577e9a7cc8
The [WebAssembly Component Model](https://component-model.bytecodealliance.org/) has added support for [cooperative multithreading](https://github.com/WebAssembly/component-model/pull/557). This has been implemented in the [Wasmtime engine](https://github.com/bytecodealliance/wasmtime/pull/11751) and is part of the wider project of [WASI preview 3](https://wasi.dev/roadmap#upcoming-wasi-03-releases), which is currently tracked [here](https://github.com/orgs/bytecodealliance/projects/16). These changes require updating the way that `__stack_pointer` and `__tls_base` work purely for a new `wasm32-wasip3` target; other targets will not be touched. Specifically, rather than using a Wasm global for tracking the stack pointer and TLS base, the new [`context.get/set`](https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#-canon-contextget) component model builtin functions will be used (the intention being that runtimes will need to aggressively optimize these calls into single load/stores). For justification on this choice rather than switching out the global at context-switch boundaries, see [this comment](https://github.com/WebAssembly/wasi-libc/issues/691#issuecomment-3716405618) and [this comment](https://github.com/WebAssembly/wasi-libc/issues/691#issuecomment-3716916730). This PR adds support for using library calls instead of globals for holding the stack pointer and TLS base. When used, this thread context ABI emits calls to `__wasm_{get,set}_{stack_pointer,tls_base}` when needed. These functions can then be implemented in `libc`. This is enabled only for the WASIp3 target. There is a temporary macro define for `__wasm_libcall_thread_context__` which can be removed once `wasi-libc` has fully migrated to the new ABI for the WASIp3 target.
29 lines
1.1 KiB
LLVM
29 lines
1.1 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
|
|
; RUN: llc < %s -mtriple=wasm32-unknown-unknown | FileCheck %s --check-prefix=WASM32
|
|
; RUN: llc < %s -mtriple=wasm64-unknown-unknown | FileCheck %s --check-prefix=WASM64
|
|
; RUN: llc < %s -mtriple=wasm32-wasip3 | FileCheck %s --check-prefix=WASM32-LIBCALL
|
|
|
|
declare ptr @llvm.thread.pointer()
|
|
|
|
define ptr @thread_pointer() nounwind {
|
|
; WASM32-LABEL: thread_pointer:
|
|
; WASM32: .functype thread_pointer () -> (i32)
|
|
; WASM32-NEXT: # %bb.0:
|
|
; WASM32-NEXT: global.get __tls_base
|
|
; WASM32-NEXT: # fallthrough-return
|
|
;
|
|
; WASM64-LABEL: thread_pointer:
|
|
; WASM64: .functype thread_pointer () -> (i64)
|
|
; WASM64-NEXT: # %bb.0:
|
|
; WASM64-NEXT: global.get __tls_base
|
|
; WASM64-NEXT: # fallthrough-return
|
|
;
|
|
; WASM32-LIBCALL-LABEL: thread_pointer:
|
|
; WASM32-LIBCALL: .functype thread_pointer () -> (i32)
|
|
; WASM32-LIBCALL-NEXT: # %bb.0:
|
|
; WASM32-LIBCALL-NEXT: call __wasm_get_tls_base
|
|
; WASM32-LIBCALL-NEXT: # fallthrough-return
|
|
;
|
|
%1 = tail call ptr @llvm.thread.pointer()
|
|
ret ptr %1
|
|
}
|