[analyzer] Provide .def-files and visitors for SVal/SymExpr/MemRegion.

Provide separate visitor templates for the three hierarchies, and also
the `FullSValVisitor' class, which is a union of all three visitors.

Additionally, add a particular example visitor, `SValExplainer', in order to
test the visitor templates. This visitor is capable of explaining the SVal,
SymExpr, or MemRegion in a natural language.

Differential Revision: http://reviews.llvm.org/D15448


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@257605 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 35 insertions, 0 deletions

diff --git a/docs/analyzer/DebugChecks.rst b/docs/analyzer/DebugChecks.rst
index 771e39fc43..bfa3142efb 100644
--- a/docs/analyzer/DebugChecks.rst
+++ b/docs/analyzer/DebugChecks.rst
@@ -162,6 +162,41 @@ ExprInspection checks
     } while(0);  // expected-warning{{SYMBOL DEAD}}
 
 
+- void clang_analyzer_explain(a single argument of any type);
+
+  This function explains the value of its argument in a human-readable manner
+  in the warning message. You can make as many overrides of its prototype
+  in the test code as necessary to explain various integral, pointer,
+  or even record-type values.
+
+  Example usage::
+
+    void clang_analyzer_explain(int);
+    void clang_analyzer_explain(void *);
+
+    void foo(int param, void *ptr) {
+      clang_analyzer_explain(param); // expected-warning{{argument 'param'}}
+      if (!ptr)
+        clang_analyzer_explain(ptr); // expected-warning{{memory address '0'}}
+    }
+
+- size_t clang_analyzer_getExtent(void *);
+
+  This function returns the value that represents the extent of a memory region
+  pointed to by the argument. This value is often difficult to obtain otherwise,
+  because no valid code that produces this value. However, it may be useful
+  for testing purposes, to see how well does the analyzer model region extents.
+
+  Example usage::
+
+    void foo() {
+      int x, *y;
+      size_t xs = clang_analyzer_getExtent(&x);
+      clang_analyzer_explain(xs); // expected-warning{{'4'}}
+      size_t ys = clang_analyzer_getExtent(&y);
+      clang_analyzer_explain(ys); // expected-warning{{'8'}}
+    }
+
 Statistics
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