[PATCH] D110910: [analyzer][solver] Fix CmpOpTable handling bug

[Gabor Marton via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG792be5df92e8: [analyzer][solver] Fix CmpOpTable handling bug (authored by martong).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D110910/new/

https://reviews.llvm.org/D110910

Files:
  clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
  clang/test/Analysis/constraint_manager_conditions.cpp


Index: clang/test/Analysis/constraint_manager_conditions.cpp
===================================================================
--- clang/test/Analysis/constraint_manager_conditions.cpp
+++ clang/test/Analysis/constraint_manager_conditions.cpp
@@ -211,3 +211,17 @@
       clang_analyzer_eval(y != x); // expected-warning{{FALSE}}
     }
 }
+
+// Test the logic of reaching the `Unknonw` tristate in CmpOpTable.
+void cmp_op_table_unknownX2(int x, int y, int z) {
+  if (x >= y) {
+                    // x >= y    [1, 1]
+    if (x + z < y)
+      return;
+                    // x + z < y [0, 0]
+    if (z != 0)
+      return;
+                    // x < y     [0, 0]
+    clang_analyzer_eval(x > y);  // expected-warning{{TRUE}} expected-warning{{FALSE}}
+  }
+}
Index: clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -1112,7 +1112,7 @@
     if (!SSE)
       return llvm::None;
 
-    BinaryOperatorKind CurrentOP = SSE->getOpcode();
+    const BinaryOperatorKind CurrentOP = SSE->getOpcode();
 
     // We currently do not support <=> (C++20).
     if (!BinaryOperator::isComparisonOp(CurrentOP) || (CurrentOP == BO_Cmp))
@@ -1126,7 +1126,12 @@
 
     SymbolManager &SymMgr = State->getSymbolManager();
 
-    int UnknownStates = 0;
+    // We use this variable to store the last queried operator (`QueriedOP`)
+    // for which the `getCmpOpState` returned with `Unknown`. If there are two
+    // different OPs that returned `Unknown` then we have to query the special
+    // `UnknownX2` column. We assume that `getCmpOpState(CurrentOP, CurrentOP)`
+    // never returns `Unknown`, so `CurrentOP` is a good initial value.
+    BinaryOperatorKind LastQueriedOpToUnknown = CurrentOP;
 
     // Loop goes through all of the columns exept the last one ('UnknownX2').
     // We treat `UnknownX2` column separately at the end of the loop body.
@@ -1163,15 +1168,18 @@
           CmpOpTable.getCmpOpState(CurrentOP, QueriedOP);
 
       if (BranchState == OperatorRelationsTable::Unknown) {
-        if (++UnknownStates == 2)
-          // If we met both Unknown states.
+        if (LastQueriedOpToUnknown != CurrentOP &&
+            LastQueriedOpToUnknown != QueriedOP) {
+          // If we got the Unknown state for both different operators.
           // if (x <= y)    // assume true
           //   if (x != y)  // assume true
           //     if (x < y) // would be also true
           // Get a state from `UnknownX2` column.
           BranchState = CmpOpTable.getCmpOpStateForUnknownX2(CurrentOP);
-        else
+        } else {
+          LastQueriedOpToUnknown = QueriedOP;
           continue;
+        }
       }
 
       return (BranchState == OperatorRelationsTable::True) ? getTrueRange(T)


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