diff options
| -rw-r--r-- | compiler/rustc_mir_transform/src/abort_unwinding_calls.rs | 37 | ||||
| -rw-r--r-- | compiler/rustc_span/src/symbol.rs | 1 | ||||
| -rw-r--r-- | tests/codegen-llvm/unwind-abis/c-unwind-abi-panic-abort.rs | 9 | ||||
| -rw-r--r-- | tests/codegen-llvm/unwind-and-panic-abort.rs | 9 | ||||
| -rw-r--r-- | tests/codegen-llvm/wasm_exceptions.rs | 57 |
5 files changed, 86 insertions, 27 deletions
diff --git a/compiler/rustc_mir_transform/src/abort_unwinding_calls.rs b/compiler/rustc_mir_transform/src/abort_unwinding_calls.rs index 5bd6fdcf485..35a21a2a834 100644 --- a/compiler/rustc_mir_transform/src/abort_unwinding_calls.rs +++ b/compiler/rustc_mir_transform/src/abort_unwinding_calls.rs @@ -3,6 +3,7 @@ use rustc_ast::InlineAsmOptions; use rustc_middle::mir::*; use rustc_middle::span_bug; use rustc_middle::ty::{self, TyCtxt, layout}; +use rustc_span::sym; use rustc_target::spec::PanicStrategy; /// A pass that runs which is targeted at ensuring that codegen guarantees about @@ -33,6 +34,19 @@ impl<'tcx> crate::MirPass<'tcx> for AbortUnwindingCalls { return; } + // Represent whether this compilation target fundamentally doesn't + // support unwinding at all at an ABI level. If this the target has no + // support for unwinding then cleanup actions, for example, are all + // unnecessary and can be considered unreachable. + // + // Currently this is only true for wasm targets on panic=abort when the + // `exception-handling` target feature is disabled. In such a + // configuration it's illegal to emit exception-related instructions so + // it's not possible to unwind. + let target_supports_unwinding = !(tcx.sess.target.is_like_wasm + && tcx.sess.panic_strategy() == PanicStrategy::Abort + && !tcx.asm_target_features(def_id).contains(&sym::exception_handling)); + // Here we test for this function itself whether its ABI allows // unwinding or not. let body_ty = tcx.type_of(def_id).skip_binder(); @@ -54,12 +68,18 @@ impl<'tcx> crate::MirPass<'tcx> for AbortUnwindingCalls { let Some(terminator) = &mut block.terminator else { continue }; let span = terminator.source_info.span; - // If we see an `UnwindResume` terminator inside a function that cannot unwind, we need - // to replace it with `UnwindTerminate`. - if let TerminatorKind::UnwindResume = &terminator.kind - && !body_can_unwind - { - terminator.kind = TerminatorKind::UnwindTerminate(UnwindTerminateReason::Abi); + // If we see an `UnwindResume` terminator inside a function then: + // + // * If the target doesn't support unwinding at all, then this is an + // unreachable block. + // * If the body cannot unwind, we need to replace it with + // `UnwindTerminate`. + if let TerminatorKind::UnwindResume = &terminator.kind { + if !target_supports_unwinding { + terminator.kind = TerminatorKind::Unreachable; + } else if !body_can_unwind { + terminator.kind = TerminatorKind::UnwindTerminate(UnwindTerminateReason::Abi); + } } if block.is_cleanup { @@ -93,8 +113,9 @@ impl<'tcx> crate::MirPass<'tcx> for AbortUnwindingCalls { _ => continue, }; - if !call_can_unwind { - // If this function call can't unwind, then there's no need for it + if !call_can_unwind || !target_supports_unwinding { + // If this function call can't unwind, or if the target doesn't + // support unwinding at all, then there's no need for it // to have a landing pad. This means that we can remove any cleanup // registered for it (and turn it into `UnwindAction::Unreachable`). let cleanup = block.terminator_mut().unwind_mut().unwrap(); diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs index 63b0de377c9..b34a64108e3 100644 --- a/compiler/rustc_span/src/symbol.rs +++ b/compiler/rustc_span/src/symbol.rs @@ -940,6 +940,7 @@ symbols! { ermsb_target_feature, exact_div, except, + exception_handling: "exception-handling", exchange_malloc, exclusive_range_pattern, exhaustive_integer_patterns, diff --git a/tests/codegen-llvm/unwind-abis/c-unwind-abi-panic-abort.rs b/tests/codegen-llvm/unwind-abis/c-unwind-abi-panic-abort.rs index 8d2745ba2f7..2ce1d1b2e00 100644 --- a/tests/codegen-llvm/unwind-abis/c-unwind-abi-panic-abort.rs +++ b/tests/codegen-llvm/unwind-abis/c-unwind-abi-panic-abort.rs @@ -1,4 +1,9 @@ //@ compile-flags: -C panic=abort +//@ revisions: NONWASM WASM WASMEXN +//@ [NONWASM] ignore-wasm32 +//@ [WASM] only-wasm32 +//@ [WASMEXN] only-wasm32 +//@ [WASMEXN] compile-flags: -Ctarget-feature=+exception-handling // Test that `nounwind` attributes are also applied to extern `C-unwind` Rust functions // when the code is compiled with `panic=abort`. @@ -9,7 +14,9 @@ #[no_mangle] pub unsafe extern "C-unwind" fn rust_item_that_can_unwind() { // Handle both legacy and v0 symbol mangling. - // CHECK: call void @{{.