Dayuxiaoshui opened a new pull request, #18582:
URL: https://github.com/apache/tvm/pull/18582

   The ACOS operator was producing incorrect results for boundary values due to 
poor precision of ASIN's Taylor series expansion near x=±1.0.
   
   Root cause:
   - ASIN used a 6-term Taylor series that converges slowly near boundaries
   - ACOS was implemented as acos(x) = π/2 - asin(x), inheriting ASIN errors
   - At x=1.0, ASIN error of 0.354874 (22.6%) caused ACOS to output 0.354874 
instead of 0.0
   
   Solution:
   - Modified ASIN to use system library function (asinf) for |x| >= 0.9
   - Modified ACOS to use system library function (acosf) for |x| >= 0.9
   - For |x| < 0.9, continue using Taylor series (accurate in this range)
   
   This ensures high precision for boundary values while maintaining the 
existing behavior for values in the middle range.
   
   Fixes #18580


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