From 9eb4a3996776f8b6a94be0a656c516852aa51cbe Mon Sep 17 00:00:00 2001 From: Guanzhong Chen Date: Tue, 16 Jul 2019 22:22:08 +0000 Subject: [PATCH] [WebAssembly] Compile all TLS on Emscripten as local-exec 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 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@366275 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../WebAssembly/WebAssemblyISelDAGToDAG.cpp | 12 ++- .../WebAssembly/tls-general-dynamic.ll | 86 +++++++++++++++++++ .../WebAssembly/{tls.ll => tls-local-exec.ll} | 0 3 files changed, 96 insertions(+), 2 deletions(-) create mode 100644 test/CodeGen/WebAssembly/tls-general-dynamic.ll rename test/CodeGen/WebAssembly/{tls.ll => tls-local-exec.ll} (100%) diff --git a/lib/Target/WebAssembly/WebAssemblyISelDAGToDAG.cpp b/lib/Target/WebAssembly/WebAssemblyISelDAGToDAG.cpp index 1efbb3b067b..26339eaef37 100644 --- a/lib/Target/WebAssembly/WebAssemblyISelDAGToDAG.cpp +++ b/lib/Target/WebAssembly/WebAssemblyISelDAGToDAG.cpp @@ -179,9 +179,17 @@ void WebAssemblyDAGToDAGISel::Select(SDNode *Node) { report_fatal_error("cannot use thread-local storage without bulk memory", false); + // Currently Emscripten does not support dynamic linking with threads. + // Therefore, if we have thread-local storage, only the local-exec model + // is possible. + // TODO: remove this and implement proper TLS models once Emscripten + // supports dynamic linking with threads. if (GA->getGlobal()->getThreadLocalMode() != - GlobalValue::LocalExecTLSModel) { - report_fatal_error("only -ftls-model=local-exec is supported for now", + GlobalValue::LocalExecTLSModel && + !Subtarget->getTargetTriple().isOSEmscripten()) { + report_fatal_error("only -ftls-model=local-exec is supported for now on " + "non-Emscripten OSes: variable " + + GA->getGlobal()->getName(), false); } diff --git a/test/CodeGen/WebAssembly/tls-general-dynamic.ll b/test/CodeGen/WebAssembly/tls-general-dynamic.ll new file mode 100644 index 00000000000..3f6d9d325c6 --- /dev/null +++ b/test/CodeGen/WebAssembly/tls-general-dynamic.ll @@ -0,0 +1,86 @@ +; RUN: not llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory 2>&1 | FileCheck %s --check-prefix=ERROR +; RUN: not llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory -fast-isel 2>&1 | FileCheck %s --check-prefix=ERROR +; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory --mtriple wasm32-unknown-emscripten | FileCheck %s --check-prefixes=CHECK,TLS +; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory --mtriple wasm32-unknown-emscripten -fast-isel | FileCheck %s --check-prefixes=CHECK,TLS +; 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 +target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128" +target triple = "wasm32-unknown-unknown" + +; ERROR: LLVM ERROR: only -ftls-model=local-exec is supported for now on non-Emscripten OSes: variable tls + +; CHECK-LABEL: address_of_tls: +; CHECK-NEXT: .functype address_of_tls () -> (i32) +define i32 @address_of_tls() { + ; TLS-DAG: global.get __tls_base + ; TLS-DAG: i32.const tls + ; TLS-NEXT: i32.add + ; TLS-NEXT: return + + ; NO-TLS-NEXT: i32.const tls + ; NO-TLS-NEXT: return + ret i32 ptrtoint(i32* @tls to i32) +} + +; CHECK-LABEL: ptr_to_tls: +; CHECK-NEXT: .functype ptr_to_tls () -> (i32) +define i32* @ptr_to_tls() { + ; TLS-DAG: global.get __tls_base + ; TLS-DAG: i32.const tls + ; TLS-NEXT: i32.add + ; TLS-NEXT: return + + ; NO-TLS-NEXT: i32.const tls + ; NO-TLS-NEXT: return + ret i32* @tls +} + +; CHECK-LABEL: tls_load: +; CHECK-NEXT: .functype tls_load () -> (i32) +define i32 @tls_load() { + ; TLS-DAG: global.get __tls_base + ; TLS-DAG: i32.const tls + ; TLS-NEXT: i32.add + ; TLS-NEXT: i32.load 0 + ; TLS-NEXT: return + + ; NO-TLS-NEXT: i32.const 0 + ; NO-TLS-NEXT: i32.load tls + ; NO-TLS-NEXT: return + %tmp = load i32, i32* @tls, align 4 + ret i32 %tmp +} + +; CHECK-LABEL: tls_store: +; CHECK-NEXT: .functype tls_store (i32) -> () +define void @tls_store(i32 %x) { + ; TLS-DAG: global.get __tls_base + ; TLS-DAG: i32.const tls + ; TLS-NEXT: i32.add + ; TLS-NEXT: i32.store 0 + ; TLS-NEXT: return + + ; NO-TLS-NEXT: i32.const 0 + ; NO-TLS-NEXT: i32.store tls + ; NO-TLS-NEXT: return + store i32 %x, i32* @tls, align 4 + ret void +} + +; CHECK-LABEL: tls_size: +; CHECK-NEXT: .functype tls_size () -> (i32) +define i32 @tls_size() { +; CHECK-NEXT: global.get __tls_size +; CHECK-NEXT: return + %1 = call i32 @llvm.wasm.tls.size.i32() + ret i32 %1 +} + +; CHECK: .type tls,@object +; TLS-NEXT: .section .tbss.tls,"",@ +; NO-TLS-NEXT: .section .bss.tls,"",@ +; CHECK-NEXT: .p2align 2 +; CHECK-NEXT: tls: +; CHECK-NEXT: .int32 0 +@tls = internal thread_local global i32 0 + +declare i32 @llvm.wasm.tls.size.i32() diff --git a/test/CodeGen/WebAssembly/tls.ll b/test/CodeGen/WebAssembly/tls-local-exec.ll similarity index 100% rename from test/CodeGen/WebAssembly/tls.ll rename to test/CodeGen/WebAssembly/tls-local-exec.ll -- 2.40.0