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bd82c7f4d1
Summary:
Currently, on Emscripten, dynamic linking is not supported with threads.
This means that if thread-local storage is used, it must be used in a
statically-linked executable. Hence, local-exec is the only possible model.
This diff compiles all TLS variables to use local-exec on Emscripten as a
temporary measure until dynamic linking is supported with threads.
The goal for this is to allow C++ types with constructors to be thread-local.
Currently, when `clang` compiles a `thread_local` variable with a constructor,
it generates `__tls_guard` variable:
@__tls_guard = internal thread_local global i8 0, align 1
As no TLS model is specified, this is treated as general-dynamic, which we do
not support (and cannot support without implementing dynamic linking support
with threads in Emscripten). As a result, any C++ constructor in `thread_local`
variables would not compile.
By compiling all `thread_local` as local-exec, `__tls_guard` will compile and
we can support C++ constructors with TLS without implementing dynamic linking
with threads.
Depends on D64537
Reviewers: tlively, aheejin, sbc100
Reviewed By: aheejin
Subscribers: dschuff, jgravelle-google, hiraditya, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64776
llvm-svn: 366275
83 lines
2.3 KiB
LLVM
83 lines
2.3 KiB
LLVM
; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory | FileCheck %s --check-prefixes=CHECK,TLS
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; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory -fast-isel | FileCheck %s --check-prefixes=CHECK,TLS
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; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=-bulk-memory | FileCheck %s --check-prefixes=CHECK,NO-TLS
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target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
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target triple = "wasm32-unknown-unknown"
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; CHECK-LABEL: address_of_tls:
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; CHECK-NEXT: .functype address_of_tls () -> (i32)
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define i32 @address_of_tls() {
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; TLS-DAG: global.get __tls_base
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; TLS-DAG: i32.const tls
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; TLS-NEXT: i32.add
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; TLS-NEXT: return
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; NO-TLS-NEXT: i32.const tls
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; NO-TLS-NEXT: return
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ret i32 ptrtoint(i32* @tls to i32)
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}
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; CHECK-LABEL: ptr_to_tls:
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; CHECK-NEXT: .functype ptr_to_tls () -> (i32)
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define i32* @ptr_to_tls() {
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; TLS-DAG: global.get __tls_base
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; TLS-DAG: i32.const tls
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; TLS-NEXT: i32.add
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; TLS-NEXT: return
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; NO-TLS-NEXT: i32.const tls
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; NO-TLS-NEXT: return
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ret i32* @tls
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}
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; CHECK-LABEL: tls_load:
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; CHECK-NEXT: .functype tls_load () -> (i32)
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define i32 @tls_load() {
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; TLS-DAG: global.get __tls_base
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; TLS-DAG: i32.const tls
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; TLS-NEXT: i32.add
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; TLS-NEXT: i32.load 0
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; TLS-NEXT: return
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; NO-TLS-NEXT: i32.const 0
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; NO-TLS-NEXT: i32.load tls
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; NO-TLS-NEXT: return
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%tmp = load i32, i32* @tls, align 4
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ret i32 %tmp
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}
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; CHECK-LABEL: tls_store:
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; CHECK-NEXT: .functype tls_store (i32) -> ()
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define void @tls_store(i32 %x) {
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; TLS-DAG: global.get __tls_base
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; TLS-DAG: i32.const tls
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; TLS-NEXT: i32.add
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; TLS-NEXT: i32.store 0
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; TLS-NEXT: return
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; NO-TLS-NEXT: i32.const 0
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; NO-TLS-NEXT: i32.store tls
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; NO-TLS-NEXT: return
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store i32 %x, i32* @tls, align 4
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ret void
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}
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; CHECK-LABEL: tls_size:
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; CHECK-NEXT: .functype tls_size () -> (i32)
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define i32 @tls_size() {
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; CHECK-NEXT: global.get __tls_size
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; CHECK-NEXT: return
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%1 = call i32 @llvm.wasm.tls.size.i32()
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ret i32 %1
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}
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; CHECK: .type tls,@object
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; TLS-NEXT: .section .tbss.tls,"",@
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; NO-TLS-NEXT: .section .bss.tls,"",@
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; CHECK-NEXT: .p2align 2
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; CHECK-NEXT: tls:
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; CHECK-NEXT: .int32 0
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@tls = internal thread_local(localexec) global i32 0
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declare i32 @llvm.wasm.tls.size.i32()
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