[mlir][Parser] Deduplicate floating-point parsing functionality (#116172)

The following functionality is duplicated in multiple places: trying to
parse an APFloat from a floating point literal or an integer in
hexadecimal representation (bit pattern). Move it to a common helper
function.

NFC apart from the slightly changed error messages. (We now print the
exact same error messages regardless of whether the float is parsed
standalone or inside of a tensor literal, etc.)

Author: matthias-springer

mlir/lib/AsmParser/AsmParserImpl.h

@@ -287,34 +287,13 @@ class AsmParserImpl : public BaseT {
                          APFloat &result) override {
     bool isNegative = parser.consumeIf(Token::minus);
     Token curTok = parser.getToken();
-    SMLoc loc = curTok.getLoc();
-
-    // Check for a floating point value.
-    if (curTok.is(Token::floatliteral)) {
-      auto val = curTok.getFloatingPointValue();
-      if (!val)
-        return emitError(loc, "floating point value too large");
-      parser.consumeToken(Token::floatliteral);
-      result = APFloat(isNegative ? -*val : *val);
-      bool losesInfo;
-      result.convert(semantics, APFloat::rmNearestTiesToEven, &losesInfo);
-      return success();
-    }
-
-    // Check for a hexadecimal float value.
-    if (curTok.is(Token::integer)) {
-      std::optional<APFloat> apResult;
-      if (failed(parser.parseFloatFromIntegerLiteral(
-              apResult, curTok, isNegative, semantics,
-              APFloat::semanticsSizeInBits(semantics))))
-        return failure();
-
-      result = *apResult;
-      parser.consumeToken(Token::integer);
-      return success();
-    }
-
-    return emitError(loc, "expected floating point literal");
+    std::optional<APFloat> apResult;
+    if (failed(parser.parseFloatFromLiteral(apResult, curTok, isNegative,
+                                            semantics)))
+      return failure();
+    parser.consumeToken();
+    result = *apResult;
+    return success();
   }
 
   /// Parse a floating point value from the stream.

mlir/lib/AsmParser/AttributeParser.cpp

@@ -424,8 +424,7 @@ Attribute Parser::parseDecOrHexAttr(Type type, bool isNegative) {
   if (auto floatType = dyn_cast<FloatType>(type)) {
     std::optional<APFloat> result;
     if (failed(parseFloatFromIntegerLiteral(result, tok, isNegative,
-                                            floatType.getFloatSemantics(),
-                                            floatType.getWidth())))
+                                            floatType.getFloatSemantics())))
       return Attribute();
     return FloatAttr::get(floatType, *result);
   }
@@ -658,36 +657,11 @@ TensorLiteralParser::getFloatAttrElements(SMLoc loc, FloatType eltTy,
   for (const auto &signAndToken : storage) {
     bool isNegative = signAndToken.first;
     const Token &token = signAndToken.second;
-
-    // Handle hexadecimal float literals.
-    if (token.is(Token::integer) && token.getSpelling().starts_with("0x")) {
-      std::optional<APFloat> result;
-      if (failed(p.parseFloatFromIntegerLiteral(result, token, isNegative,
-                                                eltTy.getFloatSemantics(),
-                                                eltTy.getWidth())))
-        return failure();
-
-      floatValues.push_back(*result);
-      continue;
-    }
-
-    // Check to see if any decimal integers or booleans were parsed.
-    if (!token.is(Token::floatliteral))
-      return p.emitError()
-             << "expected floating-point elements, but parsed integer";
-
-    // Build the float values from tokens.
-    auto val = token.getFloatingPointValue();
-    if (!val)
-      return p.emitError("floating point value too large for attribute");
-
-    APFloat apVal(isNegative ? -*val : *val);
-    if (!eltTy.isF64()) {
-      bool unused;
-      apVal.convert(eltTy.getFloatSemantics(), APFloat::rmNearestTiesToEven,
-                    &unused);
-    }
-    floatValues.push_back(apVal);
+    std::optional<APFloat> result;
+    if (failed(p.parseFloatFromLiteral(result, token, isNegative,
+                                       eltTy.getFloatSemantics())))
+      return failure();
+    floatValues.push_back(*result);
   }
   return success();
 }
@@ -905,32 +879,14 @@ ParseResult DenseArrayElementParser::parseIntegerElement(Parser &p) {
 
 ParseResult DenseArrayElementParser::parseFloatElement(Parser &p) {
   bool isNegative = p.consumeIf(Token::minus);
-
   Token token = p.getToken();
-  std::optional<APFloat> result;
-  auto floatType = cast<FloatType>(type);
-  if (p.consumeIf(Token::integer)) {
-    // Parse an integer literal as a float.
-    if (p.parseFloatFromIntegerLiteral(result, token, isNegative,
-                                       floatType.getFloatSemantics(),
-                                       floatType.getWidth()))
-      return failure();
-  } else if (p.consumeIf(Token::floatliteral)) {
-    // Parse a floating point literal.
-    std::optional<double> val = token.getFloatingPointValue();
-    if (!val)
-      return failure();
-    result = APFloat(isNegative ? -*val : *val);
-    if (!type.isF64()) {
-      bool unused;
-      result->convert(floatType.getFloatSemantics(),
-                      APFloat::rmNearestTiesToEven, &unused);
-    }
-  } else {
-    return p.emitError("expected integer or floating point literal");
-  }
-
-  append(result->bitcastToAPInt());
+  std::optional<APFloat> fromIntLit;
+  if (failed(
+          p.parseFloatFromLiteral(fromIntLit, token, isNegative,
+                                  cast<FloatType>(type).getFloatSemantics())))
+    return failure();
+  p.consumeToken();
+  append(fromIntLit->bitcastToAPInt());
   return success();
 }
 

mlir/lib/AsmParser/Parser.cpp

@@ -347,34 +347,58 @@ OptionalParseResult Parser::parseOptionalDecimalInteger(APInt &result) {
   return success();
 }
 
