Add new _endian() platform condition check; valid values are "little" and "big".

Author: bryanpkc

include/swift/Basic/LangOptions.h

@@ -233,6 +233,10 @@ namespace swift {
     /// a supported target architecture.
     static bool isPlatformConditionArchSupported(StringRef ArchName);
 
+    /// Returns true if the 'endian' platform condition argument represents
+    /// a supported target endianness.
+    static bool isPlatformConditionEndiannessSupported(StringRef endianness);
+
   private:
     llvm::SmallVector<std::pair<std::string, std::string>, 3>
         PlatformConditionValues;

lib/Basic/LangOptions.cpp

@@ -43,6 +43,11 @@ static const StringRef SupportedConditionalCompilationArches[] = {
   "powerpc64le"
 };
 
+static const StringRef SupportedConditionalCompilationEndianness[] = {
+  "little",
+  "big"
+};
+
 bool LangOptions::isPlatformConditionOSSupported(StringRef OSName) {
   auto foundIt = std::find(std::begin(SupportedConditionalCompilationOSs),
                            std::end(SupportedConditionalCompilationOSs),
@@ -58,6 +63,14 @@ LangOptions::isPlatformConditionArchSupported(StringRef ArchName) {
   return foundIt != std::end(SupportedConditionalCompilationArches);
 }
 
+bool
+LangOptions::isPlatformConditionEndiannessSupported(StringRef Endianness) {
+  auto foundIt = std::find(std::begin(SupportedConditionalCompilationEndianness),
+                           std::end(SupportedConditionalCompilationEndianness),
+                           Endianness);
+  return foundIt != std::end(SupportedConditionalCompilationEndianness);
+}
+
 StringRef
 LangOptions::getPlatformConditionValue(StringRef Name) const {
   // Last one wins.
@@ -148,6 +161,31 @@ std::pair<bool, bool> LangOptions::setTarget(llvm::Triple triple) {
   if (UnsupportedOS || UnsupportedArch)
     return { UnsupportedOS, UnsupportedArch };
 
+  // Set the "_endian" platform condition.
+  switch (Target.getArch()) {
+  case llvm::Triple::ArchType::arm:
+  case llvm::Triple::ArchType::thumb:
+    addPlatformConditionValue("_endian", "little");
+    break;
+  case llvm::Triple::ArchType::aarch64:
+    addPlatformConditionValue("_endian", "little");
+    break;
+  case llvm::Triple::ArchType::ppc64:
+    addPlatformConditionValue("_endian", "big");
+    break;
+  case llvm::Triple::ArchType::ppc64le:
+    addPlatformConditionValue("_endian", "little");
+    break;
+  case llvm::Triple::ArchType::x86:
+    addPlatformConditionValue("_endian", "little");
+    break;
+  case llvm::Triple::ArchType::x86_64:
+    addPlatformConditionValue("_endian", "little");
+    break;
+  default:
+    llvm_unreachable("undefined architecture endianness");
+  }
+
   // Set the "runtime" platform condition.
   if (EnableObjCInterop)
     addPlatformConditionValue("_runtime", "_ObjC");

lib/Parse/ParseStmt.cpp

@@ -1608,7 +1608,7 @@ ParserResult<Stmt> Parser::parseStmtGuard() {
 //    "_compiler_version"), and whose argument is a named decl ref expression
 ConditionalCompilationExprState
 Parser::evaluateConditionalCompilationExpr(Expr *condition) {
-    // Evaluate a ParenExpr.
+  // Evaluate a ParenExpr.
   if (auto *PE = dyn_cast<ParenExpr>(condition))
     return evaluateConditionalCompilationExpr(PE->getSubExpr());
 
@@ -1709,6 +1709,7 @@ Parser::evaluateConditionalCompilationExpr(Expr *condition) {
     }
 
     if (!fnName.equals("arch") && !fnName.equals("os") &&
+        !fnName.equals("_endian") &&
         !fnName.equals("_runtime") &&
         !fnName.equals("swift") &&
         !fnName.equals("_compiler_version")) {
@@ -1799,6 +1800,11 @@ Parser::evaluateConditionalCompilationExpr(Expr *condition) {
                      "architecture", fnName);
             return ConditionalCompilationExprState::error();
           }
+        } else if (fnName == "_endian") {
+          if (!LangOptions::isPlatformConditionEndiannessSupported(argument)) {
+            diagnose(UDRE->getLoc(), diag::unknown_platform_condition_argument,
+                     "endianness", fnName);
+          }
         }
         auto target = Context.LangOpts.getPlatformConditionValue(fnName);
         return {target == argument, ConditionalCompilationExprKind::DeclRef};

test/Parse/ConditionalCompilation/arm64AppleTVOSTarget.swift

@@ -7,7 +7,7 @@
 let i: Int = "Hello"
 #endif
 
-#if arch(arm64) && os(tvOS) && _runtime(_ObjC)
+#if arch(arm64) && os(tvOS) && _runtime(_ObjC) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/arm64IOSTarget.swift

@@ -7,7 +7,7 @@
 let i: Int = "Hello"
 #endif
 
-#if arch(arm64) && os(iOS) && _runtime(_ObjC)
+#if arch(arm64) && os(iOS) && _runtime(_ObjC) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/armAndroidTarget.swift

@@ -7,7 +7,7 @@
 let i: Int = "Hello"
 #endif
 
-#if arch(arm) && os(Android) && _runtime(_Native)
+#if arch(arm) && os(Android) && _runtime(_Native) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/armIOSTarget.swift

