[PATCH] D37911: [DebugInfo] Insert DW_OP_deref when spilling indirect DBG_VALUEs

[Reid Kleckner via Phabricator via llvm-commits]

rnk created this revision.
Herald added subscribers: hiraditya, qcolombet.

This comes up in optimized debug info for C++ programs that pass and
return objects indirectly by address. In these programs,
llvm.dbg.declare survives optimization, which causes us to emit indirect
DBG_VALUE instructions. The fast register allocator knows to insert
DW_OP_deref when spilling indirect DBG_VALUE instructions, but the
LiveDebugVariables did not until this change.

This fixes part of PR34513. I need to look into why this doesn't work at
-O0 and I'll send follow up patches to handle that.


https://reviews.llvm.org/D37911

Files:
  llvm/lib/CodeGen/LiveDebugVariables.cpp
  llvm/test/DebugInfo/X86/bbjoin.ll
  llvm/test/DebugInfo/X86/spill-indirect-nrvo.ll
  llvm/test/DebugInfo/X86/spill-nontrivial-param.ll

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