[compiler-rt] r293419 - General definition for weak functions
Marcos Pividori via llvm-commits
llvm-commits at lists.llvm.org
Sat Jan 28 21:45:00 PST 2017
Author: mpividori
Date: Sat Jan 28 23:44:59 2017
New Revision: 293419
URL: http://llvm.org/viewvc/llvm-project?rev=293419&view=rev
Log:
General definition for weak functions
In this diff, I define a general macro for defining weak functions
with a default implementation: "SANITIZER_INTERFACE_WEAK_DEF()".
This way, we simplify the implementation for different platforms.
For example, we cannot define weak functions on Windows, but we can
use linker pragmas to create an alias to a default implementation.
All of these implementation details are hidden in the new macro.
Also, as I modify the name for exported weak symbols on Windows, I
needed to temporarily disable "dll_host" test for asan, which checks
the list of functions included in asan_win_dll_thunk.
Differential Revision: https://reviews.llvm.org/D28596
Modified:
compiler-rt/trunk/lib/asan/asan_allocator.cc
compiler-rt/trunk/lib/asan/asan_flags.cc
compiler-rt/trunk/lib/asan/asan_report.cc
compiler-rt/trunk/lib/asan/asan_suppressions.cc
compiler-rt/trunk/lib/asan/asan_win.cc
compiler-rt/trunk/lib/asan/asan_win_dll_thunk.cc
compiler-rt/trunk/lib/sanitizer_common/sancov_flags.cc
compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.cc
compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc
compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep_new.cc
compiler-rt/trunk/lib/sanitizer_common/sanitizer_internal_defs.h
compiler-rt/trunk/lib/sanitizer_common/sanitizer_printf.cc
compiler-rt/trunk/lib/sanitizer_common/sanitizer_win.cc
compiler-rt/trunk/lib/sanitizer_common/sanitizer_win_defs.h
compiler-rt/trunk/lib/ubsan/ubsan_flags.cc
compiler-rt/trunk/test/asan/TestCases/Windows/dll_host.cc
Modified: compiler-rt/trunk/lib/asan/asan_allocator.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_allocator.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_allocator.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_allocator.cc Sat Jan 28 23:44:59 2017
@@ -958,15 +958,13 @@ uptr __sanitizer_get_allocated_size(cons
#if !SANITIZER_SUPPORTS_WEAK_HOOKS
// Provide default (no-op) implementation of malloc hooks.
-extern "C" {
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_malloc_hook(void *ptr, uptr size) {
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_malloc_hook,
+ void *ptr, uptr size) {
(void)ptr;
(void)size;
}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_free_hook(void *ptr) {
+
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_free_hook, void *ptr) {
(void)ptr;
}
-} // extern "C"
#endif
Modified: compiler-rt/trunk/lib/asan/asan_flags.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_flags.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_flags.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_flags.cc Sat Jan 28 23:44:59 2017
@@ -186,9 +186,6 @@ void InitializeFlags() {
} // namespace __asan
-#if !SANITIZER_SUPPORTS_WEAK_HOOKS
-extern "C" {
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-const char* __asan_default_options() { return ""; }
-} // extern "C"
-#endif
+SANITIZER_INTERFACE_WEAK_DEF(const char*, __asan_default_options, void) {
+ return "";
+}
Modified: compiler-rt/trunk/lib/asan/asan_report.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_report.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_report.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_report.cc Sat Jan 28 23:44:59 2017
@@ -488,9 +488,6 @@ void __sanitizer_ptr_cmp(void *a, void *
}
} // extern "C"
-#if !SANITIZER_SUPPORTS_WEAK_HOOKS
// Provide default implementation of __asan_on_error that does nothing
// and may be overriden by user.
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE NOINLINE
-void __asan_on_error() {}
-#endif
+SANITIZER_INTERFACE_WEAK_DEF(void, __asan_on_error, void) {}
Modified: compiler-rt/trunk/lib/asan/asan_suppressions.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_suppressions.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_suppressions.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_suppressions.cc Sat Jan 28 23:44:59 2017
@@ -31,15 +31,9 @@ static const char *kSuppressionTypes[] =
kInterceptorName, kInterceptorViaFunction, kInterceptorViaLibrary,
kODRViolation};
-extern "C" {
-#if SANITIZER_SUPPORTS_WEAK_HOOKS
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-const char *__asan_default_suppressions();
-#else
-// No week hooks, provide empty implementation.
