[all-commits] [llvm/llvm-project] 2cf550: [DebugInfo] Force early line-zero calls to have me...

[Jeremy Morse via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2cf550a040414aee51f7958812573723380b7a4b
      https://github.com/llvm/llvm-project/commit/2cf550a040414aee51f7958812573723380b7a4b
  Author: Jeremy Morse <jeremy.morse at sony.com>
  Date:   2025-11-20 (Thu, 20 Nov 2025)

  Changed paths:
    M llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
    M llvm/test/DebugInfo/MIR/X86/debug-loc-0.mir
    A llvm/test/DebugInfo/X86/no-prologue-end-after-line0-calls.mir

  Log Message:
  -----------
  [DebugInfo] Force early line-zero calls to have meaningful locations (#156850)

In functions that have been seriously deformed during optimisation,
there can be call instructions with line-zero immediately after frame
setup (see C reproducer in the test added). Our previous algorithms for
prologue_end ignored these, meaning someone entering a function at
prologue_end would break-in after a function call had completed. Prefer
instead to place prologue_end and the function scope-line on the line
zero call: this isn't false (it's the first meaningful instruction of the
function) and is approximately true. Given a less than ideal function,
this is an OK solution.



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