libphobos/testsuite/libphobos.gc/precisegc.d

   1 // precise GC related:
   2 // https://issues.dlang.org/show_bug.cgi?id=3463
   3 // https://issues.dlang.org/show_bug.cgi?id=4358
   4 // https://issues.dlang.org/show_bug.cgi?id=9094
   5 // https://issues.dlang.org/show_bug.cgi?id=13801
   6 // https://issues.dlang.org/show_bug.cgi?id=18900
   7 module testgc;
   8
   9 import core.memory;
  10 import core.stdc.stdio;
  11
  12 class C
  13 {
  14     __gshared int dtors;
  15     ~this() { dtors++; }
  16
  17     C next;
  18     size_t val;
  19 }
  20
  21 struct S
  22 {
  23     __gshared int dtors;
  24     ~this() { dtors++; }
  25
  26     size_t val;
  27     S* next;
  28 }
  29
  30 struct L
  31 {
  32     __gshared int dtors;
  33     ~this() { dtors++; }
  34
  35     size_t[1000] data;
  36     S* node;
  37 }
  38
  39 struct Roots
  40 {
  41     C c;
  42     S *s;
  43     L *l;
  44 };
  45
  46 Roots* roots;
  47 size_t iroots;
  48
  49 void init()
  50 {
  51     roots = new Roots;
  52     roots.c = new C;
  53     roots.c.next = new C;
  54
  55     roots.s = new S;
  56     roots.s.next = new S;
  57
  58     roots.l = new L;
  59     roots.l.node = new S;
  60 }
  61
  62 void verifyPointers()
  63 {
  64     assert(C.dtors == 0);
  65     assert(S.dtors == 0);
  66     assert(L.dtors == 0);
  67 }
  68
  69 // compiling with -gx should help eliminating false pointers on the stack
  70 Roots makeFalsePointers()
  71 {
  72     roots.c.val = cast(size_t) cast(void*) roots.c.next;
  73     roots.c.next = null;
  74     roots.s.val = cast(size_t) cast(void*) roots.s.next;
  75     roots.s.next = null;
  76     roots.l.data[7] = cast(size_t) cast(void*) roots.l.node;
  77     roots.l.node = null;
  78
  79     return Roots(null, null, null); // try to spill register contents
  80 }
  81
  82 Roots moveRoot()
  83 {
  84     iroots = cast(size_t)roots;
  85     roots = null;
  86
  87     return Roots(null, null, null); // try to spill register contents
  88 }
  89
  90 // compiling with -gx should help eliminating false pointers on the stack
  91 void verifyFalsePointers()
  92 {
  93     assert(C.dtors <= 1);
  94     if (C.dtors < 1) printf ("False pointers? C.dtors = %d, 1 expected\n", C.dtors);
  95     assert(S.dtors <= 2);
  96     if (S.dtors < 2) printf ("False pointers? S.dtors = %d, 2 expected\n", S.dtors);
  97     assert(L.dtors == 0);
  98 }
  99
 100 extern(C) __gshared string[] rt_options = [ "gcopt=gc:precise", "scanDataSeg=precise" ];
 101
 102 void main()
 103 {
 104     GC.collect(); // cleanup from unittests
 105
 106     init();
 107     GC.collect(); // should collect nothing
 108     verifyPointers();
 109
 110     makeFalsePointers();
 111     GC.collect(); // should collect roots.c.next, roots.s.next and roots.l.node
 112     verifyFalsePointers();
 113
 114     moveRoot();
 115     GC.collect(); // should collect all
 116
 117     version(Windows) // precise DATA scanning only implemented on Windows
 118     {
 119         assert(C.dtors <= 2);
 120         if (C.dtors < 2) printf ("False DATA pointers? C.dtors = %d, 2 expected\n", C.dtors);
 121         assert(S.dtors <= 3);
 122         if (S.dtors < 3) printf ("False DATA pointers? S.dtors = %d, 2 expected\n", S.dtors);
 123         assert(L.dtors <= 1);
 124         if (L.dtors < 1) printf ("False DATA pointers? L.dtors = %d, 1 expected\n", L.dtors);
 125     }
 126 }