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C++: Don't use GVN in AST DataFlow BarrierNode #2755

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Merged
MathiasVP merged 1 commit into from
Feb 4, 2020
Merged

C++: Don't use GVN in AST DataFlow BarrierNode #2755

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7 changes: 3 additions & 4 deletions cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowUtil.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@ private import cpp
private import semmle.code.cpp.dataflow.internal.FlowVar
private import semmle.code.cpp.models.interfaces.DataFlow
private import semmle.code.cpp.controlflow.Guards
private import semmle.code.cpp.valuenumbering.GlobalValueNumbering

cached
private newtype TNode =
Expand Down Expand Up @@ -689,9 +688,9 @@ class BarrierGuard extends GuardCondition {

/** Gets a node guarded by this guard. */
final ExprNode getAGuardedNode() {
exists(GVN value, boolean branch |
result.getExpr() = value.getAnExpr() and
this.checks(value.getAnExpr(), branch) and
exists(SsaDefinition def, Variable v, boolean branch |
result.getExpr() = def.getAUse(v) and
this.checks(def.getAUse(v), branch) and
this.controls(result.getExpr().getBasicBlock(), branch)
)
}
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2 changes: 1 addition & 1 deletion cpp/ql/test/library-tests/dataflow/dataflow-tests/BarrierGuard.cpp
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Expand Up @@ -48,7 +48,7 @@ struct XY {
void bg_stackstruct(XY s1, XY s2) {
s1.x = source();
if (guarded(s1.x)) {
sink(s1.x); // no flow
sink(s1.x); // no flow [FALSE POSITIVE in AST]
} else if (guarded(s1.y)) {
sink(s1.x); // flow
} else if (guarded(s2.y)) {
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1 change: 1 addition & 0 deletions cpp/ql/test/library-tests/dataflow/dataflow-tests/test.expected
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Expand Up @@ -3,6 +3,7 @@
| BarrierGuard.cpp:25:10:25:15 | source | BarrierGuard.cpp:21:17:21:22 | source |
| BarrierGuard.cpp:31:10:31:15 | source | BarrierGuard.cpp:29:16:29:21 | source |
| BarrierGuard.cpp:33:10:33:15 | source | BarrierGuard.cpp:29:16:29:21 | source |
| BarrierGuard.cpp:51:13:51:13 | x | BarrierGuard.cpp:49:10:49:15 | call to source |
| BarrierGuard.cpp:53:13:53:13 | x | BarrierGuard.cpp:49:10:49:15 | call to source |
| BarrierGuard.cpp:55:13:55:13 | x | BarrierGuard.cpp:49:10:49:15 | call to source |
| BarrierGuard.cpp:62:14:62:14 | x | BarrierGuard.cpp:60:11:60:16 | call to source |
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1 change: 1 addition & 0 deletions cpp/ql/test/library-tests/dataflow/dataflow-tests/test_diff.expected
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@@ -1,3 +1,4 @@
| BarrierGuard.cpp:49:10:49:15 | BarrierGuard.cpp:51:13:51:13 | AST only |
| BarrierGuard.cpp:60:11:60:16 | BarrierGuard.cpp:62:14:62:14 | AST only |
| clang.cpp:12:9:12:20 | clang.cpp:22:8:22:20 | AST only |
| clang.cpp:28:27:28:32 | clang.cpp:30:27:30:34 | AST only |
Expand Down