*core9panicking19panic_cannot_unwind}} + // NONWASM: call void @{{.*core9panicking19panic_cannot_unwind}} + // WASMEXN: call void @{{.*core9panicking19panic_cannot_unwind}} + // WASM-NOT: call void @{{.*core9panicking19panic_cannot_unwind}} may_unwind(); } diff --git a/tests/codegen-llvm/unwind-and-panic-abort.rs b/tests/codegen-llvm/unwind-and-panic-abort.rs index 8efa140058a..c2838be00af 100644 --- a/tests/codegen-llvm/unwind-and-panic-abort.rs +++ b/tests/codegen-llvm/unwind-and-panic-abort.rs @@ -1,4 +1,9 @@ //@ compile-flags: -C panic=abort +//@ revisions: NONWASM WASM WASMEXN +//@ [NONWASM] ignore-wasm32 +//@ [WASM] only-wasm32 +//@ [WASMEXN] only-wasm32 +//@ [WASMEXN] compile-flags: -Ctarget-feature=+exception-handling #![crate_type = "lib"] @@ -9,7 +14,9 @@ extern "C-unwind" { // CHECK: Function Attrs:{{.*}}nounwind // CHECK-NEXT: define{{.*}}void @foo // Handle both legacy and v0 symbol mangling. -// CHECK: call void @{{.*core9panicking19panic_cannot_unwind}} +// NONWASM: call void @{{.*core9panicking19panic_cannot_unwind}} +// WASMEXN: call void @{{.*core9panicking19panic_cannot_unwind}} +// WASM-NOT: call void @{{.*core9panicking19panic_cannot_unwind}} #[no_mangle] pub unsafe extern "C" fn foo() { bar(); diff --git a/tests/codegen-llvm/wasm_exceptions.rs b/tests/codegen-llvm/wasm_exceptions.rs index 796b69b722b..e718f599a3c 100644 --- a/tests/codegen-llvm/wasm_exceptions.rs +++ b/tests/codegen-llvm/wasm_exceptions.rs @@ -1,8 +1,9 @@ //@ only-wasm32 -//@ compile-flags: -C panic=unwind -Z emscripten-wasm-eh +//@ revisions: WASM WASMEXN +//@ [WASMEXN] compile-flags: -C panic=unwind -Z emscripten-wasm-eh #![crate_type = "lib"] -#![feature(core_intrinsics, wasm_exception_handling_intrinsics)] +#![feature(core_intrinsics, wasm_exception_handling_intrinsics, link_llvm_intrinsics)] extern "C-unwind" { fn may_panic(); @@ -22,7 +23,8 @@ impl Drop for LogOnDrop { } } -// CHECK-LABEL: @test_cleanup() {{.*}} @__gxx_wasm_personality_v0 +// WASM-LABEL: @test_cleanup() {{.*}} +// WASMEXN-LABEL: @test_cleanup() {{.*}} @__gxx_wasm_personality_v0 #[no_mangle] pub fn test_cleanup() { let _log_on_drop = LogOnDrop; @@ -30,12 +32,16 @@ pub fn test_cleanup() { may_panic(); } - // CHECK-NOT: call - // CHECK: invoke void @may_panic() - // CHECK: %cleanuppad = cleanuppad within none [] + // WASMEXN-NOT: call + // WASMEXN: invoke void @may_panic() + // WASMEXN: %cleanuppad = cleanuppad within none [] + // + // WASM: call void @may_panic() + // WASM-NOT: invoke void @may_panic() } -// CHECK-LABEL: @test_rtry() {{.*}} @__gxx_wasm_personality_v0 +// WASM-LABEL: @test_rtry() {{.*}} +// WASMEXN-LABEL: @test_rtry() {{.*}} @__gxx_wasm_personality_v0 #[no_mangle] pub fn test_rtry() { unsafe { @@ -51,23 +57,40 @@ pub fn test_rtry() { ); } - // CHECK-NOT: call - // CHECK: invoke void @may_panic() - // CHECK: {{.*}} = catchswitch within none [label {{.*}}] unwind to caller - // CHECK: {{.*}} = catchpad within {{.*}} [ptr null] - // CHECK: catchret + // WASMEXN-NOT: call + // WASMEXN: invoke void @may_panic() + // WASMEXN: {{.*}} = catchswitch within none [label {{.*}}] unwind to caller + // WASMEXN: {{.*}} = catchpad within {{.*}} [ptr null] + // WASMEXN: catchret + + // WASM: call void @may_panic() + // WASM-NOT: invoke void @may_panic() + // WASM-NOT: catchswitch + // WASM-NOT: catchpad + // WASM-NOT: catchret } // Make sure the intrinsic is not inferred as nounwind. This is a regression test for #132416. -// CHECK-LABEL: @test_intrinsic() {{.*}} @__gxx_wasm_personality_v0 +// +// Note that this test uses the raw `wasm_throw` intrinsic because the one from +// libstd was built with `-Cpanic=abort` and it's technically not valid to use +// when this crate is compiled with `-Cpanic=unwind`. +// +// WASMEXN-LABEL: @test_intrinsic() {{.*}} @__gxx_wasm_personality_v0 #[no_mangle] +#[cfg(wasmexn)] pub fn test_intrinsic() { let _log_on_drop = LogOnDrop; + + unsafe extern "C-unwind" { + #[link_name = "llvm.wasm.throw"] + fn wasm_throw(tag: i32, ptr: *mut u8) -> !; + } unsafe { - core::arch::wasm32::throw::<0>(core::ptr::null_mut()); + wasm_throw(0, core::ptr::null_mut()); } - // CHECK-NOT: call - // CHECK: invoke void @llvm.wasm.throw(i32 noundef 0, ptr noundef null) - // CHECK: %cleanuppad = cleanuppad within none [] + // WASMEXN-NOT: call + // WASMEXN: invoke void @llvm.wasm.throw(i32 noundef 0, ptr noundef null) + // WASMEXN: %cleanuppad = cleanuppad within none [] } |