@@ -7,7 +7,7 @@
 let i: Int = "Hello"
 #endif
 
-#if arch(arm) && os(iOS) && _runtime(_ObjC)
+#if arch(arm) && os(iOS) && _runtime(_ObjC) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/armWatchOSTarget.swift

@@ -7,7 +7,7 @@
 let i: Int = "Hello"
 #endif
 
-#if arch(arm) && os(watchOS) && _runtime(_ObjC)
+#if arch(arm) && os(watchOS) && _runtime(_ObjC) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/basicParseErrors.swift

@@ -61,3 +61,6 @@ struct S {
 
 #if arch(leg) // expected-warning {{unknown architecture for build configuration 'arch'}}
 #endif
+
+#if _endian(mid) // expected-warning {{unknown endianness for build configuration '_endian'}}
+#endif

test/Parse/ConditionalCompilation/i386AppleTVOSTarget.swift

@@ -7,7 +7,7 @@
 let i: Int = "Hello"
 #endif
 
-#if arch(i386) && os(tvOS) && _runtime(_ObjC)
+#if arch(i386) && os(tvOS) && _runtime(_ObjC) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/i386IOSTarget.swift

@@ -7,7 +7,7 @@
 let i: Int = "Hello"
 #endif
 
-#if arch(i386) && os(iOS) && _runtime(_ObjC)
+#if arch(i386) && os(iOS) && _runtime(_ObjC) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/i386WatchOSTarget.swift

@@ -7,7 +7,7 @@
 let i: Int = "Hello"
 #endif
 
-#if arch(i386) && os(watchOS) && _runtime(_ObjC)
+#if arch(i386) && os(watchOS) && _runtime(_ObjC) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/powerpc64LinuxTarget.swift

@@ -1,7 +1,7 @@
 // RUN: %swift -parse %s -verify -D FOO -D BAR -target powerpc64-unknown-linux-gnu -disable-objc-interop -D FOO -parse-stdlib
 // RUN: %swift-ide-test -test-input-complete -source-filename=%s -target powerpc64-unknown-linux-gnu
 
-#if arch(powerpc64) && os(Linux) && _runtime(_Native)
+#if arch(powerpc64) && os(Linux) && _runtime(_Native) && _endian(big)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/powerpc64leLinuxTarget.swift

@@ -1,7 +1,7 @@
 // RUN: %swift -parse %s -verify -D FOO -D BAR -target powerpc64le-unknown-linux-gnu -disable-objc-interop -D FOO -parse-stdlib
 // RUN: %swift-ide-test -test-input-complete -source-filename=%s -target powerpc64le-unknown-linux-gnu
 
-#if arch(powerpc64le) && os(Linux) && _runtime(_Native)
+#if arch(powerpc64le) && os(Linux) && _runtime(_Native) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/x64AppleTVOSTarget.swift

@@ -7,7 +7,7 @@
 let i: Int = "Hello"
 #endif
 
-#if arch(x86_64) && os(tvOS) && _runtime(_ObjC)
+#if arch(x86_64) && os(tvOS) && _runtime(_ObjC) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/x64FreeBSDTarget.swift

@@ -1,7 +1,7 @@
 // RUN: %swift -parse %s -verify -D FOO -D BAR -target x86_64-unknown-freebsd10 -disable-objc-interop -D FOO -parse-stdlib
 // RUN: %swift-ide-test -test-input-complete -source-filename=%s -target x86_64-unknown-freebsd10
 
-#if arch(x86_64) && os(FreeBSD) && _runtime(_Native)
+#if arch(x86_64) && os(FreeBSD) && _runtime(_Native) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/x64IOSTarget.swift

@@ -7,7 +7,7 @@
 let i: Int = "Hello"
 #endif
 
-#if arch(x86_64) && os(iOS) && _runtime(_ObjC)
+#if arch(x86_64) && os(iOS) && _runtime(_ObjC) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/x64LinuxTarget.swift

@@ -1,7 +1,7 @@
 // RUN: %swift -parse %s -verify -D FOO -D BAR -target x86_64-unknown-linux-gnu -disable-objc-interop -D FOO -parse-stdlib
 // RUN: %swift-ide-test -test-input-complete -source-filename=%s -target x86_64-unknown-linux-gnu
 
-#if arch(x86_64) && os(Linux) && _runtime(_Native)
+#if arch(x86_64) && os(Linux) && _runtime(_Native) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/x64OSXTarget.swift

@@ -1,7 +1,7 @@
 // RUN: %swift -parse %s -verify -D FOO -D BAR -target x86_64-apple-macosx10.9 -D FOO -parse-stdlib
 // RUN: %swift-ide-test -test-input-complete -source-filename=%s -target x86_64-apple-macosx10.9
 
-#if arch(x86_64) && os(OSX) && _runtime(_ObjC)
+#if arch(x86_64) && os(OSX) && _runtime(_ObjC) && _endian(little)
 class C {}
 var x = C()
 #endif

test/Parse/ConditionalCompilation/x64WindowsTarget.swift

@@ -1,7 +1,7 @@
 // RUN: %swift -parse %s -verify -D FOO -D BAR -target x86_64-unknown-windows-cygnus -disable-objc-interop -D FOO -parse-stdlib
 // RUN: %swift-ide-test -test-input-complete -source-filename=%s -target x86_64-unknown-windows-cygnus
 
-#if arch(x86_64) && os(Windows) && _runtime(_Native)
+#if arch(x86_64) && os(Windows) && _runtime(_Native) && _endian(little)
 class C {}
 var x = C()
 #endif