Fall back on Android triple w/o API level for runtimes search

[collinbaker]

Summary

Clang searches for runtimes (e.g. libclang_rt*) first in a
subdirectory named for the target triple (corresponding to
LLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON), then if it's not found uses
.../lib/<os>/libclang_rt* with a suffix corresponding to the arch and
environment name.

Android triples optionally include an API level indicating the minimum
Android version to be run on
(e.g. aarch64-unknown-linux-android21). When compiler-rt is built with
LLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON this API level is part of the
output path.

Linking code built for a later API level against a runtime built for
an earlier one is safe. In projects with several API level targets
this is desireable to avoid re-building the same runtimes many
times. This is difficult with the current runtime search method: if
the API levels don't exactly match Clang gives up on the per-target
runtime directory path.

To enable this more simply, this change tries target triple without
the API level before falling back on the old layout.

Another option would be to try every API level in the triple,
e.g. check aarch-64-unknown-linux-android21, then ...20, then ...19,
etc.

[collinbaker]

Fix variable name style

[thakis]

Looks like this breaks tests on Windows: https://buildkite.com/llvm-project/premerge-checks/builds/68330#746376c2-ce48-4ffc-b60f-515619dee28c

Failed Tests (2):

Clang :: Driver/ve-toolchain.c
Clang :: Driver/ve-toolchain.cpp

[thakis]

This looks right to me.

clang/lib/Driver/Driver.cpp

1874

This either needs to print all of them, or the first existing one. The first existing one sounds right actually. Currently it only prints the first one if the first one exists.

clang/lib/Driver/ToolChain.cpp

500

Why do you need the environment check?

501

leftover debug logging

[danalbert]

LGTM once the comments are addressed. (I'd also approve the alternative approach discussed in the thread of searching each older API level directory, but have no preference one way or the other)

[collinbaker]

• Address comments
• Fix VEToolchain build error
• Rebase

[collinbaker]

clang/lib/Driver/ToolChain.cpp

500

This skips adding an extra path if the triple doesn't have an Android API level.

E.g. for the target triple aarch64-unknown-linux-android23, the environment name will be "android23". The condition will be true since "android23" != "android", and the extra path will be appended. If it had just been "android" it'll skip this step.

[collinbaker]

Rebase

[thakis]

lg!

clang/include/clang/Driver/ToolChain.h

public:
   const char *
   getCompilerRTArgString(const llvm::opt::ArgList &Args, StringRef Component,
                          FileType Type = ToolChain::FT_Static) const;
 
   std::string getCompilerRTBasename(const llvm::opt::ArgList &Args,
                                     StringRef Component,
                                     FileType Type = ToolChain::FT_Static) const;
 
-  // Returns target specific runtime path if it exists.
-  virtual std::string getRuntimePath() const;
+  // Returns target specific runtime paths.
+  path_list getRuntimePaths() const;
 
-  // Returns target specific standard library path if it exists.
-  virtual std::string getStdlibPath() const;
+  // Returns target specific standard library paths.
+  path_list getStdlibPaths() const;
 
   // Returns <ResourceDir>/lib/<OSName>/<arch>.  This is used by runtimes (such
   // as OpenMP) to find arch-specific libraries.
   std::string getArchSpecificLibPath() const;
 
   // Returns <OSname> part of above.
   virtual StringRef getOSLibName() const;
 

clang/lib/Driver/Driver.cpp

for (const std::string &Path : TC.getFilePaths()) {
       else
         llvm::outs() << Path;
     }
     llvm::outs() << "\n";
     return false;
   }
 
   if (C.getArgs().hasArg(options::OPT_print_runtime_dir)) {
-    std::string CandidateRuntimePath = TC.getRuntimePath();
-    if (getVFS().exists(CandidateRuntimePath))
-      llvm::outs() << CandidateRuntimePath << '\n';
+    std::string RuntimePath;
+    // Get the first existing path, if any.
+    for (auto Path : TC.getRuntimePaths()) {
+      if (getVFS().exists(Path)) {
+        RuntimePath = Path;
+        break;
+      }
+    }
+    if (!RuntimePath.empty())
+      llvm::outs() << RuntimePath << '\n';
     else
       llvm::outs() << TC.getCompilerRTPath() << '\n';
     return false;
   }
 
