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C#: Take phi nodes into account in Steps::getARead()

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This commit is contained in:
Tom Hvitved
2021-01-11 14:34:23 +01:00
parent cb8e2d451d
commit 88b7ad001f
3 changed files with 4 additions and 6 deletions
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7
csharp/ql/src/semmle/code/csharp/dataflow/internal/Steps.qll
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@@ -6,18 +6,17 @@ import csharp
* Provides functionality for performing simple data flow analysis.
* This library is used by the dispatch library, which in turn is used by the
* SSA library, so we cannot make use of the SSA library in this library.
* Instead, this library relies on a self-contained, minimalistic SSA-like
* implementation.
* Instead, this library relies on the `BaseSsa` library.
*/
module Steps {
private import semmle.code.csharp.dataflow.internal.BaseSSA
/**
* Gets a read that is guaranteed to read the value assigned at definition `def`.
* Gets a read that may read the value assigned at definition `def`.
*/
private AssignableRead getARead(AssignableDefinition def) {
exists(BaseSsa::Definition ssaDef |
ssaDef.getDefinition() = def and
ssaDef.getAnUltimateDefinition().getDefinition() = def and
result = ssaDef.getARead()
)
or

2
csharp/ql/test/query-tests/Dead Code/DeadStoreOfLocal/DeadStoreOfLocal.cs
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@@ -278,7 +278,7 @@ public class Captured
void M10(bool b)
{
var x = ""; // GOOD [FALSE POSITIVE]
var x = ""; // GOOD
Action action;
if (b)
action = () => System.Console.WriteLine(x);

1
csharp/ql/test/query-tests/Dead Code/DeadStoreOfLocal/DeadStoreOfLocal.expected
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@@ -9,7 +9,6 @@
| DeadStoreOfLocal.cs:142:26:142:27 | Exception ex | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:142:26:142:27 | ex | ex |
| DeadStoreOfLocal.cs:246:17:246:24 | Int32 y = ... | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:246:17:246:17 | y | y |
| DeadStoreOfLocal.cs:261:17:261:21 | Int32 x = ... | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:261:17:261:17 | x | x |
| DeadStoreOfLocal.cs:281:13:281:18 | String x = ... | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:281:13:281:13 | x | x |
| DeadStoreOfLocal.cs:300:23:300:28 | Object v1 | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:300:27:300:28 | v1 | v1 |
| DeadStoreOfLocal.cs:314:18:314:23 | Object v2 | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:314:22:314:23 | v2 | v2 |
| DeadStoreOfLocal.cs:331:9:331:32 | ... = ... | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:327:23:327:23 | b | b |