/**
* Checks to see if the same invariant exists over supersequences of these variables:
*
* <p>(A[] op B[]) ^ (i == j) ==> A[i..] op B[j..] (A[] op B[]) ^ (i == j) ==> A[..i] op B[..j]
*/
private DiscardInfo superseq_implies(VarInfo[] vis) {
// Make sure the variables are SequenceScalarSubsequence with the same start/end
VarInfo v1 = vis[0];
VarInfo v2 = vis[1];
if (!v1.isDerived() || !(v1.derived instanceof SequenceScalarSubsequence)) return (null);
if (!v2.isDerived() || !(v2.derived instanceof SequenceScalarSubsequence)) return (null);
SequenceScalarSubsequence der1 = (SequenceScalarSubsequence) v1.derived;
SequenceScalarSubsequence der2 = (SequenceScalarSubsequence) v2.derived;
if ((der1.from_start != der2.from_start) || (der1.index_shift != der2.index_shift))
return (null);
// Make sure the subscripts are equal
DiscardInfo di = new DiscardInfo(this, DiscardCode.obvious, "");
if (!ppt.parent.check_implied_canonical(di, der1.sclvar(), der2.sclvar(), IntEqual.get_proto()))
return (null);
// See if the super-sequences have the same invariant
if (!ppt.parent.check_implied_canonical(
di, der1.seqvar(), der2.seqvar(), PairwiseIntLessThan.get_proto())) return (null);
// Add in the vis variables to di reason (if they are different)
di.add_implied_vis(vis);
return (di);
}
/**
* Returns true if the two original variables are related in a way that makes subsequence or
* subset detection not informative.
*/
public static boolean isObviousSubSequenceDynamically(
Invariant inv, VarInfo subvar, VarInfo supervar) {
VarInfo[] vis = {subvar, supervar};
ProglangType rep1 = subvar.rep_type;
ProglangType rep2 = supervar.rep_type;
if (!(((rep1 == ProglangType.INT_ARRAY) && (rep2 == ProglangType.INT_ARRAY))
|| ((rep1 == ProglangType.DOUBLE_ARRAY) && (rep2 == ProglangType.DOUBLE_ARRAY))
|| ((rep1 == ProglangType.STRING_ARRAY) && (rep2 == ProglangType.STRING_ARRAY))))
return false;
if (debug.isLoggable(Level.FINE)) {
debug.fine(
"Checking isObviousSubSequenceDynamically " + subvar.name() + " in " + supervar.name());
}
Object[] di = isObviousSubSequence(subvar, supervar);
if (di[1] != null) {
inv.log("ObvSubSeq- true from isObviousSubSequence: " + di[1]);
return true;
}
debug.fine(" not isObviousSubSequence(statically)");
PptTopLevel ppt_parent = subvar.ppt;
// If the elements of supervar are always the same (EltOneOf),
// we aren't going to learn anything new from this invariant,
// since each sequence should have an EltOneOf over it.
if (false) {
PptSlice1 slice = ppt_parent.findSlice(supervar);
if (slice == null) {
System.out.println("No slice: parent =" + ppt_parent);
} else {
System.out.println("Slice var =" + slice.var_infos[0]);
for (Invariant superinv : slice.invs) {
System.out.println("Inv = " + superinv);
if (superinv instanceof EltOneOf) {
EltOneOf eltinv = (EltOneOf) superinv;
if (eltinv.num_elts() > 0) {
inv.log(" obvious because of " + eltinv.format());
return true;
}
}
}
}
}
// Obvious if subvar is always just []
if (true) {
PptSlice1 slice = ppt_parent.findSlice(subvar);
if (slice != null) {
for (Invariant subinv : slice.invs) {
if (subinv instanceof OneOfSequence) {
OneOfSequence seqinv = (OneOfSequence) subinv;
if (seqinv.num_elts() == 1) {
Object elt = seqinv.elt();
if (elt instanceof long[] && ((long[]) elt).length == 0) {
Debug.log(
debug, inv.getClass(), inv.ppt, vis, "ObvSubSeq- True from subvar being []");
return true;
}
if (elt instanceof double[] && ((double[]) elt).length == 0) {
inv.log("ObvSubSeq- True from subvar being []");
return true;
}
}
}
}
}
}
// Check for a[0..i] subseq a[0..j] but i < j.
