vinx13 commented on code in PR #11646:
URL: https://github.com/apache/tvm/pull/11646#discussion_r893976673
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src/arith/const_int_bound.cc:
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@@ -341,6 +343,18 @@ class ConstIntBoundAnalyzer::Impl
}
}
+ Entry VisitLeftShift(const CallNode* op) {
+ Entry a = VisitExpr(op->args[0]);
+ Entry b = VisitExpr(op->args[1]);
+
+ // Until C++20, performing a left shift is only well-defined for
+ // positive arguments. If we have a negative argument, it just
+ // means we couldn't prove that the inputs were positive.
+ a.min_value = std::max(int64_t(0), a.min_value);
+ b.min_value = std::max(int64_t(0), b.min_value);
+ return BinaryOpBoundary(a, b, InfAwareLeftShift);
Review Comment:
if a/b has negative `min_value`, does taking the max narrow the bound? shall
we return `Everything` if the bound can't be proved?
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