[clang] [HIP] search fatbin symbols for libs passed by -l (PR #104638)

[Artem Belevich via cfe-commits]

================
@@ -76,8 +79,75 @@ class HIPUndefinedFatBinSymbols {
     return GPUBinHandleSymbols;
   }
 
+  // Collect symbols from static libraries specified by -l options.
+  void processStaticLibraries() {
+    llvm::SmallVector<llvm::StringRef, 16> LibNames;
+    llvm::SmallVector<llvm::StringRef, 16> LibPaths;
+    llvm::SmallVector<llvm::StringRef, 16> ExactLibNames;
+    llvm::Triple Triple(C.getDriver().getTargetTriple());
+    bool IsMSVC = Triple.isWindowsMSVCEnvironment();
+    llvm::StringRef Ext = IsMSVC ? ".lib" : ".a";
+
+    for (const auto *Arg : Args.filtered(options::OPT_l)) {
+      llvm::StringRef Value = Arg->getValue();
+      if (Value.starts_with(":"))
+        ExactLibNames.push_back(Value.drop_front());
+      else
+        LibNames.push_back(Value);
+    }
+    for (const auto *Arg : Args.filtered(options::OPT_L)) {
+      auto Path = Arg->getValue();
+      LibPaths.push_back(Path);
+      if (Verbose)
+        llvm::errs() << "HIP fatbin symbol search uses library path:  " << Path
+                     << "\n";
+    }
+
+    auto ProcessLib = [&](llvm::StringRef LibName, bool IsExact) {
+      llvm::SmallString<256> FullLibName;
+      if (IsExact)
+        FullLibName = LibName;
+      else {
+        if (IsMSVC)
+          (llvm::Twine(LibName) + Ext).toVector(FullLibName);
+        else
+          (llvm::Twine("lib") + LibName + Ext).toVector(FullLibName);
+      }
+
+      bool Found = false;
+      for (const auto &Path : LibPaths) {
+        llvm::SmallString<256> FullPath = Path;
+        llvm::sys::path::append(FullPath, FullLibName);
+
+        if (llvm::sys::fs::exists(FullPath)) {
+          if (Verbose)
+            llvm::errs() << "HIP fatbin symbol search found library: "
+                         << FullPath << "\n";
+          auto BufferOrErr = llvm::MemoryBuffer::getFile(FullPath);
+          if (!BufferOrErr) {
+            errorHandler(llvm::errorCodeToError(BufferOrErr.getError()));
+            continue;
+          }
+          processInput(BufferOrErr.get()->getMemBufferRef());
+          Found = true;
+          break;
+        }
+      }
+      if (!Found && Verbose)
+        llvm::errs() << "HIP fatbin symbol search could not find library: "
+                     << FullLibName << "\n";
+    };
+
+    for (const auto &LibName : ExactLibNames)
----------------
Artem-B wrote:

There's no point passing `StringRef` by reference. I think we can drop `&` here and below.

https://github.com/llvm/llvm-project/pull/104638