VarInfo subvar_super = subvar.isDerivedSubSequenceOf();
VarInfo supervar_super = supervar.isDerivedSubSequenceOf();
if (subvar_super != null && subvar_super == supervar_super) {
// both sequences are derived from the same supersequence
if ((subvar.derived instanceof SequenceScalarSubsequence
|| subvar.derived instanceof SequenceScalarArbitrarySubsequence)
&& (supervar.derived instanceof SequenceScalarSubsequence
|| supervar.derived instanceof SequenceScalarArbitrarySubsequence)) {
VarInfo sub_left_var = null,
sub_right_var = null,
super_left_var = null,
super_right_var = null;
// I'm careful not to access foo_shift unless foo_var has been set
// to a non-null value, but Java is too stupid to recognize that.
int sub_left_shift = 42,
sub_right_shift = 69,
super_left_shift = 1492,
super_right_shift = 1776;
if (subvar.derived instanceof SequenceScalarSubsequence) {
SequenceScalarSubsequence sub = (SequenceScalarSubsequence) subvar.derived;
if (sub.from_start) {
sub_right_var = sub.sclvar();
sub_right_shift = sub.index_shift;
} else {
sub_left_var = sub.sclvar();
sub_left_shift = sub.index_shift;
}
} else if (subvar.derived instanceof SequenceScalarArbitrarySubsequence) {
SequenceScalarArbitrarySubsequence sub =
(SequenceScalarArbitrarySubsequence) subvar.derived;
sub_left_var = sub.startvar();
sub_left_shift = (sub.left_closed ? 0 : 1);
sub_right_var = sub.endvar();
sub_right_shift = (sub.right_closed ? 0 : -1);
} else {
Assert.assertTrue(false);
}
if (supervar.derived instanceof SequenceScalarSubsequence) {
SequenceScalarSubsequence super_ = (SequenceScalarSubsequence) supervar.derived;
if (super_.from_start) {
super_right_var = super_.sclvar();
super_right_shift = super_.index_shift;
} else {
super_left_var = super_.sclvar();
super_left_shift = super_.index_shift;
}
} else if (supervar.derived instanceof SequenceScalarArbitrarySubsequence) {
SequenceScalarArbitrarySubsequence super_ =
(SequenceScalarArbitrarySubsequence) supervar.derived;
super_left_var = super_.startvar();
super_left_shift = (super_.left_closed ? 0 : 1);
super_right_var = super_.endvar();
super_right_shift = (super_.right_closed ? 0 : -1);
} else {
Assert.assertTrue(false);
}
boolean left_included, right_included;
if (super_left_var == null) left_included = true;
else if (sub_left_var == null) // we know super_left_var != null here
left_included = false;
else
left_included =
VarInfo.compare_vars(
super_left_var, super_left_shift, sub_left_var, sub_left_shift, true /* <= */);
if (super_right_var == null) right_included = true;
else if (sub_right_var == null) // we know super_right_var != null here
right_included = false;
else
right_included =
VarInfo.compare_vars(
super_right_var,
super_right_shift,
sub_right_var,
sub_right_shift,
false /* >= */);
// System.out.println("Is " + subvar.name() + " contained in "
// + supervar.name()
// + "? left: " + left_included + ", right: "
// + right_included);
if (left_included && right_included) {
inv.log("ObvSubSeq- True a[0..i] subseq a[0..j] and i < j");
return true;
}
} else if ((subvar.derived instanceof SequenceStringSubsequence)
&& (supervar.derived instanceof SequenceStringSubsequence)) {
// Copied from just above
SequenceStringSubsequence sss1 = (SequenceStringSubsequence) subvar.derived;
SequenceStringSubsequence sss2 = (SequenceStringSubsequence) supervar.derived;
VarInfo index1 = sss1.sclvar();
int shift1 = sss1.index_shift;
boolean start1 = sss1.from_start;
VarInfo index2 = sss2.sclvar();
int shift2 = sss2.index_shift;
boolean start2 = sss2.from_start;
if (start1 == start2)
if (VarInfo.compare_vars(index1, shift1, index2, shift2, start1)) {
inv.log("True from comparing indices");
return true;
}
} else {
Assert.assertTrue(
false,
"how can this happen? "
+ subvar.name()
+ " "
+ subvar.derived.getClass()
+ " "
+ supervar.name()
+ " "
+ supervar.derived.getClass());
}
}
// Also need to check A[0..i] subseq A[0..j] via compare_vars.
