Add LLVM libcxxabi (#1063)

* third_party: Add libcxxabi

Added libcxxabi from LLVM 17.0.6
The library implements the Itanium C++ exception handling ABI.

* third_party/libcxxabi: Enable __cxa_thread_atexit

Enable `__cxa_thread_atexit` from libcxxabi.
`__cxa_thread_atexit_impl` is still implemented by the cosmo libc.
The original `__cxa_thread_atexit` has been removed.

* third_party/libcxx: Build with exceptions

Build libcxx with exceptions enabled.

- Removed `_LIBCPP_NO_EXCEPTIONS` from `__config`.
- Switched the exception implementation to `libcxxabi`. These two files
are taken from the same `libcxx` version as mentioned in `README.cosmo`.
- Removed `new_handler_fallback` in favor of `libcxxabi` implementation.
- Enable `-fexceptions` and `-frtti` for `libcxx`.
- Removed `THIRD_PARTY_LIBCXX` dependency from `libcxxabi` and
`libunwind`. These libraries do not use any runtime `libcxx` functions,
just headers.

* libc: Remove remaining redundant cxa functions

- `__cxa_pure_virtual` in `libcxxabi` is also a stub similar to the
existing one.
- `__cxa_guard_*` from `libcxxabi` is used instead of the ones from
Android.

Now there should be no more duplicate implementations.
`__cxa_thread_atexit_impl`, `__cxa_atexit`, and related supporting
functions, are still left to other libraries as in `libcxxabi`.

`libcxxabi` is also now added to `cosmopolitan.a` to make up for the
removed functions.

Affected in-tree libraries (`third_party/double-conversion`) have been
updated.

