[analyzer] Unroll the loop when it has a unsigned counter.

[MTC]

Summary

The original implementation in the LoopUnrolling.cpp didn't consider the case where the counter is unsigned. This case is only handled in simpleCondition(), but this is not enough, we also need to deal with the unsinged counter with the counter initialization.

Since IntegerLiteral is signed, there is a ImplicitCastExpr<IntegralCast> in unsigned counter = IntergerLiteral. This patch add the ignoringParenImpCasts() in the IntegerLiteral matcher.

[george.karpenkov]

Looks reasonable

[szepet]

Yepp, thanks for the patch! One small typo below.

test/Analysis/loop-unrolling.cpp

50

typo: unsigned

[MTC]

Fix typo, unsinged -> unsigned

lib/StaticAnalyzer/Core/LoopUnrolling.cpp

return hasDescendant(stmt(
             getAddrTo(equalsBoundNode(NodeName)),
             assignedToRef(equalsBoundNode(NodeName)))));
 }
 
 static internal::Matcher<Stmt> forLoopMatcher() {
   return forStmt(
              hasCondition(simpleCondition("initVarName")),
              // Initialization should match the form: 'int i = 6' or 'i = 42'.
-             hasLoopInit(anyOf(
-                 declStmt(hasSingleDecl(varDecl(
-                     allOf(hasInitializer(integerLiteral().bind("initNum")),
+             hasLoopInit(
+                 anyOf(declStmt(hasSingleDecl(
+                           varDecl(allOf(hasInitializer(ignoringParenImpCasts(
+                                             integerLiteral().bind("initNum"))),
                                          equalsBoundNode("initVarName"))))),
-                 binaryOperator(hasLHS(declRefExpr(to(
-                                    varDecl(equalsBoundNode("initVarName"))))),
-                                hasRHS(integerLiteral().bind("initNum"))))),
+                       binaryOperator(hasLHS(declRefExpr(to(varDecl(
+                                          equalsBoundNode("initVarName"))))),
+                                      hasRHS(ignoringParenImpCasts(
+                                          integerLiteral().bind("initNum")))))),
              // Incrementation should be a simple increment or decrement
              // operator call.
              hasIncrement(unaryOperator(
                  anyOf(hasOperatorName("++"), hasOperatorName("--")),
                  hasUnaryOperand(declRefExpr(
                      to(varDecl(allOf(equalsBoundNode("initVarName"),
                                       hasType(isInteger())))))))),
              unless(hasBody(hasSuspiciousStmt("initVarName")))).bind("forLoop");

test/Analysis/loop-unrolling.cpp

for (int j = 0; j <= 9; ++j) {
     clang_analyzer_numTimesReached(); // expected-warning {{10}}
     a[j] = 42;
   }
 
   int b = 22 / (k - 42); // expected-warning {{Division by zero}}
   return 0;
 }
 
+int simple_unroll3_unsigned() {
+  int a[9];
+  int k = 42;
+  for (unsigned i = 0; i < 9; i++) {
+    clang_analyzer_numTimesReached(); // expected-warning {{9}}
+    a[i] = 42;
+  }
+  int b = 22 / (k - 42); // expected-warning {{Division by zero}}
+  return 0;
+}
+
+int simple_unroll4_unsigned() {
+  int a[9];
+  int k = 42;
+  unsigned i;
+  for (i = (0); i < 9; i++) {
+    clang_analyzer_numTimesReached(); // expected-warning {{9}}
+    a[i] = 42;
+  }
+  int b = 22 / (k - 42); // expected-warning {{Division by zero}}
+  return 0;
+}
+
 int simple_no_unroll1() {
   int a[9];
   int k = 42;
   for (int i = 0; i < 9; i++) {
     clang_analyzer_numTimesReached(); // expected-warning {{4}}
     a[i] = 42;
     foo(i);
   }