internal override void AnalyseFlow()
{
switch (flowAnalysis)
{
case 0:
break;
case 1:
return;
default:
throw new Exception("recursive call detected in '"
+ Name + "'");
}
flowAnalysis = 2;
int n = Code.Length;
int[] sa = new int[n];
for (int i = 0; i < n; i++)
{
sa[i] = Int32.MinValue;
}
sa[0] = 0;
int[] toExplore = new int[n];
int tX = 0, tY = 0;
int off = 0;
int exitSA = Int32.MinValue;
int mds = 0;
int mrs = 0;
int maxDepth = 0;
for (;;)
{
Opcode op = Code[off];
bool mft = op.MayFallThrough;
int c = sa[off];
int a;
if (op is OpcodeCall)
{
Word w = op.GetReference(TC);
w.AnalyseFlow();
SType se = w.StackEffect;
if (!se.IsKnown)
{
throw new Exception(string.Format(
"call from '{0}' to '{1}'"
+ " with unknown stack effect",
Name, w.Name));
}
if (se.NoExit)
{
mft = false;
a = 0;
}
else
{
a = se.DataOut - se.DataIn;
}
mds = Math.Max(mds, c + w.MaxDataStack);
mrs = Math.Max(mrs, w.MaxReturnStack);
maxDepth = Math.Min(maxDepth, c - se.DataIn);
}
else if (op is OpcodeRet)
{
if (exitSA == Int32.MinValue)
{
exitSA = c;
}
else if (exitSA != c)
{
throw new Exception(string.Format(
"'{0}': exit stack action"
+ " mismatch: {1} / {2}"
+ " (offset {3})",
Name, exitSA, c, off));
}
a = 0;
}
else
{
a = op.StackAction;
mds = Math.Max(mds, c + a);
}
c += a;
maxDepth = Math.Min(maxDepth, c);
int j = op.JumpDisp;
if (j != 0)
{
j += off + 1;
toExplore[tY++] = j;
MergeSA(sa, j, c);
}
off++;
if (!mft || !MergeSA(sa, off, c))
{
if (tX < tY)
{
off = toExplore[tX++];
}
else
{
break;
}
}
}
maxDataStack = mds;
maxReturnStack = 1 + NumLocals + mrs;
/*
* TODO: see about this warning. Usage of a 'fail'
* word (that does not exit) within a 'case..endcase'
* structure will make an unreachable opcode. In a future
* version we might want to automatically remove dead
* opcodes.
* for (int i = 0; i < n; i ++) {
* if (sa[i] == Int32.MinValue) {
* Console.WriteLine("warning: word '{0}',"
+ " offset {1}: unreachable opcode",
+ Name, i);
+ continue;
+ }
+ }
*/
SType computed;
if (exitSA == Int32.MinValue)
{
computed = new SType(-maxDepth, -1);
}
else
{
computed = new SType(-maxDepth, -maxDepth + exitSA);
}
if (StackEffect.IsKnown)
{
if (!computed.IsSubOf(StackEffect))
{
throw new Exception(string.Format(
"word '{0}':"
+ " computed stack effect {1}"
+ " does not match declared {2}",
Name, computed.ToString(),
StackEffect.ToString()));
}
}
else
{
StackEffect = computed;
}
flowAnalysis = 1;
}