[all-commits] [llvm/llvm-project] ab93e7: [DebugInstrRef] NFC: Separate collection of machin...

[Jeremy Morse via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: ab93e710652f764bf2ab51710980e7828ebe4a8b
      https://github.com/llvm/llvm-project/commit/ab93e710652f764bf2ab51710980e7828ebe4a8b
  Author: Jeremy Morse <jeremy.morse at sony.com>
  Date:   2020-10-23 (Fri, 23 Oct 2020)

  Changed paths:
    M llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp

  Log Message:
  -----------
  [DebugInstrRef] NFC: Separate collection of machine/variable values

This patch adjusts _when_ something happens in LiveDebugValues /
InstrRefBasedLDV, to make it more amenable to dealing with DBG_INSTR_REF
instructions. There's no functional change.

In the current InstrRefBasedLDV implementation, we collect the machine
value-number transfer function for blocks at the same time as the
variable-value transfer function. After solving machine value numbers, the
variable-value transfer function is updated so that DBG_VALUEs of live-in
registers have the correct value. The same would need to be done for
DBG_INSTR_REFs, to connect instruction-references with machine value
numbers.

Rather than writing more code for that, this patch separates the two: we
collect the (machine-value-number) transfer function and solve for
machine value numbers, then step through the MachineInstrs again collecting
the variable value transfer function. This simplifies things for the new
few patches.

Differential Revision: https://reviews.llvm.org/D85760