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bpo-30501: Make the compiler producing optimized code for condition e…
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…xpressions. (#1851)
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@serhiy-storchaka
serhiy-storchaka committed Jun 11, 2017
1 parent 1efbf92 commit 36ff451
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Showing 5 changed files with 2,537 additions and 2,448 deletions.
4 changes: 4 additions & 0 deletions Misc/NEWS
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Expand Up @@ -10,6 +10,10 @@ What's New in Python 3.7.0 alpha 1?
Core and Builtins
-----------------

- bpo-30501: The compiler now produces more optimal code for complex condition
expressions in the "if", "while" and "assert" statement, the "if" expression,
and generator expressions and comprehensions.

- bpo-28180: Implement PEP 538 (legacy C locale coercion). This means that when
a suitable coercion target locale is available, both the core interpreter and
locale-aware C extensions will assume the use of UTF-8 as the default text
Expand Down
178 changes: 137 additions & 41 deletions Python/compile.c
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Expand Up @@ -1999,6 +1999,131 @@ compiler_class(struct compiler *c, stmt_ty s)
return 1;
}

static int
cmpop(cmpop_ty op)
{
switch (op) {
case Eq:
return PyCmp_EQ;
case NotEq:
return PyCmp_NE;
case Lt:
return PyCmp_LT;
case LtE:
return PyCmp_LE;
case Gt:
return PyCmp_GT;
case GtE:
return PyCmp_GE;
case Is:
return PyCmp_IS;
case IsNot:
return PyCmp_IS_NOT;
case In:
return PyCmp_IN;
case NotIn:
return PyCmp_NOT_IN;
default:
return PyCmp_BAD;
}
}

static int
compiler_jump_if(struct compiler *c, expr_ty e, basicblock *next, int cond)
{
switch (e->kind) {
case UnaryOp_kind:
if (e->v.UnaryOp.op == Not)
return compiler_jump_if(c, e->v.UnaryOp.operand, next, !cond);
/* fallback to general implementation */
break;
case BoolOp_kind: {
asdl_seq *s = e->v.BoolOp.values;
Py_ssize_t i, n = asdl_seq_LEN(s) - 1;
assert(n >= 0);
int cond2 = e->v.BoolOp.op == Or;
basicblock *next2 = next;
if (!cond2 != !cond) {
next2 = compiler_new_block(c);
if (next2 == NULL)
return 0;
}
for (i = 0; i < n; ++i) {
if (!compiler_jump_if(c, (expr_ty)asdl_seq_GET(s, i), next2, cond2))
return 0;
}
if (!compiler_jump_if(c, (expr_ty)asdl_seq_GET(s, n), next, cond))
return 0;
if (next2 != next)
compiler_use_next_block(c, next2);
return 1;
}
case IfExp_kind: {
basicblock *end, *next2;
end = compiler_new_block(c);
if (end == NULL)
return 0;
next2 = compiler_new_block(c);
if (next2 == NULL)
return 0;
if (!compiler_jump_if(c, e->v.IfExp.test, next2, 0))
return 0;
if (!compiler_jump_if(c, e->v.IfExp.body, next, cond))
return 0;
ADDOP_JREL(c, JUMP_FORWARD, end);
compiler_use_next_block(c, next2);
if (!compiler_jump_if(c, e->v.IfExp.orelse, next, cond))
return 0;
compiler_use_next_block(c, end);
return 1;
}
case Compare_kind: {
Py_ssize_t i, n = asdl_seq_LEN(e->v.Compare.ops) - 1;
if (n > 0) {
basicblock *cleanup = compiler_new_block(c);
if (cleanup == NULL)
return 0;
VISIT(c, expr, e->v.Compare.left);
for (i = 0; i < n; i++) {
VISIT(c, expr,
(expr_ty)asdl_seq_GET(e->v.Compare.comparators, i));
ADDOP(c, DUP_TOP);
ADDOP(c, ROT_THREE);
ADDOP_I(c, COMPARE_OP,
cmpop((cmpop_ty)(asdl_seq_GET(e->v.Compare.ops, i))));
ADDOP_JABS(c, POP_JUMP_IF_FALSE, cleanup);
NEXT_BLOCK(c);
}
VISIT(c, expr, (expr_ty)asdl_seq_GET(e->v.Compare.comparators, n));
ADDOP_I(c, COMPARE_OP,
cmpop((cmpop_ty)(asdl_seq_GET(e->v.Compare.ops, n))));
ADDOP_JABS(c, cond ? POP_JUMP_IF_TRUE : POP_JUMP_IF_FALSE, next);
basicblock *end = compiler_new_block(c);
if (end == NULL)
return 0;
ADDOP_JREL(c, JUMP_FORWARD, end);
compiler_use_next_block(c, cleanup);
ADDOP(c, POP_TOP);
if (!cond) {
ADDOP_JREL(c, JUMP_FORWARD, next);
}
compiler_use_next_block(c, end);
return 1;
}
/* fallback to general implementation */
break;
}
default:
/* fallback to general implementation */
break;
}

