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increase range of relative jumps by aligning blocks to 8-byte boundaries

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* libguile/objcodes.c (OBJCODE_COOKIE): Bump again, as our jump offsets
  are now multiplied by 8.

* libguile/vm-i-system.c (BR): Interpret the 16-bit offset as a relative
  jump to the nearest 8-byte-aligned block -- increasing relative jump
  range from +/-32K to +/-240K.
  (mvra): Do the same for the mvra jump.

* libguile/vm.c (really_make_boot_program): Align the mvra.

* module/language/assembly.scm (align-block): New export, for aligning
  blocks.

* module/language/assembly/compile-bytecode.scm (write-bytecode): Emit
  jumps to the nearest 8-byte-aligned block. Effectively our range is 18
  bits in either direction. I would like to do this differently -- have
  long-br and long-br-if, and all the other br instructions go to 8 bits
  only. But the assembler doesn't have an appropriate representation to
  allow me to do this yet, so for now this is what we have.

* module/language/assembly/decompile-bytecode.scm (decode-load-program):
  Decode the 19-bit jumps.
This commit is contained in:
Andy Wingo 2009-07-26 14:01:56 +02:00
parent 28b119ee3d
commit e5dc27b86d
7 changed files with 39 additions and 26 deletions
Download patch file Download diff file Expand all files Collapse all files

20
libguile/vm-i-system.c
View file

@ -426,7 +426,7 @@ VM_DEFINE_INSTRUCTION (34, long_toplevel_set, "long-toplevel-set", 2, 1, 0)
* branch and jump
*/
/* offset must be a signed short!!! */
/* offset must be a signed 16 bit int!!! */
#define FETCH_OFFSET(offset) \
{ \
int h = FETCH (); \
@ -436,10 +436,10 @@ VM_DEFINE_INSTRUCTION (34, long_toplevel_set, "long-toplevel-set", 2, 1, 0)
#define BR(p) \
{ \
signed short offset; \
scm_t_int16 offset; \
FETCH_OFFSET (offset); \
if (p) \
ip += offset; \
ip += ((scm_t_ptrdiff)offset) * 8 - (((unsigned long)ip) % 8); \
NULLSTACK (1); \
DROP (); \
NEXT; \
@ -447,9 +447,9 @@ VM_DEFINE_INSTRUCTION (34, long_toplevel_set, "long-toplevel-set", 2, 1, 0)
VM_DEFINE_INSTRUCTION (35, br, "br", 2, 0, 0)
{
int h = FETCH ();
int l = FETCH ();
ip += (signed short) (h << 8) + l;
scm_t_int16 offset;
FETCH_OFFSET (offset);
ip += ((scm_t_ptrdiff)offset) * 8 - (((unsigned long)ip) % 8);
NEXT;
}
@ -812,10 +812,12 @@ VM_DEFINE_INSTRUCTION (46, call_nargs, "call/nargs", 0, 0, 1)
VM_DEFINE_INSTRUCTION (47, mv_call, "mv-call", 3, -1, 1)
{
SCM x;
signed short offset;
scm_t_int16 offset;
scm_t_uint8 *mvra;
nargs = FETCH ();
FETCH_OFFSET (offset);
mvra = ip + ((scm_t_ptrdiff)offset) * 8 - ((unsigned long)ip) % 8;
x = sp[-nargs];
@ -828,7 +830,7 @@ VM_DEFINE_INSTRUCTION (47, mv_call, "mv-call", 3, -1, 1)
CACHE_PROGRAM ();
INIT_ARGS ();
NEW_FRAME ();
SCM_FRAME_DATA_ADDRESS (fp)[1] = (SCM)(SCM_FRAME_RETURN_ADDRESS (fp) + offset);
SCM_FRAME_DATA_ADDRESS (fp)[1] = (SCM)mvra;
ENTER_HOOK ();
APPLY_HOOK ();
NEXT;
@ -853,7 +855,7 @@ VM_DEFINE_INSTRUCTION (47, mv_call, "mv-call", 3, -1, 1)
len = scm_length (values);
PUSH_LIST (values, SCM_NULLP);
PUSH (len);
ip += offset;
ip = mvra;
}
NEXT;
}