-const char *__asan_default_suppressions() { return ""; }
-#endif // SANITIZER_SUPPORTS_WEAK_HOOKS
-} // extern "C"
+SANITIZER_INTERFACE_WEAK_DEF(const char *, __asan_default_suppressions, void) {
+ return "";
+}
void InitializeSuppressions() {
CHECK_EQ(nullptr, suppression_ctx);
Modified: compiler-rt/trunk/lib/asan/asan_win.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_win.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_win.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_win.cc Sat Jan 28 23:44:59 2017
@@ -43,18 +43,6 @@ uptr __asan_get_shadow_memory_dynamic_ad
__asan_init();
return __asan_shadow_memory_dynamic_address;
}
-
-void __sanitizer_default_malloc_hook(void *ptr, uptr size) { }
-void __sanitizer_default_free_hook(void *ptr) { }
-const char* __asan_default_default_options() { return ""; }
-const char* __asan_default_default_suppressions() { return ""; }
-void __asan_default_on_error() {}
-
-WIN_WEAK_ALIAS(__sanitizer_malloc_hook, __sanitizer_default_malloc_hook)
-WIN_WEAK_ALIAS(__sanitizer_free_hook, __sanitizer_default_free_hook)
-WIN_WEAK_ALIAS(__asan_default_options, __asan_default_default_options)
-WIN_WEAK_ALIAS(__asan_default_suppressions, __asan_default_default_suppressions)
-WIN_WEAK_ALIAS(__asan_on_error, __asan_default_on_error)
} // extern "C"
// ---------------------- Windows-specific interceptors ---------------- {{{
Modified: compiler-rt/trunk/lib/asan/asan_win_dll_thunk.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_win_dll_thunk.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_win_dll_thunk.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_win_dll_thunk.cc Sat Jan 28 23:44:59 2017
@@ -333,8 +333,6 @@ INTERFACE_FUNCTION(__sanitizer_cov_init)
INTERFACE_FUNCTION(__sanitizer_cov_module_init)
INTERFACE_FUNCTION(__sanitizer_cov_trace_basic_block)
INTERFACE_FUNCTION(__sanitizer_cov_trace_func_enter)
-INTERFACE_FUNCTION(__sanitizer_cov_trace_pc_guard)
-INTERFACE_FUNCTION(__sanitizer_cov_trace_pc_guard_init)
INTERFACE_FUNCTION(__sanitizer_cov_with_check)
INTERFACE_FUNCTION(__sanitizer_get_allocated_size)
INTERFACE_FUNCTION(__sanitizer_get_coverage_guards)
Modified: compiler-rt/trunk/lib/sanitizer_common/sancov_flags.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sancov_flags.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sancov_flags.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sancov_flags.cc Sat Jan 28 23:44:59 2017
@@ -15,10 +15,9 @@
#include "sanitizer_flag_parser.h"
#include "sanitizer_platform.h"
-#if !SANITIZER_LINUX
-// other platforms do not have weak symbols out of the box.
-extern "C" const char* __sancov_default_options() { return ""; }
-#endif
+SANITIZER_INTERFACE_WEAK_DEF(const char*, __sancov_default_options, void) {
+ return "";
+}
using namespace __sanitizer;
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.cc Sat Jan 28 23:44:59 2017
@@ -505,9 +505,9 @@ int __sanitizer_install_malloc_and_free_
return InstallMallocFreeHooks(malloc_hook, free_hook);
}
-#if !SANITIZER_GO && !SANITIZER_SUPPORTS_WEAK_HOOKS
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_print_memory_profile(int top_percent) {
+#if !SANITIZER_GO
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_print_memory_profile,
+ int top_percent) {
(void)top_percent;
}
#endif
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc Sat Jan 28 23:44:59 2017
@@ -1016,27 +1016,16 @@ SANITIZER_INTERFACE_ATTRIBUTE
uptr __sanitizer_update_counter_bitset_and_clear_counters(u8 *bitset) {
return coverage_data.Update8bitCounterBitsetAndClearCounters(bitset);
}
+
// Default empty implementations (weak). Users should redefine them.
-#if !SANITIZER_WINDOWS // weak does not work on Windows.
