[Clang] [Driver] Canoncalise -internal-isystem include paths

Author: Sirraide

clang/include/clang/Driver/ToolChain.h

@@ -228,9 +228,13 @@ class ToolChain {
   static void addSystemFrameworkInclude(const llvm::opt::ArgList &DriverArgs,
                                         llvm::opt::ArgStringList &CC1Args,
                                         const Twine &Path);
+
+public:
   static void addSystemInclude(const llvm::opt::ArgList &DriverArgs,
                                llvm::opt::ArgStringList &CC1Args,
                                const Twine &Path);
+
+protected:
   static void addExternCSystemInclude(const llvm::opt::ArgList &DriverArgs,
                                       llvm::opt::ArgStringList &CC1Args,
                                       const Twine &Path);

clang/lib/Driver/ToolChain.cpp

@@ -1370,19 +1370,48 @@ ToolChain::CXXStdlibType ToolChain::GetCXXStdlibType(const ArgList &Args) const{
   return *cxxStdlibType;
 }
 
+
+static void ResolveAndAddSystemIncludePath(const ArgList &DriverArgs,
+                                               ArgStringList &CC1Args,
+                                               const Twine &Path) {
+  bool Canonicalize =
+        DriverArgs.hasFlag(options::OPT_canonical_prefixes,
+                           options::OPT_no_canonical_prefixes, true);
+
+  if (!Canonicalize) {
+    CC1Args.push_back(DriverArgs.MakeArgString(Path));
+    return;
+  }
+
+  // We canonicalise system include paths that were added automatically if
+  // that yields a shorter path since those can end up quite long otherwise.
+  //
+  // While we would ideally prefer to use FileManager for this, there doesn't
+  // seem to be a way to obtain one in here, so we just resolve these via the
+  // real file system; most system libraries will hopefully correspond to
+  // actual files.
+  IntrusiveRefCntPtr<vfs::FileSystem> VFS = vfs::getRealFileSystem();
+  SmallString<256> Canonical, PathStorage;
+  StringRef SimplifiedPath = Path.toStringRef(PathStorage);
+  if (!VFS->getRealPath(SimplifiedPath, Canonical) &&
+      Canonical.size() < SimplifiedPath.size())
+    SimplifiedPath = Canonical;
+  CC1Args.push_back(DriverArgs.MakeArgString(SimplifiedPath));
+}
+
 /// Utility function to add a system framework directory to CC1 arguments.
 void ToolChain::addSystemFrameworkInclude(const llvm::opt::ArgList &DriverArgs,
                                           llvm::opt::ArgStringList &CC1Args,
                                           const Twine &Path) {
   CC1Args.push_back("-internal-iframework");
-  CC1Args.push_back(DriverArgs.MakeArgString(Path));
+  ResolveAndAddSystemIncludePath(DriverArgs, CC1Args, Path);
 }
 
 /// Utility function to add a system include directory to CC1 arguments.
 void ToolChain::addSystemInclude(const ArgList &DriverArgs,
                                  ArgStringList &CC1Args, const Twine &Path) {
   CC1Args.push_back("-internal-isystem");
-  CC1Args.push_back(DriverArgs.MakeArgString(Path));
+  ResolveAndAddSystemIncludePath(DriverArgs, CC1Args, Path);
 }
 
 /// Utility function to add a system include directory with extern "C"
@@ -1397,7 +1426,7 @@ void ToolChain::addExternCSystemInclude(const ArgList &DriverArgs,
                                         ArgStringList &CC1Args,
                                         const Twine &Path) {
   CC1Args.push_back("-internal-externc-isystem");
-  CC1Args.push_back(DriverArgs.MakeArgString(Path));
+  ResolveAndAddSystemIncludePath(DriverArgs, CC1Args, Path);
 }
 
 void ToolChain::addExternCSystemIncludeIfExists(const ArgList &DriverArgs,
@@ -1411,20 +1440,16 @@ void ToolChain::addExternCSystemIncludeIfExists(const ArgList &DriverArgs,
 void ToolChain::addSystemFrameworkIncludes(const ArgList &DriverArgs,
                                            ArgStringList &CC1Args,
                                            ArrayRef<StringRef> Paths) {
-  for (const auto &Path : Paths) {
-    CC1Args.push_back("-internal-iframework");
-    CC1Args.push_back(DriverArgs.MakeArgString(Path));
-  }
+  for (const auto &Path : Paths)
+    addSystemFrameworkInclude(DriverArgs, CC1Args, Path);
 }
 
 /// Utility function to add a list of system include directories to CC1.
 void ToolChain::addSystemIncludes(const ArgList &DriverArgs,
                                   ArgStringList &CC1Args,
                                   ArrayRef<StringRef> Paths) {
-  for (const auto &Path : Paths) {
-    CC1Args.push_back("-internal-isystem");
-    CC1Args.push_back(DriverArgs.MakeArgString(Path));
-  }
+  for (const auto &Path : Paths)
+    addSystemInclude(DriverArgs, CC1Args, Path);
 }
 
 std::string ToolChain::concat(StringRef Path, const Twine &A, const Twine &B,

clang/lib/Driver/ToolChains/Clang.cpp

@@ -946,8 +946,7 @@ void Clang::AddPreprocessingOptions(Compilation &C, const JobAction &JA,
       SmallString<128> P(D.ResourceDir);
       llvm::sys::path::append(P, "include");
       llvm::sys::path::append(P, "openmp_wrappers");
-      CmdArgs.push_back("-internal-isystem");
-      CmdArgs.push_back(Args.MakeArgString(P));
+      getToolChain().addSystemInclude(Args, CmdArgs, P);
     }
 
     CmdArgs.push_back("-include");
@@ -959,7 +958,8 @@ void Clang::AddPreprocessingOptions(Compilation &C, const JobAction &JA,
     // standard library headers and other headers.
     SmallString<128> P(D.ResourceDir);
     llvm::sys::path::append(P, "include", "llvm_offload_wrappers");
-    CmdArgs.append({"-internal-isystem", Args.MakeArgString(P), "-include"});
+    getToolChain().addSystemInclude(Args, CmdArgs, P);
+    CmdArgs.push_back("-include");
     if (JA.isDeviceOffloading(Action::OFK_OpenMP))
       CmdArgs.push_back("__llvm_offload_device.h");
     else
@@ -1132,16 +1132,14 @@ void Clang::AddPreprocessingOptions(Compilation &C, const JobAction &JA,
       SmallString<128> P(llvm::sys::path::parent_path(D.Dir));
       llvm::sys::path::append(P, "include");
       llvm::sys::path::append(P, getToolChain().getTripleString());
-      CmdArgs.push_back("-internal-isystem");
-      CmdArgs.push_back(Args.MakeArgString(P));
+      getToolChain().addSystemInclude(Args, CmdArgs, P);
     } else if (C.getActiveOffloadKinds() == Action::OFK_OpenMP) {
       // TODO: CUDA / HIP include their own headers for some common functions
       // implemented here. We'll need to clean those up so they do not conflict.
       SmallString<128> P(D.ResourceDir);
       llvm::sys::path::append(P, "include");
       llvm::sys::path::append(P, "llvm_libc_wrappers");
-      CmdArgs.push_back("-internal-isystem");
-      CmdArgs.push_back(Args.MakeArgString(P));
+      getToolChain().addSystemInclude(Args, CmdArgs, P);
     }
   }