[mlir][spirv] Enable serializer to write SPIR-V modules into separate files

mlir/include/mlir/Target/SPIRV/Serialization.h

@@ -38,11 +38,14 @@ struct SerializationOptions {
   /// or an absolute path followed by the prefix. For example:
   ///
   ///   * "foo" - Create files with a `foo` prefix in the current working
-  ///     directory. For example: `foo0`, `foo1` ... `fooN`.
+  ///     directory. For example: `fooXYZ123`, `fooABC456` ... `fooXXXXXX`.
+  ///     The last 6 characters will be a unique combination as
+  ///     generated by `llvm::sys::fs::createUniqueFile`.
   ///
   ///   * "my/dir/foo" - Create files in `my/dir` with a `foo` prefix. The
-  ///     `my/dir` need to exists. For example: `foo0`, `foo1` ... `fooN`
-  ///     will be created and stored in `/my/dir`.
+  ///     `my/dir` need to exists. For example: `fooXYZ123`, `fooABC456` ...
+  ///     `fooXXXXXX` will be created and stored in `/my/dir`. Filenames
+  ///     follow the same pattern as above.
   ///
   ///   * "/home/user/my/dir" - Same as above but using an absolute path.
   std::string validationFilePrefix = "";

mlir/lib/Target/SPIRV/TranslateRegistration.cpp

@@ -98,19 +98,19 @@ serializeModule(spirv::ModuleOp moduleOp, raw_ostream &output,
       llvm::StringRef parentDir =
           llvm::sys::path::parent_path(options.validationFilePrefix);
       if (!llvm::sys::fs::is_directory(parentDir)) {
-        llvm::errs() << "validation prefix directory does not exist\n";
+        moduleOp.emitError("validation prefix directory does not exist\n");
         return failure();
       }
     }
 
     SmallString<128> filename;
-    int fd;
+    int fd = 0;
 
     std::error_code errorCode = llvm::sys::fs::createUniqueFile(
         options.validationFilePrefix + "%%%%%%", fd, filename);
     if (errorCode) {
-      llvm::errs() << "error creating validation output file: "
-                   << errorCode.message() << "\n";
+      moduleOp.emitError("error creating validation output file: ")
+          << errorCode.message() << "\n";
       return failure();
     }
 

mlir/test/Target/SPIRV/mlir-translate.mlir

@@ -1,11 +1,9 @@
-// COM: Check that `--spirv-save-validation-files-with-prefix` generates
-// COM: a correct number of files.
+// Check that `--spirv-save-validation-files-with-prefix` generates
+// a correct number of files.
 
 // REQUIRES: shell
 // RUN: rm -rf %t
-// RUN: mkdir %t
-// RUN: mlir-translate --serialize-spirv --no-implicit-module --split-input-file --spirv-save-validation-files-with-prefix=%t/foo %s
-// RUN: ls %t | wc -l | FileCheck %s
+// RUN: mkdir %t && mlir-translate --serialize-spirv --no-implicit-module --split-input-file --spirv-save-validation-files-with-prefix=%t/foo %s && ls %t | wc -l | FileCheck %s
 // RUN: rm -rf %t
 
 // CHECK: 4