/*
* Merge two type sets into an aggregate set. If one of the sets
* is a subset of the other, then that other subset is returned;
* if the two sets are equal, then the ss1 instance is returned.
*
* If merging is not possible (incompatible basic types), then
* null is returned, and err is set to an appropriate error
* message. Otherwise, the merged type is returned, and err is
* set to null.
*/
internal static CCTypeSet MergeNF(CCTypeSet ss1, CCTypeSet ss2,
out string err)
{
err = null;
if (ss2.IsSubsetOf(ss1))
{
return(ss1);
}
if (ss1.IsSubsetOf(ss2))
{
return(ss2);
}
/*
* Handling of restricted types relies on the following
* features:
*
* - A CCTypeSet that contains a restricted type can
* only contain that restricted type, none other.
*
* - Restricted types cannot have allocation nodes,
* variants, or be std::type.
*
* - The tests with IsSubsetOf() above have already
* ruled out the case of two identical restricted types.
*/
if (ss1.types.Count == 1 && ss2.types.Count == 1)
{
CCType ct1 = ss1.types.Min;
CCType ct2 = ss2.types.Min;
if (ct1.xType.IsRestricted || ct2.xType.IsRestricted)
{
err = string.Format("forbidden type merging between {0} and {1}", ct1, ct2);
return(null);
}
}
CCTypeSet ss3 = new CCTypeSet();
foreach (CCType t in ss1.types)
{
ss3.types.Add(t);
ss3.xTypes.Add(t.xType);
}
foreach (CCType t in ss2.types)
{
ss3.types.Add(t);
ss3.xTypes.Add(t.xType);
}
return(ss3);
}
internal CCLocals Set(int index, CCTypeSet cts)
{
CCTypeSet octs = locals[index];
if (!cts.IsSubsetOf(octs))
{
CCLocals r = new CCLocals(locals.Length);
Array.Copy(locals, 0, r.locals, 0, locals.Length);
r.locals[index] = cts;
return(r);
}
else
{
return(this);
}
}
internal static CCLocals MergeNF(
CCLocals l1, CCLocals l2, out string err)
{
err = null;
if (object.ReferenceEquals(l1, l2))
{
return(l1);
}
int n = l1.locals.Length;
if (n != l2.locals.Length)
{
err = string.Format("internal error: mismatch on number of locals ({0} / {1})", n, l2.locals.Length);
return(null);
}
/*
* Merge entries one by one. The destination is lazily
* updated to avoid allocation when not needed.
*/
bool r1ok = true, r2ok = true;
CCTypeSet[] nlocals = null;
for (int i = 0; i < n; i++)
{
CCTypeSet cts1 = l1.locals[i];
CCTypeSet cts2 = l2.locals[i];
if (cts1.Equals(cts2))
{
if (nlocals != null)
{
nlocals[i] = cts1;
}
}
else if (cts1.IsSubsetOf(cts2))
{
r1ok = false;
if (r2ok)
{
continue;
}
if (nlocals != null)
{
nlocals[i] = cts2;
}
}
else if (cts2.IsSubsetOf(cts1))
{
r2ok = false;
if (r1ok)
{
continue;
}
if (nlocals != null)
{
nlocals[i] = cts1;
}
}
else
{
if (nlocals == null)
{
r1ok = false;
r2ok = false;
nlocals = new CCTypeSet[n];
Array.Copy(l1.locals, 0, nlocals, 0, i);
}
CCTypeSet cts = CCTypeSet.MergeNF(
cts1, cts2, out err);
if (cts == null)
{
return(null);
}
nlocals[i] = cts;
}
}
if (r1ok)
{
return(l1);
}
if (r2ok)
{
return(l2);
}
return(new CCLocals(nlocals));
}