[llvm] [KeyInstr][DwarfDebug] Add is_stmt emission support (PR #133495)

[Orlando Cazalet-Hyams via llvm-commits]

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@@ -2087,13 +2095,18 @@ void DwarfDebug::beginInstruction(const MachineInstr *MI) {
     // If we have an ongoing unspecified location, nothing to do here.
     if (!DL)
       return;
-    // We have an explicit location, same as the previous location.
-    // But we might be coming back to it after a line 0 record.
-    if ((LastAsmLine == 0 && DL.getLine() != 0) || Flags) {
-      // Reinstate the source location but not marked as a statement.
-      RecordSourceLine(DL, Flags);
+
+    // Skip this if the instruction is Key, else we might accidentally miss an
+    // is_stmt.
+    if (!IsKey) {
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OCHyams wrote:

That puts the `return` in an awkward position - we also want to skip that if `IsKey` is true.

https://github.com/llvm/llvm-project/pull/133495