Teresa Johnson 960ebc706f [ThinLTO] Emit individual index files for distributed backends ... Summary: When launching ThinLTO backends in a distributed build (currently supported in gold via the thinlto-index-only plugin option), emit an individual index file for each backend process as described here: http://lists.llvm.org/pipermail/llvm-dev/2016-April/098272.html The individual index file encodes the summary and module information required for implementing the importing/exporting decisions made for a given module in the thin link step. This is in place of the current mechanism that uses the combined index to make importing decisions in each back end independently. It is an enabler for doing global summary based optimizations in the thin link step (which will be recorded in the individual index files), and reduces the size of the index that must be sent to each backend process, and the amount of work to scan it in the backends. Rather than create entirely new ModuleSummaryIndex structures (and all the included unique_ptrs) for each backend index file, a map is created to record all of the GUID and summary pointers needed for a particular index file. The IndexBitcodeWriter walks this map instead of the full index (hiding the details of managing the appropriate summary iteration in a new iterator subclass). This is more efficient than walking the entire combined index and filtering out just the needed summaries during each backend bitcode index write. Depends on D19481. Reviewers: joker.eph Subscribers: llvm-commits, joker.eph Differential Revision: http://reviews.llvm.org/D19556 llvm-svn: 268627		2016-05-05 13:44:56 +00:00
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llvm	[ThinLTO] Emit individual index files for distributed backends	2016-05-05 13:44:56 +00:00
llvm-c	Provide some default values for the ThinLTO Cache pruning	2016-05-03 15:17:50 +00:00