[PATCH] D75326: [entry values] X86: Describe effects of MOV{8,16}ri (PR45053)

[David Stenberg via Phabricator via llvm-commits]

dstenb added a comment.

In D75326#1898071 <https://reviews.llvm.org/D75326#1898071>, @vsk wrote:

> Thank you @dstenb and @djtodoro very much for your feedback.
>
> I think I've addressed the main issue, we now produce `DW_AT_call_value (DW_OP_constu 0x840, DW_OP_stack_value, DW_OP_piece 0x2)`. PTAL.


I might be incorrect here, but I don't think we are allowed to use DW_OP_piece operations in DW_AT_call_value attributes, as they should be DWARF expressions? As far as I have understood it, the DW_OP_piece operation is only allowed in composite location descriptions, and you can in general not go from location descriptions to DWARF expressions, with the only (?) exception being DW_OP_entry_value operations holding register location descriptions.

(This seems a bit related to D75270 <https://reviews.llvm.org/D75270>, in which I stop emitting entry values around composite location descriptions, since the DWARF standard specifies that those are only allowed to hold DWARF expressions and register location descriptions.)


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