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MathiasVP merged 3 commits into from
Jan 30, 2026
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C++: Ensure that there are AST GuardConditions for || and && #21239

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6445fd8
C++: Fix IR -> AST mapping for basic blocks.
MathiasVP Jan 28, 2026
25647ba
C++: Fix the AST wrapper for binary logical operators.
MathiasVP Jan 28, 2026
5f079c1
C++: Add change note.
MathiasVP Jan 30, 2026
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4 changes: 4 additions & 0 deletions cpp/ql/lib/change-notes/2026-01-30-guard-condition-logical-operators.md
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@@ -0,0 +1,4 @@
---
category: fix
---
* Fixed a bug in the `GuardCondition` library which sometimes prevented binary logical operators from being recognized as guard conditions. As a result, queries using `GuardCondition` may see improved results.
43 changes: 27 additions & 16 deletions cpp/ql/lib/semmle/code/cpp/controlflow/IRGuards.qll
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Expand Up @@ -8,7 +8,8 @@ import semmle.code.cpp.ir.IR
private import codeql.util.Void
private import codeql.controlflow.Guards as SharedGuards
private import semmle.code.cpp.ir.ValueNumbering
private import semmle.code.cpp.ir.implementation.raw.internal.TranslatedExpr
private import semmle.code.cpp.ir.implementation.raw.internal.TranslatedExpr as TE
private import semmle.code.cpp.ir.implementation.raw.internal.TranslatedFunction as TF
private import semmle.code.cpp.ir.implementation.raw.internal.InstructionTag

private class BasicBlock = IRCfg::BasicBlock;
Expand Down Expand Up @@ -683,24 +684,26 @@ final class GuardCondition = GuardConditionImpl;
*/
private class GuardConditionFromBinaryLogicalOperator extends GuardConditionImpl instanceof Cpp::BinaryLogicalOperation
{
GuardConditionImpl l;
GuardConditionImpl r;

GuardConditionFromBinaryLogicalOperator() {
super.getLeftOperand() = l and
super.getRightOperand() = r
}

override predicate valueControls(Cpp::BasicBlock controlled, GuardValue v) {
exists(Cpp::BinaryLogicalOperation binop, GuardCondition lhs, GuardCondition rhs |
this = binop and
lhs = binop.getLeftOperand() and
rhs = binop.getRightOperand() and
lhs.valueControls(controlled, v) and
rhs.valueControls(controlled, v)
)
// `l || r` does not control `r` even though `l` does.
not r.(Cpp::Expr).getBasicBlock() = controlled and
l.valueControls(controlled, v)
or
r.valueControls(controlled, v)
}

override predicate valueControlsEdge(Cpp::BasicBlock pred, Cpp::BasicBlock succ, GuardValue v) {
exists(Cpp::BinaryLogicalOperation binop, GuardCondition lhs, GuardCondition rhs |
this = binop and
lhs = binop.getLeftOperand() and
rhs = binop.getRightOperand() and
lhs.valueControlsEdge(pred, succ, v) and
rhs.valueControlsEdge(pred, succ, v)
)
l.valueControlsEdge(pred, succ, v)
or
r.valueControlsEdge(pred, succ, v)
}

pragma[nomagic]
Expand Down Expand Up @@ -1026,7 +1029,7 @@ private class GuardConditionFromIR extends GuardConditionImpl {

private predicate excludeAsControlledInstruction(Instruction instr) {
// Exclude the temporaries generated by a ternary expression.
exists(TranslatedConditionalExpr tce |
exists(TE::TranslatedConditionalExpr tce |
instr = tce.getInstruction(ConditionValueFalseStoreTag())
or
instr = tce.getInstruction(ConditionValueTrueStoreTag())
Expand All @@ -1038,6 +1041,14 @@ private predicate excludeAsControlledInstruction(Instruction instr) {
or
// Exclude unreached instructions, as their AST is the whole function and not a block.
instr instanceof UnreachedInstruction
or
// Exclude instructions generated by a translated function as they map to the function itself
// and the function is considered the last basic block of a function body.
any(TF::TranslatedFunction tf).getInstruction(_) = instr
or
// `ChiInstruction`s generated by instructions in the above case don't come from `getInstruction` (since they are generated by AliasedSSA)
// so we need to special case them.
excludeAsControlledInstruction(instr.(ChiInstruction).getPartial())
}

