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llvm-mirror/lib/Passes/PassPlugin.cpp
Tomas Matheson fcb829d489 [NPM] Resolve llvmGetPassPluginInfo to the plugin being loaded
Dynamically loaded plugins for the new pass manager are initialised by
calling llvmGetPassPluginInfo. This is defined as a weak symbol so that
it is continually redefined by each plugin that is loaded. When loading
a plugin from a shared library, the intention is that
llvmGetPassPluginInfo will be resolved to the definition in the most
recent plugin. However, using a global search for this resolution can
fail in situations where multiple plugins are loaded.

Currently:

* If a plugin does not define llvmGetPassPluginInfo, then it will be
  silently resolved to the previous plugin's definition.

* If loading the same plugin twice with another in between, e.g. plugin
  A/plugin B/plugin A, then the second load of plugin A will resolve to
  llvmGetPassPluginInfo in plugin B.

* The previous case can also occur when a dynamic library defines both
  NPM and legacy plugins; the legacy plugins are loaded first and then
  with `-fplugin=A -fpass-plugin=B -fpass-plugin=A`: A will be loaded as
  a legacy plugin and define llvmGetPassPluginInfo; B will be loaded
  and redefine it; and finally when A is loaded as an NPM plugin it will
  be resolved to the definition from B.

Instead of searching globally, restrict the symbol lookup to the library
that is currently being loaded.

Differential Revision: https://reviews.llvm.org/D104916
2021-06-30 18:11:28 +01:00

55 lines
2.1 KiB
C++

//===- lib/Passes/PassPluginLoader.cpp - Load Plugins for New PM Passes ---===//
//
// 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/Passes/PassPlugin.h"
#include "llvm/Support/raw_ostream.h"
#include <cstdint>
using namespace llvm;
Expected<PassPlugin> PassPlugin::Load(const std::string &Filename) {
std::string Error;
auto Library =
sys::DynamicLibrary::getPermanentLibrary(Filename.c_str(), &Error);
if (!Library.isValid())
return make_error<StringError>(Twine("Could not load library '") +
Filename + "': " + Error,
inconvertibleErrorCode());
PassPlugin P{Filename, Library};
// llvmGetPassPluginInfo should be resolved to the definition from the plugin
// we are currently loading.
intptr_t getDetailsFn =
(intptr_t)Library.getAddressOfSymbol("llvmGetPassPluginInfo");
if (!getDetailsFn)
// If the symbol isn't found, this is probably a legacy plugin, which is an
// error
return make_error<StringError>(Twine("Plugin entry point not found in '") +
Filename + "'. Is this a legacy plugin?",
inconvertibleErrorCode());
P.Info = reinterpret_cast<decltype(llvmGetPassPluginInfo) *>(getDetailsFn)();
if (P.Info.APIVersion != LLVM_PLUGIN_API_VERSION)
return make_error<StringError>(
Twine("Wrong API version on plugin '") + Filename + "'. Got version " +
Twine(P.Info.APIVersion) + ", supported version is " +
Twine(LLVM_PLUGIN_API_VERSION) + ".",
inconvertibleErrorCode());
if (!P.Info.RegisterPassBuilderCallbacks)
return make_error<StringError>(Twine("Empty entry callback in plugin '") +
Filename + "'.'",
inconvertibleErrorCode());
return P;
}