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Hood Chatham
acbfd79acf
Previously this was not correctly implemented. Each funclet may need its own terminate block, so this changes the `terminate_block` into a `terminate_blocks` `IndexVec` which can have a terminate_block for each funclet. We key on the first basic block of the funclet -- in particular, this is the start block for the old case of the top level terminate function. Rather than using a catchswitch/catchpad pair, I used a cleanuppad. The reason for the pair is to avoid catching foreign exceptions on MSVC. On wasm, it seems that the catchswitch/catchpad pair is optimized back into a single cleanuppad and a catch_all instruction is emitted which will catch foreign exceptions. Because the new logic is only used on wasm, it seemed better to take the simpler approach seeing as they do the same thing.
54 lines
1.7 KiB
Rust
54 lines
1.7 KiB
Rust
//@ revisions: emscripten wasi seh
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//@[emscripten] compile-flags: --target wasm32-unknown-emscripten -Z emscripten-wasm-eh
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//@[wasi] compile-flags: --target wasm32-wasip1 -C panic=unwind
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//@[seh] compile-flags: --target x86_64-pc-windows-msvc
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//@[emscripten] needs-llvm-components: webassembly
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//@[wasi] needs-llvm-components: webassembly
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//@[seh] needs-llvm-components: x86
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// Ensure a catch-all generates:
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// - `catchpad ... [ptr null]` on Wasm (otherwise LLVM gets confused)
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// - `catchpad ... [ptr null, i32 64, ptr null]` on Windows (otherwise we catch SEH exceptions)
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//
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// Unlike on windows, on Wasm, we specifically do want to catch foreign
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// exceptions. To catch only C++ exceptions we'd need to call
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// @llvm.wasm.get.exception and @llvm.wasm.get.ehselector in the catchpad.
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#![feature(no_core, lang_items, rustc_attrs)]
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#![crate_type = "lib"]
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#![no_std]
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#![no_core]
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#[lang = "pointee_sized"]
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pub trait PointeeSized {}
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#[lang = "meta_sized"]
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pub trait MetaSized: PointeeSized {}
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#[lang = "sized"]
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pub trait Sized: MetaSized {}
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unsafe extern "C-unwind" {
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safe fn unwinds();
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}
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#[lang = "panic_cannot_unwind"]
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fn panic_cannot_unwind() -> ! {
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loop {}
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}
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#[no_mangle]
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#[rustc_nounwind]
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pub fn doesnt_unwind() {
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// CHECK: catchswitch within none [label %{{.*}}] unwind to caller
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// emscripten: %catchpad = catchpad within %catchswitch [ptr null]
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// wasi: %catchpad = catchpad within %catchswitch [ptr null]
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// seh: %catchpad = catchpad within %catchswitch [ptr null, i32 64, ptr null]
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//
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// We don't call these intrinsics on wasm targets so we generate a catch_all
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// instruction which also picks up foreign exceptions
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// NOT: @llvm.wasm.get.exception
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// NOT: @llvm.wasm.get.ehselector
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unwinds();
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}
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