================
@@ -575,6 +575,68 @@ ValueBoundsConstraintSet::computeConstantDelta(Value
value1, Value value2,
{{value1, dim1}, {value2, dim2}});
}
+void ValueBoundsConstraintSet::populateConstraints(Value value,
+ std::optional<int64_t> dim)
{
+ // `getExpr` pushes the value/dim onto the worklist (unless it was already
+ // analyzed).
+ (void)getExpr(value, dim);
+ // Process all values/dims on the worklist. This may traverse and analyze
+ // additional IR, depending the current stop function.
+ processWorklist();
+}
+
+bool ValueBoundsConstraintSet::compare(Value value1,
+ std::optional<int64_t> dim1,
+ ComparisonOperator cmp, Value value2,
+ std::optional<int64_t> dim2) {
+ // This function returns "true" if value1/dim1 CMP value2/dim2 is proved to
+ // hold.
+ //
+ // Example for ComparisonOperator::LE and index-typed values: We would like
to
+ // prove that value1 <= value2. Proof by contradiction: add the inverse
+ // relation (value1 > value2) to the constraint set and check if the
resulting
+ // constraint set is "empty" (i.e. has no solution). In that case,
+ // value1 > value2 must be incorrect and we can deduce that value1 <= value2
+ // holds.
+
+ // We cannot use prove anything if the constraint set is already empty.
+ if (cstr.isEmpty()) {
+ LLVM_DEBUG(
+ llvm::dbgs()
+ << "cannot compare value/dims: constraint system is already empty");
+ return false;
+ }
+
+ // EQ can be expressed as LE and GE.
+ if (cmp == EQ)
+ return compare(value1, dim1, ComparisonOperator::LE, value2, dim2) &&
+ compare(value1, dim1, ComparisonOperator::GE, value2, dim2);
+
+ // Construct inequality. For the above example: value1 > value2.
+ // `IntegerRelation` inequalities are expressed in the "flattened" form and
+ // with ">= 0". I.e., value1 - value2 - 1 >= 0.
+ SmallVector<int64_t> eq(cstr.getNumDimAndSymbolVars() + 1, 0);
+ if (cmp == LT || cmp == LE) {
+ eq[getPos(value1, dim1)]++;
+ eq[getPos(value2, dim2)]--;
+ } else if (cmp == GT || cmp == GE) {
+ eq[getPos(value1, dim1)]--;
+ eq[getPos(value2, dim2)]++;
----------------
dcaballe wrote:
pre-increments per coding guidelines
https://github.com/llvm/llvm-project/pull/85895
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