yongfeng-nv commented on a change in pull request #5367:
URL: https://github.com/apache/incubator-tvm/pull/5367#discussion_r414263234
##########
File path: src/arith/int_set.cc
##########
@@ -311,6 +311,21 @@ inline IntervalSet Combine<tir::FloorModNode>(Analyzer*
analyzer,
LOG(FATAL) << "Modular by zero in CombineInterval Mod";
}
if (analyzer->CanProveGreaterEqual(divisor, 0)) {
+ if (const auto* ptr = b->min_value.as<tir::IntImmNode>()) {
+ // a mod b = a - b * (a/b) if
+ // (i) a_max - a_min < b, i.e. that before mod, a's range doesn't
cover [0, b)
+ // and (ii) a_min mod b <= a_max mod b, i.e. that a's range is still
continuous after mod
+ auto tmax = a->max_value - b->min_value * floordiv(a->max_value,
b->min_value);
+ tmax = analyzer->Simplify(tmax);
+ auto tmin = a->min_value - b->min_value * floordiv(a->min_value,
b->min_value);
+ tmin = analyzer->Simplify(tmin);
+ auto tset = IntervalSet(tmin, tmax);
+ bool within_range = analyzer->CanProveLess(a->max_value -
a->min_value, ptr->value);
+ bool wrap_around = analyzer->CanProve(tset->max_value <
tset->min_value);
Review comment:
I missed the point that CanProve is necessary but not sufficient here.
Once I modified the condition to tset->max_value >= tset->min_value,
floormod([z*8+x*4, z*8+x*4+3], 8) fell back to [0, 7], matching your earlier
suggested floormod implementation, because the it can't prove (((x*4) + 3) -
(floordiv(((x*4) + 3), 8)*8)) >= ((x*4) - (floordiv(x, 2)*8)). Therefore, I
switch to the simple implementation and modify the test.
##########
File path: src/arith/int_set.cc
##########
@@ -311,6 +311,21 @@ inline IntervalSet Combine<tir::FloorModNode>(Analyzer*
analyzer,
LOG(FATAL) << "Modular by zero in CombineInterval Mod";
}
if (analyzer->CanProveGreaterEqual(divisor, 0)) {
+ if (const auto* ptr = b->min_value.as<tir::IntImmNode>()) {
+ // a mod b = a - b * (a/b) if
+ // (i) a_max - a_min < b, i.e. that before mod, a's range doesn't
cover [0, b)
+ // and (ii) a_min mod b <= a_max mod b, i.e. that a's range is still
continuous after mod
+ auto tmax = a->max_value - b->min_value * floordiv(a->max_value,
b->min_value);
+ tmax = analyzer->Simplify(tmax);
+ auto tmin = a->min_value - b->min_value * floordiv(a->min_value,
b->min_value);
+ tmin = analyzer->Simplify(tmin);
+ auto tset = IntervalSet(tmin, tmax);
+ bool within_range = analyzer->CanProveLess(a->max_value -
a->min_value, ptr->value);
+ bool wrap_around = analyzer->CanProve(tset->max_value <
tset->min_value);
+ if (within_range && !wrap_around) {
+ return tset;
Review comment:
No longer an issue with the update.
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