diff options
| -rw-r--r-- | llvm/include/llvm/ADT/FunctionExtras.h | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/llvm/include/llvm/ADT/FunctionExtras.h b/llvm/include/llvm/ADT/FunctionExtras.h index 95b30541c79..b115ffabce5 100644 --- a/llvm/include/llvm/ADT/FunctionExtras.h +++ b/llvm/include/llvm/ADT/FunctionExtras.h @@ -243,8 +243,23 @@ public: // Now move into the storage. new (CallableAddr) CallableT(std::move(Callable)); +#ifndef _MSC_VER // See if we can create a trivial callback. - // FIXME: we should use constexpr if here and below to avoid instantiating + // + // This requires two things. First, we need to put a function pointer into + // a `PointerIntPair` and a `PointerUnion`. We assume that function + // pointers on almost every platform have at least 4-byte alignment which + // allows this to work, but on some platforms this appears to not hold, and + // so we need to disable this optimization on those platforms. + // + // FIXME: Currently, Windows appears to fail the asserts that check this. + // We should investigate why, and if fixed removed the #ifndef above. + // + // Second, we need the callable to be trivially moved and trivially + // destroyed so that we don't have to store type erased callbacks for those + // operations. + // + // FIXME: We should use constexpr if here and below to avoid instantiating // the non-trivial static objects when unnecessary. While the linker should // remove them, it is still wasteful. if (llvm::is_trivially_move_constructible<CallableT>::value && @@ -252,6 +267,7 @@ public: CallbackAndInlineFlag = {&CallImpl<CallableT>, IsInlineStorage}; return; } +#endif // Otherwise, we need to point at an object with a vtable that contains all // the different type erased behaviors needed. Create a static instance of |
