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Merge pull request #2750 from Cornelius-Riemenschneider/cpp-range-analysis-casts

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C++: Support implicit casts better in range analysis
This commit is contained in:
Dave Bartolomeo
2020-02-05 13:59:09 -07:00
committed by GitHub
parent 81b1bd4177 eafd7b6045
commit c53f80175f
3 changed files with 33 additions and 1 deletions
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9
cpp/ql/src/semmle/code/cpp/rangeanalysis/RangeAnalysis.qll
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@@ -187,6 +187,13 @@ private predicate boundFlowStepSsa(
guard.controls(op2.getUse().getBlock(), testIsTrue) and
reason = TCondReason(guard)
)
or
exists(IRGuardCondition guard, boolean testIsTrue, SafeCastInstruction cast |
valueNumberOfOperand(op2) = valueNumber(cast.getUnary()) and
guard = boundFlowCond(valueNumber(cast), op1, delta, upper, testIsTrue) and
guard.controls(op2.getUse().getBlock(), testIsTrue) and
reason = TCondReason(guard)
)
}
/**
@@ -259,7 +266,7 @@ private predicate safeCast(IntegralType fromtyp, IntegralType totyp) {
private class SafeCastInstruction extends ConvertInstruction {
SafeCastInstruction() {
safeCast(getResultType(), getUnary().getResultType())
safeCast(getUnary().getResultType(), getResultType())
or
getResultType() instanceof PointerType and
getUnary().getResultType() instanceof PointerType

3
cpp/ql/test/library-tests/rangeanalysis/rangeanalysis/RangeAnalysis.expected
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@@ -59,3 +59,6 @@
| test.cpp:183:10:183:10 | Load: i | test.cpp:175:23:175:23 | InitializeParameter: x | -1 | true | CompareLT: ... < ... | test.cpp:182:9:182:13 | test.cpp:182:9:182:13 |
| test.cpp:185:10:185:10 | Load: i | test.cpp:175:23:175:23 | InitializeParameter: x | 0 | true | CompareLT: ... < ... | test.cpp:176:7:176:11 | test.cpp:176:7:176:11 |
| test.cpp:187:10:187:10 | Store: i | test.cpp:175:23:175:23 | InitializeParameter: x | 0 | false | CompareLT: ... < ... | test.cpp:182:9:182:13 | test.cpp:182:9:182:13 |
| test.cpp:199:10:199:10 | Load: i | test.cpp:197:25:197:25 | InitializeParameter: l | -1 | true | CompareLT: ... < ... | test.cpp:198:7:198:11 | test.cpp:198:7:198:11 |
| test.cpp:202:11:202:11 | Load: i | test.cpp:197:25:197:25 | InitializeParameter: l | -3 | true | CompareLT: ... < ... | test.cpp:201:7:201:15 | test.cpp:201:7:201:15 |
| test.cpp:208:10:208:10 | Load: x | test.cpp:206:24:206:24 | InitializeParameter: y | -3 | true | CompareLT: ... < ... | test.cpp:207:7:207:15 | test.cpp:207:7:207:15 |

22
cpp/ql/test/library-tests/rangeanalysis/rangeanalysis/test.cpp
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@@ -186,3 +186,25 @@ int test15(int i, int x) {
}
return i;
}
// safe integer type conversion
int test16(int i) {
long l;
l = i;
}
// implicit integer casts
void test17(int i, long l) {
if (i < l) {
sink(i);
}
if (i < l - 2) {
sink (i);
}
}
void test18(int x, int y) {
if (x < y - 2) {
sink(x);
}
}