[PATCH] D45086: [analyzer] Unroll the loop when it has a unsigned counter.

[Henry Wong via Phabricator via cfe-commits]

MTC created this revision.
MTC added reviewers: szepet, a.sidorin, NoQ.
Herald added subscribers: cfe-commits, rnkovacs, xazax.hun.
Herald added a reviewer: george.karpenkov.
MTC edited the summary of this revision.

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.


Repository:
  rC Clang

https://reviews.llvm.org/D45086

Files:
  lib/StaticAnalyzer/Core/LoopUnrolling.cpp
  test/Analysis/loop-unrolling.cpp


Index: test/Analysis/loop-unrolling.cpp
===================================================================
--- test/Analysis/loop-unrolling.cpp
+++ test/Analysis/loop-unrolling.cpp
@@ -36,6 +36,29 @@
   return 0;
 }
 
+int simple_unroll3_unsinged() {
+  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_unsinged() {
+  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;
Index: lib/StaticAnalyzer/Core/LoopUnrolling.cpp
===================================================================
--- lib/StaticAnalyzer/Core/LoopUnrolling.cpp
+++ lib/StaticAnalyzer/Core/LoopUnrolling.cpp
@@ -141,13 +141,15 @@
   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(


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