[all-commits] [llvm/llvm-project] 624e52: [DebugInfo] Handle trailing empty blocks when seek...

[Jeremy Morse via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 624e52b1e310c349e21cc0b4f67452b0fa9d1f96
      https://github.com/llvm/llvm-project/commit/624e52b1e310c349e21cc0b4f67452b0fa9d1f96
  Author: Jeremy Morse <jeremy.morse at sony.com>
  Date:   2024-11-26 (Tue, 26 Nov 2024)

  Changed paths:
    M llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
    M llvm/test/DebugInfo/MIR/X86/dbg-prologue-backup-loc2.mir

  Log Message:
  -----------
  [DebugInfo] Handle trailing empty blocks when seeking prologue_end spot (#117320)

The optimiser will produce empty blocks that are unconditionally
executed according to the CFG -- while it may not be meaningful code,
and won't get a prologue_end position, we need to not crash on this
input.

The fault comes from assuming that there's always a next block with some
instructions in it, that will eventually produce some meaningful control
flow to stop at -- in the given reproducer in issue #117206 this isn't
true, because the function terminates with `unreachable`. Thus, I've
refactored the "get next instruction logic" into a helper that'll step
through all blocks and terminate if there aren't any more.

Reproducer from aeubanks



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