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llvm-mirror/test/Transforms/EarlyCSE
Philip Reames d2d22a2dd9 Allow value forwarding past release fences in EarlyCSE
A release fence acts as a publication barrier for stores within the current thread to become visible to other threads which might observe the release fence. It does not require the current thread to observe stores performed on other threads. As a result, we can allow store-load and load-store forwarding across a release fence.

We do need to make sure that stores before the fence can't be eliminated even if there's another store to the same location after the fence. In theory, we could reorder the second store above the fence and *then* eliminate the former, but we can't do this if the stores are on opposite sides of the fence.

Note: While more aggressive then what's there, this patch is still implementing a really conservative ordering.  In particular, I'm not trying to exploit undefined behavior via races, or the fact that the LangRef says only 'atomic' accesses are ordered w.r.t. fences.

Differential Revision: http://reviews.llvm.org/D11434

llvm-svn: 246134
2015-08-27 01:32:33 +00:00
..
AArch64 [PM] Port EarlyCSE to the new pass manager. 2015-02-01 10:51:23 +00:00
basic.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
commute.ll Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change. 2013-07-14 01:42:54 +00:00
conditional.ll Extend EarlyCSE to handle basic cases from JumpThreading and CVP 2015-05-22 23:53:24 +00:00
edge.ll Correct a mistaken comment from 238071 [NFC] 2015-05-23 00:05:43 +00:00
fence.ll Allow value forwarding past release fences in EarlyCSE 2015-08-27 01:32:33 +00:00
floatingpoint.ll Initially forgotten-to-svn-add test case for r177279. 2013-03-18 12:07:24 +00:00
instsimplify-dom.ll Catch more CHECK that can be converted to CHECK-LABEL in Transforms for easier debugging. No functionality change. 2013-07-14 01:50:49 +00:00
read-reg.ll Preserve the order of READ_REGISTER and WRITE_REGISTER 2015-05-18 16:42:10 +00:00