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21c68fac74
When folding an addi into a memory access that can take an immediate offset, we were implicitly assuming that the existing offset was zero. This was incorrect. If we're dealing with an addi with a plain constant, we can add it to the existing offset (assuming that doesn't overflow the immediate, etc.), but if we have anything else (i.e. something that will become a relocation expression), we'll go back to requiring the existing immediate offset to be zero (because we don't know what the requirements on that relocation expression might be - e.g. maybe it is paired with some addis in some relevant way). On the other hand, when dealing with a plain addi with a regular constant immediate, the alignment restrictions (from the TOC base pointer, etc.) are irrelevant. I've added the test case from PR30280, which demonstrated the bug, but also demonstrates a missed optimization opportunity (i.e. we don't need the memory accesses at all). Fixes PR30280. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280789 91177308-0d34-0410-b5e6-96231b3b80d8
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