Merging r340416:

Merging r340416:
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r340416 | hakzsam | 2018-08-22 18:08:43 +0200 (Wed, 22 Aug 2018) | 8 lines

AMDGPU: fix existing alias rules for constant and global

Constant and global may alias, also one rules table wasn't
ordered correctly.

Pinpointed by Matt.

v2: add a test with swapped parameters
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_70@341040 91177308-0d34-0410-b5e6-96231b3b80d8