forked from OSchip/llvm-project
5f312ad450
Summary: The old legacy LTO API had a separate cache key computation, which was a subset of the cache key computation in the new LTO API (from what I can tell this is largely just because certain features such as CFI, dsoLocal, etc are only utilized via the new LTO API). However, having separate computations is unnecessary (much of the code is duplicated), and can lead to bugs when adding new optimizations if both cache computation algorithms aren't updated properly - it's much easier to maintain if we have a single facility. This patch refactors the old LTO API code to use the cache key computation from the new LTO API. To do this, we set up an lto::Config object and fill in the fields that the old LTO was hashing (the others will just use the defaults). There are two notable changes: - I added a Freestanding flag to the LTO Config. Currently this is only used by the legacy LTO API. In the patch that added it (D30791) I had asked about adding it to the new LTO API, but it looks like that was not addressed. This should probably be discussed as a follow up to this change, as it is orthogonal. - The legacy LTO API had some code that was hashing the GUID of all preserved symbols defined in the module. I looked back at the history of this (which was added with the original hashing in the legacy LTO API in D18494), and there is a comment in the review thread that it was added in preparation for future internalization. We now do the internalization of course, and that is handled in the new LTO API cache key computation by hashing the recorded linkage type of all defined globals. Therefore I didn't try to move over and keep the preserved symbols handling. Reviewers: steven_wu, pcc Subscribers: mehdi_amini, inglorion, eraman, dexonsmith, dang, llvm-commits Differential Revision: https://reviews.llvm.org/D54635 llvm-svn: 347592 |
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