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Wenlei He c7934c2798 [LICM] Make Loop ICM profile aware again
D65060 was reverted because it introduced non-determinism by using BFI counts from already freed blocks. The parent of this revision fixes that by using a VH callback on blocks to prevent this from happening and makes sure BFI data is passed correctly in LoopStandardAnalysisResults.

This re-introduces the previous optimization of using BFI data to prevent LICM from hoisting/sinking if the instruction will end up moving to a colder block.

Internally at Facebook this change results in a ~7% win in a CPU related metric in one of our big services by preventing hoisting cold code into a hot pre-header like the added test case demonstrates.

Testing:
ninja check

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D87551
2020-09-15 17:21:58 -07:00
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