Change Details

Tries to perform (Xshr (add (i2^n X), (i2^n Y)), 2^(n-1)) -> (icmp ult (add (trunc X), (trunc Y)), X) where - Only the K leading bits of X and Y can be non-zero. - The add is only used by the shr, or by iK (or narrower) truncates. - The lshr type has more than 2 bits (other types are boolean math). - X > 1 This seems to be a pattern that just comes from OpenCL front-ends, so adding DAG/GISel combines doesn't seem to be worth the complexity. Original patch D107552 by @abinavpp - adapted to use (a + b < a) instead of uaddo following discussion on the review. See this issue https://github.com/RadeonOpenCompute/ROCm/issues/488

Tries to perform (lshr (add (zext X), (zext Y)), K) -> (icmp ult (add X, Y), X) where - The add's operands are zexts from a K-bits integer to a bigger type. - The add is only used by the shr, or by iK (or narrower) truncates. - The lshr type has more than 2 bits (other types are boolean math). - K > 1 This seems to be a pattern that just comes from OpenCL front-ends, so adding DAG/GISel combines doesn't seem to be worth the complexity. Original patch D107552 by @abinavpp - adapted to use (a + b < a) instead of uaddo following discussion on the review. See this issue https://github.com/RadeonOpenCompute/ROCm/issues/488

Tries to perform (Xlshr (add (i2^n Xzext X), (i2^n Yzext Y)), 2^(n-1)K) -> (icmp ult (add (trunc X)X, (trunc Y)Y), X) where - Only the K leading bits of X and Y can be non-zero- The add's operands are zexts from a K-bits integer to a bigger type. - The add is only used by the shr, or by iK (or narrower) truncates. - The lshr type has more than 2 bits (other types are boolean math). - X- K > 1 This seems to be a pattern that just comes from OpenCL front-ends, so adding DAG/GISel combines doesn't seem to be worth the complexity. Original patch D107552 by @abinavpp - adapted to use (a + b < a) instead of uaddo following discussion on the review. See this issue https://github.com/RadeonOpenCompute/ROCm/issues/488