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new bed8a865f [FIX] Omit loop constraints for zero extents (#107)
bed8a865f is described below
commit bed8a865f47bf9ac382c7eb07b30577c5a882c07
Author: Tianqi Chen <[email protected]>
AuthorDate: Wed Oct 28 08:32:41 2026 -0400
[FIX] Omit loop constraints for zero extents (#107)
Skip range and positivity constraints when a loop has zero extent. This
avoids invalid loop-variable bounds while traversing unreachable bodies
---
src/tirx/ir/structural_constraints.cc | 3 ++-
.../test_structural_visit_with_constraint_context.py | 16 ++++++++++++++++
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/src/tirx/ir/structural_constraints.cc
b/src/tirx/ir/structural_constraints.cc
index 151f0888e..97d3998d0 100644
--- a/src/tirx/ir/structural_constraints.cc
+++ b/src/tirx/ir/structural_constraints.cc
@@ -61,11 +61,12 @@ ffi::Expected<void> AddLoopRange(Traversal* traversal,
PrimVar var, PrimExpr beg
try {
const auto* stride = step.as<IntImmObj>();
if (stride && stride->value > 0) {
+ PrimExpr extent = Range::GetExtentFromBeginEnd(begin, end);
+ if (prim::IsZero(extent)) return {};
traversal->AppendConstraint(sym::RangeConstraint(var, Range(begin,
end)));
// These are facts at an executed positive-step loop body, not an
assertion
// that every RangeConstraint supplied by an arbitrary caller is
nonempty.
traversal->AppendConstraint(sym::PredicateConstraint(end > begin));
- PrimExpr extent = Range::GetExtentFromBeginEnd(begin, end);
traversal->AppendConstraint(sym::PredicateConstraint(extent >
IntImm(extent.ty(), 0)));
}
return {};
diff --git a/tests/python/tirx/test_structural_visit_with_constraint_context.py
b/tests/python/tirx/test_structural_visit_with_constraint_context.py
index b64213bf3..963760ad7 100644
--- a/tests/python/tirx/test_structural_visit_with_constraint_context.py
+++ b/tests/python/tirx/test_structural_visit_with_constraint_context.py
@@ -44,6 +44,22 @@ def test_walk_collects_binding_and_loop_range():
assert int(loop_range.range.begin) == 0 and int(loop_range.range.extent)
== 4
+def test_walk_omits_zero_trip_loop_constraints():
+ @T.function
+ def before():
+ for i in T.serial(0):
+ T.evaluate(T.truncmod(1, i))
+
+ collected = []
+
+ def observe(value, constraints):
+ if isinstance(value, ir.Evaluate):
+ collected.append(list(constraints))
+
+ structural.structural_walk_with_constraint_context(before.body, observe)
+ assert collected == [[]]
+
+
def test_visit_collects_branch_predicates():
@T.function
def before(x: T.int32):
