[analyzer] Make CloneDetector consider macro expansions.

So far macro-generated code was treated by the CloneDetector as normal code.
This caused that some macros where reported as false-positive clones because
large chunks of code coming from otherwise concise macro expansions were treated
as copy-pasted code.

This patch ensures that macros are treated in the same way as literals/function
calls. This prevents macros that expand into multiple statements
from being reported as clones.

Patch by Raphael Isemann!

Differential Revision: https://reviews.llvm.org/D23316

llvm-svn: 279367

1 files changed, 67 insertions, 0 deletions

diff --git a/clang/test/Analysis/copypaste/macros.cpp b/clang/test/Analysis/copypaste/macros.cpp
new file mode 100644
index 00000000000..170e034095d
--- /dev/null
+++ b/clang/test/Analysis/copypaste/macros.cpp
@@ -0,0 +1,67 @@
+// RUN: %clang_cc1 -analyze -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+
+// Tests that macros and non-macro clones aren't mixed into the same hash
+// group. This is currently necessary as all clones in a hash group need
+// to have the same complexity value. Macros have smaller complexity values
+// and need to be in their own hash group.
+
+int foo(int a) { // expected-warning{{Detected code clone.}}
+  a = a + 1;
+  a = a + 1 / 1;
+  a = a + 1 + 1 + 1;
+  a = a + 1 - 1 + 1 + 1;
+  a = a + 1 * 1 + 1 + 1 + 1;
+  a = a + 1 / 1 + 1 + 1 + 1;
+  return a;
+}
+
+int fooClone(int a) { // expected-note{{Related code clone is here.}}
+  a = a + 1;
+  a = a + 1 / 1;
+  a = a + 1 + 1 + 1;
+  a = a + 1 - 1 + 1 + 1;
+  a = a + 1 * 1 + 1 + 1 + 1;
+  a = a + 1 / 1 + 1 + 1 + 1;
+  return a;
+}
+
+// Below is the same AST as above but this time generated with macros. The
+// clones below should land in their own hash group for the reasons given above.
+
+#define ASSIGN(T, V) T = T + V
+
+int macro(int a) { // expected-warning{{Detected code clone.}}
+  ASSIGN(a, 1);
+  ASSIGN(a, 1 / 1);
+  ASSIGN(a, 1 + 1 + 1);
+  ASSIGN(a, 1 - 1 + 1 + 1);
+  ASSIGN(a, 1 * 1 + 1 + 1 + 1);
+  ASSIGN(a, 1 / 1 + 1 + 1 + 1);
+  return a;
+}
+
+int macroClone(int a) { // expected-note{{Related code clone is here.}}
+  ASSIGN(a, 1);
+  ASSIGN(a, 1 / 1);
+  ASSIGN(a, 1 + 1 + 1);
+  ASSIGN(a, 1 - 1 + 1 + 1);
+  ASSIGN(a, 1 * 1 + 1 + 1 + 1);
+  ASSIGN(a, 1 / 1 + 1 + 1 + 1);
+  return a;
+}
+
+// FIXME: Macros with empty definitions in the AST are currently ignored.
+
+#define EMPTY
+
+int fooFalsePositiveClone(int a) { // expected-note{{Related code clone is here.}}
+  a = EMPTY a + 1;
+  a = a + 1 / 1;
+  a = a + 1 + 1 + 1;
+  a = a + 1 - 1 + 1 + 1;
+  a = a + 1 * 1 + 1 + 1 + 1;
+  a = a + 1 / 1 + 1 + 1 + 1;
+  return a;
+}
+
+