[llvm] [KeyInstr] Use DISubprogram's is-key-instructions-on flag at DWARF emission (PR #144104)

[Jeremy Morse via llvm-commits]

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@@ -2651,7 +2662,13 @@ void DwarfDebug::beginFunctionImpl(const MachineFunction *MF) {
   PrologEndLoc = emitInitialLocDirective(
       *MF, Asm->OutStreamer->getContext().getDwarfCompileUnitID());
 
-  if (KeyInstructionsAreStmts)
+  // If this function wasn't built with Key Instructions but has a function
+  // inlined into it that was, we treat the inlined instance as if it wasn't
+  // built with Key Instructions. If this function was built with Key
+  // Instructions but a function inlined into it wasn't then we continue to use
+  // Key Instructions for this function and fall back to non-key behaviour for
+  // the inlined function (except it doesn't beneit from findForceIsStmtInstrs).
----------------
jmorse wrote:

```suggestion
  // the inlined function (except it doesn't benefit from findForceIsStmtInstrs).
```

https://github.com/llvm/llvm-project/pull/144104