[PATCH] D98781: [AArch64] Enable UseAA globally in the AArch64 backend

[Dave Green via Phabricator via llvm-commits]

dmgreen added inline comments.


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Comment at: llvm/test/CodeGen/AArch64/arm64-variadic-aapcs.ll:135
 
-; CHECK: ldp [[BLOCK:q[0-9]+]], [[BLOCK:q[0-9]+]], [x[[SRC]]]
+; CHECK: ldr [[BLOCKB:q[0-9]+]], [x[[SRC]], #16]
 ; CHECK: add x[[DST:[0-9]+]], {{x[0-9]+}}, :lo12:second_list
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david-arm wrote:
> This looks like there is potentially a regression here? We've gone from a `ldp` to two `'ldr` instructions here.
There are already a lot of command lines added to this test, presumably to attempt to get it to work in the same way as it did in the past. `-pre-RA-sched=linearize -enable-misched=false -disable-post-ra`. Without those flags this performs the same with and without UseAA.

In general, UseAA can give more scheduling freedom and the compiler is perfectly able to shoot itself in the foot with that extra freedom. The opposite can be true too though, where it does help things, and it should help more than it hinders. And it's already enabled for certain CPU's. This just makes it global.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D98781/new/

https://reviews.llvm.org/D98781