Commit Graph

2 Commits

Author SHA1 Message Date
Nirav Dave da8f221273 Elide stores which are overwritten without being observed.
Summary:
In SelectionDAG, when a store is immediately chained to another store
to the same address, elide the first store as it has no observable
effects. This is causes small improvements dealing with intrinsics
lowered to stores.

Test notes:

* Many testcases overwrite store addresses multiple times and needed
  minor changes, mainly making stores volatile to prevent the
  optimization from optimizing the test away.

* Many X86 test cases optimized out instructions associated with
  associated with va_start.

* Note that test_splat in CodeGen/AArch64/misched-stp.ll no longer has
  dependencies to check and can probably be removed and potentially
  replaced with another test.

Reviewers: rnk, john.brawn

Subscribers: aemerson, rengolin, qcolombet, jyknight, nemanjai, nhaehnle, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D33206

llvm-svn: 303198
2017-05-16 19:43:56 +00:00
John Brawn 3a9c842a9d [AArch64] Fix incorrect MachinePointerInfo in splitStoreSplat
When splitting up one store into several in splitStoreSplat we have to
make sure we get the MachinePointerInfo right, otherwise alias
analysis thinks they all store to the same location. This can then
cause invalid scheduling later on.

Differential Revision: https://reviews.llvm.org/D29446

llvm-svn: 294203
2017-02-06 18:07:20 +00:00