[Modules] Add platform and environment features to requires clause

Allows module map writers to add build requirements based on
platform/os. This helps when target features and language dialects
aren't enough to conditionalize building a module, among other things,
it allow module maps for different platforms to live in the same file.

rdar://problem/43909745

Differential Revision: https://reviews.llvm.org/D51910

llvm-svn: 342499

1 files changed, 33 insertions, 1 deletions

diff --git a/clang/lib/Basic/Module.cpp b/clang/lib/Basic/Module.cpp
index 9ff976c03b9..440151dd061 100644
--- a/clang/lib/Basic/Module.cpp
+++ b/clang/lib/Basic/Module.cpp
@@ -71,6 +71,37 @@ Module::~Module() {
   }
 }
 
+static bool isPlatformEnvironment(const TargetInfo &Target, StringRef Feature) {
+  StringRef Platform = Target.getPlatformName();
+  StringRef Env = Target.getTriple().getEnvironmentName();
+
+  // Attempt to match platform and environment.
+  if (Platform == Feature || Target.getTriple().getOSName() == Feature ||
+      Env == Feature)
+    return true;
+
+  auto CmpPlatformEnv = [](StringRef LHS, StringRef RHS) {
+    auto Pos = LHS.find("-");
+    if (Pos == StringRef::npos)
+      return false;
+    SmallString<128> NewLHS = LHS.slice(0, Pos);
+    NewLHS += LHS.slice(Pos+1, LHS.size());
+    return NewLHS == RHS;
+  };
+
+  SmallString<128> PlatformEnv = Target.getTriple().getOSAndEnvironmentName();
+  // Darwin has different but equivalent variants for simulators, example:
+  //   1. x86_64-apple-ios-simulator
+  //   2. x86_64-apple-iossimulator
+  // where both are valid examples of the same platform+environment but in the
+  // variant (2) the simulator is hardcoded as part of the platform name. Both
+  // forms above should match for "iossimulator" requirement.
+  if (Target.getTriple().isOSDarwin() && PlatformEnv.endswith("simulator"))
+    return PlatformEnv == Feature || CmpPlatformEnv(PlatformEnv, Feature);
+
+  return PlatformEnv == Feature;
+}
+
 /// Determine whether a translation unit built using the current
 /// language options has the given feature.
 static bool hasFeature(StringRef Feature, const LangOptions &LangOpts,
@@ -93,7 +124,8 @@ static bool hasFeature(StringRef Feature, const LangOptions &LangOpts,
                         .Case("opencl", LangOpts.OpenCL)
                         .Case("tls", Target.isTLSSupported())
                         .Case("zvector", LangOpts.ZVector)
-                        .Default(Target.hasFeature(Feature));
+                        .Default(Target.hasFeature(Feature) ||
+                                 isPlatformEnvironment(Target, Feature));
   if (!HasFeature)
     HasFeature = std::find(LangOpts.ModuleFeatures.begin(),
                            LangOpts.ModuleFeatures.end(),