// A subseq B[0..n] => A subseq B
List<Derivation> derivees = supervar.derivees();
// For each variable derived from supervar ("B")
for (Derivation der : derivees) {
// System.out.println(" ... der = " + der.getVarInfo().name() + " " + der);
if (der instanceof SequenceScalarSubsequence) {
// If that variable is "B[0..n]"
VarInfo supervar_part = der.getVarInfo();
// Get the canonical version; being equal to it is good enough.
if (supervar_part.get_equalitySet_leader() == subvar) {
Debug.log(debug, inv.getClass(), inv.ppt, vis, "ObvSubSeq- True from canonical leader");
return true;
}
if (supervar_part.isCanonical()) {
if (subvar == supervar_part) {
System.err.println(
"Error: variables "
+ subvar.name()
+ " and "
+ supervar_part.name()
+ " are identical. Canonical");
System.err.println(subvar.isCanonical());
System.err.println(supervar_part.isCanonical());
throw new Error();
}
// Check to see if there is a subsequence over the supervar
if (ppt_parent.is_subsequence(subvar, supervar_part)) {
if (Debug.logOn())
inv.log(
"ObvSubSeq- true from A subseq B[0..n] "
+ subvar.name()
+ "/"
+ supervar_part.name());
return (true);
}
}
}
}
return false;
}
/**
* @return Array "a" such that a[0] is a valid discardCode and a[1] is a valid discardString. If
* the Invariant is not an obvious subsequence, both are null
*/
public static Object[] isObviousSubSequence(VarInfo subvar, VarInfo supervar) {
// Must typecheck since this could be called with non sequence variables in
// some methods.
ProglangType rep1 = subvar.rep_type;
ProglangType rep2 = supervar.rep_type;
if (!(((rep1 == ProglangType.INT_ARRAY) && (rep2 == ProglangType.INT_ARRAY))
|| ((rep1 == ProglangType.DOUBLE_ARRAY) && (rep2 == ProglangType.DOUBLE_ARRAY))
|| ((rep1 == ProglangType.STRING_ARRAY) && (rep2 == ProglangType.STRING_ARRAY)))) {
return new Object[] {null, null};
}
if (debug.isLoggable(Level.FINE)) {
debug.fine("isObviousSubSequence " + subvar.name() + "in " + supervar.name());
}
// Standard discard reason/string
DiscardCode discardCode = DiscardCode.obvious;
String discardString = subvar.name() + " obvious subset/subsequence of " + supervar.name();
// For unions and intersections, it probably doesn't make sense to
// do subsequence or subset detection. This is mainly to prevent
// invariants of the form (x subset of union(x, y)) but this means
// we also miss those of the form (z subset of union(x,y)) which
// might be useful. Subsequence, however, seems totally useless
// on unions and intersections.
if (supervar.derived instanceof SequenceScalarIntersection
|| supervar.derived instanceof SequenceScalarUnion
|| subvar.derived instanceof SequenceScalarIntersection
|| subvar.derived instanceof SequenceScalarUnion) {
discardCode = DiscardCode.obvious;
discardString =
"Invariants involving subsets/subsequences of unions/intersections" + "are suppressed";
debug.fine(" returning true because of union or intersection");
return new Object[] {discardCode, discardString};
}
if (subvar.derived instanceof SequencesPredicate) {
// It's not useful that predicate(x[], b[]) is a subsequence or subset
// of x[]
SequencesPredicate derived = (SequencesPredicate) subvar.derived;
if (derived.var1().equals(supervar)) {
discardCode = DiscardCode.obvious;
discardString = subvar.name() + " is derived from " + supervar.name();
debug.fine(" returning true because of predicate slicing");
return new Object[] {discardCode, discardString + " [pred slicing]"};
}
}
VarInfo subvar_super = subvar.isDerivedSubSequenceOf();
if (subvar_super == null) {
// If it's not a union, intersection or a subsequence, it's not obvious
debug.fine(" returning false because subvar_super == null");
return new Object[] {null, null};
}
if (subvar_super == supervar) {
// System.out.println("SubSequence.isObviousDerived(" + subvar.name() + ", " + supervar.name +
// ") = true");
// System.out.println(" details: subvar_super=" + subvar_super.name + "; supervar_super=" +
// supervar.isDerivedSubSequenceOf() == null ? "null" :
// supervar.isDerivedSubSequenceOf().name);
discardCode = DiscardCode.obvious;
discardString = subvar.name() + "==" + supervar.name();
debug.fine(" returning true because subvar_super == supervar");
return new Object[] {discardCode, discardString + " [subvar_super == supervar]"};
}
// a[i+a..j+b] cmp a[i+c..j+d]
VarInfo supervar_super = supervar.isDerivedSubSequenceOf();
// we know subvar_super != null due to check above
if (subvar_super == supervar_super) {
// both sequences are derived from the same supersequence
if ((subvar.derived instanceof SequenceScalarSubsequence
|| subvar.derived instanceof SequenceScalarArbitrarySubsequence)
&& (supervar.derived instanceof SequenceScalarSubsequence
|| supervar.derived instanceof SequenceScalarArbitrarySubsequence)) {
// In "A[i..j] subseq B[k..l]": i=sub_left_var, j=sub_right_var,
// k=super_left_var, l=super_right_var.
