[llvm] [SPIRV] Migrate NSDI emission from a machine pass to DebugHandlerBase (PR #191212)

[Diego Novillo via llvm-commits]

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@@ -861,6 +897,13 @@ void SPIRVAsmPrinter::outputModuleSections() {
 
 bool SPIRVAsmPrinter::doInitialization(Module &M) {
   ModuleSectionsEmitted = false;
+  // Register the NSDI handler before calling the base class so that
+  // AsmPrinter::doInitialization() calls Handler->beginModule(M) for it.
+  if (M.getNamedMetadata("llvm.dbg.cu")) {
+    auto Handler = std::make_unique<SPIRVNonSemanticDebugHandler>(*this);
+    NSDebugHandler = Handler.get();
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dnovillo wrote:

Yes, that's correct. The handler list is owned by the `AsmPrinter` base class, which lives as long as the `SPIRVAsmPrinter` does. Both are destroyed together when the printer object goes out of scope. Added a comment.

https://github.com/llvm/llvm-project/pull/191212