[PATCH] D44493: [libunwind] Add a cmake option for disabling the use of the dynamic linker

[Martin Storsjö via Phabricator via cfe-commits]

mstorsjo created this revision.
mstorsjo added reviewers: rnk, compnerd.
Herald added a subscriber: mgorny.

On windows, the psapi function for querying the dynamic linker for loaded modules (EnumProcessModules) are unavailable when targeting the UWP/"Windows Store" api subsets.

Such a build relies on the static frame registration functions for finding exception handlers.


Repository:
  rUNW libunwind

https://reviews.llvm.org/D44493

Files:
  CMakeLists.txt
  src/AddressSpace.hpp


Index: src/AddressSpace.hpp
===================================================================
--- src/AddressSpace.hpp
+++ src/AddressSpace.hpp
@@ -377,19 +377,7 @@
 
 inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
                                                   UnwindInfoSections &info) {
-#ifdef __APPLE__
-  dyld_unwind_sections dyldInfo;
-  if (_dyld_find_unwind_sections((void *)targetAddr, &dyldInfo)) {
-    info.dso_base                      = (uintptr_t)dyldInfo.mh;
- #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
-    info.dwarf_section                 = (uintptr_t)dyldInfo.dwarf_section;
-    info.dwarf_section_length          = dyldInfo.dwarf_section_length;
- #endif
-    info.compact_unwind_section        = (uintptr_t)dyldInfo.compact_unwind_section;
-    info.compact_unwind_section_length = dyldInfo.compact_unwind_section_length;
-    return true;
-  }
-#elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_LIBUNWIND_IS_BAREMETAL)
+#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_LIBUNWIND_IS_BAREMETAL)
   // Bare metal is statically linked, so no need to ask the dynamic loader
   info.dwarf_section_length = (uintptr_t)(&__eh_frame_end - &__eh_frame_start);
   info.dwarf_section =        (uintptr_t)(&__eh_frame_start);
@@ -411,6 +399,19 @@
                              (void *)info.arm_section, (void *)info.arm_section_length);
   if (info.arm_section && info.arm_section_length)
     return true;
+#elif !defined(_LIBUNWIND_DISABLE_DYNAMIC_LINKER)
+#ifdef __APPLE__
+  dyld_unwind_sections dyldInfo;
+  if (_dyld_find_unwind_sections((void *)targetAddr, &dyldInfo)) {
+    info.dso_base                      = (uintptr_t)dyldInfo.mh;
+ #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
+    info.dwarf_section                 = (uintptr_t)dyldInfo.dwarf_section;
+    info.dwarf_section_length          = dyldInfo.dwarf_section_length;
+ #endif
+    info.compact_unwind_section        = (uintptr_t)dyldInfo.compact_unwind_section;
+    info.compact_unwind_section_length = dyldInfo.compact_unwind_section_length;
+    return true;
+  }
 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_WIN32)
   HMODULE mods[1024];
   HANDLE process = GetCurrentProcess();
@@ -557,6 +558,7 @@
       &cb_data);
   return static_cast<bool>(found);
 #endif
+#endif // !_LIBUNWIND_DISABLE_DYNAMIC_LINKER
 
   return false;
 }
Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -47,6 +47,7 @@
 option(LIBUNWIND_ENABLE_THREADS "Build libunwind with threading support." ON)
 option(LIBUNWIND_USE_COMPILER_RT "Use compiler-rt instead of libgcc" OFF)
 option(LIBUNWIND_INCLUDE_DOCS "Build the libunwind documentation." ${LLVM_INCLUDE_DOCS})
+option(LIBUNWIND_ENABLE_DYNAMIC_LINKER "Query the dynamic linker for finding exception frames." ON)
 
 set(LIBUNWIND_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}" CACHE STRING
     "Define suffix of library directory name (32/64)")
@@ -226,6 +227,11 @@
   list(APPEND LIBUNWIND_COMPILE_FLAGS -D__ARM_WMMX)
 endif()
 
+# Ability to disable the use of the dynamic linker
+if (NOT LIBUNWIND_ENABLE_DYNAMIC_LINKER)
+  list(APPEND LIBUNWIND_COMPILE_FLAGS -D_LIBUNWIND_DISABLE_DYNAMIC_LINKER)
+endif()
+
 # This is the _ONLY_ place where add_definitions is called.
 if (MSVC)
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)


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