[PATCH] D80929: [NFC][LiveDebugvalues] Document how LiveDebugValues operates

[Jeremy Morse via Phabricator via llvm-commits]

jmorse created this revision.
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Comment at: llvm/lib/CodeGen/LiveDebugValues.cpp:9-13
-/// This pass implements a data flow analysis that propagates debug location
-/// information by inserting additional DBG_VALUE insts into the machine
-/// instruction stream. Before running, each DBG_VALUE inst corresponds to a
-/// source assignment of a variable. Afterwards, a DBG_VALUE inst specifies a
-/// variable location for the current basic block (see SourceLevelDebugging.rst).
----------------
(This was determined to be probably-wrong in another review, that I forget the details of. DBG_VALUEs don't change meaning, there are just very few of them if LiveDebugValues doesn't run).


This is a docu-comment for the LiveDebugValues pass explaining what it does, and how it's structured. I remembered I was going to write this up; see D67500 <https://reviews.llvm.org/D67500> for some thrashing out of what the pass Really (TM) does.

The lattice could be presented as going up or down, or be mirrored; which way doesn't bother me.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D80929

Files:
  llvm/lib/CodeGen/LiveDebugValues.cpp

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