[PATCH] D37221: [AtomicExpand][X86] Let atomic expand generate inline sequence for unaligned load/store of atomic primitive integer types on x86_64

[James Y Knight via llvm-commits]

I'm pretty sure the x86-64 manual said this was *not* guaranteed for
accesses that cross a cacheline. (On vacation, so am not going to lookup
quote)

Do you read something that makes you think this is actually safe?


On Aug 28, 2017 1:36 PM, "Wei Mi via Phabricator" <reviews at reviews.llvm.org>
wrote:

wmi created this revision.
Herald added a subscriber: sanjoy.

The patch is to fix PR34347.

Now llvm generates library calls of atomic_load/store for unaligned
load/store of atomic primitive integer type vars on x86_64. Since x86_64
support unaligned atomic load/store for primitive integers, this is not
efficient. The patch fixes that.

To fix PR34347, change in clang is also needed. That will be included in
another patch.


Repository:
  rL LLVM

https://reviews.llvm.org/D37221

Files:
  include/llvm/Target/TargetLowering.h
  lib/CodeGen/AtomicExpandPass.cpp
  lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  lib/Target/X86/X86ISelLowering.cpp
  lib/Target/X86/X86ISelLowering.h
  test/Transforms/AtomicExpand/X86/expand-unaligned-expansion.ll
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