[PATCH] D63279: [Analyzer] Unroll for-loops where the upper boundary is a variable with know value

[Kristóf Umann via Phabricator via cfe-commits]

Szelethus added inline comments.


================
Comment at: lib/StaticAnalyzer/Core/LoopUnrolling.cpp:214-216
+  const Expr *BoundExpr = CondOp->getLHS()->IgnoreParenImpCasts();
+  if (BoundExpr == Matches[0].getNodeAs<Expr>("boundVarOperand"))
+    BoundExpr = CondOp->getRHS()->IgnoreParenImpCasts();
----------------
Alright, I stood on top of this for longer than I'd like to admit, what's happening here? Like, `CondExpr`, with the given testfile, should be `i < n`, right? Then `BoundExpr` is supposed to be `i`, and if that is equal to `Matches[0].getNodeAs<Expr>("boundVarOperand")` (which I guess is supposed to `n`), which I'm not sure how it could ever happen, we assign the RHS of the assignment to `BoundExpr`?

What does this do? Why is it needed? Which 2 test cases cover these lines?


================
Comment at: lib/StaticAnalyzer/Core/LoopUnrolling.cpp:221-230
+  if (BoundNumVal.isUnknown()) {
+    if (const auto *BoundDeclRefExpr = dyn_cast<DeclRefExpr>(BoundExpr)) {
+      // FIXME: Add other declarations such as Objective-C fields
+      if (const auto *BoundVarDecl =
+              dyn_cast<VarDecl>(BoundDeclRefExpr->getDecl())) {
+        BoundNumVal = State->getSVal(
+            State->getLValue(BoundVarDecl, Pred->getLocationContext()));
----------------
I don't see obvious test case for which `BoundNumVal` would be unknown, am I wrong?


Repository:
  rC Clang

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D63279/new/

https://reviews.llvm.org/D63279