420544a34a
rustc assumes that regular `extern "Rust"` functions unwind only if the `unwind` panic runtime is linked. `throw` was annotated as such, but unwound unconditionally. This could cause UB when a crate built with `-C panic=abort` called `throw` from `core` built with `-C panic=unwind`, since no terminator was added to handle the panic arising from calling an allegedly non-unwinding `extern "Rust"` function. rustc was taught to recognize this condition since https://github.com/rust-lang/rust/pull/144225 and prevented such linkage, but this caused regressions in https://github.com/rust-lang/rust/issues/148246, since this meant that Emscripten projects could not be built with `-C panic=abort` without recompiling std. The most straightforward solution would be to move `throw` into the `panic_unwind` crate, so that it's only compiled if the panic runtime is guaranteed to be `unwind`, but this is messy due to our architecture. Instead, move it into `unwind::wasm`, which is only compiled for bare-metal targets that default to `panic = "abort"`, rendering the issue moot.
97 lines
2.4 KiB
Rust
97 lines
2.4 KiB
Rust
//@ only-wasm32
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//@ revisions: WASM WASMEXN
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//@ [WASMEXN] compile-flags: -C panic=unwind -Z emscripten-wasm-eh
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#![crate_type = "lib"]
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#![feature(core_intrinsics, link_llvm_intrinsics)]
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extern "C-unwind" {
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fn may_panic();
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}
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extern "C" {
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fn log_number(number: usize);
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}
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struct LogOnDrop;
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impl Drop for LogOnDrop {
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fn drop(&mut self) {
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unsafe {
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log_number(0);
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}
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}
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}
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// WASM-LABEL: @test_cleanup() {{.*}}
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// WASMEXN-LABEL: @test_cleanup() {{.*}} @__gxx_wasm_personality_v0
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#[no_mangle]
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pub fn test_cleanup() {
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let _log_on_drop = LogOnDrop;
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unsafe {
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may_panic();
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}
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// WASMEXN-NOT: call
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// WASMEXN: invoke void @may_panic()
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// WASMEXN: %cleanuppad = cleanuppad within none []
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//
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// WASM: call void @may_panic()
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// WASM-NOT: invoke void @may_panic()
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}
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// WASM-LABEL: @test_rtry() {{.*}}
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// WASMEXN-LABEL: @test_rtry() {{.*}} @__gxx_wasm_personality_v0
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#[no_mangle]
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pub fn test_rtry() {
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unsafe {
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core::intrinsics::catch_unwind(
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|_| {
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may_panic();
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},
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core::ptr::null_mut(),
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|data, exception| {
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log_number(data as usize);
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log_number(exception as usize);
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},
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);
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}
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// WASMEXN-NOT: call
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// WASMEXN: invoke void @may_panic()
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// WASMEXN: {{.*}} = catchswitch within none [label {{.*}}] unwind to caller
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// WASMEXN: {{.*}} = catchpad within {{.*}} [ptr null]
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// WASMEXN: catchret
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// WASM: call void @may_panic()
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// WASM-NOT: invoke void @may_panic()
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// WASM-NOT: catchswitch
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// WASM-NOT: catchpad
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// WASM-NOT: catchret
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}
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// Make sure the intrinsic is not inferred as nounwind. This is a regression test for #132416.
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//
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// Note that this test uses the raw `wasm_throw` intrinsic because the one from
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// libstd was built with `-Cpanic=abort` and it's technically not valid to use
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// when this crate is compiled with `-Cpanic=unwind`.
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//
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// WASMEXN-LABEL: @test_intrinsic() {{.*}} @__gxx_wasm_personality_v0
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#[no_mangle]
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#[cfg(wasmexn)]
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pub fn test_intrinsic() {
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let _log_on_drop = LogOnDrop;
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unsafe extern "C-unwind" {
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#[link_name = "llvm.wasm.throw"]
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fn wasm_throw(tag: i32, ptr: *mut u8) -> !;
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}
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unsafe {
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wasm_throw(0, core::ptr::null_mut());
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}
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// WASMEXN-NOT: call
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// WASMEXN: invoke void @llvm.wasm.throw(i32 noundef 0, ptr noundef null)
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// WASMEXN: %cleanuppad = cleanuppad within none []
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}
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