[clang] 67e8421 - [analyzer][Solver] Teach SymbolicRangeInferrer about commutativity (2/2) (#112887)

[via cfe-commits]

Author: Balazs Benics
Date: 2024-10-18T16:15:33+02:00
New Revision: 67e84213f59e1f9485d15421bdb7243d25cee07e

URL: https://github.com/llvm/llvm-project/commit/67e84213f59e1f9485d15421bdb7243d25cee07e
DIFF: https://github.com/llvm/llvm-project/commit/67e84213f59e1f9485d15421bdb7243d25cee07e.diff

LOG: [analyzer][Solver] Teach SymbolicRangeInferrer about commutativity (2/2) (#112887)

This patch should not introduce much overhead as it only does one more
constraint map lookup, which is really quick.

Depends on #112583

Added: 
    

Modified: 
    clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
    clang/test/Analysis/unary-sym-expr.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
index ecf7974c838650..f0311b7028f56d 100644
--- a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -1249,6 +1249,8 @@ class SymbolicRangeInferrer
         // calculate the effective range set by intersecting the range set
         // for A - B and the negated range set of B - A.
         getRangeForNegatedSymSym(SSE),
+        // If commutative, we may have constaints for the commuted variant.
+        getRangeCommutativeSymSym(SSE),
         // If Sym is a comparison expression (except <=>),
         // find any other comparisons with the same operands.
         // See function description.
@@ -1485,6 +1487,21 @@ class SymbolicRangeInferrer
         Sym->getType());
   }
 
+  std::optional<RangeSet> getRangeCommutativeSymSym(const SymSymExpr *SSE) {
+    auto Op = SSE->getOpcode();
+    bool IsCommutative = llvm::is_contained(
+        // ==, !=, |, &, +, *, ^
+        {BO_EQ, BO_NE, BO_Or, BO_And, BO_Add, BO_Mul, BO_Xor}, Op);
+    if (!IsCommutative)
+      return std::nullopt;
+
+    SymbolRef Commuted = State->getSymbolManager().getSymSymExpr(
+        SSE->getRHS(), Op, SSE->getLHS(), SSE->getType());
+    if (const RangeSet *Range = getConstraint(State, Commuted))
+      return *Range;
+    return std::nullopt;
+  }
+
   // Returns ranges only for binary comparison operators (except <=>)
   // when left and right operands are symbolic values.
   // Finds any other comparisons with the same operands.

diff  --git a/clang/test/Analysis/unary-sym-expr.c b/clang/test/Analysis/unary-sym-expr.c
index 7c4774f3cca82f..92e11b295bee7c 100644
--- a/clang/test/Analysis/unary-sym-expr.c
+++ b/clang/test/Analysis/unary-sym-expr.c
@@ -29,12 +29,39 @@ int test(int x, int y) {
   return 42;
 }
 
-void test_svalbuilder_simplification(int x, int y) {
+void test_svalbuilder_simplification_add(int x, int y) {
   if (x + y != 3)
     return;
   clang_analyzer_eval(-(x + y) == -3); // expected-warning{{TRUE}}
-  // FIXME Commutativity is not supported yet.
-  clang_analyzer_eval(-(y + x) == -3); // expected-warning{{UNKNOWN}}
+  clang_analyzer_eval(-(y + x) == -3); // expected-warning{{TRUE}}
+}
+
+void test_svalbuilder_simplification_mul(int x, int y) {
+  if (x * y != 3)
+    return;
+  clang_analyzer_eval(-(x * y) == -3); // expected-warning{{TRUE}}
+  clang_analyzer_eval(-(y * x) == -3); // expected-warning{{TRUE}}
+}
+
+void test_svalbuilder_simplification_and(int x, int y) {
+  if ((x & y) != 3)
+    return;
+  clang_analyzer_eval(-(x & y) == -3); // expected-warning{{TRUE}}
+  clang_analyzer_eval(-(y & x) == -3); // expected-warning{{TRUE}}
+}
+
+void test_svalbuilder_simplification_or(int x, int y) {
+  if ((x | y) != 3)
+    return;
+  clang_analyzer_eval(-(x | y) == -3); // expected-warning{{TRUE}}
+  clang_analyzer_eval(-(y | x) == -3); // expected-warning{{TRUE}}
+}
+
+void test_svalbuilder_simplification_xor(int x, int y) {
+  if ((x ^ y) != 3)
+    return;
+  clang_analyzer_eval(-(x ^ y) == -3); // expected-warning{{TRUE}}
+  clang_analyzer_eval(-(y ^ x) == -3); // expected-warning{{TRUE}}
 }
 
 int test_fp(int flag) {