rustc: Prepare the atomics feature for wasm
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This commit adds a few changes for atomic instructions on the `wasm32-unknown-unknown` target. Atomic instructions are not yet stable in WebAssembly itself but there are multiple implementations and LLVM has support for the proposed instruction set, so let's work on exposing it! Here there are a few inclusions: * The `atomics` feature was whitelisted for LLVM, allowing code in Rust to enable/disable/gate on this. * The `singlethread` option is turned off for wasm when the `atomics` feature is enabled. This means that by default wasm won't be lowering with atomics, but when atomics are enabled globally we'll turn off single-threaded mode to actually codegen atomics. This probably isn't what we'll want in the long term but for now it should work. * Finally the maximum atomic width is increased to 64 to reflect the current wasm spec.
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rustc: Prepare the `atomics` feature for wasm This commit adds a few changes for atomic instructions on the `wasm32-unknown-unknown` target. Atomic instructions are not yet stable in WebAssembly itself but there are multiple implementations and LLVM has support for the proposed instruction set, so let's work on exposing it! Here there are a few inclusions: * The `atomics` feature was whitelisted for LLVM, allowing code in Rust to enable/disable/gate on this. * The `singlethread` option is turned off for wasm when the `atomics` feature is enabled. This means that by default wasm won't be lowering with atomics, but when atomics are enabled globally we'll turn off single-threaded mode to actually codegen atomics. This probably isn't what we'll want in the long term but for now it should work. * Finally the maximum atomic width is increased to 64 to reflect the current wasm spec.
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This commit adds a few changes for atomic instructions on the
wasm32-unknown-unknowntarget. Atomic instructions are not yet stable inWebAssembly itself but there are multiple implementations and LLVM has support
for the proposed instruction set, so let's work on exposing it!
Here there are a few inclusions:
The
atomicsfeature was whitelisted for LLVM, allowing code in Rust toenable/disable/gate on this.
The
singlethreadoption is turned off for wasm when theatomicsfeature isenabled. This means that by default wasm won't be lowering with atomics, but
when atomics are enabled globally we'll turn off single-threaded mode to
actually codegen atomics. This probably isn't what we'll want in the long term
but for now it should work.
Finally the maximum atomic width is increased to 64 to reflect the current
wasm spec.