[spirv-to-ir-wrapper] Prevent non-IR from being passed along

llvm/test/tools/spirv-to-ir-wrapper/skip-unknown-input.txt

@@ -0,0 +1,9 @@
+; RUN: spirv-to-ir-wrapper %s -o %t.out -skip-unknown-input
+; RUN: FileCheck %s --input-file %t.out --allow-empty --check-prefix=CHECK_EMPTY
+; CHECK_EMPTY-NOT: JUST SOME TEXT
+
+; RUN: spirv-to-ir-wrapper %s -o %t2.out
+; RUN: FileCheck %s --input-file %t2.out --check-prefix=CHECK_PASSTHROUGH
+; CHECK_PASSTHROUGH: JUST SOME TEXT
+
+JUST SOME TEXT

llvm/test/tools/spirv-to-ir-wrapper/spirv-to-ir-wrapper.ll

@@ -1,6 +1,6 @@
 ; Check for passthrough abilities
 ; RUN: llvm-as %s -o %t.bc
-; RUN: spirv-to-ir-wrapper %t.bc -o %t_1.bc
+; RUN: spirv-to-ir-wrapper %t.bc -o %t_1.bc -skip-unknown-input
 ; RUN: llvm-dis %t_1.bc -o %t_1.ll
 ; RUN: FileCheck %s --input-file %t_1.ll
 

llvm/tools/spirv-to-ir-wrapper/spirv-to-ir-wrapper.cpp

@@ -26,6 +26,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/Process.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/StringSaver.h"
@@ -46,6 +47,12 @@ static cl::opt<std::string>
     LlvmSpirvOpts("llvm-spirv-opts", cl::value_desc("llvm-spirv options"),
                   cl::desc("options to pass to llvm-spirv"));
 
+// SkipUnknown - Skip unknown files (create empty output instead)
+static cl::opt<bool>
+    SkipUnknown("skip-unknown-input",
+                cl::desc("Only pass through files that are LLVM-IR or "
+                         "converted from SPIR-V"));
+
 static void error(const Twine &Message) {
   llvm::errs() << "spirv-to-ir-wrapper: " << Message << '\n';
   exit(1);
@@ -82,6 +89,14 @@ static int copyInputToOutput() {
   return llvm::sys::fs::copy_file(InputFilename, Output).value();
 }
 
+static int createEmptyOutput() {
+  int FD;
+  if (std::error_code EC = openFileForWrite(
+          Output, FD, sys::fs::CD_CreateAlways, sys::fs::OF_None))
+    return EC.value();
+  return llvm::sys::Process::SafelyCloseFileDescriptor(FD).value();
+}
+
 static bool isSPIRVBinary(const std::string &File) {
   auto FileOrError = MemoryBuffer::getFile(File, /*IsText=*/false,
                                            /*RequiresNullTerminator=*/false);
@@ -114,6 +129,9 @@ static int checkInputFileIsAlreadyLLVM(const char *Argv0) {
   if (Ext == "spv" || isSPIRVBinary(InputFilename))
     return convertSPIRVToLLVMIR(Argv0);
 
+  if (SkipUnknown)
+    return createEmptyOutput();
+
   // We could not directly determine the input file, so we just copy it
   // to the output file.
   return copyInputToOutput();