clang/test/Analysis/infeasible-sink.c

   1 // RUN: %clang_analyze_cc1 %s \
   2 // RUN:   -analyzer-checker=core \
   3 // RUN:   -analyzer-checker=debug.ExprInspection \
   4 // RUN:   -analyzer-config eagerly-assume=false \
   5 // RUN:   -verify
   6
   7 // Here we test that if it turns out that the parent state is infeasible then
   8 // both children States (more precisely the ExplodedNodes) are marked as a
   9 // Sink.
  10 // We rely on existing defects of the underlying constraint solver. However,
  11 // in the future we might strengthen the solver to discover the infeasibility
  12 // right when we create the parent state. At that point some of these tests
  13 // will fail, and either we shall find another solver weakness to have the test
  14 // case functioning, or we shall simply remove that.
  15
  16 void clang_analyzer_warnIfReached();
  17 void clang_analyzer_eval(int);
  18
  19 void test1(int x) {
  20   if (x * x != 4)
  21     return;
  22   if (x < 0 || x > 1)
  23     return;
  24
  25   // { x^2 == 4 and x:[0,1] }
  26   // This state is already infeasible.
  27
  28   // Perfectly constraining 'x' will trigger constant folding,
  29   // when we realize we were already infeasible.
  30   // The same happens for the 'else' branch.
  31   if (x == 0) {
  32     clang_analyzer_warnIfReached(); // no-warning
  33   } else {
  34     clang_analyzer_warnIfReached(); // no-warning
  35   }
  36   clang_analyzer_warnIfReached(); // no-warning
  37   (void)x;
  38 }
  39
  40 int a, b, c, d, e;
  41 void test2() {
  42
  43   if (a == 0)
  44     return;
  45
  46   if (e != c)
  47     return;
  48
  49   d = e - c;
  50   b = d;
  51   a -= d;
  52
  53   if (a != 0)
  54     return;
  55
  56   clang_analyzer_warnIfReached(); // expected-warning{{REACHABLE}}
  57
  58   /* The BASELINE passes these checks ('wrning' is used to avoid lit to match)
  59   // The parent state is already infeasible, look at this contradiction:
  60   clang_analyzer_eval(b > 0);  // expected-wrning{{FALSE}}
  61   clang_analyzer_eval(b <= 0); // expected-wrning{{FALSE}}
  62   // Crashes with expensive checks.
  63   if (b > 0) {
  64     clang_analyzer_warnIfReached(); // no-warning, OK
  65     return;
  66   }
  67   // Should not be reachable.
  68   clang_analyzer_warnIfReached(); // expected-wrning{{REACHABLE}}
  69   */
  70
  71   // The parent state is already infeasible, but we realize that only if b is
  72   // constrained.
  73   clang_analyzer_eval(b > 0);  // expected-warning{{UNKNOWN}}
  74   clang_analyzer_eval(b <= 0); // expected-warning{{UNKNOWN}}
  75   if (b > 0) {
  76     clang_analyzer_warnIfReached(); // no-warning
  77     return;
  78   }
  79   clang_analyzer_warnIfReached(); // no-warning
  80 }