From 9a826136de9e5efe497ffeeb40feca1aec93b62c Mon Sep 17 00:00:00 2001
From: Daniel Dunbar <daniel_dunbar@apple.com>
Date: Mon, 19 Nov 2018 18:03:01 -0700
Subject: [PATCH] [WASM] Add minimal support for targeting
 wasm32-unknown-unknown-wasm.

 - This is nothing beyond preventing the compiler from rejecting this target
   triple.

 - There doesn't yet appear to be a well-defined convention around a triple
   which detects WASM based on an "OS" field, so we use the "wasm" indicator in
   the environment component.
---
 include/swift/Basic/LangOptions.h |  2 ++
 lib/Basic/LangOptions.cpp         | 12 ++++++++++++
 lib/Basic/Platform.cpp            |  5 +++++
 lib/Driver/Driver.cpp             |  5 +++++
 4 files changed, 24 insertions(+)

diff --git a/include/swift/Basic/LangOptions.h b/include/swift/Basic/LangOptions.h
index ab8c18a433750..d5bbc79f22f9c 100644
--- a/include/swift/Basic/LangOptions.h
+++ b/include/swift/Basic/LangOptions.h
@@ -316,6 +316,8 @@ namespace swift {
                  Target.isPS4() || Target.isOSHaiku() ||
                  Target.getTriple().empty()) {
         major = minor = revision = 0;
+      } else if (Target.isOSBinFormatWasm()) {
+        major = minor = revision = 0;
       } else {
         llvm_unreachable("Unsupported target OS");
       }
diff --git a/lib/Basic/LangOptions.cpp b/lib/Basic/LangOptions.cpp
index a2ac8787099fb..f1b0f39e0baff 100644
--- a/lib/Basic/LangOptions.cpp
+++ b/lib/Basic/LangOptions.cpp
@@ -192,6 +192,8 @@ std::pair<bool, bool> LangOptions::setTarget(llvm::Triple triple) {
     addPlatformConditionValue(PlatformConditionKind::OS, "PS4");
   else if (Target.isOSHaiku())
     addPlatformConditionValue(PlatformConditionKind::OS, "Haiku");
+  else if (Target.isOSBinFormatWasm())
+    addPlatformConditionValue(PlatformConditionKind::OS, "WebAssembly");
   else
     UnsupportedOS = true;
 
@@ -221,6 +223,12 @@ std::pair<bool, bool> LangOptions::setTarget(llvm::Triple triple) {
   case llvm::Triple::ArchType::systemz:
     addPlatformConditionValue(PlatformConditionKind::Arch, "s390x");
     break;
+  case llvm::Triple::ArchType::wasm32:
+    addPlatformConditionValue(PlatformConditionKind::Arch, "wasm32");
+    break;
+  case llvm::Triple::ArchType::wasm64:
+    addPlatformConditionValue(PlatformConditionKind::Arch, "wasm64");
+    break;
   default:
     UnsupportedArch = true;
   }
@@ -252,6 +260,10 @@ std::pair<bool, bool> LangOptions::setTarget(llvm::Triple triple) {
   case llvm::Triple::ArchType::systemz:
     addPlatformConditionValue(PlatformConditionKind::Endianness, "big");
     break;
+  case llvm::Triple::ArchType::wasm32:
+  case llvm::Triple::ArchType::wasm64:
+    addPlatformConditionValue(PlatformConditionKind::Endianness, "little");
+    break;
   default:
     llvm_unreachable("undefined architecture endianness");
   }
diff --git a/lib/Basic/Platform.cpp b/lib/Basic/Platform.cpp
index 9e793fa5037a4..e67247060b0ae 100644
--- a/lib/Basic/Platform.cpp
+++ b/lib/Basic/Platform.cpp
@@ -116,6 +116,11 @@ static StringRef getPlatformNameForDarwin(const DarwinPlatformKind platform) {
 StringRef swift::getPlatformNameForTriple(const llvm::Triple &triple) {
   switch (triple.getOS()) {
   case llvm::Triple::UnknownOS:
+    // NOTE: WebAssembly doesn't yet have a defined OS convention in triples.
+    if (triple.isOSBinFormatWasm()) {
+      return "wasm";
+    }
+  
     llvm_unreachable("unknown OS");
   case llvm::Triple::Ananas:
   case llvm::Triple::CloudABI:
diff --git a/lib/Driver/Driver.cpp b/lib/Driver/Driver.cpp
index d69785e122272..68f0f72f439f4 100644
--- a/lib/Driver/Driver.cpp
+++ b/lib/Driver/Driver.cpp
@@ -286,6 +286,11 @@ Driver::buildToolChain(const llvm::opt::InputArgList &ArgList) {
   case llvm::Triple::Haiku:
     return llvm::make_unique<toolchains::GenericUnix>(*this, target);
   default:
+    // NOTE: WebAssembly doesn't yet have a defined OS convention in triples.
+    if (target.isOSBinFormatWasm()) {
+      return llvm::make_unique<toolchains::GenericUnix>(*this, target);
+    }
+  
     Diags.diagnose(SourceLoc(), diag::error_unknown_target,
                    ArgList.getLastArg(options::OPT_target)->getValue());
     break;