[compiler-rt] r351152 - [libFuzzer][MSVC] Use alternatename for ext functions
Jonathan Metzman via llvm-commits
llvm-commits at lists.llvm.org
Mon Jan 14 18:20:53 PST 2019
Author: metzman
Date: Mon Jan 14 18:20:53 2019
New Revision: 351152
URL: http://llvm.org/viewvc/llvm-project?rev=351152&view=rev
Log:
[libFuzzer][MSVC] Use alternatename for ext functions
Summary:
Use alternatename for external functions only when using
MSVC since Clang doesn't support it and MSVC doesn't support
Clang's method (weak aliases).
Reviewers: morehouse
Reviewed By: morehouse
Subscribers: rnk, thakis, mgorny
Differential Revision: https://reviews.llvm.org/D56514
Added:
compiler-rt/trunk/lib/fuzzer/FuzzerExtFunctionsWindows.cpp
Removed:
compiler-rt/trunk/lib/fuzzer/FuzzerExtFunctionsWeakAlias.cpp
Modified:
compiler-rt/trunk/lib/fuzzer/CMakeLists.txt
Modified: compiler-rt/trunk/lib/fuzzer/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/fuzzer/CMakeLists.txt?rev=351152&r1=351151&r2=351152&view=diff
==============================================================================
--- compiler-rt/trunk/lib/fuzzer/CMakeLists.txt (original)
+++ compiler-rt/trunk/lib/fuzzer/CMakeLists.txt Mon Jan 14 18:20:53 2019
@@ -3,8 +3,8 @@ set(LIBFUZZER_SOURCES
FuzzerDataFlowTrace.cpp
FuzzerDriver.cpp
FuzzerExtFunctionsDlsym.cpp
- FuzzerExtFunctionsWeakAlias.cpp
FuzzerExtFunctionsWeak.cpp
+ FuzzerExtFunctionsWindows.cpp
FuzzerExtraCounters.cpp
FuzzerIO.cpp
FuzzerIOPosix.cpp
Removed: compiler-rt/trunk/lib/fuzzer/FuzzerExtFunctionsWeakAlias.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/fuzzer/FuzzerExtFunctionsWeakAlias.cpp?rev=351151&view=auto
==============================================================================
--- compiler-rt/trunk/lib/fuzzer/FuzzerExtFunctionsWeakAlias.cpp (original)
+++ compiler-rt/trunk/lib/fuzzer/FuzzerExtFunctionsWeakAlias.cpp (removed)
@@ -1,56 +0,0 @@
-//===- FuzzerExtFunctionsWeakAlias.cpp - Interface to external functions --===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-// Implementation using weak aliases. Works for Windows.
-//===----------------------------------------------------------------------===//
-#include "FuzzerDefs.h"
-#if LIBFUZZER_WINDOWS
-
-#include "FuzzerExtFunctions.h"
-#include "FuzzerIO.h"
-
-using namespace fuzzer;
-
-extern "C" {
-// Declare these symbols as weak to allow them to be optionally defined.
-#define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
- RETURN_TYPE NAME##Def FUNC_SIG { \
- Printf("ERROR: Function \"%s\" not defined.\n", #NAME); \
- exit(1); \
- } \
- RETURN_TYPE NAME FUNC_SIG __attribute__((weak, alias(#NAME "Def")));
-
-#include "FuzzerExtFunctions.def"
-
-#undef EXT_FUNC
-}
-
-template <typename T>
-static T *GetFnPtr(T *Fun, T *FunDef, const char *FnName, bool WarnIfMissing) {
- if (Fun == FunDef) {
- if (WarnIfMissing)
- Printf("WARNING: Failed to find function \"%s\".\n", FnName);
- return nullptr;
- }
- return Fun;
-}
-
-namespace fuzzer {
-
-ExternalFunctions::ExternalFunctions() {
-#define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
- this->NAME = GetFnPtr<decltype(::NAME)>(::NAME, ::NAME##Def, #NAME, WARN);
-
-#include "FuzzerExtFunctions.def"
-
-#undef EXT_FUNC
-}
-
-} // namespace fuzzer
-
-#endif // LIBFUZZER_WINDOWS
Added: compiler-rt/trunk/lib/fuzzer/FuzzerExtFunctionsWindows.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/fuzzer/FuzzerExtFunctionsWindows.cpp?rev=351152&view=auto
==============================================================================
--- compiler-rt/trunk/lib/fuzzer/FuzzerExtFunctionsWindows.cpp (added)
+++ compiler-rt/trunk/lib/fuzzer/FuzzerExtFunctionsWindows.cpp Mon Jan 14 18:20:53 2019
@@ -0,0 +1,83 @@
+//=== FuzzerExtWindows.cpp - Interface to external functions --------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// Implementation of FuzzerExtFunctions for Windows. Uses alternatename when
+// compiled with MSVC. Uses weak aliases when compiled with clang. Unfortunately
+// the method each compiler supports is not supported by the other.
+//===----------------------------------------------------------------------===//
+#include "FuzzerDefs.h"
+#if LIBFUZZER_WINDOWS
+
+#include "FuzzerExtFunctions.h"
+#include "FuzzerIO.h"
+
+using namespace fuzzer;
+
+// Intermediate macro to ensure the parameter is expanded before stringified.
+#define STRINGIFY_(A) #A
+#define STRINGIFY(A) STRINGIFY_(A)
+
+#if LIBFUZZER_MSVC
+// Copied from compiler-rt/lib/sanitizer_common/sanitizer_win_defs.h
+#if defined(_M_IX86) || defined(__i386__)
+#define WIN_SYM_PREFIX "_"
+#else
+#define WIN_SYM_PREFIX
+#endif
+
+// Declare external functions as having alternativenames, so that we can
+// determine if they are not defined.
+#define EXTERNAL_FUNC(Name, Default) \
+ __pragma(comment(linker, "/alternatename:" WIN_SYM_PREFIX STRINGIFY( \
+ Name) "=" WIN_SYM_PREFIX STRINGIFY(Default)))
+#else
+// Declare external functions as weak to allow them to default to a specified
+// function if not defined explicitly. We must use weak symbols because clang's
+// support for alternatename is not 100%, see
+// https://bugs.llvm.org/show_bug.cgi?id=40218 for more details.
+#define EXTERNAL_FUNC(Name, Default) \
+ __attribute__((weak, alias(STRINGIFY(Default))))
+#endif // LIBFUZZER_MSVC
+
+extern "C" {
+#define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
+ RETURN_TYPE NAME##Def FUNC_SIG { \
+ Printf("ERROR: Function \"%s\" not defined.\n", #NAME); \
+ exit(1); \
+ } \
+ EXTERNAL_FUNC(NAME, NAME##Def) RETURN_TYPE NAME FUNC_SIG;
+
+#include "FuzzerExtFunctions.def"
+
+#undef EXT_FUNC
+}
+
+template <typename T>
+static T *GetFnPtr(T *Fun, T *FunDef, const char *FnName, bool WarnIfMissing) {
+ if (Fun == FunDef) {
+ if (WarnIfMissing)
+ Printf("WARNING: Failed to find function \"%s\".\n", FnName);
+ return nullptr;
+ }
+ return Fun;
+}
+
+namespace fuzzer {
+
+ExternalFunctions::ExternalFunctions() {
+#define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN) \
+ this->NAME = GetFnPtr<decltype(::NAME)>(::NAME, ::NAME##Def, #NAME, WARN);
+
+#include "FuzzerExtFunctions.def"
+
+#undef EXT_FUNC
+}
+
+} // namespace fuzzer
+
+#endif // LIBFUZZER_WINDOWS
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