[clang] [dataflow] Add global condition to DataflowAnalysisContext (PR #65949)

[Sam McCall via cfe-commits]

================
@@ -172,27 +179,33 @@ bool DataflowAnalysisContext::equivalentFormulas(const Formula &Val1,
 }
 
 void DataflowAnalysisContext::addTransitiveFlowConditionConstraints(
-    Atom Token, llvm::SetVector<const Formula *> &Constraints,
-    llvm::DenseSet<Atom> &VisitedTokens) {
-  auto Res = VisitedTokens.insert(Token);
-  if (!Res.second)
-    return;
-
-  auto ConstraintsIt = FlowConditionConstraints.find(Token);
-  if (ConstraintsIt == FlowConditionConstraints.end()) {
-    Constraints.insert(&arena().makeAtomRef(Token));
-  } else {
-    // Bind flow condition token via `iff` to its set of constraints:
-    // FC <=> (C1 ^ C2 ^ ...), where Ci are constraints
-    Constraints.insert(&arena().makeEquals(arena().makeAtomRef(Token),
-                                           *ConstraintsIt->second));
-  }
+    Atom Token, llvm::SetVector<const Formula *> &Constraints) {
+  llvm::DenseSet<Atom> AddedTokens;
+  std::vector<Atom> Remaining = {Token};
+
+  if (GlobalConstraints)
+    Constraints.insert(GlobalConstraints);
+  // Define all the flow conditions that might be referenced in constraints.
+  while (!Remaining.empty()) {
+    auto Token = Remaining.back();
+    Remaining.pop_back();
+    if (!AddedTokens.insert(Token).second)
+      continue;
+
+    auto ConstraintsIt = FlowConditionConstraints.find(Token);
+    if (ConstraintsIt == FlowConditionConstraints.end()) {
+      Constraints.insert(&arena().makeAtomRef(Token));
+    } else {
+      // Bind flow condition token via `iff` to its set of constraints:
+      // FC <=> (C1 ^ C2 ^ ...), where Ci are constraints
+      Constraints.insert(&arena().makeEquals(arena().makeAtomRef(Token),
+                                             *ConstraintsIt->second));
+    }
----------------
sam-mccall wrote:

braces are required here because the `else` has a comment and the `then` should be consistent with it

https://llvm.org/docs/CodingStandards.html#don-t-use-braces-on-simple-single-statement-bodies-of-if-else-loop-statements

https://github.com/llvm/llvm-project/pull/65949