libunwind: fix building on mingw-w64

[martell]

Summary

This needs to be updated to actually handle dwarf unwind tables for mingw-w64.
Getting this initial diff onto phab so we can have a discussion about it.
This should build for mingw-w64 even if it is not useful.

[EricWF]

src/assembly.h

30

This seems like it's obviously not correct. What is going on with this?

src/config.h

41

Why are these commented out?

55

Shouldn't this be change to be a DLL import/export?

[compnerd]

Im not sure that this is a reasonable patch. I think that specializing a AddressSpace for _WIN32 is more likely what we want. Furthermore, this actually should be more restrictive, since the unwind library cannot be used for Windows -- the unwinding model on Windows is completely different. This only makes sense for MinGW and cygwin, and so we should ensure that the environment matches that.

src/AddressSpace.hpp

293

Huh? This doesn't make sense. mach_header_64 on _WIN64? Plus, how does dladdr work here?

src/config.h

54

Please use defined.

55

This should be using __declspec(dllexport) and .

[mati865]

src/AddressSpace.hpp

293

It's guarded by __APPLE__ and probably was added by mistake when modifying __LP64__ checks.

[mstorsjo]

@martell I think this patch can be discarded now. The CMake parts for mingw libs have been committed, and libunwind works for SjLj exceptions on mingw on x86, x86_64 and armv7 now (although only for static builds).

[martell]

This and a lot more has been handled by martin in other patches.
Closing/Abandoning

cmake/config-ix.cmake

if (LIBUNWIND_HAS_NODEFAULTLIBS_FLAG)
   endif ()
   if (LIBUNWIND_USE_COMPILER_RT)
     list(APPEND CMAKE_REQUIRED_FLAGS -rtlib=compiler-rt)
     find_compiler_rt_library(builtins LIBUNWIND_BUILTINS_LIBRARY)
     list(APPEND CMAKE_REQUIRED_LIBRARIES "${LIBUNWIND_BUILTINS_LIBRARY}")
   elseif (LIBUNWIND_HAS_GCC_S_LIB)
     list(APPEND CMAKE_REQUIRED_LIBRARIES gcc_s)
   endif ()
+  if (MINGW)
+    # Mingw64 requires quite a few "C" runtime libraries in order for basic
+    # programs to link successfully with -nodefaultlibs.
+    if (LIBUNWIND_USE_COMPILER_RT)
+      set(MINGW_RUNTIME ${LIBUNWIND_BUILTINS_LIBRARY})
+    else ()
+      set(MINGW_RUNTIME gcc_s gcc)
+    endif()
+    set(MINGW_LIBRARIES mingw32 ${MINGW_RUNTIME} moldname mingwex msvcrt advapi32
+                        shell32 user32 kernel32 mingw32 ${MINGW_RUNTIME}
+                        moldname mingwex msvcrt)
+    list(APPEND CMAKE_REQUIRED_LIBRARIES ${MINGW_LIBRARIES})
+  endif()
   if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize)
     set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all")
   endif ()
   if (CMAKE_C_FLAGS MATCHES -fsanitize-coverage OR CMAKE_CXX_FLAGS MATCHES -fsanitize-coverage)
     set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters")
   endif ()
 endif ()
 

include/unwind.h

 typedef struct _Unwind_Exception _Unwind_Exception;
 
 struct _Unwind_Exception {
   uint64_t exception_class;
   void (*exception_cleanup)(_Unwind_Reason_Code reason,
                             _Unwind_Exception *exc);
   uintptr_t private_1; // non-zero means forced unwind
   uintptr_t private_2; // holds sp that phase1 found for phase2 to use
-#ifndef __LP64__
+#if !defined(__LP64__) && !defined(_WIN64)
   // The implementation of _Unwind_Exception uses an attribute mode on the
   // above fields which has the side effect of causing this whole struct to
   // round up to 32 bytes in size. To be more explicit, we add pad fields
   // added for binary compatibility.
   uint32_t reserved[3];
 #endif
   // The Itanium ABI requires that _Unwind_Exception objects are "double-word
   // aligned".  GCC has interpreted this to mean "use the maximum useful

src/AddressSpace.hpp

 #ifndef __ADDRESSSPACE_HPP__
 #define __ADDRESSSPACE_HPP__
 
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-#ifndef _LIBUNWIND_IS_BAREMETAL
+#if !defined(_LIBUNWIND_IS_BAREMETAL) && !defined(_WIN32)
 #include <dlfcn.h>
 #endif
 
 #ifdef __APPLE__
 #include <mach-o/getsect.h>
 namespace libunwind {
    bool checkKeyMgrRegisteredFDEs(uintptr_t targetAddr, void *&fde);
 }

 };
 
