[llvm] [DXIL][Analysis] Add DXILMetadataAnalysis pass (PR #102079)

[Justin Bogner via llvm-commits]

================
@@ -0,0 +1,83 @@
+//=- DXILMetadataAnalysis.h - Representation of Module metadata --*- C++ -*-=//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_DXILMETADATA_H
+#define LLVM_ANALYSIS_DXILMETADATA_H
+
+#include "llvm/ADT/MapVector.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/Value.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/DXILABI.h"
+#include "llvm/Support/VersionTuple.h"
+#include "llvm/TargetParser/Triple.h"
+
+namespace llvm {
+
+namespace dxil {
+
+struct ModuleMetadataInfo {
+  VersionTuple DXILVersion;
+  Triple::OSType ShaderModel;
+  Triple::EnvironmentType ShaderStage;
+
+  void dump(raw_ostream &OS = errs());
+};
+
+} // namespace dxil
+
+class DXILMetadataAnalysis : public AnalysisInfoMixin<DXILMetadataAnalysis> {
+  friend AnalysisInfoMixin<DXILMetadataAnalysis>;
+
+  static AnalysisKey Key;
+
+public:
+  using Result = dxil::ModuleMetadataInfo;
+  /// Gather module metadata info for the module \c M.
+  dxil::ModuleMetadataInfo run(Module &M, ModuleAnalysisManager &AM);
+};
+
+/// Printer pass for the \c DXILMetadataAnalysis results.
+class DXILMetadataAnalysisPrinterPass
+    : public PassInfoMixin<DXILMetadataAnalysisPrinterPass> {
+  raw_ostream &OS;
+
+public:
+  explicit DXILMetadataAnalysisPrinterPass(raw_ostream &OS) : OS(OS) {}
+
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+
+  static bool isRequired() { return true; }
+};
+
+/// Wrapper pass to be used by other passes using legacy pass manager
+class DXILMetadataAnalysisWrapperPass : public ModulePass {
+  std::unique_ptr<dxil::ModuleMetadataInfo> ModuleMetadata;
----------------
bogner wrote:

This just means that we never release the memory though? While the `dxil::ModuleMetadataInfo` is (currently) only about 6.5x the size of a pointer it's likely to continue growing, and the [lifetime of a pass in the legacy pass manager is the whole compilation process](https://llvm.org/docs/WritingAnLLVMPass.html#the-releasememory-method). It really is better to just use a unique_ptr here.

https://github.com/llvm/llvm-project/pull/102079