llvm-project
5bbce06a - [PseudoProbe] Mix block and call probe ID in lexical order (#75092)

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1 year ago
[PseudoProbe] Mix block and call probe ID in lexical order (#75092) Before all the call probe ids are after block ids, in this change, it mixed the call probe and block probe by reordering them in lexical(line-number) order. For example: ``` main(): BB1 if(...) BB2 foo(..); else BB3 bar(...); BB4 ``` Before the profile is ``` main 1: .. 2: .. 3: ... 4: ... 5: foo ... 6: bar ... ``` Now the new order is ``` main 1: .. 2: .. 3: foo ... 4: ... 5: bar ... 6: ... ``` This can potentially make it more tolerant of profile mismatch, either from stale profile or frontend change. e.g. before if we add one block, even the block is the last one, all the call probes are shifted and mismatched. Moreover, this makes better use of call-anchor based stale profile matching. Blocks are matched based on the closest anchor, there would be more anchors used for the matching, reduce the mismatch scope.
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