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_cov_trace_cmp() {}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_cov_trace_cmp1() {}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_cov_trace_cmp2() {}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_cov_trace_cmp4() {}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_cov_trace_cmp8() {}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_cov_trace_switch() {}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_cov_trace_div4() {}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_cov_trace_div8() {}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_cov_trace_gep() {}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void __sanitizer_cov_trace_pc_indir() {}
-#endif // !SANITIZER_WINDOWS
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_cmp, void) {}
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_cmp1, void) {}
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_cmp2, void) {}
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_cmp4, void) {}
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_cmp8, void) {}
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_switch, void) {}
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_div4, void) {}
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_div8, void) {}
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_gep, void) {}
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_pc_indir, void) {}
} // extern "C"
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep_new.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep_new.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep_new.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep_new.cc Sat Jan 28 23:44:59 2017
@@ -156,14 +156,13 @@ SANITIZER_INTERFACE_ATTRIBUTE void __san
return __sancov::SanitizerDumpCoverage(pcs, len);
}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE void
-__sanitizer_cov_trace_pc_guard(u32* guard) {
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_pc_guard, u32* guard) {
if (!*guard) return;
__sancov::pc_guard_controller.TracePcGuard(guard, GET_CALLER_PC() - 1);
}
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE void
-__sanitizer_cov_trace_pc_guard_init(u32* start, u32* end) {
+SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_pc_guard_init,
+ u32* start, u32* end) {
if (start == end || *start) return;
__sancov::pc_guard_controller.InitTracePcGuard(start, end);
}
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_internal_defs.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_internal_defs.h?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_internal_defs.h (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_internal_defs.h Sat Jan 28 23:44:59 2017
@@ -22,7 +22,6 @@
// Only use SANITIZER_*ATTRIBUTE* before the function return type!
#if SANITIZER_WINDOWS
# define SANITIZER_INTERFACE_ATTRIBUTE __declspec(dllexport)
-// FIXME find out what we need on Windows, if anything.
# define SANITIZER_WEAK_ATTRIBUTE
#elif SANITIZER_GO
# define SANITIZER_INTERFACE_ATTRIBUTE
@@ -32,11 +31,46 @@
# define SANITIZER_WEAK_ATTRIBUTE __attribute__((weak))
#endif
-#if (SANITIZER_LINUX || SANITIZER_MAC || SANITIZER_WINDOWS) && !SANITIZER_GO
+//--------------------------- WEAK FUNCTIONS ---------------------------------//
+// When working with weak functions, to simplify the code and make it more
+// portable, when possible define a default implementation using this macro:
+//
+// SANITIZER_INTERFACE_WEAK_DEF(<return_type>, <name>, <parameter list>)
+//
+// For example:
+// SANITIZER_INTERFACE_WEAK_DEF(bool, compare, int a, int b) { return a > b; }
+//
+#if SANITIZER_WINDOWS
+#include "sanitizer_win_defs.h"
+# define SANITIZER_INTERFACE_WEAK_DEF(ReturnType, Name, ...) \
+ WIN_WEAK_EXPORT_DEF(ReturnType, Name, __VA_ARGS__)
+#else
+# define SANITIZER_INTERFACE_WEAK_DEF(ReturnType, Name, ...) \
+ extern "C" SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE \
+ ReturnType Name(__VA_ARGS__)
+#endif
+
+// SANITIZER_SUPPORTS_WEAK_HOOKS means that we support real weak functions that
+// will evaluate to a null pointer when not defined.
+#if (SANITIZER_LINUX || SANITIZER_MAC) && !SANITIZER_GO
# define SANITIZER_SUPPORTS_WEAK_HOOKS 1
#else
# define SANITIZER_SUPPORTS_WEAK_HOOKS 0
#endif
+// For some weak hooks that will be called very often and we want to avoid the
+// overhead of executing the default implementation when it is not necessary,
+// we can use the flag SANITIZER_SUPPORTS_WEAK_HOOKS to only define the default
+// implementation for platforms that doesn't support weak symbols. For example:
+//
+// #if !SANITIZER_SUPPORT_WEAK_HOOKS
+// SANITIZER_INTERFACE_WEAK_DEF(bool, compare_hook, int a, int b) {
+// return a > b;
+// }
+// #endif
+//
+// And then use it as: if (compare_hook) compare_hook(a, b);
+//----------------------------------------------------------------------------//
+
// We can use .preinit_array section on Linux to call sanitizer initialization
// functions very early in the process startup (unless PIC macro is defined).
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_printf.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_printf.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_printf.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_printf.cc Sat Jan 28 23:44:59 2017
@@ -214,15 +214,11 @@ void SetPrintfAndReportCallback(void (*c
}
// Can be overriden in frontend.
-#if SANITIZER_SUPPORTS_WEAK_HOOKS
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-void OnPrint(const char *str) {
- (void)str;
-}
-#elif SANITIZER_GO && defined(TSAN_EXTERNAL_HOOKS)
-void OnPrint(const char *str);
+#if SANITIZER_GO && defined(TSAN_EXTERNAL_HOOKS)
+// Implementation must be defined in frontend.