third_party/libcxxabi/cxa_vector.cc

@@ -0,0 +1,421 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//
+//  This file implements the "Array Construction and Destruction APIs"
+//  https://itanium-cxx-abi.github.io/cxx-abi/abi.html#array-ctor
+//
+//===----------------------------------------------------------------------===//
+
+#include "third_party/libcxxabi/include/cxxabi.h"
+#include "third_party/libcxxabi/include/__cxxabi_config.h"
+
+#include "third_party/libcxx/exception"        // for std::terminate
+#include "third_party/libcxx/new"              // for std::bad_array_new_length
+
+#include "third_party/libcxxabi/abort_message.h"
+
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+namespace __cxxabiv1 {
+
+//
+// Helper routines and classes
+//
+
+namespace {
+    inline static size_t __get_element_count ( void *p ) {
+        return static_cast <size_t *> (p)[-1];
+        }
+
+    inline static void __set_element_count ( void *p, size_t element_count ) {
+        static_cast <size_t *> (p)[-1] = element_count;
+        }
+
+
+//  A pair of classes to simplify exception handling and control flow.
+//  They get passed a block of memory in the constructor, and unless the
+//  'release' method is called, they deallocate the memory in the destructor.
+//  Preferred usage is to allocate some memory, attach it to one of these objects,
+//  and then, when all the operations to set up the memory block have succeeded,
+//  call 'release'. If any of the setup operations fail, or an exception is
+//  thrown, then the block is automatically deallocated.
+//
+//  The only difference between these two classes is the signature for the
+//  deallocation function (to match new2/new3 and delete2/delete3.
+    class st_heap_block2 {
+    public:
+        typedef void (*dealloc_f)(void *);
+
+        st_heap_block2 ( dealloc_f dealloc, void *ptr )
+            : dealloc_ ( dealloc ), ptr_ ( ptr ), enabled_ ( true ) {}
+        ~st_heap_block2 () { if ( enabled_ ) dealloc_ ( ptr_ ) ; }
+        void release () { enabled_ = false; }
+
+    private:
+        dealloc_f dealloc_;
+        void *ptr_;
+        bool enabled_;
+    };
+
+    class st_heap_block3 {
+    public:
+        typedef void (*dealloc_f)(void *, size_t);
+
+        st_heap_block3 ( dealloc_f dealloc, void *ptr, size_t size )
+            : dealloc_ ( dealloc ), ptr_ ( ptr ), size_ ( size ), enabled_ ( true ) {}
+        ~st_heap_block3 () { if ( enabled_ ) dealloc_ ( ptr_, size_ ) ; }
+        void release () { enabled_ = false; }
+
+    private:
+        dealloc_f dealloc_;
+        void *ptr_;
+        size_t size_;
+        bool enabled_;
+    };
+
+    class st_cxa_cleanup {
+    public:
+        typedef void (*destruct_f)(void *);
+
+        st_cxa_cleanup ( void *ptr, size_t &idx, size_t element_size, destruct_f destructor )
+            : ptr_ ( ptr ), idx_ ( idx ), element_size_ ( element_size ),
+                destructor_ ( destructor ), enabled_ ( true ) {}
+        ~st_cxa_cleanup () {
+            if ( enabled_ )
+                __cxa_vec_cleanup ( ptr_, idx_, element_size_, destructor_ );
+            }
+
+        void release () { enabled_ = false; }
+
+    private:
+        void *ptr_;
+        size_t &idx_;
+        size_t element_size_;
+        destruct_f destructor_;
+        bool enabled_;
+    };
+
+    class st_terminate {
+    public:
+        st_terminate ( bool enabled = true ) : enabled_ ( enabled ) {}
+        ~st_terminate () { if ( enabled_ ) std::terminate (); }
+        void release () { enabled_ = false; }
+    private:
+        bool enabled_ ;
+    };
+}
+
+//
+// Externally visible routines
+//
+
+namespace {
+_LIBCXXABI_NORETURN
+void throw_bad_array_new_length() {
+#ifndef _LIBCXXABI_NO_EXCEPTIONS
+  throw std::bad_array_new_length();
+#else
+  abort_message("__cxa_vec_new failed to allocate memory");
+#endif
+}
+
+bool mul_overflow(size_t x, size_t y, size_t *res) {
+#if (defined(_LIBCXXABI_COMPILER_CLANG) && __has_builtin(__builtin_mul_overflow)) \
+    || defined(_LIBCXXABI_COMPILER_GCC)
+    return __builtin_mul_overflow(x, y, res);
+#else
+    *res = x * y;
+    return x && ((*res / x) != y);
+#endif
+}
+
+bool add_overflow(size_t x, size_t y, size_t *res) {
+#if (defined(_LIBCXXABI_COMPILER_CLANG) && __has_builtin(__builtin_add_overflow)) \
+    || defined(_LIBCXXABI_COMPILER_GCC)
+  return __builtin_add_overflow(x, y, res);
+#else
+  *res = x + y;
+  return *res < y;
+#endif
+}
+
+size_t calculate_allocation_size_or_throw(size_t element_count,
+                                          size_t element_size,
+                                          size_t padding_size) {
+  size_t element_heap_size;
+  if (mul_overflow(element_count, element_size, &element_heap_size))
+    throw_bad_array_new_length();
+
+  size_t allocation_size;
+  if (add_overflow(element_heap_size, padding_size, &allocation_size))
+    throw_bad_array_new_length();
+
+  return allocation_size;
+}
+
+} // namespace
+
+extern "C" {
+
+// Equivalent to
+//
+//   __cxa_vec_new2(element_count, element_size, padding_size, constructor,
+//                  destructor, &::operator new[], &::operator delete[])
+_LIBCXXABI_FUNC_VIS void *
+__cxa_vec_new(size_t element_count, size_t element_size, size_t padding_size,
+              void (*constructor)(void *), void (*destructor)(void *)) {
+    return __cxa_vec_new2 ( element_count, element_size, padding_size,
+        constructor, destructor, &::operator new [], &::operator delete [] );
+}
+
+
+// Given the number and size of elements for an array and the non-negative