   // FIXME: The following handlers should use a callback mechanism, we don't
   // know what the client would like to do.
   if (Arg *A = C.getArgs().getLastArg(options::OPT_print_file_name_EQ)) {

clang/lib/Driver/ToolChain.cpp

static ToolChain::RTTIMode CalculateRTTIMode(const ArgList &Args,
   // -frtti is default, except for the PS4 CPU.
   return (Triple.isPS4CPU()) ? ToolChain::RM_Disabled : ToolChain::RM_Enabled;
 }
 
 ToolChain::ToolChain(const Driver &D, const llvm::Triple &T,
                      const ArgList &Args)
     : D(D), Triple(T), Args(Args), CachedRTTIArg(GetRTTIArgument(Args)),
       CachedRTTIMode(CalculateRTTIMode(Args, Triple, CachedRTTIArg)) {
-  std::string RuntimePath = getRuntimePath();
-  if (getVFS().exists(RuntimePath))
-    getLibraryPaths().push_back(RuntimePath);
-
-  std::string StdlibPath = getStdlibPath();
-  if (getVFS().exists(StdlibPath))
-    getFilePaths().push_back(StdlibPath);
-
-  std::string CandidateLibPath = getArchSpecificLibPath();
-  if (getVFS().exists(CandidateLibPath))
-    getFilePaths().push_back(CandidateLibPath);
+  auto addIfExists = [this](path_list &List, const std::string &Path) {
+    if (getVFS().exists(Path))
+      List.push_back(Path);
+  };
+
+  for (const auto &Path : getRuntimePaths())
+    addIfExists(getLibraryPaths(), Path);
+  for (const auto &Path : getStdlibPaths())
+    addIfExists(getFilePaths(), Path);
+  addIfExists(getFilePaths(), getArchSpecificLibPath());
 }
 
 void ToolChain::setTripleEnvironment(llvm::Triple::EnvironmentType Env) {
   Triple.setEnvironment(Env);
   if (EffectiveTriple != llvm::Triple())
     EffectiveTriple.setEnvironment(Env);
 }
 

 }
 
 const char *ToolChain::getCompilerRTArgString(const llvm::opt::ArgList &Args,
                                               StringRef Component,
                                               FileType Type) const {
   return Args.MakeArgString(getCompilerRT(Args, Component, Type));
 }
 
-std::string ToolChain::getRuntimePath() const {
+ToolChain::path_list ToolChain::getRuntimePaths() const {
+  path_list Paths;
+  auto addPathForTriple = [this, &Paths](const llvm::Triple &Triple) {
     SmallString<128> P(D.ResourceDir);
-  llvm::sys::path::append(P, "lib", getTripleString());
-  return std::string(P.str());
+    llvm::sys::path::append(P, "lib", Triple.str());
+    Paths.push_back(std::string(P.str()));
+  };
+
+  addPathForTriple(getTriple());
+
+  // Android targets may include an API level at the end. We still want to fall
+  // back on a path without the API level.
+  if (getTriple().isAndroid() &&
+      getTriple().getEnvironmentName() != "android") {
+    llvm::Triple TripleWithoutLevel = getTriple();
+    TripleWithoutLevel.setEnvironmentName("android");
+    addPathForTriple(TripleWithoutLevel);
+  }
+
+  return Paths;
 }
 
-std::string ToolChain::getStdlibPath() const {
+ToolChain::path_list ToolChain::getStdlibPaths() const {
+  path_list Paths;
   SmallString<128> P(D.Dir);
   llvm::sys::path::append(P, "..", "lib", getTripleString());
-  return std::string(P.str());
+  Paths.push_back(std::string(P.str()));
+
+  return Paths;
 }
 
 std::string ToolChain::getArchSpecificLibPath() const {
   SmallString<128> Path(getDriver().ResourceDir);
   llvm::sys::path::append(Path, "lib", getOSLibName(),
                           llvm::Triple::getArchTypeName(getArch()));
   return std::string(Path.str());
 }