+extern "C" void OnPrint(const char *str);
#else
-void OnPrint(const char *str) {
+SANITIZER_INTERFACE_WEAK_DEF(void, OnPrint, const char *str) {
(void)str;
}
#endif
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_win.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_win.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_win.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_win.cc Sat Jan 28 23:44:59 2017
@@ -940,15 +940,4 @@ void GetMemoryProfile(fill_profile_f cb,
} // namespace __sanitizer
-#if !SANITIZER_GO
-// Workaround to implement weak hooks on Windows. COFF doesn't directly support
-// weak symbols, but it does support /alternatename, which is similar. If the
-// user does not override the hook, we will use this default definition instead
-// of null.
-extern "C" void __sanitizer_print_memory_profile(int top_percent) {}
-
-WIN_WEAK_ALIAS(__sanitizer_print_memory_profile,
- __sanitizer_default_print_memory_profile)
-#endif
-
#endif // _WIN32
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_win_defs.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_win_defs.h?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_win_defs.h (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_win_defs.h Sat Jan 28 23:44:59 2017
@@ -29,19 +29,19 @@
// We don't have a direct equivalent of weak symbols when using MSVC, but we can
// use the /alternatename directive to tell the linker to default a specific
// symbol to a specific value.
-// Take into account that the function will be marked as UNDEF in the symbol
-// table of the resulting object file, even if we provided a default value, and
-// the linker won't find the default implementation until it links with that
-// object file.
+// Take into account that this is a pragma directive for the linker, so it will
+// be ignored by the compiler and the function will be marked as UNDEF in the
+// symbol table of the resulting object file. The linker won't find the default
+// implementation until it links with that object file.
// So, suppose we provide a default implementation "fundef" for "fun", and this
-// is compiled into the object file "test.obj".
+// is compiled into the object file "test.obj" including the pragma directive.
// If we have some code with references to "fun" and we link that code with
// "test.obj", it will work because the linker always link object files.
// But, if "test.obj" is included in a static library, like "test.lib", then the
// liker will only link to "test.obj" if necessary. If we only included the
// definition of "fun", it won't link to "test.obj" (from test.lib) because
-// "fun" appears as UNDEF, so it doesn't resolve the symbol "fun", and this will
-// result in a link error.
+// "fun" appears as UNDEF, so it doesn't resolve the symbol "fun", and will
+// result in a link error (the linker doesn't find the pragma directive).
// So, a workaround is to force linkage with the modules that include weak
// definitions, with the following macro: WIN_FORCE_LINK()
@@ -55,5 +55,93 @@
#define WIN_FORCE_LINK(Name) \
__pragma(comment(linker, "/include:" WIN_SYM_PREFIX STRINGIFY(Name)))
+#define WIN_EXPORT(ExportedName, Name) \
+ __pragma(comment(linker, "/export:" WIN_SYM_PREFIX STRINGIFY(ExportedName) \
+ "=" WIN_SYM_PREFIX STRINGIFY(Name)))
+
+// We cannot define weak functions on Windows, but we can use WIN_WEAK_ALIAS()
+// which defines an alias to a default implementation, and only works when
+// linking statically.
+// So, to define a weak function "fun", we define a default implementation with
+// a different name "fun__def" and we create a "weak alias" fun = fun__def.
+// Then, users can override it just defining "fun".
+// We impose "extern "C"" because otherwise WIN_WEAK_ALIAS() will fail because
+// of name mangling.
+
+// Dummy name for default implementation of weak function.
+# define WEAK_DEFAULT_NAME(Name) Name##__def
+// Name for exported implementation of weak function.
+# define WEAK_EXPORT_NAME(Name) Name##__dll
+
+// Use this macro when you need to define and export a weak function from a
+// library. For example:
+// WIN_WEAK_EXPORT_DEF(bool, compare, int a, int b) { return a > b; }
+# define WIN_WEAK_EXPORT_DEF(ReturnType, Name, ...) \
+ WIN_WEAK_ALIAS(Name, WEAK_DEFAULT_NAME(Name)) \
+ WIN_EXPORT(WEAK_EXPORT_NAME(Name), Name) \
+ extern "C" ReturnType Name(__VA_ARGS__); \
+ extern "C" ReturnType WEAK_DEFAULT_NAME(Name)(__VA_ARGS__)
+
+// Use this macro when you need to import a weak function from a library. It
+// defines a weak alias to the imported function from the dll. For example:
+// WIN_WEAK_IMPORT_DEF(compare)
+# define WIN_WEAK_IMPORT_DEF(Name) \
+ WIN_WEAK_ALIAS(Name, WEAK_EXPORT_NAME(Name))
+
+// So, for Windows we provide something similar to weak symbols in Linux, with
+// some differences:
+// + A default implementation must always be provided.
