diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs index 78d47f36f918b..e32c38644aafb 100644 --- a/compiler/rustc_codegen_llvm/src/llvm_util.rs +++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs @@ -5,6 +5,7 @@ use crate::errors::{ }; use crate::llvm; use libc::c_int; +use rustc_codegen_ssa::base::wants_wasm_eh; use rustc_codegen_ssa::traits::PrintBackendInfo; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_data_structures::small_c_str::SmallCStr; @@ -98,6 +99,10 @@ unsafe fn configure_llvm(sess: &Session) { } } + if wants_wasm_eh(sess) { + add("-wasm-enable-eh", false); + } + if sess.target.os == "emscripten" && sess.panic_strategy() == PanicStrategy::Unwind { add("-enable-emscripten-cxx-exceptions", false); } @@ -523,6 +528,10 @@ pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec> FunctionCx<'a, 'tcx, Bx> { let funclet; let llbb; let mut bx; - if base::wants_msvc_seh(self.cx.sess()) { + if base::wants_new_eh_instructions(self.cx.sess()) { // This is a basic block that we're aborting the program for, // notably in an `extern` function. These basic blocks are inserted // so that we assert that `extern` functions do indeed not panic, diff --git a/library/panic_unwind/src/gcc.rs b/library/panic_unwind/src/gcc.rs index 54eb6627c0129..589d3c1b4d2d0 100644 --- a/library/panic_unwind/src/gcc.rs +++ b/library/panic_unwind/src/gcc.rs @@ -62,7 +62,7 @@ pub unsafe fn panic(data: Box) -> u32 { let exception = Box::new(Exception { _uwe: uw::_Unwind_Exception { exception_class: rust_exception_class(), - exception_cleanup, + exception_cleanup: Some(exception_cleanup), private: [core::ptr::null(); uw::unwinder_private_data_size], }, canary: &CANARY, diff --git a/library/panic_unwind/src/lib.rs b/library/panic_unwind/src/lib.rs index 7a0bae34642d6..dde1c64c6f193 100644 --- a/library/panic_unwind/src/lib.rs +++ b/library/panic_unwind/src/lib.rs @@ -53,12 +53,12 @@ cfg_if::cfg_if! { target_os = "solid_asp3", all(target_family = "unix", not(target_os = "espidf")), all(target_vendor = "fortanix", target_env = "sgx"), + target_family = "wasm", ))] { #[path = "gcc.rs"] mod real_imp; } else { // Targets that don't support unwinding. - // - family=wasm // - os=none ("bare metal" targets) // - os=uefi // - os=espidf diff --git a/library/std/src/sys/personality/mod.rs b/library/std/src/sys/personality/mod.rs index d37b8ce634654..1a6ea1dafcb53 100644 --- a/library/std/src/sys/personality/mod.rs +++ b/library/std/src/sys/personality/mod.rs @@ -16,11 +16,12 @@ mod dwarf; cfg_if::cfg_if! { if #[cfg(target_os = "emscripten")] { mod emcc; - } else if #[cfg(target_env = "msvc")] { + } else if #[cfg(any(target_env = "msvc", target_family = "wasm"))] { // This is required by the compiler to exist (e.g., it's a lang item), // but it's never actually called by the compiler because - // _CxxFrameHandler3 is the personality function that is always used. - // Hence this is just an aborting stub. + // __CxxFrameHandler3 (msvc) / __gxx_wasm_personality_v0 (wasm) is the + // personality function that is always used. Hence this is just an + // aborting stub. #[lang = "eh_personality"] fn rust_eh_personality() { core::intrinsics::abort() @@ -36,7 +37,6 @@ cfg_if::cfg_if! { mod gcc; } else { // Targets that don't support unwinding. - // - family=wasm // - os=none ("bare metal" targets) // - os=uefi // - os=espidf diff --git a/library/unwind/src/lib.rs b/library/unwind/src/lib.rs index a64f290463374..45aa0ea4fbb8d 100644 --- a/library/unwind/src/lib.rs +++ b/library/unwind/src/lib.rs @@ -6,6 +6,10 @@ #![cfg_attr(bootstrap, feature(cfg_target_abi))] #![feature(strict_provenance)] #![cfg_attr(not(target_env = "msvc"), feature(libc))] +#![cfg_attr( + all(target_family = "wasm", not(target_os = "emscripten")), + feature(link_llvm_intrinsics) +)] #![allow(internal_features)] cfg_if::cfg_if! { @@ -29,9 +33,11 @@ cfg_if::cfg_if! { } else if #[cfg(target_os = "xous")] { mod unwinding; pub use unwinding::*; + } else if #[cfg(target_family = "wasm")] { + mod wasm; + pub use wasm::*; } else { // no unwinder on the system! - // - wasm32 (not emscripten, which is "unix" family) // - os=none ("bare metal" targets) // - os=hermit // - os=uefi diff --git a/library/unwind/src/libunwind.rs b/library/unwind/src/libunwind.rs index 527c408c89edd..0a0dc9438b305 100644 --- a/library/unwind/src/libunwind.rs +++ b/library/unwind/src/libunwind.rs @@ -91,7 +91,7 @@ pub struct _Unwind_Exception { pub enum _Unwind_Context {} pub type _Unwind_Exception_Cleanup_Fn = - extern "C" fn(unwind_code: _Unwind_Reason_Code, exception: *mut _Unwind_Exception); + Option; // FIXME: The `#[link]` attributes on `extern "C"` block marks those symbols declared in // the block are reexported in dylib build of std. This is needed when build rustc with diff --git a/library/unwind/src/unwinding.rs b/library/unwind/src/unwinding.rs index 1a4187b22200d..95e2eb000ccbd 100644 --- a/library/unwind/src/unwinding.rs +++ b/library/unwind/src/unwinding.rs @@ -46,7 +46,7 @@ pub const unwinder_private_data_size: usize = core::mem::size_of::(); pub type _Unwind_Exception_Cleanup_Fn = - extern "C" fn(unwind_code: _Unwind_Reason_Code, exception: *mut _Unwind_Exception); + Option; #[repr(C)] pub struct _Unwind_Exception { diff --git a/library/unwind/src/wasm.rs b/library/unwind/src/wasm.rs new file mode 100644 index 0000000000000..b06671bcb8309 --- /dev/null +++ b/library/unwind/src/wasm.rs @@ -0,0 +1,65 @@ +//! A shim for libunwind implemented in terms of the native wasm `throw` instruction. + +#![allow(nonstandard_style)] + +#[repr(C)] +#[derive(Debug, Copy, Clone, PartialEq)] +pub enum _Unwind_Reason_Code { + _URC_NO_REASON = 0, + _URC_FOREIGN_EXCEPTION_CAUGHT = 1, + _URC_FATAL_PHASE2_ERROR = 2, + _URC_FATAL_PHASE1_ERROR = 3, + _URC_NORMAL_STOP = 4, + _URC_END_OF_STACK = 5, + _URC_HANDLER_FOUND = 6, + _URC_INSTALL_CONTEXT = 7, + _URC_CONTINUE_UNWIND = 8, + _URC_FAILURE = 9, // used only by ARM EHABI +} +pub use _Unwind_Reason_Code::*; + +pub type _Unwind_Exception_Class = u64; +pub type _Unwind_Word = *const u8; + +pub const unwinder_private_data_size: usize = 2; + +#[repr(C)] +pub struct _Unwind_Exception { + pub exception_class: _Unwind_Exception_Class, + pub exception_cleanup: _Unwind_Exception_Cleanup_Fn, + pub private: [_Unwind_Word; unwinder_private_data_size], +} + +pub type _Unwind_Exception_Cleanup_Fn = + Option; + +pub unsafe fn _Unwind_DeleteException(exception: *mut _Unwind_Exception) { + if let Some(exception_cleanup) = unsafe { (*exception).exception_cleanup } { + exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, exception); + } +} + +pub unsafe fn _Unwind_RaiseException(exception: *mut _Unwind_Exception) -> _Unwind_Reason_Code { + #[cfg(panic = "unwind")] + extern "C" { + /// LLVM lowers this intrinsic to the `throw` instruction. + // FIXME(coolreader18): move to stdarch + #[link_name = "llvm.wasm.throw"] + fn wasm_throw(tag: i32, ptr: *mut u8) -> !; + } + + // The wasm `throw` instruction takes a "tag", which differentiates certain + // types of exceptions from others. LLVM currently just identifies these + // via integers, with 0 corresponding to C++ exceptions and 1 to C setjmp()/longjmp(). + // Ideally, we'd be able to choose something unique for Rust, but for now, + // we pretend to be C++ and implement the Itanium exception-handling ABI. + cfg_if::cfg_if! { + // for now, unless we're -Zbuild-std with panic=unwind, never codegen a throw. + if #[cfg(panic = "unwind")] { + wasm_throw(0, exception.cast()) + } else { + let _ = exception; + core::arch::wasm32::unreachable() + } + } +}