/**
Expand Down
22 changes: 10 additions & 12 deletions cpp/ql/test/library-tests/controlflow/guards-ir/tests.expected
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Expand Up @@ -384,7 +384,9 @@ astGuardsControl
| test.c:126:7:126:7 | 1 | true | 131 | 132 |
| test.c:126:7:126:7 | 1 | true | 134 | 123 |
| test.c:126:7:126:28 | ... && ... | true | 126 | 128 |
| test.c:126:7:126:28 | ... && ... | true | 131 | 131 |
| test.c:126:7:126:28 | ... && ... | true | 131 | 132 |
| test.c:126:7:126:28 | ... && ... | true | 134 | 123 |
| test.c:126:12:126:26 | call to test3_condition | true | 126 | 128 |
| test.c:126:12:126:26 | call to test3_condition | true | 131 | 132 |
| test.c:131:7:131:7 | b | true | 131 | 132 |
Expand All @@ -405,9 +407,7 @@ astGuardsControl
| test.c:181:9:181:9 | x | true | 181 | 182 |
| test.c:181:9:181:9 | x | true | 186 | 180 |
| test.cpp:18:8:18:10 | call to get | true | 19 | 19 |
| test.cpp:31:7:31:13 | ... == ... | false | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | false | 34 | 34 |
| test.cpp:31:7:31:13 | ... == ... | true | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | true | 31 | 32 |
| test.cpp:42:13:42:20 | call to getABool | true | 43 | 45 |
astGuardsEnsure
Expand Down Expand Up @@ -589,13 +589,9 @@ astGuardsEnsure
| test.c:175:13:175:32 | ... == ... | test.c:175:13:175:15 | call to foo | == | test.c:175:32:175:32 | 0 | 0 | 175 | 175 |
| test.c:175:13:175:32 | ... == ... | test.c:175:32:175:32 | 0 | != | test.c:175:13:175:15 | call to foo | 0 | 175 | 175 |
| test.c:175:13:175:32 | ... == ... | test.c:175:32:175:32 | 0 | == | test.c:175:13:175:15 | call to foo | 0 | 175 | 175 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:7 | x | != | test.cpp:31:12:31:13 | - ... | 0 | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:7 | x | != | test.cpp:31:12:31:13 | - ... | 0 | 34 | 34 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:7 | x | == | test.cpp:31:12:31:13 | - ... | 0 | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:7 | x | == | test.cpp:31:12:31:13 | - ... | 0 | 31 | 32 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:12:31:13 | - ... | != | test.cpp:31:7:31:7 | x | 0 | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:12:31:13 | - ... | != | test.cpp:31:7:31:7 | x | 0 | 34 | 34 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:12:31:13 | - ... | == | test.cpp:31:7:31:7 | x | 0 | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:12:31:13 | - ... | == | test.cpp:31:7:31:7 | x | 0 | 31 | 32 |
astGuardsEnsure_const
| test.c:7:9:7:13 | ... > ... | test.c:7:9:7:13 | ... > ... | != | 0 | 7 | 9 |
Expand Down Expand Up @@ -793,13 +789,21 @@ astGuardsEnsure_const
| test.c:126:7:126:7 | 1 | test.c:126:7:126:7 | 1 | == | 1 | 131 | 132 |
| test.c:126:7:126:7 | 1 | test.c:126:7:126:7 | 1 | == | 1 | 134 | 123 |
| test.c:126:7:126:28 | ... && ... | test.c:126:7:126:7 | 1 | != | 0 | 126 | 128 |
| test.c:126:7:126:28 | ... && ... | test.c:126:7:126:7 | 1 | != | 0 | 131 | 131 |
| test.c:126:7:126:28 | ... && ... | test.c:126:7:126:7 | 1 | != | 0 | 131 | 132 |
| test.c:126:7:126:28 | ... && ... | test.c:126:7:126:7 | 1 | != | 0 | 134 | 123 |
| test.c:126:7:126:28 | ... && ... | test.c:126:7:126:7 | 1 | == | 1 | 126 | 128 |
| test.c:126:7:126:28 | ... && ... | test.c:126:7:126:7 | 1 | == | 1 | 131 | 131 |
| test.c:126:7:126:28 | ... && ... | test.c:126:7:126:7 | 1 | == | 1 | 131 | 132 |
| test.c:126:7:126:28 | ... && ... | test.c:126:7:126:7 | 1 | == | 1 | 134 | 123 |