+//
+// + When linking statically it works quite similarly. For example:
+//
+// // libExample.cc
+// WIN_WEAK_EXPORT_DEF(bool, compare, int a, int b) { return a > b; }
+//
+// // client.cc
+// // We can use the default implementation from the library:
+// compare(1, 2);
+// // Or we can override it:
+// extern "C" bool compare (int a, int b) { return a >= b; }
+//
+// And it will work fine. If we don't override the function, we need to ensure
+// that the linker includes the object file with the default implementation.
+// We can do so with the linker option "-wholearchive:".
+//
+// + When linking dynamically with a library (dll), weak functions are exported
+// with "__dll" suffix. Clients can use the macro WIN_WEAK_IMPORT_DEF(fun)
+// which defines a "weak alias" fun = fun__dll.
+//
+// // libExample.cc
+// WIN_WEAK_EXPORT_DEF(bool, compare, int a, int b) { return a > b; }
+//
+// // client.cc
+// WIN_WEAK_IMPORT_DEF(compare)
+// // We can use the default implementation from the library:
+// compare(1, 2);
+// // Or we can override it:
+// extern "C" bool compare (int a, int b) { return a >= b; }
+//
+// But if we override the function, the dlls don't have access to it (which
+// is different in linux). If that is desired, the strong definition must be
+// exported and interception can be used from the rest of the dlls.
+//
+// // libExample.cc
+// WIN_WEAK_EXPORT_DEF(bool, compare, int a, int b) { return a > b; }
+// // When initialized, check if the main executable defined "compare".
+// int libExample_init() {
+// uptr fnptr = __interception::InternalGetProcAddress(
+// (void *)GetModuleHandleA(0), "compare");
+// if (fnptr && !__interception::OverrideFunction((uptr)compare, fnptr, 0))
+// abort();
+// return 0;
+// }
+//
+// // client.cc
+// WIN_WEAK_IMPORT_DEF(compare)
+// // We override and export compare:
+// extern "C" __declspec(dllexport) bool compare (int a, int b) {
+// return a >= b;
+// }
+//
#endif // SANITIZER_WINDOWS
#endif // SANITIZER_WIN_DEFS_H
Modified: compiler-rt/trunk/lib/ubsan/ubsan_flags.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/ubsan/ubsan_flags.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/lib/ubsan/ubsan_flags.cc (original)
+++ compiler-rt/trunk/lib/ubsan/ubsan_flags.cc Sat Jan 28 23:44:59 2017
@@ -17,7 +17,6 @@
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_flags.h"
#include "sanitizer_common/sanitizer_flag_parser.h"
-#include "sanitizer_common/sanitizer_win_defs.h"
namespace __ubsan {
@@ -68,19 +67,8 @@ void InitializeFlags() {
} // namespace __ubsan
-extern "C" {
-
-#if !SANITIZER_SUPPORTS_WEAK_HOOKS
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-const char *__ubsan_default_options() { return ""; }
-#endif
-
-#if SANITIZER_WINDOWS
-const char *__ubsan_default_default_options() { return ""; }
-
-WIN_WEAK_ALIAS(__ubsan_default_options, __ubsan_default_default_options)
-#endif
-
-} // extern "C"
+SANITIZER_INTERFACE_WEAK_DEF(const char *, __ubsan_default_options, void) {
+ return "";
+}
#endif // CAN_SANITIZE_UB
Modified: compiler-rt/trunk/test/asan/TestCases/Windows/dll_host.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/Windows/dll_host.cc?rev=293419&r1=293418&r2=293419&view=diff
==============================================================================
--- compiler-rt/trunk/test/asan/TestCases/Windows/dll_host.cc (original)
+++ compiler-rt/trunk/test/asan/TestCases/Windows/dll_host.cc Sat Jan 28 23:44:59 2017
@@ -41,6 +41,7 @@
// RUN: echo "=== NOTE === If you see a mismatch below, please update asan_win_dll_thunk.cc"
// RUN: diff %t.dll_imports-sorted %t.exported_wrappers-sorted
// REQUIRES: asan-static-runtime
+// XFAIL: win
#include <stdio.h>
#include <windows.h>
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