[PATCH] D24180: Emit 'no line' information for interesting 'orphan' instructions

[Paul Robinson via llvm-commits]

probinson updated this revision to Diff 75364.
probinson added a comment.

Updated patch to take care of four things.

1. Internal testing came up with situations where the patch would emit multiple line-0 records in a row.  We now avoid that.

2. We also found cases along these lines:

  .loc 1 9 0
  instr1
  instr2
  .loc 1 0 0
  instr3
  .loc 1 9 0
  instr4

The naive statement-marking algorithm would put `is_stmt 1` on both instr1 and instr4, which is not good for debugging.  The updated patch detects this situation and puts `is_stmt 0` on instr4.

3. We aren't sure what to emit for CodeView, so as advised by @rnk this patch now does nothing for CodeView.

4. The updated patch exposed an inadvertent flaw in test/CodeGen/X86/stack-protector.ll where a function marked as having debug info actually had no source location attached to any instructions.  This led to emitting `.loc 1 0 0 prologue_end` which is obviously flawed.  Attaching an actual source location to one of the instructions emits a much more sensible line table.


https://reviews.llvm.org/D24180

Files:
  lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
  lib/CodeGen/AsmPrinter/DebugHandlerBase.h
  lib/CodeGen/AsmPrinter/DwarfDebug.cpp
  test/CodeGen/X86/stack-protector.ll
  test/DebugInfo/AArch64/line-header.ll
  test/DebugInfo/X86/dwarf-no-source-loc.ll

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