Bump libunwind to llvmorg-16.0.4 (#76)

- https://github.com/llvm/llvm-project/releases/tag/llvmorg-16.0.4

UpdateLibunwind

@@ -5,7 +5,7 @@ cd -P -- "$(dirname -- "${BASH_SOURCE[0]}")"
 git diff --exit-code -- . ':(exclude)UpdateLibunwind' > /dev/null || { echo "Commit changes before updating!" ; exit 1 ; }
 
 # https://github.com/llvm/llvm-project/releases
-COMMIT="${1:-llvmorg-16.0.3}"
+COMMIT="${1:-llvmorg-16.0.4}"
 
 pushd vendor >/dev/null
 rm -rf libunwind

vendor/libunwind/llvm/CMakeLists.txt

@@ -22,7 +22,7 @@ if(NOT DEFINED LLVM_VERSION_MINOR)
   set(LLVM_VERSION_MINOR 0)
 endif()
 if(NOT DEFINED LLVM_VERSION_PATCH)
-  set(LLVM_VERSION_PATCH 3)
+  set(LLVM_VERSION_PATCH 4)
 endif()
 if(NOT DEFINED LLVM_VERSION_SUFFIX)
   set(LLVM_VERSION_SUFFIX)

vendor/libunwind/llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -582,6 +582,16 @@ if ( LLVM_COMPILER_IS_GCC_COMPATIBLE OR CMAKE_CXX_COMPILER_ID MATCHES "XL" )
   add_flag_if_supported("-Werror=unguarded-availability-new" WERROR_UNGUARDED_AVAILABILITY_NEW)
 endif( LLVM_COMPILER_IS_GCC_COMPATIBLE OR CMAKE_CXX_COMPILER_ID MATCHES "XL" )
 
+if ( LLVM_COMPILER_IS_GCC_COMPATIBLE )
+  # LLVM data structures like llvm::User and llvm::MDNode rely on
+  # the value of object storage persisting beyond the lifetime of the
+  # object (#24952).  This is not standard compliant and causes a runtime
+  # crash if LLVM is built with GCC and LTO enabled (#57740).  Until
+  # these bugs are fixed, we need to disable dead store eliminations
+  # based on object lifetime.
+  add_flag_if_supported("-fno-lifetime-dse" CMAKE_CXX_FLAGS)
+endif ( LLVM_COMPILER_IS_GCC_COMPATIBLE )
+
 # Modules enablement for GCC-compatible compilers:
 if ( LLVM_COMPILER_IS_GCC_COMPATIBLE AND LLVM_ENABLE_MODULES )
   set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})