py: This time, real proper overflow checking of small int power.
Previous overflow test was inadequate.
diff --git a/py/runtime.c b/py/runtime.c
index a5afe0e..a5f45a2 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -16,7 +16,7 @@
#include "builtin.h"
#include "builtintables.h"
#include "bc.h"
-#include "intdivmod.h"
+#include "smallint.h"
#include "objgenerator.h"
#if 0 // print debugging info
@@ -289,7 +289,7 @@
// If long long type exists and is larger than machine_int_t, then
// we can use the following code to perform overflow-checked multiplication.
- // Otherwise (eg in x64 case) we must use the branching code below.
+ // Otherwise (eg in x64 case) we must use mp_small_int_mul_overflow.
#if 0
// compute result using long long precision
long long res = (long long)lhs_val * (long long)rhs_val;
@@ -302,36 +302,14 @@
}
#endif
- if (lhs_val > 0) { // lhs_val is positive
- if (rhs_val > 0) { // lhs_val and rhs_val are positive
- if (lhs_val > (MP_SMALL_INT_MAX / rhs_val)) {
- goto mul_overflow;
- }
- } else { // lhs_val positive, rhs_val nonpositive
- if (rhs_val < (MP_SMALL_INT_MIN / lhs_val)) {
- goto mul_overflow;
- }
- } // lhs_val positive, rhs_val nonpositive
- } else { // lhs_val is nonpositive
- if (rhs_val > 0) { // lhs_val is nonpositive, rhs_val is positive
- if (lhs_val < (MP_SMALL_INT_MIN / rhs_val)) {
- goto mul_overflow;
- }
- } else { // lhs_val and rhs_val are nonpositive
- if (lhs_val != 0 && rhs_val < (MP_SMALL_INT_MAX / lhs_val)) {
- goto mul_overflow;
- }
- } // End if lhs_val and rhs_val are nonpositive
- } // End if lhs_val is nonpositive
-
- // use standard precision
- return MP_OBJ_NEW_SMALL_INT(lhs_val * rhs_val);
-
- mul_overflow:
- // use higher precision
- lhs = mp_obj_new_int_from_ll(lhs_val);
- goto generic_binary_op;
-
+ if (mp_small_int_mul_overflow(lhs_val, rhs_val)) {
+ // use higher precision
+ lhs = mp_obj_new_int_from_ll(lhs_val);
+ goto generic_binary_op;
+ } else {
+ // use standard precision
+ return MP_OBJ_NEW_SMALL_INT(lhs_val * rhs_val);
+ }
break;
}
case MP_BINARY_OP_FLOOR_DIVIDE:
@@ -339,7 +317,7 @@
if (rhs_val == 0) {
goto zero_division;
}
- lhs_val = python_floor_divide(lhs_val, rhs_val);
+ lhs_val = mp_small_int_floor_divide(lhs_val, rhs_val);
break;
#if MICROPY_ENABLE_FLOAT
@@ -352,11 +330,11 @@
#endif
case MP_BINARY_OP_MODULO:
- case MP_BINARY_OP_INPLACE_MODULO:
- {
- lhs_val = python_modulo(lhs_val, rhs_val);
+ case MP_BINARY_OP_INPLACE_MODULO: {
+ lhs_val = mp_small_int_modulo(lhs_val, rhs_val);
break;
}
+
case MP_BINARY_OP_POWER:
case MP_BINARY_OP_INPLACE_POWER:
if (rhs_val < 0) {
@@ -370,21 +348,19 @@
machine_int_t ans = 1;
while (rhs_val > 0) {
if (rhs_val & 1) {
- machine_int_t old = ans;
- ans *= lhs_val;
- if (ans < old) {
+ if (mp_small_int_mul_overflow(ans, lhs_val)) {
goto power_overflow;
}
+ ans *= lhs_val;
}
if (rhs_val == 1) {
break;
}
rhs_val /= 2;
- machine_int_t old = lhs_val;
- lhs_val *= lhs_val;
- if (lhs_val < old) {
+ if (mp_small_int_mul_overflow(lhs_val, lhs_val)) {
goto power_overflow;
}
+ lhs_val *= lhs_val;
}
lhs_val = ans;
}