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Merge pull request #4389 from gsingh93/bitwise-and

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Improve range analysis for bitwise and
This commit is contained in:
Jonas Jensen
2020-10-08 15:18:15 +02:00
committed by GitHub
parent f179e7ebf4 662736eb2d
commit b409cf6cea
5 changed files with 179 additions and 0 deletions
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59
cpp/ql/test/experimental/library-tests/rangeanalysis/bitwiseand/bitwiseand.cpp Normal file
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typedef unsigned char uint8_t;
typedef signed char int8_t;
typedef unsigned uint32_t;
typedef signed long long int64_t;
void test_assign_operator(uint8_t x) {
x &= 7; // [0 .. 7]
}
void test_non_negative_const(uint8_t x) {
uint8_t unsigned_const = 7;
// Non-negative range operand and non-negative constant. The operands are promoted
// to signed ints.
x & 0; // [0 .. 0]
x & 7; // [0 .. 7]
x & unsigned_const; // [0 .. 7]
// This tests what happens when both arguments are promoted to `unsigned int` instead
// of `int`, and when the constant is larger than the max bound
x & 0xFFFFFFFF; // [0 .. 255]
}
void test_non_const(uint8_t a, uint8_t b, uint32_t c, uint32_t d) {
if (b <= 100) {
// `a` and `b` are promoted to signed ints, meaning neither the range analysis library
// nor this extension handle it
a & b; // [-2147483648 .. 2147483647]
}
if (d <= 100) {
// Handled by the range analysis library
c & d; // [0 .. 100]
}
}
void test_negative_operand(uint8_t x, int8_t y) {
uint8_t unsigned_const = 7;
int8_t signed_const = -7;
// The right operand can be negative
x & -7; // [-2147483648 .. 2147483647]
x & signed_const; // [-2147483648 .. 2147483647]
x & y; // [-2147483648 .. 2147483647]
// The left operand can be negative
y & 7; // [-2147483648 .. 2147483647]
y & unsigned_const; // [-2147483648 .. 2147483647]
y & 0xFFFFFFFF; // [0 .. 4294967295]
(int64_t)y & 0xFFFFFFFF; // [-9223372036854776000 .. 9223372036854776000]
y & x; // [-2147483648 .. 2147483647]
// Both can be negative
y & -7; // [-2147483648 .. 2147483647]
y & signed_const; // [-2147483648 .. 2147483647]
signed_const & -7; // [-2147483648 .. 2147483647]
signed_const & y; // [-2147483648 .. 2147483647]
-7 & y; // [-2147483648 .. 2147483647]
-7 & signed_const; // [-2147483648 .. 2147483647]
}

21
cpp/ql/test/experimental/library-tests/rangeanalysis/bitwiseand/bitwiseand.expected Normal file
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| bitwiseand.cpp:7:3:7:8 | ... &= ... | 0.0 | 7.0 |
| bitwiseand.cpp:15:3:15:7 | ... & ... | 0.0 | 0.0 |
| bitwiseand.cpp:16:3:16:7 | ... & ... | 0.0 | 7.0 |
| bitwiseand.cpp:17:3:17:20 | ... & ... | 0.0 | 7.0 |
| bitwiseand.cpp:21:3:21:16 | ... & ... | 0.0 | 255.0 |
| bitwiseand.cpp:28:5:28:9 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:32:5:32:9 | ... & ... | 0.0 | 100.0 |
| bitwiseand.cpp:41:3:41:8 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:42:3:42:18 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:43:3:43:7 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:46:3:46:7 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:47:3:47:20 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:48:3:48:16 | ... & ... | 0.0 | 4.294967295E9 |
| bitwiseand.cpp:49:3:49:25 | ... & ... | -9.223372036854776E18 | 9.223372036854776E18 |
| bitwiseand.cpp:50:3:50:7 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:53:3:53:8 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:54:3:54:18 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:55:3:55:19 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:56:3:56:18 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:57:3:57:8 | ... & ... | -2.147483648E9 | 2.147483647E9 |
| bitwiseand.cpp:58:3:58:19 | ... & ... | -2.147483648E9 | 2.147483647E9 |

8
cpp/ql/test/experimental/library-tests/rangeanalysis/bitwiseand/bitwiseand.ql Normal file
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import experimental.semmle.code.cpp.rangeanalysis.ExtendedRangeAnalysis
from Operation expr, float lower, float upper
where
(expr instanceof BitwiseAndExpr or expr instanceof AssignAndExpr) and
lower = lowerBound(expr) and
upper = upperBound(expr)
select expr, lower, upper