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C++: Use SEH exception edges in IR and generate SEH exception edges for calls in __try blocks #19746

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Merged
MathiasVP merged 7 commits into from
Jun 16, 2025
Merged

C++: Use SEH exception edges in IR and generate SEH exception edges for calls in __try blocks #19746

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0038d0f
C++: Deprecate `ThrowingFunction` and no longer use in IR
jketema Dec 10, 2024
6f41d3c
C++: Use SEH exception edges for functions that unconditionally throw…
jketema Dec 10, 2024
400424f
C++: Add change note
jketema Dec 13, 2024
c7a7447
C++: Generate an SEH exception edge for each call inside a SEH block
jketema Dec 10, 2024
4a42ca8
C++: Limit SEH exception edges to calls in `__try` blocks
jketema Jun 13, 2025
815ae37
C++: Add test case with call in initialization
jketema Jun 13, 2025
1b2813d
C++: Also generate an SEH edge for calls in initializers
jketema Jun 13, 2025
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2 changes: 1 addition & 1 deletion cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/internal/TranslatedCall.qll
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Expand Up @@ -364,7 +364,7 @@ class TranslatedFunctionCall extends TranslatedCallExpr, TranslatedDirectCall {
final override predicate mayThrowException(ExceptionEdge e) {
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Copilot AI Jun 13, 2025

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The override for mayThrowException in TranslatedFunctionCall no longer delegates to ThrowingFunction for C++ exception edges. You should add a branch such as e instanceof CppExceptionEdge and expr.getTarget().(ThrowingFunction).mayThrowException(e) to restore C++ exception support.

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@jketema jketema Jun 13, 2025

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That's on purpose, Copilot.

this.mustThrowException(e)
or
exists(MicrosoftTryStmt tryStmt | tryStmt.getStmt().getAChild*() = expr) and
exists(MicrosoftTryStmt tryStmt | tryStmt.getStmt() = expr.getEnclosingStmt().getParent*()) and
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@MathiasVP MathiasVP Jun 16, 2025

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Good catch! 🚀

e instanceof SehExceptionEdge
}

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51 changes: 45 additions & 6 deletions cpp/ql/test/library-tests/ir/ir/aliased_ir.expected
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Expand Up @@ -39210,13 +39210,52 @@ try_except.c:
# 49| r49_3(int) = Call[i] : func:r49_2
# 49| m49_4(unknown) = ^CallSideEffect : ~m46_4
# 49| m49_5(unknown) = Chi : total:m46_4, partial:m49_4
# 49| m49_6(int) = Store[y] : &:r49_1, r49_3
# 54| v54_1(void) = NoOp :
# 46| v46_7(void) = ReturnVoid :
# 46| v46_8(void) = AliasedUse : ~m49_5
# 46| v46_9(void) = ExitFunction :
#-----| Goto -> Block 1
#-----| SEH Exception -> Block 4

# 49| Block 1
# 49| m49_6(int) = Store[y] : &:r49_1, r49_3
#-----| Goto -> Block 6

# 51| Block 2
# 51| r51_1(int) = Constant[0] :
# 51| r51_2(bool) = CompareEQ : r51_7, r51_1
# 51| v51_3(void) = ConditionalBranch : r51_2
#-----| False -> Block 3
#-----| True -> Block 7

# 51| Block 3
# 51| r51_4(int) = Constant[1] :
# 51| r51_5(bool) = CompareEQ : r51_7, r51_4
# 51| v51_6(void) = ConditionalBranch : r51_5
#-----| False -> Block 7
#-----| True -> Block 5

# 51| Block 4
# 51| r51_7(int) = Constant[1] :
# 51| r51_8(int) = Constant[-1] :
# 51| r51_9(bool) = CompareEQ : r51_7, r51_8
# 51| v51_10(void) = ConditionalBranch : r51_9
#-----| False -> Block 2
#-----| True -> Block 7

# 52| Block 5
# 52| r52_1(glval<unknown>) = FunctionAddress[sink] :
# 52| r52_2(glval<int>) = VariableAddress[x] :
# 52| r52_3(int) = Load[x] : &:r52_2, m47_3
# 52| v52_4(void) = Call[sink] : func:r52_1, 0:r52_3
# 52| m52_5(unknown) = ^CallSideEffect : ~m49_5
# 52| m52_6(unknown) = Chi : total:m49_5, partial:m52_5
#-----| Goto -> Block 6

