llvm-project

45c0b291 - [LV] Ignore user-specified interleave count when unsafe. (#153009)

[LV] Ignore user-specified interleave count when unsafe. (#153009) When an VF is specified via a loop hint, it will be clamped to a safe VF or ignored if it is found to be unsafe. This is not the case for user-specified interleave counts, which can lead to loops such as the following with a memory dependence being vectorised with interleaving: ``` #pragma clang loop interleave_count(4) for (int i = 4; i < LEN; i++) b[i] = b[i - 4] + a[i]; ``` According to [1], loop hints are ignored if they are not safe to apply. This patch adds a check to prevent vectorisation with interleaving if isSafeForAnyVectorWidth() returns false. This is already checked in selectInterleaveCount(). [1] https://llvm.org/docs/LangRef.html#llvm-loop-vectorize-and-llvm-loop-interleave