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C++: Teach range analysis to pay attention to NaNs.

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This commit is contained in:
Jason Reed
2019-02-21 10:57:21 -05:00
committed by Jason Reed
parent 886e52468d
commit 23ee7ee928
4 changed files with 102 additions and 8 deletions
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27
cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/PointlessComparison.c
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@@ -265,3 +265,30 @@ int negative_zero(double dbl) {
}
return 0;
}
int nan(double x) {
if (x < 0.0) {
return 100;
}
else if (x >= 0.0) { // GOOD [x could be NaN]
return 200;
}
else {
return 300;
}
}
int nan2(double x) {
if (x == x) {
// If x compares with anything at all, it's not NaN
if (x < 0.0) {
return 100;
}
else if (x >= 0.0) { // BAD [Always true]
return 200;
}
else {
return 300;
}
}
}

1
cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/PointlessComparison.expected
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@@ -32,5 +32,6 @@
| PointlessComparison.c:129:12:129:16 | ... > ... | Comparison is always false because a <= 3. |
| PointlessComparison.c:197:7:197:11 | ... < ... | Comparison is always false because x >= 0. |
| PointlessComparison.c:264:12:264:22 | ... >= ... | Comparison is always true because dbl >= 0 and -0 >= - .... |
| PointlessComparison.c:287:14:287:21 | ... >= ... | Comparison is always true because x >= 0. |
| RegressionTests.cpp:57:7:57:22 | ... <= ... | Comparison is always true because * ... <= 4294967295. |
| Templates.cpp:9:10:9:24 | ... <= ... | Comparison is always true because local <= 32767. |