[analyzer] Also transform "a < b" to "(b - a) > 0" in the constraint manager.

We can support the full range of comparison operations between two locations
by canonicalizing them as subtraction, as in the previous commit.

This won't work (well) if either location includes an offset, or (again)
if the comparisons are not consistent about which region comes first.

<rdar://problem/13239003>

llvm-svn: 177803

1 files changed, 44 insertions, 0 deletions

diff --git a/clang/test/Analysis/ptr-arith.c b/clang/test/Analysis/ptr-arith.c
index d9c5a0ff999..35faff4a170 100644
--- a/clang/test/Analysis/ptr-arith.c
+++ b/clang/test/Analysis/ptr-arith.c
@@ -204,6 +204,50 @@ void zero_implies_equal(int *lhs, int *rhs) {
   clang_analyzer_eval(lhs != rhs); // expected-warning{{TRUE}}
 }
 
+void comparisons_imply_size(int *lhs, int *rhs) {
+  clang_analyzer_eval(lhs <= rhs); // expected-warning{{UNKNOWN}}
+
+  if (lhs > rhs) {
+    clang_analyzer_eval((rhs - lhs) == 0); // expected-warning{{FALSE}}
+    return;
+  }
+
+  clang_analyzer_eval(lhs <= rhs); // expected-warning{{TRUE}}
+  clang_analyzer_eval((rhs - lhs) >= 0); // expected-warning{{TRUE}}
+  clang_analyzer_eval((rhs - lhs) > 0); // expected-warning{{UNKNOWN}}
+
+  if (lhs >= rhs) {
+    clang_analyzer_eval((rhs - lhs) == 0); // expected-warning{{TRUE}}
+    return;
+  }
+
+  clang_analyzer_eval(lhs == rhs); // expected-warning{{FALSE}}
+  clang_analyzer_eval(lhs < rhs); // expected-warning{{TRUE}}
+  clang_analyzer_eval((rhs - lhs) > 0); // expected-warning{{TRUE}}
+}
+
+void size_implies_comparison(int *lhs, int *rhs) {
+  clang_analyzer_eval(lhs <= rhs); // expected-warning{{UNKNOWN}}
+
+  if ((rhs - lhs) < 0) {
+    clang_analyzer_eval(lhs == rhs); // expected-warning{{FALSE}}
+    return;
+  }
+
+  clang_analyzer_eval(lhs <= rhs); // expected-warning{{TRUE}}
+  clang_analyzer_eval((rhs - lhs) >= 0); // expected-warning{{TRUE}}
+  clang_analyzer_eval((rhs - lhs) > 0); // expected-warning{{UNKNOWN}}
+
+  if ((rhs - lhs) <= 0) {
+    clang_analyzer_eval(lhs == rhs); // expected-warning{{TRUE}}
+    return;
+  }
+
+  clang_analyzer_eval(lhs == rhs); // expected-warning{{FALSE}}
+  clang_analyzer_eval(lhs < rhs); // expected-warning{{TRUE}}
+  clang_analyzer_eval((rhs - lhs) > 0); // expected-warning{{TRUE}}
+}
+
 //-------------------------------
 // False positives
 //-------------------------------