/* general implementation */
VISIT(c, expr, e);
ADDOP_JABS(c, cond ? POP_JUMP_IF_TRUE : POP_JUMP_IF_FALSE, next);
return 1;
}

static int
compiler_ifexp(struct compiler *c, expr_ty e)
{
Expand All @@ -2011,8 +2136,8 @@ compiler_ifexp(struct compiler *c, expr_ty e)
next = compiler_new_block(c);
if (next == NULL)
return 0;
VISIT(c, expr, e->v.IfExp.test);
ADDOP_JABS(c, POP_JUMP_IF_FALSE, next);
if (!compiler_jump_if(c, e->v.IfExp.test, next, 0))
return 0;
VISIT(c, expr, e->v.IfExp.body);
ADDOP_JREL(c, JUMP_FORWARD, end);
compiler_use_next_block(c, next);
Expand Down Expand Up @@ -2101,8 +2226,8 @@ compiler_if(struct compiler *c, stmt_ty s)
}
else
next = end;
VISIT(c, expr, s->v.If.test);
ADDOP_JABS(c, POP_JUMP_IF_FALSE, next);
if (!compiler_jump_if(c, s->v.If.test, next, 0))
return 0;
VISIT_SEQ(c, stmt, s->v.If.body);
if (asdl_seq_LEN(s->v.If.orelse)) {
ADDOP_JREL(c, JUMP_FORWARD, end);
Expand Down Expand Up @@ -2261,8 +2386,8 @@ compiler_while(struct compiler *c, stmt_ty s)
if (!compiler_push_fblock(c, LOOP, loop))
return 0;
if (constant == -1) {
VISIT(c, expr, s->v.While.test);
ADDOP_JABS(c, POP_JUMP_IF_FALSE, anchor);
if (!compiler_jump_if(c, s->v.While.test, anchor, 0))
return 0;
}
VISIT_SEQ(c, stmt, s->v.While.body);
ADDOP_JABS(c, JUMP_ABSOLUTE, loop);
Expand Down Expand Up @@ -2721,11 +2846,11 @@ compiler_assert(struct compiler *c, stmt_ty s)
}
Py_DECREF(msg);
}
VISIT(c, expr, s->v.Assert.test);
end = compiler_new_block(c);
if (end == NULL)
return 0;
ADDOP_JABS(c, POP_JUMP_IF_TRUE, end);
if (!compiler_jump_if(c, s->v.Assert.test, end, 1))
return 0;
ADDOP_O(c, LOAD_GLOBAL, assertion_error, names);
if (s->v.Assert.msg) {
VISIT(c, expr, s->v.Assert.msg);
Expand Down Expand Up @@ -2909,35 +3034,6 @@ binop(struct compiler *c, operator_ty op)
}
}

static int
cmpop(cmpop_ty op)
{
switch (op) {
case Eq:
return PyCmp_EQ;
case NotEq:
return PyCmp_NE;
case Lt:
return PyCmp_LT;
case LtE:
return PyCmp_LE;
case Gt:
return PyCmp_GT;
case GtE:
return PyCmp_GE;
case Is:
return PyCmp_IS;
case IsNot:
return PyCmp_IS_NOT;
case In:
return PyCmp_IN;
case NotIn:
return PyCmp_NOT_IN;
default:
return PyCmp_BAD;
}
}

static int
inplace_binop(struct compiler *c, operator_ty op)
{
Expand Down Expand Up @@ -3676,8 +3772,8 @@ compiler_sync_comprehension_generator(struct compiler *c,
n = asdl_seq_LEN(gen->ifs);
for (i = 0; i < n; i++) {
expr_ty e = (expr_ty)asdl_seq_GET(gen->ifs, i);
VISIT(c, expr, e);
ADDOP_JABS(c, POP_JUMP_IF_FALSE, if_cleanup);
if (!compiler_jump_if(c, e, if_cleanup, 0))
return 0;
NEXT_BLOCK(c);
}

Expand Down Expand Up @@ -3807,8 +3903,8 @@ compiler_async_comprehension_generator(struct compiler *c,
n = asdl_seq_LEN(gen->ifs);
for (i = 0; i < n; i++) {
expr_ty e = (expr_ty)asdl_seq_GET(gen->ifs, i);
VISIT(c, expr, e);
ADDOP_JABS(c, POP_JUMP_IF_FALSE, if_cleanup);
if (!compiler_jump_if(c, e, if_cleanup, 0))
return 0;
NEXT_BLOCK(c);
}

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