+ParseResult Parser::parseFloatFromLiteral(std::optional<APFloat> &result,
+                                          const Token &tok, bool isNegative,
+                                          const llvm::fltSemantics &semantics) {
+  // Check for a floating point value.
+  if (tok.is(Token::floatliteral)) {
+    auto val = tok.getFloatingPointValue();
+    if (!val)
+      return emitError(tok.getLoc()) << "floating point value too large";
+
+    result.emplace(isNegative ? -*val : *val);
+    bool unused;
+    result->convert(semantics, APFloat::rmNearestTiesToEven, &unused);
+    return success();
+  }
+
+  // Check for a hexadecimal float value.
+  if (tok.is(Token::integer))
+    return parseFloatFromIntegerLiteral(result, tok, isNegative, semantics);
+
+  return emitError(tok.getLoc()) << "expected floating point literal";
+}
+
 /// Parse a floating point value from an integer literal token.
-ParseResult Parser::parseFloatFromIntegerLiteral(
-    std::optional<APFloat> &result, const Token &tok, bool isNegative,
-    const llvm::fltSemantics &semantics, size_t typeSizeInBits) {
-  SMLoc loc = tok.getLoc();
+ParseResult
+Parser::parseFloatFromIntegerLiteral(std::optional<APFloat> &result,
+                                     const Token &tok, bool isNegative,
+                                     const llvm::fltSemantics &semantics) {
   StringRef spelling = tok.getSpelling();
   bool isHex = spelling.size() > 1 && spelling[1] == 'x';
   if (!isHex) {
-    return emitError(loc, "unexpected decimal integer literal for a "
-                          "floating point value")
+    return emitError(tok.getLoc(), "unexpected decimal integer literal for a "
+                                   "floating point value")
                .attachNote()
            << "add a trailing dot to make the literal a float";
   }
   if (isNegative) {
-    return emitError(loc, "hexadecimal float literal should not have a "
-                          "leading minus");
+    return emitError(tok.getLoc(),
+                     "hexadecimal float literal should not have a "
+                     "leading minus");
   }
 
   APInt intValue;
   tok.getSpelling().getAsInteger(isHex ? 0 : 10, intValue);
-  if (intValue.getActiveBits() > typeSizeInBits)
-    return emitError(loc, "hexadecimal float constant out of range for type");
+  auto typeSizeInBits = APFloat::semanticsSizeInBits(semantics);
+  if (intValue.getActiveBits() > typeSizeInBits) {
+    return emitError(tok.getLoc(),
+                     "hexadecimal float constant out of range for type");
+  }
 
   APInt truncatedValue(typeSizeInBits, intValue.getNumWords(),
                        intValue.getRawData());
-
   result.emplace(semantics, truncatedValue);
-
   return success();
 }
 

mlir/lib/AsmParser/Parser.h

@@ -16,6 +16,7 @@
 
 namespace mlir {
 namespace detail {
+
 //===----------------------------------------------------------------------===//
 // Parser
 //===----------------------------------------------------------------------===//
@@ -151,11 +152,15 @@ class Parser {
   /// Parse an optional integer value only in decimal format from the stream.
   OptionalParseResult parseOptionalDecimalInteger(APInt &result);
 
+  /// Parse a floating point value from a literal.
+  ParseResult parseFloatFromLiteral(std::optional<APFloat> &result,
+                                    const Token &tok, bool isNegative,
+                                    const llvm::fltSemantics &semantics);
+
   /// Parse a floating point value from an integer literal token.
   ParseResult parseFloatFromIntegerLiteral(std::optional<APFloat> &result,
                                            const Token &tok, bool isNegative,
-                                           const llvm::fltSemantics &semantics,
-                                           size_t typeSizeInBits);
+                                           const llvm::fltSemantics &semantics);
 
   /// Returns true if the current token corresponds to a keyword.
   bool isCurrentTokenAKeyword() const {

mlir/test/IR/invalid-builtin-attributes.mlir

@@ -45,7 +45,8 @@ func.func @elementsattr_floattype1() -> () {
 // -----
 
 func.func @elementsattr_floattype2() -> () {
-  // expected-error@+1 {{expected floating-point elements, but parsed integer}}
+  // expected-error@below {{unexpected decimal integer literal for a floating point value}}
+  // expected-note@below {{add a trailing dot to make the literal a float}}
   "foo"(){bar = dense<[4]> : tensor<1xf32>} : () -> ()
 }
 
@@ -138,21 +139,22 @@ func.func @float_in_int_tensor() {
 // -----
 
 func.func @float_in_bool_tensor() {
-  // expected-error @+1 {{expected integer elements, but parsed floating-point}}
+  // expected-error@below {{expected integer elements, but parsed floating-point}}
   "foo"() {bar = dense<[true, 42.0]> : tensor<2xi1>} : () -> ()
 }
 
 // -----
 
 func.func @decimal_int_in_float_tensor() {
-  // expected-error @+1 {{expected floating-point elements, but parsed integer}}
+  // expected-error@below {{unexpected decimal integer literal for a floating point value}}
+  // expected-note@below {{add a trailing dot to make the literal a float}}
   "foo"() {bar = dense<[42, 42.0]> : tensor<2xf32>} : () -> ()
 }
 
 // -----
 
 func.func @bool_in_float_tensor() {
-  // expected-error @+1 {{expected floating-point elements, but parsed integer}}
+  // expected-error @+1 {{expected floating point literal}}
   "foo"() {bar = dense<[42.0, true]> : tensor<2xf32>} : () -> ()
 }