Only run new pass if llvm passes are not disabled.

Author: s-perron

clang/lib/CodeGen/BackendUtil.cpp

@@ -1099,7 +1099,7 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
   if (CodeGenOpts.LinkBitcodePostopt)
     MPM.addPass(LinkInModulesPass(BC));
 
-  if (LangOpts.HLSL) {
+  if (LangOpts.HLSL && !CodeGenOpts.DisableLLVMPasses) {
     // HLSL legalization passes
     MPM.addPass(HLSLFinalizeLinkage());
     MPM.addPass(GlobalOptPass());

llvm/include/llvm/Transforms/HLSL/HLSLFinalizeLinkage.h

@@ -0,0 +1,39 @@
+//===- HLSLFinalizeLinkage.h - Finalize linkage of functions --------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// HLSLFinalizeLinkage pass updates the linkage of functions to make sure only
+/// shader entry points and exported functions are visible from the module (have
+/// program linkage). All other functions and variables will be updated to have
+/// internal linkage.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_HLSL_HLSLFINALIZELINKAGE_H
+#define LLVM_TRANSFORMS_HLSL_HLSLFINALIZELINKAGE_H
+
+#include "llvm/IR/PassManager.h"
+#include "llvm/Pass.h"
+
+namespace llvm {
+
+class HLSLFinalizeLinkage : public PassInfoMixin<HLSLFinalizeLinkage> {
+public:
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &);
+  static bool isRequired() { return true; }
+};
+
+class HLSLFinalizeLinkageLegacy : public ModulePass {
+public:
+  HLSLFinalizeLinkageLegacy() : ModulePass(ID) {}
+  bool runOnModule(Module &M) override;
+
+  static char ID; // Pass identification.
+};
+} // namespace llvm
+
+#endif // LLVM_TRANSFORMS_HLSL_HLSLFINALIZELINKAGE_H

llvm/lib/Transforms/HLSL/HLSLFinalizeLinkage.cpp

@@ -0,0 +1,51 @@
+//===- HLSLFinalizeLinkage.cpp - Finalize linkage of functions ------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/HLSL/HLSLFinalizeLinkage.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/GlobalValue.h"
+#include "llvm/IR/Module.h"
+
+#define DEBUG_TYPE "dxil-finalize-linkage"
+
+using namespace llvm;
+
+static bool finalizeLinkage(Module &M) {
+  SmallPtrSet<Function *, 8> Funcs;
+
+  for(auto &Var : M.globals()) {
+    if (Var.getLinkage() == GlobalValue::ExternalLinkage) {
+      Var.setLinkage(GlobalValue::InternalLinkage);
+    }
+  }
+
+  // Collect non-entry and non-exported functions to set to internal linkage.
+  for (Function &EF : M.functions()) {
+    if (EF.isIntrinsic())
+      continue;
+    if (EF.hasFnAttribute("hlsl.shader") || EF.hasFnAttribute("hlsl.export"))
+      continue;
+    Funcs.insert(&EF);
+  }
+
+  for (Function *F : Funcs) {
+    if (F->getLinkage() == GlobalValue::ExternalLinkage)
+      F->setLinkage(GlobalValue::InternalLinkage);
+    if (F->isDefTriviallyDead())
+      M.getFunctionList().erase(F);
+  }
+
+  return false;
+}
+
+PreservedAnalyses HLSLFinalizeLinkage::run(Module &M,
+                                           ModuleAnalysisManager &AM) {
+  if (finalizeLinkage(M))
+    return PreservedAnalyses::none();
+  return PreservedAnalyses::all();
+}