+// size of prefix padding for a cookie, allocate space (using alloc) for
+// the array preceded by the specified padding, initialize the cookie if
+// the padding is non-zero, and call the given constructor on each element.
+// Return the address of the array proper, after the padding.
+//
+// If alloc throws an exception, rethrow the exception. If alloc returns
+// NULL, return NULL. If the constructor throws an exception, call
+// destructor for any already constructed elements, and rethrow the
+// exception. If the destructor throws an exception, call std::terminate.
+//
+// The constructor may be NULL, in which case it must not be called. If the
+// padding_size is zero, the destructor may be NULL; in that case it must
+// not be called.
+//
+// Neither alloc nor dealloc may be NULL.
+_LIBCXXABI_FUNC_VIS void *
+__cxa_vec_new2(size_t element_count, size_t element_size, size_t padding_size,
+               void (*constructor)(void *), void (*destructor)(void *),
+               void *(*alloc)(size_t), void (*dealloc)(void *)) {
+  const size_t heap_size = calculate_allocation_size_or_throw(
+      element_count, element_size, padding_size);
+  char* const heap_block = static_cast<char*>(alloc(heap_size));
+  char* vec_base = heap_block;
+
+  if (NULL != vec_base) {
+    st_heap_block2 heap(dealloc, heap_block);
+
+    //  put the padding before the array elements
+        if ( 0 != padding_size ) {
+            vec_base += padding_size;
+            __set_element_count ( vec_base, element_count );
+        }
+
+    //  Construct the elements
+        __cxa_vec_ctor ( vec_base, element_count, element_size, constructor, destructor );
+        heap.release ();    // We're good!
+    }
+
+    return vec_base;
+}
+
+
+// Same as __cxa_vec_new2 except that the deallocation function takes both
+// the object address and its size.
+_LIBCXXABI_FUNC_VIS void *
+__cxa_vec_new3(size_t element_count, size_t element_size, size_t padding_size,
+               void (*constructor)(void *), void (*destructor)(void *),
+               void *(*alloc)(size_t), void (*dealloc)(void *, size_t)) {
+  const size_t heap_size = calculate_allocation_size_or_throw(
+      element_count, element_size, padding_size);
+  char* const heap_block = static_cast<char*>(alloc(heap_size));
+  char* vec_base = heap_block;
+
+  if (NULL != vec_base) {
+    st_heap_block3 heap(dealloc, heap_block, heap_size);
+
+    //  put the padding before the array elements
+        if ( 0 != padding_size ) {
+            vec_base += padding_size;
+            __set_element_count ( vec_base, element_count );
+        }
+
+    //  Construct the elements
+        __cxa_vec_ctor ( vec_base, element_count, element_size, constructor, destructor );
+        heap.release ();    // We're good!
+    }
+
+    return vec_base;
+}
+
+
+// Given the (data) addresses of a destination and a source array, an
+// element count and an element size, call the given copy constructor to
+// copy each element from the source array to the destination array. The
+// copy constructor's arguments are the destination address and source
+// address, respectively. If an exception occurs, call the given destructor
+// (if non-NULL) on each copied element and rethrow. If the destructor
+// throws an exception, call terminate(). The constructor and or destructor
+// pointers may be NULL. If either is NULL, no action is taken when it
+// would have been called.
+
+_LIBCXXABI_FUNC_VIS void __cxa_vec_cctor(void *dest_array, void *src_array,
+                                         size_t element_count,
+                                         size_t element_size,
+                                         void (*constructor)(void *, void *),
+                                         void (*destructor)(void *)) {
+    if ( NULL != constructor ) {
+        size_t idx = 0;
+        char *src_ptr  = static_cast<char *>(src_array);
+        char *dest_ptr = static_cast<char *>(dest_array);
+        st_cxa_cleanup cleanup ( dest_array, idx, element_size, destructor );
+
+        for ( idx = 0; idx < element_count;
+                    ++idx, src_ptr += element_size, dest_ptr += element_size )
+            constructor ( dest_ptr, src_ptr );
+        cleanup.release ();     // We're good!
+    }
+}
+
+
+// Given the (data) address of an array, not including any cookie padding,
+// and the number and size of its elements, call the given constructor on
+// each element. If the constructor throws an exception, call the given
+// destructor for any already-constructed elements, and rethrow the
+// exception. If the destructor throws an exception, call terminate(). The
+// constructor and/or destructor pointers may be NULL. If either is NULL,
+// no action is taken when it would have been called.
+_LIBCXXABI_FUNC_VIS void
+__cxa_vec_ctor(void *array_address, size_t element_count, size_t element_size,
+               void (*constructor)(void *), void (*destructor)(void *)) {
+    if ( NULL != constructor ) {
+        size_t idx;
+        char *ptr = static_cast <char *> ( array_address );
+        st_cxa_cleanup cleanup ( array_address, idx, element_size, destructor );
+
+    //  Construct the elements
+        for ( idx = 0; idx < element_count; ++idx, ptr += element_size )
+            constructor ( ptr );
+        cleanup.release ();     // We're good!
+    }
+}
+
+// Given the (data) address of an array, the number of elements, and the
+// size of its elements, call the given destructor on each element. If the
+// destructor throws an exception, rethrow after destroying the remaining
+// elements if possible. If the destructor throws a second exception, call
