[llvm] r328049 - [WebAssembly] Strip threadlocal attribute from globals in single thread mode

[Derek Schuff via llvm-commits]

Author: dschuff
Date: Tue Mar 20 15:01:32 2018
New Revision: 328049

URL: http://llvm.org/viewvc/llvm-project?rev=328049&view=rev
Log:
[WebAssembly] Strip threadlocal attribute from globals in single thread mode

The default thread model for wasm is single, and in this mode thread-local
global variables can be lowered identically to non-thread-local variables.

Differential Revision: https://reviews.llvm.org/D44703

Added:
    llvm/trunk/test/CodeGen/WebAssembly/tls.ll
Modified:
    llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp?rev=328049&r1=328048&r2=328049&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp Tue Mar 20 15:01:32 2018
@@ -126,6 +126,22 @@ WebAssemblyTargetMachine::getSubtargetIm
 }
 
 namespace {
+class StripThreadLocal final : public ModulePass {
+  // The default thread model for wasm is single, where thread-local variables
+  // are identical to regular globals and should be treated the same. So this
+  // pass just converts all GlobalVariables to NotThreadLocal
+  static char ID;
+
+ public:
+  StripThreadLocal() : ModulePass(ID) {}
+  bool runOnModule(Module &M) override {
+    for (auto &GV : M.globals())
+      GV.setThreadLocalMode(GlobalValue::ThreadLocalMode::NotThreadLocal);
+    return true;
+  }
+};
+char StripThreadLocal::ID = 0;
+
 /// WebAssembly Code Generator Pass Configuration Options.
 class WebAssemblyPassConfig final : public TargetPassConfig {
 public:
@@ -166,13 +182,15 @@ FunctionPass *WebAssemblyPassConfig::cre
 //===----------------------------------------------------------------------===//
 
 void WebAssemblyPassConfig::addIRPasses() {
-  if (TM->Options.ThreadModel == ThreadModel::Single)
+  if (TM->Options.ThreadModel == ThreadModel::Single) {
     // In "single" mode, atomics get lowered to non-atomics.
     addPass(createLowerAtomicPass());
-  else
+    addPass(new StripThreadLocal());
+  } else {
     // Expand some atomic operations. WebAssemblyTargetLowering has hooks which
     // control specifically what gets lowered.
     addPass(createAtomicExpandPass());
+  }
 
   // Lower .llvm.global_dtors into .llvm_global_ctors with __cxa_atexit calls.
   addPass(createWebAssemblyLowerGlobalDtors());

Added: llvm/trunk/test/CodeGen/WebAssembly/tls.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/tls.ll?rev=328049&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/tls.ll (added)
+++ llvm/trunk/test/CodeGen/WebAssembly/tls.ll Tue Mar 20 15:01:32 2018
@@ -0,0 +1,17 @@
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals -thread-model=single | FileCheck --check-prefix=SINGLE %s
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+; SINGLE-LABEL: address_of_tls:
+define i32 @address_of_tls() {
+  ; SINGLE: i32.const $push0=, tls
+  ; SINGLE-NEXT: return $pop0
+  ret i32 ptrtoint(i32* @tls to i32)
+}
+
+; SINGLE: .type	tls, at object
+; SINGLE-NEXT: .section	.bss.tls,"",@
+; SINGLE-NEXT: .p2align 2
+; SINGLE-NEXT: tls:
+; SINGLE-NEXT: .int32 0
+ at tls = internal thread_local global i32 0