to operate directly
  on a malloc'd buffer, so that the program will be 8-byte aligned.

* module/language/assembly.scm (*program-header-len*): Add another 4 for
  the padding.
  (object->assembly): Fix case in which we would return (make-int8 0)
  instead of (make-int8:0). This would throw off compile-assembly.scm's
  use of addr+.

* module/language/assembly/compile-bytecode.scm (write-bytecode): Write
  out the padding int.

* module/language/assembly/decompile-bytecode.scm (decode-load-program):
  And pop off the padding int too.

* module/language/glil/compile-assembly.scm (glil->assembly): Don't pack
  the assembly, assume that assembly.scm has done it for us. If a
  program has a meta, pad out the program so that meta will be aligned.

* test-suite/tests/asm-to-bytecode.test: Adapt to expect programs to
  have the extra 4-byte padding int.
This commit is contained in:
Andy Wingo 2009-07-26 12:56:11 +02:00
parent 9efc2d1404
commit 28b119ee3d
10 changed files with 52 additions and 44 deletions
Download patch file Download diff file Expand all files Collapse all files

2
libguile/objcodes.c
View file

@ -50,7 +50,7 @@
/* The objcode magic header. */
#define OBJCODE_COOKIE \
"GOOF-0.7-" OBJCODE_ENDIANNESS "-" OBJCODE_WORD_SIZE "---"
"GOOF-0.8-" OBJCODE_ENDIANNESS "-" OBJCODE_WORD_SIZE "---"
/* The length of the header must be a multiple of 8 bytes. */
verify (((sizeof (OBJCODE_COOKIE) - 1) & 7) == 0);

1
libguile/objcodes.h
View file

@ -29,6 +29,7 @@ struct scm_objcode {
scm_t_uint32 len; /* the maximum index of base[] */
scm_t_uint32 metalen; /* well, i lie. this many bytes at the end of
base[] for metadata */
scm_t_uint32 unused; /* pad so that `base' is 8-byte aligned */
scm_t_uint8 base[0];
};

4
libguile/vm-engine.h
View file

@ -130,11 +130,14 @@
#ifdef VM_ENABLE_PARANOID_ASSERTIONS
#define CHECK_IP() \
do { if (ip < bp->base || ip - bp->base > bp->len) abort (); } while (0)
#define ASSERT_ALIGNED_PROCEDURE() \
do { if ((scm_t_bits)bp % 8) abort (); } while (0)
#define ASSERT_BOUND(x) \
do { if ((x) == SCM_UNDEFINED) { SYNC_REGISTER (); abort(); } \
} while (0)
#else
#define CHECK_IP()
#define ASSERT_ALIGNED_PROCEDURE()
#define ASSERT_BOUND(x)
#endif
@ -143,6 +146,7 @@
{ \
if (bp != SCM_PROGRAM_DATA (program)) { \
bp = SCM_PROGRAM_DATA (program); \
ASSERT_ALIGNED_PROCEDURE (); \
if (SCM_I_IS_VECTOR (SCM_PROGRAM_OBJTABLE (program))) { \
objects = SCM_I_VECTOR_WELTS (SCM_PROGRAM_OBJTABLE (program)); \
object_count = SCM_I_VECTOR_LENGTH (SCM_PROGRAM_OBJTABLE (program)); \

2
libguile/vm-i-system.c
View file

@ -283,7 +283,7 @@ VM_DEFINE_INSTRUCTION (26, long_local_ref, "long-local-ref", 2, 0, 1)
unsigned int i = FETCH ();
i <<= 8;
i += FETCH ();
PUSH (LOCAL_REF (i))
PUSH (LOCAL_REF (i));
ASSERT_BOUND (*sp);
NEXT;
}

47
libguile/vm.c
View file

@ -220,44 +220,33 @@ static SCM sym_vm_run;
static SCM sym_vm_error;
static SCM sym_debug;
static SCM make_u8vector (const scm_t_uint8 *bytes, size_t len)
{
scm_t_uint8 *new_bytes = scm_gc_malloc (len, "make-u8vector");
memcpy (new_bytes, bytes, len);
return scm_take_u8vector (new_bytes, len);
}
/* Dummy structure to guarantee 32-bit alignment. */
struct t_32bit_aligned
{
scm_t_int32 dummy;
scm_t_uint8 bytes[18];
};
static SCM
really_make_boot_program (long nargs)
{
SCM u8vec;
struct t_32bit_aligned bytes =
{
.dummy = 0,
.bytes = { 0, 0, 0, 0,
0, 0, 0, 0,
0, 0, 0, 0,
scm_op_mv_call, 0, 0, 1,
scm_op_make_int8_1, scm_op_halt }
};
/* Make sure "bytes" is 64-bit aligned. */
scm_t_uint8 text[] = { scm_op_mv_call, 0, 0, 1,
scm_op_make_int8_1,
scm_op_halt };
struct scm_objcode *bp;
SCM ret;
/* Set length in current endianness, no meta. */
((scm_t_uint32 *) bytes.bytes)[1] = 6;
if (SCM_UNLIKELY (nargs > 255 || nargs < 0))
abort ();
bytes.bytes[13] = (scm_byte_t) nargs;
text[1] = (scm_t_uint8)nargs;
u8vec = make_u8vector (bytes.bytes, sizeof (bytes.bytes));
bp = scm_gc_malloc (sizeof (struct scm_objcode) + sizeof (text),
"make-u8vector");
memcpy (bp->base, text, sizeof (text));
bp->nargs = 0;
bp->nrest = 0;
bp->nlocs = 0;
bp->len = sizeof(text);
bp->metalen = 0;
bp->unused = 0;
u8vec = scm_take_u8vector ((scm_t_uint8*)bp,
sizeof (struct scm_objcode) + sizeof (text));
ret = scm_make_program (scm_bytecode_to_objcode (u8vec),
SCM_BOOL_F, SCM_BOOL_F);
SCM_SET_SMOB_FLAGS (ret, SCM_F_PROGRAM_IS_BOOT);

