Don't flag idempotent '+' or '-' warnings for pointer arithmetic (typically false positives).
Fixes <rdar://problem/8601243>.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@117635 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Checker/IdempotentOperationChecker.cpp b/lib/Checker/IdempotentOperationChecker.cpp
index 3dcbea4..7b9ff75 100644
--- a/lib/Checker/IdempotentOperationChecker.cpp
+++ b/lib/Checker/IdempotentOperationChecker.cpp
@@ -629,6 +629,13 @@
// The next cases require recursion for subexpressions
case Stmt::BinaryOperatorClass: {
const BinaryOperator *B = cast<const BinaryOperator>(Ex);
+
+ // Exclude cases involving pointer arithmetic. These are usually
+ // false positives.
+ if (B->getOpcode() == BO_Sub || B->getOpcode() == BO_Add)
+ if (B->getLHS()->getType()->getAs<PointerType>())
+ return false;
+
return CanVary(B->getRHS(), AC)
|| CanVary(B->getLHS(), AC);
}
diff --git a/test/Analysis/idempotent-operations.c b/test/Analysis/idempotent-operations.c
index c673f00..197357f 100644
--- a/test/Analysis/idempotent-operations.c
+++ b/test/Analysis/idempotent-operations.c
@@ -224,3 +224,13 @@
return pred;
}
+// <rdar://problem/8601243> - Don't warn on pointer arithmetic. This
+// is often idiomatic.
+unsigned rdar8601243_aux(unsigned n);
+void rdar8601243() {
+ char arr[100];
+ char *start = arr;
+ start = start + rdar8601243_aux(sizeof(arr) - (arr - start)); // no-warning
+ (void) start;
+}
+