[all-commits] [llvm/llvm-project] ad18b0: DebugInfo: Add support for always using ranges (ra...

[David Blaikie via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: ad18b075fd63935148b460f9c6b4dce130c56b15
      https://github.com/llvm/llvm-project/commit/ad18b075fd63935148b460f9c6b4dce130c56b15
  Author: David Blaikie <dblaikie at gmail.com>
  Date:   2021-01-05 (Tue, 05 Jan 2021)

  Changed paths:
    M llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
    M llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
    M llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
    A llvm/test/DebugInfo/X86/ranges_always.ll

  Log Message:
  -----------
  DebugInfo: Add support for always using ranges (rather than low/high pc) in DWARFv5

Given the ability provided by DWARFv5 rnglists to reuse addresses in the
address pool, it can be advantageous to object file size to use range
encodings even when the range could be described by a direct low/high
pc.

Add a flag to allow enabling this in DWARFv5 for the purpose of
experimentation/data gathering.

It might be that it makes sense to enable this functionality by default
for DWARFv5 + Split DWARF at least, where the tradeoff/desire to
optimize for .o file size is more explicit and .o bytes are higher
priority than .dwo bytes.