[GitHub] [tvm] Lunderberg commented on a diff in pull request #13724: [Arith] Use ConstIntBound to remove negative numerator when lowering

[GitBox <gi...@apache.org>]

Lunderberg commented on code in PR #13724:
URL: https://github.com/apache/tvm/pull/13724#discussion_r1065832687


##########
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))) {

Review Comment:
   Thank you, and op.h's `min_value` is exactly what I had been looking for.  I had checked whether `ConstIntBound::Everything(dtype)` was public, but wasn't aware of `min_value`.  PR updated to use `min_value` instead of doing the calculation here.



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