mirror of
https://github.com/bitcoin/bitcoin.git
synced 2025-03-13 19:37:04 +01:00
71 lines
3 KiB
Diff
71 lines
3 KiB
Diff
From 74560f26f75dda4257dce541ca362a1e763b2971 Mon Sep 17 00:00:00 2001
|
|
From: Ryan Ofsky <ryan@ofsky.org>
|
|
Date: Thu, 6 Feb 2025 08:39:05 -0500
|
|
Subject: [PATCH 1/1] Avoid gcc/clang ABI incompatibility caused by
|
|
PlacementNew
|
|
|
|
GCC and clang do not use same calling convention for passing empty struct
|
|
parameters. There is more information about this in
|
|
https://itanium-cxx-abi.github.io/cxx-abi/cxx-abi-dev/archives/2015-December/002869.html
|
|
|
|
Unfortunately this can create an issue in capnproto if it is built without
|
|
optimizations in GCC, and the resulting static libraries are used in a clang
|
|
program, or vice versa.
|
|
|
|
Depending on what order libraries are specified on the linker command line, and
|
|
whether code compiled with the other compiler is calling any header functions
|
|
that cause weak a `operator new(unsigned int, kj::_::PlacementNew, void*)`
|
|
symbol to be defined in its own objects, this can cause the linker to link a
|
|
GCC-generated `kj::ctor` with a clang-generated `operator new`, and the
|
|
resulting program to crash due to the compilers using different calling
|
|
conventions for `operator new`.
|
|
|
|
This problem is difficult to avoid in general, but pretty easy to avoid here by
|
|
changing `operator new` parameter order so the empty struct parameter is last.
|
|
|
|
This change should be beneficial for capnproto users that may be compiling it
|
|
without optimizations, and not necessarily using a single compiler to build all
|
|
their dependencies.
|
|
|
|
The problem does not occur if any optimizations are enabled because `operator
|
|
new` calls are inlined in that case.
|
|
---
|
|
c++/src/kj/common.h | 11 +++++++----
|
|
1 file changed, 7 insertions(+), 4 deletions(-)
|
|
|
|
diff --git a/c++/src/kj/common.h b/c++/src/kj/common.h
|
|
index b8edde3c..28ab11d6 100644
|
|
--- a/c++/src/kj/common.h
|
|
+++ b/c++/src/kj/common.h
|
|
@@ -1034,24 +1034,27 @@ private:
|
|
|
|
// We want placement new, but we don't want to #include <new>. operator new cannot be defined in
|
|
// a namespace, and defining it globally conflicts with the definition in <new>. So we have to
|
|
-// define a dummy type and an operator new that uses it.
|
|
+// define a dummy type and an operator new that uses it. The dummy type is intentionally passed
|
|
+// as the last parameter so clang and GCC ABI calling conventions for empty struct struct parameters
|
|
+// are compatible, and there are not segfaults trying to call clang operator new/delete from GCC or
|
|
+// vice versa.
|
|
|
|
namespace _ { // private
|
|
struct PlacementNew {};
|
|
} // namespace _ (private)
|
|
} // namespace kj
|
|
|
|
-inline void* operator new(size_t, kj::_::PlacementNew, void* __p) noexcept {
|
|
+inline void* operator new(size_t, void* __p, kj::_::PlacementNew) noexcept {
|
|
return __p;
|
|
}
|
|
|
|
-inline void operator delete(void*, kj::_::PlacementNew, void* __p) noexcept {}
|
|
+inline void operator delete(void*, void* __p, kj::_::PlacementNew) noexcept {}
|
|
|
|
namespace kj {
|
|
|
|
template <typename T, typename... Params>
|
|
inline void ctor(T& location, Params&&... params) {
|
|
- new (_::PlacementNew(), &location) T(kj::fwd<Params>(params)...);
|
|
+ new (&location, _::PlacementNew()) T(kj::fwd<Params>(params)...);
|
|
}
|
|
|
|
template <typename T>
|