r328919 - [analyzer] Unroll the loop when it has a unsigned counter.

[Henry Wong via cfe-commits]

Author: henrywong
Date: Sat Mar 31 05:46:46 2018
New Revision: 328919

URL: http://llvm.org/viewvc/llvm-project?rev=328919&view=rev
Log:
[analyzer] Unroll the loop when it has a unsigned counter.

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.

Reviewers: szepet, a.sidorin, NoQ, george.karpenkov

Reviewed By: szepet, george.karpenkov

Subscribers: xazax.hun, rnkovacs, cfe-commits, MTC

Differential Revision: https://reviews.llvm.org/D45086

Modified:
    cfe/trunk/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
    cfe/trunk/test/Analysis/loop-unrolling.cpp

Modified: cfe/trunk/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/LoopUnrolling.cpp?rev=328919&r1=328918&r2=328919&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Core/LoopUnrolling.cpp (original)
+++ cfe/trunk/lib/StaticAnalyzer/Core/LoopUnrolling.cpp Sat Mar 31 05:46:46 2018
@@ -141,13 +141,15 @@ static internal::Matcher<Stmt> forLoopMa
   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")),
-                           equalsBoundNode("initVarName"))))),
-                 binaryOperator(hasLHS(declRefExpr(to(
-                                    varDecl(equalsBoundNode("initVarName"))))),
-                                hasRHS(integerLiteral().bind("initNum"))))),
+             hasLoopInit(
+                 anyOf(declStmt(hasSingleDecl(
+                           varDecl(allOf(hasInitializer(ignoringParenImpCasts(
+                                             integerLiteral().bind("initNum"))),
+                                         equalsBoundNode("initVarName"))))),
+                       binaryOperator(hasLHS(declRefExpr(to(varDecl(
+                                          equalsBoundNode("initVarName"))))),
+                                      hasRHS(ignoringParenImpCasts(
+                                          integerLiteral().bind("initNum")))))),
              // Incrementation should be a simple increment or decrement
              // operator call.
              hasIncrement(unaryOperator(

Modified: cfe/trunk/test/Analysis/loop-unrolling.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/loop-unrolling.cpp?rev=328919&r1=328918&r2=328919&view=diff
==============================================================================
--- cfe/trunk/test/Analysis/loop-unrolling.cpp (original)
+++ cfe/trunk/test/Analysis/loop-unrolling.cpp Sat Mar 31 05:46:46 2018
@@ -36,6 +36,29 @@ int simple_unroll2() {
   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;