Lunderberg commented on code in PR #13724:
URL: https://github.com/apache/tvm/pull/13724#discussion_r1065866224
##########
src/tir/transforms/lower_intrin.cc:
##########
@@ -112,20 +113,33 @@ class IntrinInjecter : public
tvm::arith::IRMutatorWithAnalyzer {
// Common path, positive divisor
if (analyzer_->CanProveGreaterEqual(op->a, 0) ||
analyzer_->CanProveGreaterEqual(e, 0)) {
return truncdiv(op->a, op->b);
+ }
+
+ // If the numerator's lower bound is known, express the floordiv
+ // in terms of truncdiv using only positive operands.
+ arith::ConstIntBound const_int_bound = analyzer_->const_int_bound(op->a);
+ if (const_int_bound->min_value != arith::ConstIntBound::kNegInf &&
+ const_int_bound->min_value < 0 &&
+ const_int_bound->min_value > -(1LL << (op->a->dtype.bits() - 1))) {
+ IntImm min(op->a->dtype, const_int_bound->min_value);
+ PrimExpr ceildiv = truncdiv((op->b - 1) - min, op->b);
+ PrimExpr offset_numerator = analyzer_->Simplify(op->a + op->b *
ceildiv);
+ return truncdiv(offset_numerator, op->b) - ceildiv;
Review Comment:
Yup, that is the rationale. I've added the derivation in a comment, which I
probably should have done from the start.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
