Jeremy Morse a3936a6c19 [DebugInfo][InstrRef] Use PHI placement utilities for machine locations ...

InstrRefBasedLDV used to try and determine which values are in which
registers using a lattice approach; however this is hard to understand, and
broken in various ways. This patch replaces that approach with a standard
SSA approach using existing LLVM utilities. PHIs are placed at dominance
frontiers; value propagation then eliminates un-necessary PHIs.

This patch also adds a bunch of unit tests that should cover many of the
weirder forms of control flow.

Differential Revision: https://reviews.llvm.org/D110173

2021-10-13 12:49:04 +01:00

95 KiB

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