clang/lib/Driver/ToolChains/Fuchsia.cpp

Fuchsia::Fuchsia(const Driver &D, const llvm::Triple &Triple,
   if (!D.SysRoot.empty()) {
     SmallString<128> P(D.SysRoot);
     llvm::sys::path::append(P, "lib");
     getFilePaths().push_back(std::string(P.str()));
   }
 
   auto FilePaths = [&](const Multilib &M) -> std::vector<std::string> {
     std::vector<std::string> FP;
-    SmallString<128> P(getStdlibPath());
+    for (const std::string &Path : getStdlibPaths()) {
+      SmallString<128> P(Path);
       llvm::sys::path::append(P, M.gccSuffix());
       FP.push_back(std::string(P.str()));
+    }
     return FP;
   };
 
   Multilibs.push_back(Multilib());
   // Use the noexcept variant with -fno-exceptions to avoid the extra overhead.
   Multilibs.push_back(Multilib("noexcept", {}, {}, 1)
                           .flag("-fexceptions")
                           .flag("+fno-exceptions"));

clang/lib/Driver/ToolChains/VEToolchain.cpp

VEToolChain::VEToolChain(const Driver &D, const llvm::Triple &Triple,
 
   // Define file paths from scratch here.
   getFilePaths().clear();
 
   // Add library directories:
   //   ${BINPATH}/../lib/ve-unknown-linux-gnu, (== getStdlibPath)
   //   ${RESOURCEDIR}/lib/linux/ve, (== getArchSpecificLibPath)
   //   ${SYSROOT}/opt/nec/ve/lib,
-  getFilePaths().push_back(getStdlibPath());
+  for (auto &Path : getStdlibPaths())
+    getFilePaths().push_back(std::move(Path));
   getFilePaths().push_back(getArchSpecificLibPath());
   getFilePaths().push_back(computeSysRoot() + "/opt/nec/ve/lib");
 }
 
 Tool *VEToolChain::buildAssembler() const {
   return new tools::gnutools::Assembler(*this);
 }
 

clang/test/Driver/linux-per-target-runtime-dir.c

 // RUN:   | FileCheck --check-prefix=CHECK-CLANGRT-X8664 %s
 // CHECK-CLANGRT-X8664: lib{{/|\\}}x86_64-unknown-linux-gnu{{/|\\}}libclang_rt.builtins.a
 
 // RUN: %clang -rtlib=compiler-rt -print-file-name=libclang_rt.builtins.a 2>&1 \
 // RUN:     --target=x86_64-unknown-linux-gnu \
 // RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
 // RUN:   | FileCheck --check-prefix=CHECK-FILE-NAME-X8664 %s
 // CHECK-FILE-NAME-X8664: lib{{/|\\}}x86_64-unknown-linux-gnu{{/|\\}}libclang_rt.builtins.a
+
+// RUN: %clang -rtlib=compiler-rt -print-file-name=libclang_rt.builtins.a 2>&1 \
+// RUN:     --target=aarch64-unknown-linux-android21 \
+// RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
+// RUN:   | FileCheck --check-prefix=CHECK-FILE-NAME-ANDROID21 %s
+// CHECK-FILE-NAME-ANDROID21: lib{{/|\\}}aarch64-unknown-linux-android21{{/|\\}}libclang_rt.builtins.a
+
+// RUN: %clang -rtlib=compiler-rt -print-file-name=libclang_rt.builtins.a 2>&1 \
+// RUN:     --target=aarch64-unknown-linux-android23 \
+// RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
+// RUN:   | FileCheck --check-prefix=CHECK-FILE-NAME-ANDROID23 %s
+// CHECK-FILE-NAME-ANDROID23: lib{{/|\\}}aarch64-unknown-linux-android{{/|\\}}libclang_rt.builtins.a
+
+// RUN: %clang -rtlib=compiler-rt -print-file-name=libclang_rt.builtins.a 2>&1 \
+// RUN:     --target=aarch64-unknown-linux-android \
+// RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
+// RUN:   | FileCheck --check-prefix=CHECK-FILE-NAME-ANDROID %s
+// CHECK-FILE-NAME-ANDROID: lib{{/|\\}}aarch64-unknown-linux-android{{/|\\}}libclang_rt.builtins.a