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C++: Fix global flow without an SSA definition #12740

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MathiasVP wants to merge 3 commits into from
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C++: Fix global flow without an SSA definition #12740

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dbfea8e
C++: Add failing test.
MathiasVP Apr 2, 2023
adfa5a5
C++: Fix an issue where we didn't create 'GlobalUse' dataflow nodes w…
MathiasVP Mar 31, 2023
87b6c5a
C++: Accept test changes.
MathiasVP Apr 2, 2023
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8 changes: 5 additions & 3 deletions cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaInternals.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -155,11 +155,13 @@ private newtype TDefOrUseImpl =
TGlobalUse(GlobalLikeVariable v, IRFunction f, int indirectionIndex) {
// Represents a final "use" of a global variable to ensure that
// the assignment to a global variable isn't ruled out as dead.
exists(VariableAddressInstruction vai, int defIndex |
exists(VariableAddressInstruction vai, int i |
vai.getEnclosingIRFunction() = f and
vai.getAstVariable() = v and
isDef(_, _, _, vai, _, defIndex) and
indirectionIndex = [0 .. defIndex] + 1
indirectionIndex = [0 .. i] + 1
|
isDef(_, _, _, vai, indirectionIndex, i) or
isUse(_, _, vai, indirectionIndex, i)
)
} or
TGlobalDefImpl(GlobalLikeVariable v, IRFunction f, int indirectionIndex) {
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1 change: 1 addition & 0 deletions cpp/ql/test/library-tests/dataflow/dataflow-tests/dataflow-consistency.expected
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Expand Up @@ -44,6 +44,7 @@ postWithInFlow
| example.c:28:23:28:25 | pos [inner post update] | PostUpdateNode should not be the target of local flow. |
| globals.cpp:13:5:13:19 | flowTestGlobal1 [post update] | PostUpdateNode should not be the target of local flow. |
| globals.cpp:23:5:23:19 | flowTestGlobal2 [post update] | PostUpdateNode should not be the target of local flow. |
| globals.cpp:34:18:34:18 | x [post update] | PostUpdateNode should not be the target of local flow. |
| lambdas.cpp:23:3:23:14 | v [post update] | PostUpdateNode should not be the target of local flow. |
| lambdas.cpp:43:3:43:3 | c [post update] | PostUpdateNode should not be the target of local flow. |
| ref.cpp:11:5:11:7 | lhs [post update] | PostUpdateNode should not be the target of local flow. |
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17 changes: 17 additions & 0 deletions cpp/ql/test/library-tests/dataflow/dataflow-tests/globals.cpp
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Expand Up @@ -22,3 +22,20 @@ void readGlobal2() {
void writeGlobal2() {
flowTestGlobal2 = source();
}

namespace MyNamespace {
struct A {
int x;
};

A global_a;

void set_without_ssa_def() {
global_a.x = source();
}

void call_set_without_ssa_def() {
set_without_ssa_def();
sink(global_a.x); // $ ir MISSING: ast
}
}