[clang][Driver][SPIR-V] Allow linking IR using llvm-link

clang/lib/Driver/Driver.cpp

@@ -4265,8 +4265,11 @@ void Driver::handleArguments(Compilation &C, DerivedArgList &Args,
       Args.AddFlagArg(nullptr,
                       getOpts().getOption(options::OPT_frtlib_add_rpath));
     }
-    // Emitting LLVM while linking disabled except in HIPAMD Toolchain
-    if (Args.hasArg(options::OPT_emit_llvm) && !Args.hasArg(options::OPT_hip_link))
+    // Emitting LLVM while linking disabled except in the HIPAMD or SPIR-V
+    // Toolchains
+    if (Args.hasArg(options::OPT_emit_llvm) &&
+        !Args.hasArg(options::OPT_hip_link) &&
+        !C.getDefaultToolChain().getTriple().isSPIRV())
       Diag(clang::diag::err_drv_emit_llvm_link);
     if (C.getDefaultToolChain().getTriple().isWindowsMSVCEnvironment() &&
         LTOMode != LTOK_None &&
@@ -4595,7 +4598,14 @@ void Driver::BuildDefaultActions(Compilation &C, DerivedArgList &Args,
       LA->propagateHostOffloadInfo(C.getActiveOffloadKinds(),
                                    /*BoundArch=*/nullptr);
     } else {
-      LA = C.MakeAction<LinkJobAction>(LinkerInputs, types::TY_Image);
+      // If we are linking but were passed -emit-llvm, we will be calling
+      // llvm-link, so set the output type accordingly. This is only allowed in
+      // rare cases, so make sure we aren't going to error about it.
+      types::ID LT =
+          Args.hasArg(options::OPT_emit_llvm) && !Diags.hasErrorOccurred()
+              ? types::TY_LLVM_BC
+              : types::TY_Image;
+      LA = C.MakeAction<LinkJobAction>(LinkerInputs, LT);
     }
     if (!UseNewOffloadingDriver)
       LA = OffloadBuilder->processHostLinkAction(LA);

clang/lib/Driver/ToolChains/SPIRV.cpp

@@ -70,6 +70,28 @@ void SPIRV::constructAssembleCommand(Compilation &C, const Tool &T,
                                          Exec, CmdArgs, Input, Output));
 }
 
+void SPIRV::constructLLVMLinkCommand(Compilation &C, const Tool &T,
+                                     const JobAction &JA,
+                                     const InputInfo &Output,
+                                     const InputInfoList &Inputs,
+                                     const llvm::opt::ArgStringList &Args) {
+  // Construct llvm-link command.
+  // The output from llvm-link is a bitcode file.
+  ArgStringList LlvmLinkArgs;
+
+  assert(!Inputs.empty() && "Must have at least one input.");
+
+  LlvmLinkArgs.append({"-o", Output.getFilename()});
+  for (auto Input : Inputs)
+    LlvmLinkArgs.push_back(Input.getFilename());
+
+  const char *LlvmLink =
+      C.getArgs().MakeArgString(T.getToolChain().GetProgramPath("llvm-link"));
+  C.addCommand(std::make_unique<Command>(JA, T, ResponseFileSupport::None(),
+                                         LlvmLink, LlvmLinkArgs, Inputs,
+                                         Output));
+}
+
 void SPIRV::Translator::ConstructJob(Compilation &C, const JobAction &JA,
                                      const InputInfo &Output,
                                      const InputInfoList &Inputs,
@@ -121,6 +143,10 @@ void SPIRV::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                                  const InputInfoList &Inputs,
                                  const ArgList &Args,
                                  const char *LinkingOutput) const {
+  if (JA.getType() == types::TY_LLVM_BC) {
+    constructLLVMLinkCommand(C, *this, JA, Output, Inputs, {});
+    return;
+  }
   const ToolChain &ToolChain = getToolChain();
   std::string Linker = ToolChain.GetProgramPath(getShortName());
   ArgStringList CmdArgs;

clang/lib/Driver/ToolChains/SPIRV.h

@@ -27,6 +27,11 @@ void constructAssembleCommand(Compilation &C, const Tool &T,
                               const InputInfo &Input,
                               const llvm::opt::ArgStringList &Args);
 