VarInfo sub_left_var = null,
sub_right_var = null,
super_left_var = null,
super_right_var = null;
// I'm careful not to access foo_shift unless foo_var has been set
// to a non-null value, but Java is too stupid to recognize that.
int sub_left_shift = 42,
sub_right_shift = 69,
super_left_shift = 1492,
super_right_shift = 1776;
if (subvar.derived instanceof SequenceScalarSubsequence) {
SequenceScalarSubsequence sub = (SequenceScalarSubsequence) subvar.derived;
if (sub.from_start) {
sub_right_var = sub.sclvar();
sub_right_shift = sub.index_shift;
} else {
sub_left_var = sub.sclvar();
sub_left_shift = sub.index_shift;
}
} else if (subvar.derived instanceof SequenceScalarArbitrarySubsequence) {
SequenceScalarArbitrarySubsequence sub =
(SequenceScalarArbitrarySubsequence) subvar.derived;
sub_left_var = sub.startvar();
sub_left_shift = (sub.left_closed ? 0 : 1);
sub_right_var = sub.endvar();
sub_right_shift = (sub.right_closed ? 0 : -1);
} else {
Assert.assertTrue(false);
}
if (supervar.derived instanceof SequenceScalarSubsequence) {
SequenceScalarSubsequence super_ = (SequenceScalarSubsequence) supervar.derived;
if (super_.from_start) {
super_right_var = super_.sclvar();
super_right_shift = super_.index_shift;
} else {
super_left_var = super_.sclvar();
super_left_shift = super_.index_shift;
}
} else if (supervar.derived instanceof SequenceScalarArbitrarySubsequence) {
SequenceScalarArbitrarySubsequence super_ =
(SequenceScalarArbitrarySubsequence) supervar.derived;
super_left_var = super_.startvar();
super_left_shift = (super_.left_closed ? 0 : 1);
super_right_var = super_.endvar();
super_right_shift = (super_.right_closed ? 0 : -1);
} else {
Assert.assertTrue(false);
}
boolean left_included = false, right_included = false;
if (super_left_var == null) left_included = true;
if (super_left_var == sub_left_var) {
if (super_left_shift < sub_left_shift) left_included = true;
}
if (super_right_var == null) right_included = true;
if (super_right_var == sub_right_var) {
if (super_right_shift > sub_right_shift) right_included = true;
}
if (left_included && right_included) {
discardCode = DiscardCode.obvious;
discardString = subvar.name() + " obvious subset/subsequence of " + supervar.name();
return new Object[] {discardCode, discardString + " [obvious]"};
}
} else if ((subvar.derived instanceof SequenceStringSubsequence)
&& (supervar.derived instanceof SequenceStringSubsequence)) {
// Copied from (an old version) just above
// XXX I think this code is dead; why isn't it just produced
// from the above by macro expansion? -smcc
SequenceStringSubsequence sss1 = (SequenceStringSubsequence) subvar.derived;
SequenceStringSubsequence sss2 = (SequenceStringSubsequence) supervar.derived;
VarInfo index1 = sss1.sclvar();
int shift1 = sss1.index_shift;
boolean start1 = sss1.from_start;
VarInfo index2 = sss2.sclvar();
int shift2 = sss2.index_shift;
boolean start2 = sss2.from_start;
if (index1 == index2) {
if (start1 == true && start2 == true) {
if (shift1 <= shift2) return new Object[] {discardCode, discardString + " [shift1]"};
} else if (start1 == false && start2 == false) {
if (shift1 >= shift2) return new Object[] {discardCode, discardString + " [shift2]"};
}
}
} else {
Assert.assertTrue(
false,
"how can this happen? "
+ subvar.name()
+ " "
+ subvar.derived.getClass()
+ " "
+ supervar.name()
+ " "
+ supervar.derived.getClass());
}
}
return new Object[] {null, null};
}