[MLIR][parser] Add token type and parser methods for forward slashes

This adds a token for a forward slash to the token definition list and
the methods to `AsmParser::parseSlash()` and
`AsmParser::parseOptionalSlash()`, similar to other tokens used as
operators (e.g., star, plus, etc.). This allows implementations of
attributes that contain arithmetic expressions to support operators
with a forward slash, e.g., a division.

The newly added check tests trigger the parsing of a slash in an
attribute.

Author: andidr

mlir/include/mlir/IR/OpImplementation.h

@@ -641,6 +641,12 @@ class AsmParser {
   /// Parse a '+' token if present.
   virtual ParseResult parseOptionalPlus() = 0;
 
+  /// Parse a '/' token.
+  virtual ParseResult parseSlash() = 0;
+
+  /// Parse a '/' token if present.
+  virtual ParseResult parseOptionalSlash() = 0;
+
   /// Parse a '-' token.
   virtual ParseResult parseMinus() = 0;
 

mlir/lib/AsmParser/AsmParserImpl.h

@@ -206,6 +206,16 @@ class AsmParserImpl : public BaseT {
     return success(parser.consumeIf(Token::question));
   }
 
+  /// Parses a '/' token.
+  ParseResult parseSlash() override {
+    return parser.parseToken(Token::slash, "expected '/'");
+  }
+
+  /// Parses a '/' if present.
+  ParseResult parseOptionalSlash() override {
+    return success(parser.consumeIf(Token::slash));
+  }
+
   /// Parses a '*' token.
   ParseResult parseStar() override {
     return parser.parseToken(Token::star, "expected '*'");

mlir/lib/AsmParser/Lexer.cpp

@@ -157,7 +157,7 @@ Token Lexer::lexToken() {
         skipComment();
         continue;
       }
-      return emitError(tokStart, "unexpected character");
+      return formToken(Token::slash, tokStart);
 
     case '@':
       return lexAtIdentifier(tokStart);

mlir/lib/AsmParser/TokenKinds.def

@@ -70,6 +70,7 @@ TOK_PUNCTUATION(question, "?")
 TOK_PUNCTUATION(r_brace, "}")
 TOK_PUNCTUATION(r_paren, ")")
 TOK_PUNCTUATION(r_square, "]")
+TOK_PUNCTUATION(slash, "/")
 TOK_PUNCTUATION(star, "*")
 TOK_PUNCTUATION(vertical_bar, "|")
 

mlir/test/IR/parser.mlir

@@ -1219,6 +1219,13 @@ func.func @parse_base64_test() {
   return
 }
 
+// CHECK-LABEL: func @parse_slash_test
+func.func @parse_slash_test() {
+  // CHECK: "test.slash_attr"() <{attr = #test.slash_attr<1 / 2>}> : () -> ()
+  "test.slash_attr"() { attr = #test.slash_attr<1 / 2> } : () -> ()
+  return
+}
+
 // CHECK-LABEL: func @"\22_string_symbol_reference\22"
 func.func @"\"_string_symbol_reference\""() {
   // CHECK: ref = @"\22_string_symbol_reference\22"

mlir/test/lib/Dialect/Test/TestAttrDefs.td

@@ -395,4 +395,17 @@ def TestCustomLocationAttr : Test_LocAttr<"TestCustomLocation"> {
   let assemblyFormat = "`<` $file `*` $line `>`";
 }
 
+// Test attribute containing a slash token
+def SlashAttr: Test_Attr<"Slash">{
+  let mnemonic = "slash_attr";
+
+  let parameters = (
+    ins
+    "int":$lhs,
+    "int":$rhs
+  );
+
+  let hasCustomAssemblyFormat = 1;
+}
+
 #endif // TEST_ATTRDEFS

mlir/test/lib/Dialect/Test/TestAttributes.cpp

@@ -393,6 +393,24 @@ getDynamicCustomAssemblyFormatAttr(TestDialect *testDialect) {
                                     std::move(parser), std::move(printer));
 }
 
+//===----------------------------------------------------------------------===//
+// SlashAttr
+//===----------------------------------------------------------------------===//
+
+Attribute SlashAttr::parse(AsmParser &parser, Type type) {
+  int lhs, rhs;
+
+  if (parser.parseLess() || parser.parseInteger(lhs) || parser.parseSlash() ||
+      parser.parseInteger(rhs) || parser.parseGreater())
+    return Attribute();
+
+  return SlashAttr::get(parser.getContext(), lhs, rhs);
+}
+
+void SlashAttr::print(AsmPrinter &printer) const {
+  printer << "<" << getLhs() << " / " << getRhs() << ">";
+}
+
 //===----------------------------------------------------------------------===//
 // TestDialect
 //===----------------------------------------------------------------------===//

mlir/test/lib/Dialect/Test/TestOps.td

@@ -330,6 +330,10 @@ def DenseArrayAttrOp : TEST_Op<"dense_array_attr"> {
   }];
 }
 
+def SlashAttrOp : TEST_Op<"slash_attr"> {
+  let arguments = (ins SlashAttr:$attr);
+}
+
 //===----------------------------------------------------------------------===//
 // Test Attributes Constraints
 //===----------------------------------------------------------------------===//