 
 /// LocalAddressSpace is used as a template parameter to UnwindCursor when
 /// unwinding a thread in the same process.  The wrappers compile away,
 /// making local unwinds fast.
 class __attribute__((visibility("hidden"))) LocalAddressSpace {
 public:
-#ifdef __LP64__
+#if defined(__LP64__) || defined(_WIN64)
   typedef uint64_t pint_t;
   typedef int64_t  sint_t;
 #else
   typedef uint32_t pint_t;
   typedef int32_t  sint_t;
 #endif
   uint8_t         get8(pint_t addr) {
     uint8_t val;
#else
     // that this requires a newer version of libmacho (from cctools) than is
     // present in libSystem on 10.6.x (for getsectiondata).
     static inline bool _dyld_find_unwind_sections(void* addr, 
                                                     dyld_unwind_sections* info) {
       // Find mach-o image containing address.
       Dl_info dlinfo;
       if (!dladdr(addr, &dlinfo))
         return false;
-#if __LP64__
+#if defined(__LP64__) || defined(_WIN64)
       const struct mach_header_64 *mh = (const struct mach_header_64 *)dlinfo.dli_fbase;
 #else
       const struct mach_header *mh = (const struct mach_header *)dlinfo.dli_fbase;
 #endif
 
       // Initialize the return struct
       info->mh = (const struct mach_header *)mh;
       info->dwarf_section = getsectiondata(mh, "__TEXT", "__eh_frame", &info->dwarf_section_length);

 
 #elif defined(_LIBUNWIND_ARM_EHABI) || defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
 
 // ELF-based systems may use dl_iterate_phdr() to access sections
 // containing unwinding information. The ElfW() macro for pointer-size
 // independent ELF header traversal is not provided by <link.h> on some
 // systems (e.g., FreeBSD). On these systems the data structures are
 // just called Elf_XXX. Define ElfW() locally.
+#ifndef _WIN32
 #include <link.h>
+#endif
 #if !defined(ElfW)
 #define ElfW(type) Elf_##type
 #endif
 
 #endif
 
 inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
                                                   UnwindInfoSections &info) {
#else
   (void)fde;
   return false;
 #endif
 }
 
 inline bool LocalAddressSpace::findFunctionName(pint_t addr, char *buf,
                                                 size_t bufLen,
                                                 unw_word_t *offset) {
-#ifndef _LIBUNWIND_IS_BAREMETAL
+#if !defined(_LIBUNWIND_IS_BAREMETAL) && !defined(_WIN32)
   Dl_info dyldInfo;
   if (dladdr((void *)addr, &dyldInfo)) {
     if (dyldInfo.dli_sname != NULL) {
       snprintf(buf, bufLen, "%s", dyldInfo.dli_sname);
       *offset = (addr - (pint_t) dyldInfo.dli_saddr);
       return true;
     }
   }

src/assembly.h

 #elif defined(__arm64__)
 #define SEPARATOR %%
 #else
 #define SEPARATOR ;
 #endif
 
 #if defined(__APPLE__)
 #define HIDDEN_DIRECTIVE .private_extern
+#elif defined(_WIN32)
+#define HIDDEN_DIRECTIVE .globl
 #else
 #define HIDDEN_DIRECTIVE .hidden
 #endif
 
 #define GLUE2(a, b) a ## b
 #define GLUE(a, b) GLUE2(a, b)
 #define SYMBOL_NAME(name) GLUE(__USER_LABEL_PREFIX__, name)
 

src/config.h

 // Platform specific configuration defines.
 #ifdef __APPLE__
   #if defined(FOR_DYLD)
     #define _LIBUNWIND_SUPPORT_COMPACT_UNWIND
   #else
     #define _LIBUNWIND_SUPPORT_COMPACT_UNWIND
     #define _LIBUNWIND_SUPPORT_DWARF_UNWIND   1
   #endif
+#elif defined(_WIN32)
+  // #define _LIBUNWIND_BUILD_SJLJ_APIS
+  // #define _LIBUNWIND_SUPPORT_FRAME_APIS
+  #define _LIBUNWIND_SUPPORT_COMPACT_UNWIND 1
+  // #define _LIBUNWIND_SUPPORT_DWARF_UNWIND
+  // #define _LIBUNWIND_SUPPORT_DWARF_INDEX
+  #define bzero(s,n) memset(s,0,n)
 #else
   #if defined(__ARM_DWARF_EH__) || !defined(__arm__)
     #define _LIBUNWIND_SUPPORT_DWARF_UNWIND 1
     #define _LIBUNWIND_SUPPORT_DWARF_INDEX 1
   #endif
 #endif
 
-// FIXME: these macros are not correct for COFF targets
+#ifdef _WIN32
+#define _LIBUNWIND_EXPORT
+#define _LIBUNWIND_HIDDEN
+#else
 #define _LIBUNWIND_EXPORT __attribute__((visibility("default")))
 #define _LIBUNWIND_HIDDEN __attribute__((visibility("hidden")))
+#endif
 
 #if (defined(__APPLE__) && defined(__arm__)) || defined(__USING_SJLJ_EXCEPTIONS__)
 #define _LIBUNWIND_BUILD_SJLJ_APIS
 #endif
 
 #if defined(__i386__) || defined(__x86_64__) || defined(__ppc__) || defined(__ppc64__)
 #define _LIBUNWIND_SUPPORT_FRAME_APIS
 #endif