[PATCH] Improve DAG combine pass on certain IR vector patterns

[Fiona Glaser]

Okay, I ported the test case to aarch64 and armv7. My patch doesn’t change the code output with i16 or float vectors. The current status of those is:

armv7/aarch64 float vectors: ideal code
armv7 with i16 vectors: bad code, but same for all three IRs
aarch64 with i16 vectors: bad code, which turns into utterly awful code for the first two out of three IRs.

Fiona