[WebAssembly] Add a __wasi__ target macro

[sunfish]

Summary

This adds a __wasi__ macro for the wasi OS, similar to __linux__ etc. for other OS's.

[dschuff]

LGTM; don't forget to include all the context in the future

cfe/trunk/lib/Basic/Targets.cpp

if (Triple.getOS() != llvm::Triple::UnknownOS ||
       return nullptr;
     return new SPIR64TargetInfo(Triple, Opts);
   }
   case llvm::Triple::wasm32:
     if (Triple.getSubArch() != llvm::Triple::NoSubArch ||
         Triple.getVendor() != llvm::Triple::UnknownVendor ||
         !Triple.isOSBinFormatWasm())
       return nullptr;
-    if (Triple.getOS() != llvm::Triple::UnknownOS &&
-        Triple.getOS() != llvm::Triple::WASI)
-      return nullptr;
+    switch (Triple.getOS()) {
+      case llvm::Triple::WASI:
+        return new WASITargetInfo<WebAssembly32TargetInfo>(Triple, Opts);
+      case llvm::Triple::UnknownOS:
         return new WebAssemblyOSTargetInfo<WebAssembly32TargetInfo>(Triple, Opts);
+      default:
+        return nullptr;
+    }
   case llvm::Triple::wasm64:
     if (Triple.getSubArch() != llvm::Triple::NoSubArch ||
         Triple.getVendor() != llvm::Triple::UnknownVendor ||
         !Triple.isOSBinFormatWasm())
       return nullptr;
-    if (Triple.getOS() != llvm::Triple::UnknownOS &&
-        Triple.getOS() != llvm::Triple::WASI)
-      return nullptr;
+    switch (Triple.getOS()) {
+      case llvm::Triple::WASI:
+        return new WASITargetInfo<WebAssembly64TargetInfo>(Triple, Opts);
+      case llvm::Triple::UnknownOS:
         return new WebAssemblyOSTargetInfo<WebAssembly64TargetInfo>(Triple, Opts);
+      default:
+        return nullptr;
+    }
 
   case llvm::Triple::renderscript32:
     return new LinuxTargetInfo<RenderScript32TargetInfo>(Triple, Opts);
   case llvm::Triple::renderscript64:
     return new LinuxTargetInfo<RenderScript64TargetInfo>(Triple, Opts);
   }
 }
 } // namespace targets

cfe/trunk/lib/Basic/Targets/OSTargets.h

FuchsiaTargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
     this->MCountName = "__mcount";
   }
 };
 
 // WebAssembly target
 template <typename Target>
 class LLVM_LIBRARY_VISIBILITY WebAssemblyOSTargetInfo
     : public OSTargetInfo<Target> {
+protected:
   void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
-                    MacroBuilder &Builder) const final {
+                    MacroBuilder &Builder) const {
     // A common platform macro.
     if (Opts.POSIXThreads)
       Builder.defineMacro("_REENTRANT");
     // Follow g++ convention and predefine _GNU_SOURCE for C++.
     if (Opts.CPlusPlus)
       Builder.defineMacro("_GNU_SOURCE");
     // Indicate that we have __float128.
     Builder.defineMacro("__FLOAT128__");
   }
 
 public:
   explicit WebAssemblyOSTargetInfo(const llvm::Triple &Triple,
                                    const TargetOptions &Opts)
       : OSTargetInfo<Target>(Triple, Opts) {
     this->MCountName = "__mcount";
     this->TheCXXABI.set(TargetCXXABI::WebAssembly);
     this->HasFloat128 = true;
   }
 };
 
+// WASI target
+template <typename Target>
+class LLVM_LIBRARY_VISIBILITY WASITargetInfo
+    : public WebAssemblyOSTargetInfo<Target> {
+  void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
+                    MacroBuilder &Builder) const final {
+    WebAssemblyOSTargetInfo<Target>::getOSDefines(Opts, Triple, Builder);
+    Builder.defineMacro("__wasi__");
+  }
+
+public:
+  explicit WASITargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
+      : WebAssemblyOSTargetInfo<Target>(Triple, Opts) {}
+};
+
 } // namespace targets
 } // namespace clang
 #endif // LLVM_CLANG_LIB_BASIC_TARGETS_OSTARGETS_H

cfe/trunk/test/Preprocessor/init.c

 // XCORE:#define __XS1B__ 1
 //
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=wasm32-unknown-unknown \
 // RUN:   < /dev/null \
 // RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY32 %s
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=wasm64-unknown-unknown \
 // RUN:   < /dev/null \
 // RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY64 %s
+// RUN: %clang_cc1 -E -dM -ffreestanding -triple=wasm32-unknown-wasi \
+// RUN:   < /dev/null \
+// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY32,WEBASSEMBLY-WASI %s
+// RUN: %clang_cc1 -E -dM -ffreestanding -triple=wasm64-unknown-wasi \
+// RUN:   < /dev/null \
+// RUN:   | FileCheck -match-full-lines -check-prefixes=WEBASSEMBLY,WEBASSEMBLY64,WEBASSEMBLY-WASI %s
 //
 // WEBASSEMBLY32:#define _ILP32 1
 // WEBASSEMBLY32-NOT:#define _LP64
 // WEBASSEMBLY64-NOT:#define _ILP32
 // WEBASSEMBLY64:#define _LP64 1
 // WEBASSEMBLY-NEXT:#define __ATOMIC_ACQUIRE 2
 // WEBASSEMBLY-NEXT:#define __ATOMIC_ACQ_REL 4
 // WEBASSEMBLY-NEXT:#define __ATOMIC_CONSUME 1

 // WEBASSEMBLY-NEXT:#define __clang__ 1
 // WEBASSEMBLY-NEXT:#define __clang_major__ {{.*}}
 // WEBASSEMBLY-NEXT:#define __clang_minor__ {{.*}}
 // WEBASSEMBLY-NEXT:#define __clang_patchlevel__ {{.*}}
 // WEBASSEMBLY-NEXT:#define __clang_version__ "{{.*}}"
 // WEBASSEMBLY-NEXT:#define __llvm__ 1
 // WEBASSEMBLY-NOT:#define __unix
 // WEBASSEMBLY-NOT:#define __unix__
+// WEBASSEMBLY-WASI-NEXT:#define __wasi__ 1
 // WEBASSEMBLY-NOT:#define __wasm_simd128__
 // WEBASSEMBLY-NOT:#define __wasm_simd256__
 // WEBASSEMBLY-NOT:#define __wasm_simd512__
 // WEBASSEMBLY-NEXT:#define __wasm 1
 // WEBASSEMBLY32-NEXT:#define __wasm32 1
 // WEBASSEMBLY64-NOT:#define __wasm32
 // WEBASSEMBLY32-NEXT:#define __wasm32__ 1
 // WEBASSEMBLY64-NOT:#define __wasm32__