This corrects the debug information for the cloned functions so that it contains the correct linkage name.
g++-13 warned that:
llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp:1645:8: warning: variable ‘PrevIterCreatedNode’ set but not used [-Wunused-but-set-variable]
1645 | bool PrevIterCreatedNode = false;
| ^~~~~~~~~~~~~~~~~~~
When asserts were not enabled.
To aid in debugging, (optionally) dump the dot graph immediately after the stack update phase (which matches nodes to interior callsites) and before we cleanup mismatched callee edges (either via tail call fixup, indirect call fixup, or nulling otherwise).
Reapply PR142507 with fix for test: add in the same x86_64-linux requirement as other tests as the stack ids are currently computed differently on big endian systems. This will be investigated separately. In order to allow selective reporting of context hinting during the LTO link, and in the future to allow selective more aggressive cloning, add an option to specify a minimum percent of the max cold size in the profile summary. Contexts that meet that threshold will get context size info metadata (and ThinLTO summary information) on the associated allocations. Specifying -memprof-report-hinted-sizes during the pre-LTO compile step will continue to cause all contexts to receive this metadata. But specifying -memprof-report-hinted-sizes only during the LTO link will cause only those that meet the new threshold and have the metadata to get reported. To support this, because the alloc info summary and associated bitcode requires the context size information to be in the same order as the other context information, 0s are inserted for contexts without this metadata. The bitcode writer uses a more compact format for the context ids to allow better compression of the 0s. As part of this change several helper methods are added to query whether metadata contains context size info on any or all contexts.
Reverts llvm/llvm-project#142507 due to buildbot failures that I will look into tomorrow.
In order to allow selective reporting of context hinting during the LTO link, and in the future to allow selective more aggressive cloning, add an option to specify a minimum percent of the max cold size in the profile summary. Contexts that meet that threshold will get context size info metadata (and ThinLTO summary information) on the associated allocations. Specifying -memprof-report-hinted-sizes during the pre-LTO compile step will continue to cause all contexts to receive this metadata. But specifying -memprof-report-hinted-sizes only during the LTO link will cause only those that meet the new threshold and have the metadata to get reported. To support this, because the alloc info summary and associated bitcode requires the context size information to be in the same order as the other context information, 0s are inserted for contexts without this metadata. The bitcode writer uses a more compact format for the context ids to allow better compression of the 0s. As part of this change several helper methods are added to query whether metadata contains context size info on any or all contexts.
Guard a loop that only exists to do assertion checking of stack ids on memprof metadata so that it isn't compiled and executed under NDEBUG. This is similar to how callsite metadata stack id verification is guarded further below.