[Opt] Enable support for statically linked plugins

llvm/lib/Passes/PassPlugin.cpp

@@ -14,20 +14,37 @@
 using namespace llvm;
 
 Expected<PassPlugin> PassPlugin::Load(const std::string &Filename) {
+  // First, see if the plugin is available in the current executable, with the
+  // suffix of the symbol being given by the `Filename` otherwise, try loading
+  // the plugin via the file
   std::string Error;
-  auto Library =
-      sys::DynamicLibrary::getPermanentLibrary(Filename.c_str(), &Error);
+
+  auto Library = sys::DynamicLibrary::getPermanentLibrary(nullptr, &Error);
   if (!Library.isValid())
-    return make_error<StringError>(Twine("Could not load library '") +
-                                       Filename + "': " + Error,
+    return make_error<StringError>("Could not load current executable",
                                    inconvertibleErrorCode());
 
-  PassPlugin P{Filename, Library};
-
   // llvmGetPassPluginInfo should be resolved to the definition from the plugin
   // we are currently loading.
+  std::string symbolName = "llvmGetPassPluginInfo" + Filename;
   intptr_t getDetailsFn =
-      (intptr_t)Library.getAddressOfSymbol("llvmGetPassPluginInfo");
+      (intptr_t)Library.getAddressOfSymbol(symbolName.c_str());
+
+  if (!getDetailsFn) {
+    Library = sys::DynamicLibrary::getPermanentLibrary(
+        (Filename == "") ? nullptr : Filename.c_str(), &Error);
+    if (!Library.isValid())
+      return make_error<StringError>(Twine("Could not load library '") +
+                                         Filename + "': " + Error,
+                                     inconvertibleErrorCode());
+
+    // llvmGetPassPluginInfo should be resolved to the definition from the
+    // plugin we are currently loading.
+    getDetailsFn =
+        (intptr_t)Library.getAddressOfSymbol("llvmGetPassPluginInfo");
+  }
+
+  PassPlugin P{Filename, Library};
 
   if (!getDetailsFn)
     // If the symbol isn't found, this is probably a legacy plugin, which is an

llvm/test/Feature/load_staticextension.ll

@@ -0,0 +1,15 @@
+; REQUIRES: x86-registered-target
+; RUN: opt-printplugin %s -load-pass-plugin="PrintPlugin" -passes="printpass" -disable-output 2>&1 | FileCheck %s
+
+; REQUIRES: plugins
+
+; CHECK: [PrintPass] Found function: somefunk
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+@junk = global i32 0
+
+define ptr @somefunk() {
+  ret ptr @junk
+}
+

llvm/tools/opt/CMakeLists.txt

@@ -30,6 +30,7 @@ set(LLVM_LINK_COMPONENTS
   )
 
 add_llvm_tool(opt
+    PARTIAL_SOURCES_INTENDED
   NewPMDriver.cpp
   opt.cpp
 
@@ -38,3 +39,16 @@ add_llvm_tool(opt
   SUPPORT_PLUGINS
   )
 export_executable_symbols_for_plugins(opt)
+
+if (LLVM_ENABLE_PLUGINS)
+add_llvm_tool(opt-printplugin
+  NewPMDriver.cpp
+  opt.cpp
+  PrintPlugin.cpp
+
+  DEPENDS
+  intrinsics_gen
+  SUPPORT_PLUGINS
+  )
+target_link_options(opt-printplugin PUBLIC -Wl,--export-dynamic-symbol=llvmGetPassPluginInfoPrintPlugin)
+endif()

llvm/tools/opt/PrintPlugin.cpp

@@ -0,0 +1,63 @@
+//===- LLVMPrintFunctionNames.cpp
+//---------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Example opt plugin which simply prints the names of all the functions
+// within the generated LLVM code.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/PassManager.h"
+#include "llvm/Passes/OptimizationLevel.h"
+#include "llvm/Passes/PassBuilder.h"
+#include "llvm/Passes/PassPlugin.h"
+#include "llvm/Support/Registry.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+namespace {
+
+class PrintPass final : public llvm::AnalysisInfoMixin<PrintPass> {
+  friend struct llvm::AnalysisInfoMixin<PrintPass>;
+
+private:
+  static llvm::AnalysisKey key;
+
+public:
+  using Result = llvm::PreservedAnalyses;
+
+  Result run(llvm::Module &M, llvm::ModuleAnalysisManager &MAM) {
+    for (auto &F : M)
+      llvm::outs() << "[PrintPass] Found function: " << F.getName() << "\n";
+    return llvm::PreservedAnalyses::all();
+  }
+  static bool isRequired() { return true; }
+};
+
+} // namespace
+
+llvm::PassPluginLibraryInfo getPrintPluginInfo() {
+  return {LLVM_PLUGIN_API_VERSION, "PrintPlugin", LLVM_VERSION_STRING,
+          [](PassBuilder &PB) {
+            PB.registerPipelineParsingCallback(
+                [](StringRef Name, llvm::ModulePassManager &PM,
+                   ArrayRef<llvm::PassBuilder::PipelineElement>) {
+                  if (Name == "printpass") {
+                    PM.addPass(PrintPass());
+                    return true;
+                  }
+                  return false;
+                });
+          }};
+}
+
+extern "C" LLVM_ATTRIBUTE_WEAK ::llvm::PassPluginLibraryInfo
+llvmGetPassPluginInfoPrintPlugin() {
+  return getPrintPluginInfo();
+}