Change Details

LSR may optimize the loop such that the IV of the terminating condition is solely used as the terminating condition. We can improve on this when other existing IV can replace the terminating condition.

If the loop has a predictable back-edge count and we have another IV (say IV-B) that is an affine add recursion, we will be able to calculate the terminating value of IV-B in the loop preheader. This patch adds attempts to replace IV-B as the new terminating condition and remove IV-A. It is safe to do so when IV-A is only used as the terminating condition. This transformation is suitable to be appended after LSR as it may optimize the lopp into the situation mentioned above. The transformation can reduce number of IV-s in the loop by one.

LSR may optimize the loop such that the IV of the terminating condition isIf the loop has a predictable back-edge count and we have another IV (say IV-B) solethat is an affine add recursion, we will be able to calculate the terminating value of IV-B in the loop preheader. This patch adds attempts to replace IV-B as the new terminating condition and remove IV-A. It is safe to do so when IV-A is only used as the terminating condition. This transformation is suitable to be appended after LSR as it may optimize the lopp into the situation mentioned above. WeThe transformation can improve oreduce number of IV-s in this whene loop by one. other existing IV can replace the terminating condition.