+void constructLLVMLinkCommand(Compilation &C, const Tool &T,
+                              const JobAction &JA, const InputInfo &Output,
+                              const InputInfoList &Inputs,
+                              const llvm::opt::ArgStringList &Args);
+
 class LLVM_LIBRARY_VISIBILITY Translator : public Tool {
 public:
   Translator(const ToolChain &TC)

clang/test/Driver/spirv-llvm-link.c

@@ -0,0 +1,31 @@
+// Check BC input
+// RUN: mkdir -p %t
+// RUN: touch %t/a.bc
+// RUN: touch %t/b.bc
+// RUN: %clang -### --target=spirv64 -emit-llvm %t/a.bc %t/b.bc 2>&1 | FileCheck --check-prefix=CHECK-TOOL-BC %s
+
+// CHECK-TOOL-BC: "-cc1" {{.*}} "-o" "[[TMP1_BC:.+]]" "-x" "ir" "{{.*}}.bc"
+// CHECK-TOOL-BC: "-cc1" {{.*}} "-o" "[[TMP2_BC:.+]]" "-x" "ir" "{{.*}}.bc"
+// CHECK-TOOL-BC: llvm-link{{.*}} "-o" {{.*}} "[[TMP1_BC]]" "[[TMP2_BC]]"
+
+// RUN: %clang -ccc-print-bindings --target=spirv64 -emit-llvm %t/a.bc %t/b.bc 2>&1 | FileCheck -check-prefix=CHECK-BINDINGS-BC %s
+
+// CHECK-BINDINGS-BC: "spirv64" - "clang", inputs: ["{{.*}}.bc"], output: "[[TMP1_BINDINGS_BC:.+]]"
+// CHECK-BINDINGS-BC: "spirv64" - "clang", inputs: ["{{.*}}.bc"], output: "[[TMP2_BINDINGS_BC:.+]]"
+// CHECK-BINDINGS-BC: "spirv64" - "SPIR-V::Linker", inputs: ["[[TMP1_BINDINGS_BC]]", "[[TMP2_BINDINGS_BC]]"], output: "{{.*}}.bc"
+
+// Check source input
+// RUN: touch %t/foo.c
+// RUN: touch %t/bar.c
+
+// RUN: %clang -### --target=spirv64 -emit-llvm %t/foo.c %t/bar.c 2>&1 | FileCheck --check-prefix=CHECK-TOOL-SRC %s
+
+// CHECK-TOOL-SRC: "-cc1" {{.*}} "-o" "[[TMP1_SRC_BC:.+]]" "-x" "c" "{{.*}}foo.c"
+// CHECK-TOOL-SRC: "-cc1" {{.*}} "-o" "[[TMP2_SRC_BC:.+]]" "-x" "c" "{{.*}}bar.c"
+// CHECK-TOOL-SRC: llvm-link{{.*}} "-o" {{.*}} "[[TMP1_SRC_BC]]" "[[TMP2_SRC_BC]]"
+
+// RUN: %clang -ccc-print-bindings --target=spirv64 -emit-llvm %t/foo.c %t/bar.c 2>&1 | FileCheck -check-prefix=CHECK-BINDINGS-SRC %s
+
+// CHECK-BINDINGS-SRC: "spirv64" - "clang", inputs: ["{{.*}}foo.c"], output: "[[TMP1_BINDINGS_SRC_BC:.+]]"
+// CHECK-BINDINGS-SRC: "spirv64" - "clang", inputs: ["{{.*}}bar.c"], output: "[[TMP2_BINDINGS_SRC_BC:.+]]"
+// CHECK-BINDINGS-SRC: "spirv64" - "SPIR-V::Linker", inputs: ["[[TMP1_BINDINGS_SRC_BC]]", "[[TMP2_BINDINGS_SRC_BC]]"], output: "{{.*}}.bc"