6
module/language/assembly.scm
View file

@ -28,8 +28,8 @@
assembly-pack assembly-unpack
object->assembly assembly->object))
;; nargs, nrest, nlocs, <unused>, len, metalen
(define *program-header-len* (+ 1 1 1 1 4 4))
;; nargs, nrest, nlocs, len, metalen, padding
(define *program-header-len* (+ 1 1 2 4 4 4))
;; lengths are encoded in 3 bytes
(define *len-len* 3)
@ -109,7 +109,7 @@
((null? x) `(make-eol))
((and (integer? x) (exact? x))
(cond ((and (<= -128 x) (< x 128))
`(make-int8 ,(modulo x 256)))
(assembly-pack `(make-int8 ,(modulo x 256))))
((and (<= -32768 x) (< x 32768))
(let ((n (if (< x 0) (+ x 65536) x)))
`(make-int16 ,(quotient n 256) ,(modulo n 256))))

1
module/language/assembly/compile-bytecode.scm
View file

@ -102,6 +102,7 @@
(write-uint16 nlocs)
(write-uint32 length)
(write-uint32 (if meta (1- (byte-length meta)) 0))
(write-uint32 0) ; padding
(letrec ((i 0)
(write (lambda (x) (set! i (1+ i)) (write-byte x)))
(get-addr (lambda () i)))

1
module/language/assembly/decompile-bytecode.scm
View file

@ -57,6 +57,7 @@
(len (+ a (ash b 8) (ash c 16) (ash d 24)))
(metalen (+ e (ash f 8) (ash g 16) (ash h 24)))
(totlen (+ len metalen))
(pad0 (pop)) (pad1 (pop)) (pad2 (pop)) (pad3 (pop))
(labels '())
(i 0))
(define (ensure-label rel1 rel2)

17
module/language/glil/compile-assembly.scm
View file

@ -137,9 +137,9 @@
(define (glil->assembly glil toplevel? bindings
source-alist label-alist object-alist addr)
(define (emit-code x)
(values (map assembly-pack x) bindings source-alist label-alist object-alist))
(values x bindings source-alist label-alist object-alist))
(define (emit-code/object x object-alist)
(values (map assembly-pack x) bindings source-alist label-alist object-alist))
(values x bindings source-alist label-alist object-alist))
(record-case glil
((<glil-program> nargs nrest nlocs meta body)
@ -164,10 +164,15 @@
(receive (code bindings sources labels objects len)
(process-body)
(let ((prog `(load-program ,nargs ,nrest ,nlocs ,labels
,len
,(make-meta bindings sources meta)
. ,code)))
(let* ((meta (make-meta bindings sources meta))
(meta-pad (if meta (modulo (- 8 (modulo len 8)) 8) 0))
(prog `(load-program ,nargs ,nrest ,nlocs ,labels
,(+ len meta-pad)
,meta
,@code
,@(if meta
(make-list meta-pad '(nop))
'()))))
(cond
(toplevel?
;; toplevel bytecode isn't loaded by the vm, no way to do

15
test-suite/tests/asm-to-bytecode.test
View file

@ -95,22 +95,29 @@
3 2 (uint16 1) ;; nargs, nrest, nlocs
(uint32 3) ;; len
(uint32 0) ;; metalen
(uint32 0) ;; padding
make-int8 3
return))
(comp-test '(load-program 3 2 1 () 3
;; the nops are to pad meta to an 8-byte alignment. not strictly
;; necessary for this test, but representative of the common case.
(comp-test '(load-program 3 2 1 () 8
(load-program 3 2 1 () 3
#f
(make-int8 3) (return))
(make-int8 3) (return))
(make-int8 3) (return)
(nop) (nop) (nop) (nop) (nop))
#(load-program
3 2 (uint16 1) ;; nargs, nrest, nlocs
(uint32 3) ;; len
(uint32 15) ;; metalen
(uint32 8) ;; len
(uint32 19) ;; metalen
(uint32 0) ;; padding
make-int8 3
return
nop nop nop nop nop
3 2 (uint16 1) ;; nargs, nrest, nlocs
(uint32 3) ;; len
(uint32 0) ;; metalen
(uint32 0) ;; padding
make-int8 3
return))))