[analyzer] Do not continue to analyze a path if the constraints contradict with builtin assume

[xazax.hun]

Summary

This is how asserts are working right now. This way the semantics of __builtin_assume will be identical to asserts.

I also moved the tests to another file.

[NoQ]

Hmm, yeah, right :)

cfe/trunk/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp

case Builtin::BI__builtin_assume: {
     assert (CE->arg_begin() != CE->arg_end());
     SVal ArgSVal = state->getSVal(CE->getArg(0), LCtx);
     if (ArgSVal.isUndef())
       return true; // Return true to model purity.
 
     state = state->assume(ArgSVal.castAs<DefinedOrUnknownSVal>(), true);
     // FIXME: do we want to warn here? Not right now. The most reports might
     // come from infeasible paths, thus being false positives.
-    if (!state)
+    if (!state) {
+      C.generateSink(C.getState(), C.getPredecessor());
       return true;
+    }
 
     C.addTransition(state);
     return true;
   }
 
   case Builtin::BI__builtin_unpredictable:
   case Builtin::BI__builtin_expect:
   case Builtin::BI__builtin_assume_aligned:

cfe/trunk/test/Analysis/builtin-assume.c

-// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -verify %s
-
-void clang_analyzer_eval(int);
-
-void f(int i) {
-  __builtin_assume(i < 10);
-  clang_analyzer_eval(i < 15); // expected-warning {{TRUE}}
-}

cfe/trunk/test/Analysis/builtin-functions.cpp

 // RUN: %clang_analyze_cc1 -triple x86_64-apple-darwin10 -analyzer-checker=core,debug.ExprInspection %s -std=c++11 -verify
 
 void clang_analyzer_eval(bool);
+void clang_analyzer_warnIfReached();
 
 void testAddressof(int x) {
   clang_analyzer_eval(&x == __builtin_addressof(x)); // expected-warning{{TRUE}}
 }
 
 void testSize() {
   struct {
     int x;

 }
 
 void test_assume_aligned_4(char *p) {
   char *q;
 
   q = (char*) __builtin_assume_aligned(p + 1, 16);
   clang_analyzer_eval(p == q); // expected-warning{{FALSE}}
 }
+
+void f(int i) {
+  __builtin_assume(i < 10);
+  clang_analyzer_eval(i < 15); // expected-warning {{TRUE}}
+}
+
+void g(int i) {
+  if (i > 5) {
+    __builtin_assume(i < 5);
+    clang_analyzer_warnIfReached(); // Assumtion contradicts constraints.
+                                    // We give up the analysis on this path.
+  }
+}