+// terminate(). The destructor pointer may be NULL, in which case this
+// routine does nothing.
+_LIBCXXABI_FUNC_VIS void __cxa_vec_dtor(void *array_address,
+                                        size_t element_count,
+                                        size_t element_size,
+                                        void (*destructor)(void *)) {
+    if ( NULL != destructor ) {
+        char *ptr = static_cast <char *> (array_address);
+        size_t idx = element_count;
+        st_cxa_cleanup cleanup ( array_address, idx, element_size, destructor );
+        {
+            st_terminate exception_guard (__cxa_uncaught_exception ());
+            ptr +=  element_count * element_size;   // one past the last element
+
+            while ( idx-- > 0 ) {
+                ptr -= element_size;
+                destructor ( ptr );
+            }
+            exception_guard.release (); //  We're good !
+        }
+        cleanup.release ();     // We're still good!
+    }
+}
+
+// Given the (data) address of an array, the number of elements, and the
+// size of its elements, call the given destructor on each element. If the
+// destructor throws an exception, call terminate(). The destructor pointer
+// may be NULL, in which case this routine does nothing.
+_LIBCXXABI_FUNC_VIS void __cxa_vec_cleanup(void *array_address,
+                                           size_t element_count,
+                                           size_t element_size,
+                                           void (*destructor)(void *)) {
+    if ( NULL != destructor ) {
+        char *ptr = static_cast <char *> (array_address);
+        size_t idx = element_count;
+        st_terminate exception_guard;
+
+        ptr += element_count * element_size;    // one past the last element
+        while ( idx-- > 0 ) {
+            ptr -= element_size;
+            destructor ( ptr );
+            }
+        exception_guard.release ();     // We're done!
+    }
+}
+
+
+// If the array_address is NULL, return immediately. Otherwise, given the
+// (data) address of an array, the non-negative size of prefix padding for
+// the cookie, and the size of its elements, call the given destructor on
+// each element, using the cookie to determine the number of elements, and
+// then delete the space by calling ::operator delete[](void *). If the
+// destructor throws an exception, rethrow after (a) destroying the
+// remaining elements, and (b) deallocating the storage. If the destructor
+// throws a second exception, call terminate(). If padding_size is 0, the
+// destructor pointer must be NULL. If the destructor pointer is NULL, no
+// destructor call is to be made.
+//
+// The intent of this function is to permit an implementation to call this
+// function when confronted with an expression of the form delete[] p in
+// the source code, provided that the default deallocation function can be
+// used. Therefore, the semantics of this function are consistent with
+// those required by the standard. The requirement that the deallocation
+// function be called even if the destructor throws an exception derives
+// from the resolution to DR 353 to the C++ standard, which was adopted in
+// April, 2003.
+_LIBCXXABI_FUNC_VIS void __cxa_vec_delete(void *array_address,
+                                          size_t element_size,
+                                          size_t padding_size,
+                                          void (*destructor)(void *)) {
+    __cxa_vec_delete2 ( array_address, element_size, padding_size,
+               destructor, &::operator delete [] );
+}
+
+// Same as __cxa_vec_delete, except that the given function is used for
+// deallocation instead of the default delete function. If dealloc throws
+// an exception, the result is undefined. The dealloc pointer may not be
+// NULL.
+_LIBCXXABI_FUNC_VIS void
+__cxa_vec_delete2(void *array_address, size_t element_size, size_t padding_size,
+                  void (*destructor)(void *), void (*dealloc)(void *)) {
+    if ( NULL != array_address ) {
+        char *vec_base   = static_cast <char *> (array_address);
+        char *heap_block = vec_base - padding_size;
+        st_heap_block2 heap ( dealloc, heap_block );
+
+        if ( 0 != padding_size && NULL != destructor ) // call the destructors
+            __cxa_vec_dtor ( array_address, __get_element_count ( vec_base ),
+                                    element_size, destructor );
+    }
+}
+
+
+// Same as __cxa_vec_delete, except that the given function is used for
+// deallocation instead of the default delete function. The deallocation
+// function takes both the object address and its size. If dealloc throws
+// an exception, the result is undefined. The dealloc pointer may not be
+// NULL.
+_LIBCXXABI_FUNC_VIS void
+__cxa_vec_delete3(void *array_address, size_t element_size, size_t padding_size,
+                  void (*destructor)(void *), void (*dealloc)(void *, size_t)) {
+    if ( NULL != array_address ) {
+        char *vec_base   = static_cast <char *> (array_address);
+        char *heap_block = vec_base - padding_size;
+        const size_t element_count = padding_size ? __get_element_count ( vec_base ) : 0;
+        const size_t heap_block_size = element_size * element_count + padding_size;
+        st_heap_block3 heap ( dealloc, heap_block, heap_block_size );
+
+        if ( 0 != padding_size && NULL != destructor ) // call the destructors
+            __cxa_vec_dtor ( array_address, element_count, element_size, destructor );
+    }
+}
+
+
+}  // extern "C"
+
+}  // abi