| test.c:126:7:126:28 | ... && ... | test.c:126:12:126:26 | call to test3_condition | != | 0 | 126 | 128 |
| test.c:126:7:126:28 | ... && ... | test.c:126:12:126:26 | call to test3_condition | != | 0 | 131 | 131 |
| test.c:126:7:126:28 | ... && ... | test.c:126:12:126:26 | call to test3_condition | != | 0 | 131 | 132 |
| test.c:126:7:126:28 | ... && ... | test.c:126:12:126:26 | call to test3_condition | != | 0 | 134 | 123 |
| test.c:126:7:126:28 | ... && ... | test.c:126:12:126:26 | call to test3_condition | == | 1 | 126 | 128 |
| test.c:126:7:126:28 | ... && ... | test.c:126:12:126:26 | call to test3_condition | == | 1 | 131 | 131 |
| test.c:126:7:126:28 | ... && ... | test.c:126:12:126:26 | call to test3_condition | == | 1 | 131 | 132 |
| test.c:126:7:126:28 | ... && ... | test.c:126:12:126:26 | call to test3_condition | == | 1 | 134 | 123 |
| test.c:126:12:126:26 | call to test3_condition | test.c:126:12:126:26 | call to test3_condition | != | 0 | 126 | 128 |
| test.c:126:12:126:26 | call to test3_condition | test.c:126:12:126:26 | call to test3_condition | != | 0 | 131 | 132 |
| test.c:126:12:126:26 | call to test3_condition | test.c:126:12:126:26 | call to test3_condition | == | 1 | 126 | 128 |
Expand Down Expand Up @@ -846,17 +850,11 @@ astGuardsEnsure_const
| test.c:181:9:181:9 | x | test.c:181:9:181:9 | x | == | 1 | 186 | 180 |
| test.cpp:18:8:18:10 | call to get | test.cpp:18:8:18:10 | call to get | != | 0 | 19 | 19 |
| test.cpp:18:8:18:10 | call to get | test.cpp:18:8:18:10 | call to get | == | 1 | 19 | 19 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:7 | x | != | -1 | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:7 | x | != | -1 | 34 | 34 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:7 | x | == | -1 | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:7 | x | == | -1 | 31 | 32 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:13 | ... == ... | != | 0 | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:13 | ... == ... | != | 0 | 31 | 32 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:13 | ... == ... | != | 1 | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:13 | ... == ... | != | 1 | 34 | 34 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:13 | ... == ... | == | 0 | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:13 | ... == ... | == | 0 | 34 | 34 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:13 | ... == ... | == | 1 | 30 | 30 |
| test.cpp:31:7:31:13 | ... == ... | test.cpp:31:7:31:13 | ... == ... | == | 1 | 31 | 32 |
| test.cpp:42:13:42:20 | call to getABool | test.cpp:42:13:42:20 | call to getABool | != | 0 | 43 | 45 |
| test.cpp:42:13:42:20 | call to getABool | test.cpp:42:13:42:20 | call to getABool | == | 1 | 43 | 45 |
Expand Down
18 changes: 4 additions & 14 deletions cpp/ql/test/library-tests/controlflow/guards/GuardsControl.expected
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Expand Up @@ -105,9 +105,13 @@
| test.c:126:7:126:7 | 1 | true | test.c:131:10:132:16 | { ... } |
| test.c:126:7:126:7 | 1 | true | test.c:134:1:123:10 | return ... |
| test.c:126:7:126:28 | ... && ... | not 0 | test.c:126:31:128:16 | { ... } |
| test.c:126:7:126:28 | ... && ... | not 0 | test.c:131:3:131:7 | if (...) ... |
| test.c:126:7:126:28 | ... && ... | not 0 | test.c:131:10:132:16 | { ... } |
| test.c:126:7:126:28 | ... && ... | not 0 | test.c:134:1:123:10 | return ... |
