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GH-99554: Pack location tables more effectively (GH-99556)
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brandtbucher authored Dec 22, 2022
1 parent bbf4a66 commit 3c033a2
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Showing 3 changed files with 53 additions and 34 deletions.
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Pack debugging location tables more efficiently during bytecode compilation.
19 changes: 8 additions & 11 deletions Programs/test_frozenmain.h

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67 changes: 44 additions & 23 deletions Python/compile.c
Original file line number Diff line number Diff line change
Expand Up @@ -150,6 +150,15 @@ location_is_after(location loc1, location loc2) {
(loc1.col_offset > loc2.end_col_offset));
}

static inline bool
same_location(location a, location b)
{
return a.lineno == b.lineno &&
a.end_lineno == b.end_lineno &&
a.col_offset == b.col_offset &&
a.end_col_offset == b.end_col_offset;
}

#define LOC(x) SRC_LOCATION_FROM_AST(x)

typedef struct jump_target_label_ {
Expand Down Expand Up @@ -7722,15 +7731,15 @@ write_location_info_oneline_form(struct assembler* a, int length, int line_delta
}

static void
write_location_info_long_form(struct assembler* a, struct instr* i, int length)
write_location_info_long_form(struct assembler* a, location loc, int length)
{
assert(length > 0 && length <= 8);
write_location_first_byte(a, PY_CODE_LOCATION_INFO_LONG, length);
write_location_signed_varint(a, i->i_loc.lineno - a->a_lineno);
assert(i->i_loc.end_lineno >= i->i_loc.lineno);
write_location_varint(a, i->i_loc.end_lineno - i->i_loc.lineno);
write_location_varint(a, i->i_loc.col_offset + 1);
write_location_varint(a, i->i_loc.end_col_offset + 1);
write_location_signed_varint(a, loc.lineno - a->a_lineno);
assert(loc.end_lineno >= loc.lineno);
write_location_varint(a, loc.end_lineno - loc.lineno);
write_location_varint(a, loc.col_offset + 1);
write_location_varint(a, loc.end_col_offset + 1);
}

static void
Expand All @@ -7749,7 +7758,7 @@ write_location_info_no_column(struct assembler* a, int length, int line_delta)
#define THEORETICAL_MAX_ENTRY_SIZE 25 /* 1 + 6 + 6 + 6 + 6 */

static int
write_location_info_entry(struct assembler* a, struct instr* i, int isize)
write_location_info_entry(struct assembler* a, location loc, int isize)
{
Py_ssize_t len = PyBytes_GET_SIZE(a->a_linetable);
if (a->a_location_off + THEORETICAL_MAX_ENTRY_SIZE >= len) {
Expand All @@ -7758,49 +7767,51 @@ write_location_info_entry(struct assembler* a, struct instr* i, int isize)
return -1;
}
}
if (i->i_loc.lineno < 0) {
if (loc.lineno < 0) {
write_location_info_none(a, isize);
return 0;
}
int line_delta = i->i_loc.lineno - a->a_lineno;
int column = i->i_loc.col_offset;
int end_column = i->i_loc.end_col_offset;
int line_delta = loc.lineno - a->a_lineno;
int column = loc.col_offset;
int end_column = loc.end_col_offset;
assert(column >= -1);
assert(end_column >= -1);
if (column < 0 || end_column < 0) {
if (i->i_loc.end_lineno == i->i_loc.lineno || i->i_loc.end_lineno == -1) {
if (loc.end_lineno == loc.lineno || loc.end_lineno == -1) {
write_location_info_no_column(a, isize, line_delta);
a->a_lineno = i->i_loc.lineno;
a->a_lineno = loc.lineno;
return 0;
}
}
else if (i->i_loc.end_lineno == i->i_loc.lineno) {
else if (loc.end_lineno == loc.lineno) {
if (line_delta == 0 && column < 80 && end_column - column < 16 && end_column >= column) {
write_location_info_short_form(a, isize, column, end_column);
return 0;
}
if (line_delta >= 0 && line_delta < 3 && column < 128 && end_column < 128) {
write_location_info_oneline_form(a, isize, line_delta, column, end_column);
a->a_lineno = i->i_loc.lineno;
a->a_lineno = loc.lineno;
return 0;
}
}
write_location_info_long_form(a, i, isize);
a->a_lineno = i->i_loc.lineno;
write_location_info_long_form(a, loc, isize);
a->a_lineno = loc.lineno;
return 0;
}

static int
assemble_emit_location(struct assembler* a, struct instr* i)
assemble_emit_location(struct assembler* a, location loc, int isize)
{
int isize = instr_size(i);
if (isize == 0) {
return 0;
}
while (isize > 8) {
if (write_location_info_entry(a, i, 8) < 0) {
if (write_location_info_entry(a, loc, 8)) {
return -1;
}
isize -= 8;
}
return write_location_info_entry(a, i, isize);
return write_location_info_entry(a, loc, isize);
}

/* assemble_emit()
Expand Down Expand Up @@ -8860,13 +8871,23 @@ assemble(struct compiler *c, int addNone)

/* Emit location info */
a.a_lineno = c->u->u_firstlineno;
location loc = NO_LOCATION;
int size = 0;
for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) {
for (int j = 0; j < b->b_iused; j++) {
if (assemble_emit_location(&a, &b->b_instr[j]) < 0) {
goto error;
if (!same_location(loc, b->b_instr[j].i_loc)) {
if (assemble_emit_location(&a, loc, size)) {
goto error;
}
loc = b->b_instr[j].i_loc;
size = 0;
}
size += instr_size(&b->b_instr[j]);
}
}
if (assemble_emit_location(&a, loc, size)) {
goto error;
}

if (assemble_exception_table(&a, g->g_entryblock) < 0) {
goto error;
Expand Down

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