[Driver] Fix `ToolChain::getCompilerRTPath()` to return the correct path on Apple platforms.

[delcypher]

Summary

When the target triple was an Apple platform ToolChain::getOSLibName()
(called by getCompilerRTPath()) would return the full OS name
including the version number (e.g. darwin20.3.0). This is not correct
because the library directory for all Apple platforms is darwin.

This in turn caused

• -print-runtime-dir to return a non-existant path.
• -print-file-name=<any compiler-rt library> to return the filename instead of the full path to the library.

Two regression tests are included.

rdar://77417317

[arphaman]

clang/lib/Driver/ToolChain.cpp

401

Should this also apply to llvm::Triple::MacOSX , iOS, and other Darwin OSes?

[delcypher]

• Support other Apple target triples.

[delcypher]

clang/lib/Driver/ToolChain.cpp

401

Good catch. I've fixed this.

[arphaman]

LGTM, the only suggestion I have is below.

clang/lib/Driver/ToolChain.cpp

404

It might be cleaner to do a check for isOSDarwin here, as that will help with any other Darwin platforms that we need to support.

[delcypher]

Use isOSDarwin() instead of explicitly checking Darwin OS enum values.

[delcypher]

clang/lib/Driver/ToolChain.cpp

404

@arphaman That seems like a good idea. I didn't know this API existed. I'll try to switch to that.

clang/lib/Driver/ToolChain.cpp

StringRef ToolChain::getOSLibName() const {
   case llvm::Triple::NetBSD:
     return "netbsd";
   case llvm::Triple::OpenBSD:
     return "openbsd";
   case llvm::Triple::Solaris:
     return "sunos";
   case llvm::Triple::AIX:
     return "aix";
+  case llvm::Triple::Darwin:
+    return "darwin";
   default:
     return getOS();
   }
 }
 
 std::string ToolChain::getCompilerRTPath() const {
   SmallString<128> Path(getDriver().ResourceDir);
   if (Triple.isOSUnknown()) {
     llvm::sys::path::append(Path, "lib");
   } else {

clang/test/Driver/darwin-print-file-name.c

+// Regression test. Previously Clang just returned the library name instead
+// of the full path.
+// RUN: %clang -print-file-name=libclang_rt.osx.a --target=x86_64-apple-darwin20.3.0 \
+// RUN:        -resource-dir=%S/Inputs/resource_dir \
+// RUN:      | FileCheck --check-prefix=PRINT-RUNTIME-DIR %s
+// PRINT-RUNTIME-DIR: lib{{/|\\}}darwin{{/|\\}}libclang_rt.osx.a
 No newline at end of file

clang/test/Driver/darwin-print-runtime-dir.c

+// Regression test. Previously the output included the OS version number
+// which was not correct.
+// RUN: %clang -print-runtime-dir --target=x86_64-apple-darwin20.3.0 \
+// RUN:        -resource-dir=%S/Inputs/resource_dir \
+// RUN:      | FileCheck --check-prefix=PRINT-RUNTIME-DIR %s
+// PRINT-RUNTIME-DIR: lib{{/|\\}}darwin{{$}}
 No newline at end of file