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turn goto into do while loop

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Benjamin Peterson 2009-11-20 02:15:50 +00:00
parent 009b89d22a
commit cef9782810
1 changed files with 32 additions and 37 deletions
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69
Python/compile.c
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@ -3586,49 +3586,47 @@ static void
assemble_jump_offsets(struct assembler *a, struct compiler *c)
{
basicblock *b;
int bsize, totsize, extended_arg_count, last_extended_arg_count = 0;
int bsize, totsize, extended_arg_count = 0, last_extended_arg_count;
int i;
/* Compute the size of each block and fixup jump args.
Replace block pointer with position in bytecode. */
start:
totsize = 0;
for (i = a->a_nblocks - 1; i >= 0; i--) {
b = a->a_postorder[i];
bsize = blocksize(b);
b->b_offset = totsize;
totsize += bsize;
}
extended_arg_count = 0;
for (b = c->u->u_blocks; b != NULL; b = b->b_list) {
bsize = b->b_offset;
for (i = 0; i < b->b_iused; i++) {
struct instr *instr = &b->b_instr[i];
/* Relative jumps are computed relative to
the instruction pointer after fetching
the jump instruction.
*/
bsize += instrsize(instr);
if (instr->i_jabs)
instr->i_oparg = instr->i_target->b_offset;
else if (instr->i_jrel) {
int delta = instr->i_target->b_offset - bsize;
instr->i_oparg = delta;
}
else
continue;
if (instr->i_oparg > 0xffff)
extended_arg_count++;
do {
totsize = 0;
for (i = a->a_nblocks - 1; i >= 0; i--) {
b = a->a_postorder[i];
bsize = blocksize(b);
b->b_offset = totsize;
totsize += bsize;
}
last_extended_arg_count = extended_arg_count;
extended_arg_count = 0;
for (b = c->u->u_blocks; b != NULL; b = b->b_list) {
bsize = b->b_offset;
for (i = 0; i < b->b_iused; i++) {
struct instr *instr = &b->b_instr[i];
/* Relative jumps are computed relative to
the instruction pointer after fetching
the jump instruction.
*/
bsize += instrsize(instr);
if (instr->i_jabs)
instr->i_oparg = instr->i_target->b_offset;
else if (instr->i_jrel) {
int delta = instr->i_target->b_offset - bsize;
instr->i_oparg = delta;
}
else
continue;
if (instr->i_oparg > 0xffff)
extended_arg_count++;
}
}
}
/* XXX: This is an awful hack that could hurt performance, but
on the bright side it should work until we come up
with a better solution.
In the meantime, should the goto be dropped in favor
of a loop?
The issue is that in the first loop blocksize() is called
which calls instrsize() which requires i_oparg be set
appropriately. There is a bootstrap problem because
@ -3639,10 +3637,7 @@ start:
ones in jump instructions. So this should converge
fairly quickly.
*/
if (last_extended_arg_count != extended_arg_count) {
last_extended_arg_count = extended_arg_count;
goto start;
}
} while (last_extended_arg_count != extended_arg_count);
}
static PyObject *