On Tue, 17 Sep 2024 07:02:20 GMT, Jatin Bhateja <jbhat...@openjdk.org> wrote:
>> src/hotspot/share/opto/vectornode.cpp line 2122: >> >>> 2120: // index format by subsequent VectorLoadShuffle. >>> 2121: int cast_vopc = VectorCastNode::opcode(0, index_elem_bt, true); >>> 2122: Node* index_byte_vec = >>> phase->transform(VectorCastNode::make(cast_vopc, index_vec, T_BYTE, >>> num_elem)); >> >> This cast assumes that the indices cannot have more than 8 bits. This would >> allow vector lengths of up to 256. This is fine for intel. But as far as I >> know ARM has in principle longer vectors - up to 2048 bytes. Should we maybe >> add some assert here to make sure we never badly truncate the index? > > Shuffle overhaul is on our todo list, its a know limitation which we tried > lifting once, yes you read it correctly, its a limitation for AARCH64 SVE > once a 2048 bits vector systems are available, IIRC current max vector size > on any available AARCH64 system is 256 bits, with Neoverse V2 they shrink the > vector size back to 16 bytes. Are there any asserts that would catch this? ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/20508#discussion_r1764943566
