[LinkerWrapper] report on missing libraries

The linker wrapper does its own library searching for static archives
that can contain device code. The device linking phases happen before
the host linking phases so that we can generate the necessary
registration code and link it in with the rest of the code. Previously,
If a library containing needed device code was not found the execution
would continue silently until it failed with undefined symbols. This
patch allows the linker wrapper to perform its own check beforehand to
catch these errors.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D137180

Author: jhuber6

clang/test/Driver/linker-wrapper-image.c

@@ -115,7 +115,7 @@
 // RUN: %clang -cc1 %s -triple x86_64-unknown-linux-gnu -emit-obj -o %t.o \
 // RUN:   -fembed-offload-object=%t.out
 // RUN: clang-linker-wrapper --print-wrapped-module --dry-run --host-triple=x86_64-unknown-linux-gnu \
-// RUN:   -linker-path /usr/bin/ld -- %t.o -o a.out 2>&1 | FileCheck %s --check-prefix=HIP
+// RUN:   --linker-path=/usr/bin/ld -- %t.o -o a.out 2>&1 | FileCheck %s --check-prefix=HIP
 
 //      HIP: @.fatbin_image = internal constant [0 x i8] zeroinitializer, section ".hip_fatbin"
 // HIP-NEXT: @.fatbin_wrapper = internal constant %fatbin_wrapper { i32 1212764230, i32 1, ptr @.fatbin_image, ptr null }, section ".hipFatBinSegment", align 8

clang/test/Driver/linker-wrapper.c

@@ -115,8 +115,8 @@
 // RUN:   --image=file=%S/Inputs/dummy-elf.o,kind=hip,triple=amdgcn-amd-amdhsa,arch=gfx908
 // RUN: %clang -cc1 %s -triple x86_64-unknown-linux-gnu -emit-obj -o %t.o \
 // RUN:   -fembed-offload-object=%t.out
-// RUN: clang-linker-wrapper --dry-run --host-triple=x86_64-unknown-linux-gnu -linker-path \
-// RUN:   /usr/bin/ld -- %t.o -o a.out 2>&1 | FileCheck %s --check-prefix=HIP
+// RUN: clang-linker-wrapper --dry-run --host-triple=x86_64-unknown-linux-gnu \
+// RUN:   --linker-path=/usr/bin/ld -- %t.o -o a.out 2>&1 | FileCheck %s --check-prefix=HIP
 
 // HIP: lld{{.*}}-flavor gnu --no-undefined -shared -plugin-opt=-amdgpu-internalize-symbols -plugin-opt=mcpu=gfx908 -o {{.*}}.out {{.*}}.o
 // HIP: lld{{.*}}-flavor gnu --no-undefined -shared -plugin-opt=-amdgpu-internalize-symbols -plugin-opt=mcpu=gfx90a -o {{.*}}.out {{.*}}.o
@@ -134,6 +134,12 @@
 // LINKER_ARGS: lld{{.*}}-flavor gnu --no-undefined -shared -plugin-opt=-amdgpu-internalize-symbols -plugin-opt=mcpu=gfx908 -o {{.*}}.out {{.*}}.o a
 // LINKER_ARGS: nvlink{{.*}}-m64 -o {{.*}}.out -arch sm_70 {{.*}}.o a b
 
+// RUN: not clang-linker-wrapper --dry-run --host-triple=x86_64-unknown-linux-gnu -ldummy \
+// RUN:   --linker-path=/usr/bin/ld --device-linker=a --device-linker=nvptx64-nvidia-cuda=b -- \
+// RUN:   -o a.out 2>&1 | FileCheck %s --check-prefix=MISSING-LIBRARY
+
+// MISSING-LIBRARY: error: unable to find library -ldummy
+
 /// Ensure that temp files aren't leftoever from static libraries.
 // RUN: clang-offload-packager -o %t-lib.out \
 // RUN:   --image=file=%S/Inputs/dummy-elf.o,kind=openmp,triple=nvptx64-nvidia-cuda,arch=sm_70 \

clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp

@@ -1219,7 +1219,7 @@ Optional<std::string> searchLibraryBaseName(StringRef Name, StringRef Root,
                                             ArrayRef<StringRef> SearchPaths) {
   for (StringRef Dir : SearchPaths) {
     if (Optional<std::string> File = findFile(Dir, Root, "lib" + Name + ".so"))
-      return None;
+      return File;
     if (Optional<std::string> File = findFile(Dir, Root, "lib" + Name + ".a"))
       return File;
   }
@@ -1266,16 +1266,23 @@ Expected<SmallVector<OffloadFile>> getDeviceInput(const ArgList &Args) {
       return std::move(Err);
   }
 
-  // Try to extract input from input libraries.
+  // Try to extract input from input archive libraries.
   for (const opt::Arg *Arg : Args.filtered(OPT_library)) {
     if (auto Library = searchLibrary(Arg->getValue(), Root, LibraryPaths)) {
       ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
           MemoryBuffer::getFileOrSTDIN(*Library);
       if (std::error_code EC = BufferOrErr.getError())
         reportError(createFileError(*Library, EC));
 
+      if (identify_magic((*BufferOrErr)->getBuffer()) != file_magic::archive)
+        continue;
+
       if (Error Err = extractOffloadBinaries(**BufferOrErr, LazyInputFiles))
         return std::move(Err);
+    } else {
+      reportError(createStringError(inconvertibleErrorCode(),
+                                    "unable to find library -l%s",
+                                    Arg->getValue()));
     }
   }