# 54| Block 6
# 54| m54_1(unknown) = Phi : from 1:~m49_5, from 5:~m52_6
# 54| v54_2(void) = NoOp :
# 46| v46_7(void) = ReturnVoid :
# 46| v46_8(void) = AliasedUse : ~m54_1
# 46| v46_9(void) = ExitFunction :

# 46| Block 1
# 46| Block 7
# 46| v46_10(void) = Unreached :

try_except.cpp:
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2 changes: 0 additions & 2 deletions cpp/ql/test/library-tests/ir/ir/raw_consistency.expected
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Expand Up @@ -21,8 +21,6 @@ lostReachability
backEdgeCountMismatch
useNotDominatedByDefinition
| ir.cpp:1535:8:1535:8 | Unary | Operand 'Unary' is not dominated by its definition in function '$@'. | ir.cpp:1535:8:1535:8 | void StructuredBindingDataMemberStruct::StructuredBindingDataMemberStruct() | void StructuredBindingDataMemberStruct::StructuredBindingDataMemberStruct() |
| try_except.c:51:13:51:13 | Left | Operand 'Left' is not dominated by its definition in function '$@'. | try_except.c:46:6:46:6 | void j(int) | void j(int) |
| try_except.c:51:13:51:13 | Left | Operand 'Left' is not dominated by its definition in function '$@'. | try_except.c:46:6:46:6 | void j(int) | void j(int) |
switchInstructionWithoutDefaultEdge
notMarkedAsConflated
wronglyMarkedAsConflated
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26 changes: 15 additions & 11 deletions cpp/ql/test/library-tests/ir/ir/raw_ir.expected
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Expand Up @@ -37484,8 +37484,8 @@ try_except.c:
# 49| r49_2(glval<unknown>) = FunctionAddress[i] :
# 49| r49_3(int) = Call[i] : func:r49_2
# 49| mu49_4(unknown) = ^CallSideEffect : ~m?
# 49| mu49_5(int) = Store[y] : &:r49_1, r49_3
#-----| Goto -> Block 7
#-----| Goto -> Block 3
#-----| SEH Exception -> Block 6

# 46| Block 1
# 46| v46_6(void) = AliasedUse : ~m?
Expand All @@ -37495,36 +37495,40 @@ try_except.c:
# 46| v46_8(void) = Unwind :
#-----| Goto -> Block 1

# 51| Block 3
# 49| Block 3
# 49| mu49_5(int) = Store[y] : &:r49_1, r49_3
#-----| Goto -> Block 8

# 51| Block 4
# 51| r51_1(int) = Constant[0] :
# 51| r51_2(bool) = CompareEQ : r51_7, r51_1
# 51| v51_3(void) = ConditionalBranch : r51_2
#-----| False -> Block 4
#-----| False -> Block 5
#-----| True -> Block 2

# 51| Block 4
# 51| Block 5
# 51| r51_4(int) = Constant[1] :
# 51| r51_5(bool) = CompareEQ : r51_7, r51_4
# 51| v51_6(void) = ConditionalBranch : r51_5
#-----| True -> Block 6
#-----| True -> Block 7

# 51| Block 5
# 51| Block 6
# 51| r51_7(int) = Constant[1] :
# 51| r51_8(int) = Constant[-1] :
# 51| r51_9(bool) = CompareEQ : r51_7, r51_8
# 51| v51_10(void) = ConditionalBranch : r51_9
#-----| False -> Block 3
#-----| False -> Block 4
#-----| True -> Block 2

# 52| Block 6
# 52| Block 7
# 52| r52_1(glval<unknown>) = FunctionAddress[sink] :
# 52| r52_2(glval<int>) = VariableAddress[x] :
# 52| r52_3(int) = Load[x] : &:r52_2, ~m?
# 52| v52_4(void) = Call[sink] : func:r52_1, 0:r52_3
# 52| mu52_5(unknown) = ^CallSideEffect : ~m?
#-----| Goto -> Block 7
#-----| Goto -> Block 8

# 54| Block 7
# 54| Block 8
# 54| v54_1(void) = NoOp :
# 46| v46_9(void) = ReturnVoid :
#-----| Goto -> Block 1
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