| test.c:126:7:126:28 | ... && ... | true | test.c:126:31:128:16 | { ... } |
| test.c:126:7:126:28 | ... && ... | true | test.c:131:3:131:7 | if (...) ... |
| test.c:126:7:126:28 | ... && ... | true | test.c:131:10:132:16 | { ... } |
| test.c:126:7:126:28 | ... && ... | true | test.c:134:1:123:10 | return ... |
| test.c:126:12:126:26 | call to test3_condition | not 0 | test.c:126:31:128:16 | { ... } |
| test.c:126:12:126:26 | call to test3_condition | not 0 | test.c:131:10:132:16 | { ... } |
| test.c:126:12:126:26 | call to test3_condition | true | test.c:126:31:128:16 | { ... } |
Expand Down Expand Up @@ -162,17 +166,11 @@
| test.c:219:9:219:22 | call to __builtin_expect | true | test.c:219:25:221:5 | { ... } |
| test.cpp:18:8:18:10 | call to get | not null | test.cpp:19:5:19:14 | ExprStmt |
| test.cpp:18:8:18:10 | call to get | true | test.cpp:19:5:19:14 | ExprStmt |
| test.cpp:30:22:30:22 | x | -1 | test.cpp:30:6:30:16 | doSomething |
| test.cpp:30:22:30:22 | x | -1 | test.cpp:31:16:32:21 | { ... } |
| test.cpp:30:22:30:22 | x | not -1 | test.cpp:30:6:30:16 | doSomething |
| test.cpp:30:22:30:22 | x | not -1 | test.cpp:34:1:34:1 | return ... |
| test.cpp:31:7:31:7 | x | -1 | test.cpp:30:6:30:16 | doSomething |
| test.cpp:31:7:31:7 | x | -1 | test.cpp:31:16:32:21 | { ... } |
| test.cpp:31:7:31:7 | x | not -1 | test.cpp:30:6:30:16 | doSomething |
| test.cpp:31:7:31:7 | x | not -1 | test.cpp:34:1:34:1 | return ... |
| test.cpp:31:7:31:13 | ... == ... | false | test.cpp:30:6:30:16 | doSomething |
| test.cpp:31:7:31:13 | ... == ... | false | test.cpp:34:1:34:1 | return ... |
| test.cpp:31:7:31:13 | ... == ... | true | test.cpp:30:6:30:16 | doSomething |
| test.cpp:31:7:31:13 | ... == ... | true | test.cpp:31:16:32:21 | { ... } |
| test.cpp:42:13:42:20 | call to getABool | true | test.cpp:43:9:45:23 | { ... } |
| test.cpp:60:31:60:31 | i | 0 | test.cpp:62:5:64:12 | case ...: |
Expand Down Expand Up @@ -408,19 +406,11 @@
| test.cpp:400:11:400:25 | call to testEnumWrapper | 2 | test.cpp:404:5:406:12 | case ...: |
| test.cpp:400:27:400:27 | b | false | test.cpp:404:5:406:12 | case ...: |
| test.cpp:400:27:400:27 | b | true | test.cpp:401:5:403:12 | case ...: |
| test.cpp:410:26:410:26 | o | not null | test.cpp:410:6:410:18 | ensureNotNull |
| test.cpp:410:26:410:26 | o | not null | test.cpp:412:1:412:1 | return ... |
| test.cpp:410:26:410:26 | o | null | test.cpp:410:6:410:18 | ensureNotNull |
| test.cpp:410:26:410:26 | o | null | test.cpp:411:11:411:18 | ExprStmt |
| test.cpp:411:7:411:8 | ! ... | false | test.cpp:410:6:410:18 | ensureNotNull |
| test.cpp:411:7:411:8 | ! ... | false | test.cpp:412:1:412:1 | return ... |
| test.cpp:411:7:411:8 | ! ... | true | test.cpp:410:6:410:18 | ensureNotNull |
| test.cpp:411:7:411:8 | ! ... | true | test.cpp:411:11:411:18 | ExprStmt |
| test.cpp:411:8:411:8 | o | false | test.cpp:410:6:410:18 | ensureNotNull |
| test.cpp:411:8:411:8 | o | false | test.cpp:411:11:411:18 | ExprStmt |
| test.cpp:411:8:411:8 | o | not null | test.cpp:410:6:410:18 | ensureNotNull |
| test.cpp:411:8:411:8 | o | not null | test.cpp:412:1:412:1 | return ... |
| test.cpp:411:8:411:8 | o | null | test.cpp:410:6:410:18 | ensureNotNull |
| test.cpp:411:8:411:8 | o | null | test.cpp:411:11:411:18 | ExprStmt |
| test.cpp:411:8:411:8 | o | true | test.cpp:410:6:410:18 | ensureNotNull |
| test.cpp:411:8:411:8 | o | true | test.cpp:412:1:412:1 | return ... |
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