[Driver][SYCL] Initial support for allowing fat static -lname processing (#5413)

When processing for fat static libraries, add searches for -lname type
libraries passed on the command line.  This also takes advantage of
the -Ldir options and LIBRARY_PATH environment variable for locating
the libraries.

When a library is found (with a .a extension) that is what is used for
unbundling and added to the device link.

NOTE:  This behavior does not match the recent implementation done for OpenMP
offloading with fat static libraries.  That implementation is directly
integrated into the llvm-link call.  It would be good to also follow this
for consistency, but will require some refactoring to accomplish.

Author: mdtoguchi

clang/lib/Driver/Driver.cpp

@@ -2977,6 +2977,41 @@ static bool optionMatches(const std::string &Option,
 static SmallVector<const char *, 16>
 getLinkerArgs(Compilation &C, DerivedArgList &Args, bool IncludeObj = false) {
   SmallVector<const char *, 16> LibArgs;
+  SmallVector<std::string, 8> LibPaths;
+  // Add search directories from LIBRARY_PATH env variable
+  llvm::Optional<std::string> LibPath =
+      llvm::sys::Process::GetEnv("LIBRARY_PATH");
+  if (LibPath) {
+    SmallVector<StringRef, 8> SplitPaths;
+    const char EnvPathSeparatorStr[] = {llvm::sys::EnvPathSeparator, '\0'};
+    llvm::SplitString(*LibPath, SplitPaths, EnvPathSeparatorStr);
+    for (StringRef Path : SplitPaths)
+      LibPaths.emplace_back(Path.trim());
+  }
+  // Add directories from user-specified -L options
+  for (std::string LibDirs : Args.getAllArgValues(options::OPT_L))
+    LibPaths.emplace_back(LibDirs);
+
+  // Do processing for any -l<arg> options passed and see if any static
+  // libraries representing the name exists.  If so, convert the name and
+  // use that inline with the rest of the libraries.
+  // TODO: The static archive processing for SYCL is done in a different
+  // manner than the OpenMP processing.  We should try and refactor this
+  // to use the OpenMP flow (adding -l<name> to the llvm-link step)
+  auto resolveStaticLib = [&](StringRef LibName) -> bool {
+    if (!LibName.startswith("-l"))
+      return false;
+    for (auto LPath : LibPaths) {
+      SmallString<128> FullName(LPath);
+      llvm::sys::path::append(FullName,
+                              Twine("lib" + LibName.substr(2) + ".a").str());
+      if (llvm::sys::fs::exists(FullName)) {
+        LibArgs.push_back(Args.MakeArgString(FullName));
+        return true;
+      }
+    }
+    return false;
+  };
   for (const auto *A : Args) {
     std::string FileName = A->getAsString(Args);
     if (A->getOption().getKind() == Option::InputClass) {
@@ -3014,6 +3049,7 @@ getLinkerArgs(Compilation &C, DerivedArgList &Args, bool IncludeObj = false) {
             LibArgs.push_back(Args.MakeArgString(V));
             return;
           }
+          resolveStaticLib(V);
         };
         if (Value[0] == '@') {
           // Found a response file, we want to expand contents to try and
@@ -3053,6 +3089,8 @@ getLinkerArgs(Compilation &C, DerivedArgList &Args, bool IncludeObj = false) {
       LibArgs.push_back("--no-whole-archive");
       continue;
     }
+    if (A->getOption().matches(options::OPT_l))
+      resolveStaticLib(A->getAsString(Args));
   }
   return LibArgs;
 }

clang/test/Driver/sycl-offload-static-lib-2.cpp

@@ -34,6 +34,25 @@
 // STATIC_LIB_NVPTX: llvm-link{{.*}} "[[OUTFILE]]"
 // STATIC_LIB: ld{{.*}} "{{.*}}_lib.{{(a|lo)}}" "[[HOSTOBJ]]"
 
+// Test using -l<name> style for passing libraries.
+// RUN: %clangxx -target x86_64-unknown-linux-gnu -fsycl -L%S/Inputs/SYCL -llin64 -### %t_obj.o 2>&1 \
+// RUN:   | FileCheck %s -check-prefixes=STATIC_L_LIB,STATIC_L_LIB_DEF -DBUNDLE_TRIPLE=sycl-spir64-unknown-unknown
+// RUN: %clangxx -target x86_64-unknown-linux-gnu -fsycl -fsycl-targets=nvptx64-nvidia-cuda -L%S/Inputs/SYCL -llin64 -### %t_obj.o 2>&1 \
+// RUN:   | FileCheck %s -check-prefixes=STATIC_L_LIB,STATIC_L_LIB_NVPTX -DBUNDLE_TRIPLE=sycl-nvptx64-nvidia-cuda-sm_50
+// STATIC_L_LIB: clang-offload-bundler{{.*}} "-type=o" "-targets={{.*}},[[BUNDLE_TRIPLE]]" "-inputs=[[INPUTO:.+\.o]]" "-outputs=[[HOSTOBJ:.+\.o]],{{.+\.o}}"
+// STATIC_L_LIB: clang-offload-deps{{.*}} "-targets=[[BUNDLE_TRIPLE]]"
+// STATIC_L_LIB_DEF: clang-offload-bundler{{.*}} "-type=aoo" "-targets=[[BUNDLE_TRIPLE]]" "-inputs={{.*}}liblin64.a" "-outputs=[[OUTFILE:.+\.txt]]"
+// STATIC_L_LIB_NVPTX: clang-offload-bundler{{.*}} "-type=a" "-targets=[[BUNDLE_TRIPLE]]" "-inputs={{.*}}liblin64.a" "-outputs=[[OUTFILE:.+\.a]]"
+// STATIC_L_LIB_DEF: llvm-foreach{{.*}} "--out-ext=txt" "--in-file-list=[[OUTFILE]]" "--in-replace=[[OUTFILE]]" "--out-file-list=[[IROUTFILE:.+\.txt]]" "--out-replace=[[IROUTFILE]]" "--" {{.*}}spirv-to-ir-wrapper{{.*}} "[[OUTFILE]]" "-o" "[[IROUTFILE]]"
+// STATIC_L_LIB_DEF: llvm-link{{.*}} "@[[IROUTFILE]]"
+// STATIC_L_LIB_NVPTX: llvm-link{{.*}} "[[OUTFILE]]"
+// STATIC_L_LIB: ld{{.*}} "-llin64" "[[HOSTOBJ]]"
+
+// non-fat libraries should not trigger the unbundling step.
+// RUN: %clangxx -target x86_64-unknown-linux-gnu -fsycl -lc -lm -ldl -### 2>&1 \
+// RUN:   | FileCheck %s -check-prefixes=NO_STATIC_UNBUNDLE
+// NO_STATIC_UNBUNDLE-NOT: clang-offload-bundler{{.*}} "-type=aoo" {{.*}} "-inputs={{.*}}lib{{.*}}.a"
+
 /// ###########################################################################
 
 /// test behaviors of fat static lib with multiple objects