[clang] 95da64d - [WebAssembly] Use single-threaded mode when -matomics isn't enabled.

[Dan Gohman via cfe-commits]

Author: Dan Gohman
Date: 2021-02-04T18:16:48-08:00
New Revision: 95da64da23ac3a5855a8934a738b0fa10aa1323c

URL: https://github.com/llvm/llvm-project/commit/95da64da23ac3a5855a8934a738b0fa10aa1323c
DIFF: https://github.com/llvm/llvm-project/commit/95da64da23ac3a5855a8934a738b0fa10aa1323c.diff

LOG: [WebAssembly] Use single-threaded mode when -matomics isn't enabled.

When the -matomics feature is not enabled, disable POSIXThreads
mode and set the thread model to Single, so that we don't predefine
macros like `__STDCPP_THREADS__`.

Differential Revision: https://reviews.llvm.org/D96091

Added: 
    

Modified: 
    clang/lib/Basic/Targets/WebAssembly.cpp
    clang/lib/Basic/Targets/WebAssembly.h
    clang/test/Preprocessor/init.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Basic/Targets/WebAssembly.cpp b/clang/lib/Basic/Targets/WebAssembly.cpp
index dcb3d8fd7790..89babe85794d 100644
--- a/clang/lib/Basic/Targets/WebAssembly.cpp
+++ b/clang/lib/Basic/Targets/WebAssembly.cpp
@@ -253,6 +253,15 @@ ArrayRef<Builtin::Info> WebAssemblyTargetInfo::getTargetBuiltins() const {
                                              Builtin::FirstTSBuiltin);
 }
 
+void WebAssemblyTargetInfo::adjust(LangOptions &Opts) {
+  // If the Atomics feature isn't available, turn off POSIXThreads and
+  // ThreadModel, so that we don't predefine _REENTRANT or __STDCPP_THREADS__.
+  if (!HasAtomics) {
+    Opts.POSIXThreads = false;
+    Opts.setThreadModel(LangOptions::ThreadModelKind::Single);
+  }
+}
+
 void WebAssembly32TargetInfo::getTargetDefines(const LangOptions &Opts,
                                                MacroBuilder &Builder) const {
   WebAssemblyTargetInfo::getTargetDefines(Opts, Builder);

diff  --git a/clang/lib/Basic/Targets/WebAssembly.h b/clang/lib/Basic/Targets/WebAssembly.h
index 0068ccb5d71f..9150d849f601 100644
--- a/clang/lib/Basic/Targets/WebAssembly.h
+++ b/clang/lib/Basic/Targets/WebAssembly.h
@@ -138,6 +138,8 @@ class LLVM_LIBRARY_VISIBILITY WebAssemblyTargetInfo : public TargetInfo {
   bool hasExtIntType() const override { return true; }
 
   bool hasProtectedVisibility() const override { return false; }
+
+  void adjust(LangOptions &Opts) override;
 };
 
 class LLVM_LIBRARY_VISIBILITY WebAssembly32TargetInfo

diff  --git a/clang/test/Preprocessor/init.c b/clang/test/Preprocessor/init.c
index 23c4989c5152..e29b6d3972f8 100644
--- a/clang/test/Preprocessor/init.c
+++ b/clang/test/Preprocessor/init.c
@@ -1479,6 +1479,12 @@
 // RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=wasm64-wasi \
 // RUN:   < /dev/null \
 // RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY64,WEBASSEMBLY-WASI %s
+// RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=wasm32-unknown-unknown -x c++ \
+// RUN:   < /dev/null \
+// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY-CXX %s
+// RUN: %clang_cc1 -E -dM -ffreestanding -fgnuc-version=4.2.1 -triple=wasm32-unknown-unknown -x c++ -pthread -target-feature +atomics \
+// RUN:   < /dev/null \
+// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY-CXX-ATOMICS %s
 //
 // WEBASSEMBLY32:#define _ILP32 1
 // WEBASSEMBLY32-NOT:#define _LP64
@@ -1847,6 +1853,10 @@
 // WEBASSEMBLY64-NEXT:#define __wasm64 1
 // WEBASSEMBLY64-NEXT:#define __wasm64__ 1
 // WEBASSEMBLY-NEXT:#define __wasm__ 1
+// WEBASSEMBLY-CXX-NOT:_REENTRANT
+// WEBASSEMBLY-CXX-NOT:__STDCPP_THREADS__
+// WEBASSEMBLY-CXX-ATOMICS:#define _REENTRANT 1
+// WEBASSEMBLY-CXX-ATOMICS:#define __STDCPP_THREADS__ 1
 
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple i686-windows-cygnus < /dev/null | FileCheck -match-full-lines -check-prefix CYGWIN-X32 %s
 // CYGWIN-X32: #define __USER_LABEL_PREFIX__ _