[PATCH] D123991: [LangRef] Clarify load/store of non-byte-sized types

Tue Apr 19 14:43:17 PDT 2022

nikic planned changes to this revision.
nikic added a comment.

In D123991#3460290 <https://reviews.llvm.org/D123991#3460290>, @craig.topper wrote:

> For loads, the default lowering in the backends assume that the padding bits are 0. Which is only possible if the store explicitly wrote those padding bits to 0. The default lowering of stores does that if it was stored with the same type. I know we've had bugs in X86 related to this. I'll see if I can find any.

Oh wow, you're right: https://llvm.godbolt.org/z/nf3898b89 These semantics aren't going to work then.

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https://reviews.llvm.org/D123991