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Date:      Sun, 2 Aug 2020 18:12:14 +0000 (UTC)
From:      Dimitry Andric <dim@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-projects@freebsd.org
Subject:   svn commit: r363774 - projects/clang1100-import/contrib/llvm-project/libunwind/src
Message-ID:  <202008021812.072ICEm3065370@repo.freebsd.org>
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Author: dim
Date: Sun Aug  2 18:12:14 2020
New Revision: 363774
URL: https://svnweb.freebsd.org/changeset/base/363774

Log:
  Reapply r310365 (by emaste):
  
  libunwind: make __{de,}register_frame compatible with libgcc API
  
  The libgcc __register_frame and __deregister_frame functions take a
  pointer to a set of FDE/CIEs, terminated by an entry where length is 0.
  
  In Apple's libunwind implementation the pointer is taken to be to a
  single FDE. I suspect this was just an Apple bug, compensated by Apple-
  specific code in LLVM.
  
  See lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp and
  http://lists.llvm.org/pipermail/llvm-dev/2013-April/061737.html
  for more detail.
  
  This change is based on the LLVM RTDyldMemoryManager.cpp. It should
  later be changed to be alignment-safe.
  
  Reported by:	dim
  Reviewed by:	dim
  Sponsored by:	The FreeBSD Foundation
  Differential Revision:	https://reviews.freebsd.org/D8869
  
  Reapply r351610:
  
  Update libunwind custom frame register and deregister functions for
  FreeBSD: use the new doubly underscored names for unw_add_dynamic_fde
  and unw_remove_dynamic_fde.
  
  NOTE: this should be upstreamed...

Modified:
  projects/clang1100-import/contrib/llvm-project/libunwind/src/UnwindLevel1-gcc-ext.c

Modified: projects/clang1100-import/contrib/llvm-project/libunwind/src/UnwindLevel1-gcc-ext.c
==============================================================================
--- projects/clang1100-import/contrib/llvm-project/libunwind/src/UnwindLevel1-gcc-ext.c	Sun Aug  2 18:07:16 2020	(r363773)
+++ projects/clang1100-import/contrib/llvm-project/libunwind/src/UnwindLevel1-gcc-ext.c	Sun Aug  2 18:12:14 2020	(r363774)
@@ -234,6 +234,46 @@ _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _
 
 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
 
+#if defined(__FreeBSD__)
+
+// Based on LLVM's lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
+// and XXX should be fixed to be alignment-safe.
+static void processFDE(const char *addr, bool isDeregister) {
+  uint64_t length;
+  while ((length = *((const uint32_t *)addr)) != 0) {
+    const char *p = addr + 4;
+    if (length == 0xffffffff) {
+      length = *((const uint64_t *)p);
+      p += 8;
+    }
+    uint32_t offset = *((const uint32_t *)p);
+    if (offset != 0) {
+      if (isDeregister)
+        __unw_remove_dynamic_fde((unw_word_t)(uintptr_t)addr);
+      else
+        __unw_add_dynamic_fde((unw_word_t)(uintptr_t)addr);
+    }
+    addr = p + length;
+  }
+}
+
+/// Called by programs with dynamic code generators that want to register
+/// dynamically generated FDEs, with a libgcc-compatible API.
+
+_LIBUNWIND_EXPORT void __register_frame(const void *addr) {
+  _LIBUNWIND_TRACE_API("__register_frame(%p)", addr);
+  processFDE(addr, false);
+}
+
+/// Called by programs with dynamic code generators that want to unregister
+/// dynamically generated FDEs, with a libgcc-compatible API.
+_LIBUNWIND_EXPORT void __deregister_frame(const void *addr) {
+  _LIBUNWIND_TRACE_API("__deregister_frame(%p)", addr);
+  processFDE(addr, true);
+}
+
+#else // defined(__FreeBSD__)
+
 /// Called by programs with dynamic code generators that want
 /// to register a dynamically generated FDE.
 /// This function has existed on Mac OS X since 10.4, but
@@ -243,7 +283,6 @@ _LIBUNWIND_EXPORT void __register_frame(const void *fd
   __unw_add_dynamic_fde((unw_word_t)(uintptr_t)fde);
 }
 
-
 /// Called by programs with dynamic code generators that want
 /// to unregister a dynamically generated FDE.
 /// This function has existed on Mac OS X since 10.4, but
@@ -253,6 +292,7 @@ _LIBUNWIND_EXPORT void __deregister_frame(const void *
   __unw_remove_dynamic_fde((unw_word_t)(uintptr_t)fde);
 }
 
+#endif // defined(__FreeBSD__)
 
 // The following register/deregister functions are gcc extensions.
 // They have existed on Mac OS X, but have never worked because Mac OS X

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