[MLIR] Extend floating point parsing support

[orbiri]

Parsing support for floating point types was missing a few features:

1. Parsing floating point attributes from integer literals was supported only for types with bitwidth smaller or equal to 64.
2. Downstream users could not use AsmParser::parseFloat to parse float types which are printed as integer literals.

This commit addresses both these points. It extends Parser::parseFloatFromIntegerLiteral to support arbitrary bitwidth, and exposes a new API to parse arbitrary floating point given an fltSemantics as input. The usage of this new API is introduced in the Test Dialect.

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[llvmbot]

@llvm/pr-subscribers-mlir

@llvm/pr-subscribers-mlir-core

Author: None (orbiri)

Changes

Parsing support for floating point types was missing a few features: 1. Parsing floating point attributes from integer literals was supported only for types with bitwidth smaller or equal to 64. 2. Downstream users could not use `AsmParser::parseFloat` to parse float types which are printed as integer literals. This commit addresses both these points. It extends `Parser::parseFloatFromIntegerLiteral` to support arbitrary bitwidth, and exposes a new API to parse arbitrary floating point given an fltSemantics as input. The usage of this new API is introduced in the Test Dialect. --- Full diff: https://github.com/llvm/llvm-project/pull/90442.diff 7 Files Affected: - (modified) mlir/include/mlir/IR/OpImplementation.h (+4) - (modified) mlir/lib/AsmParser/AsmParserImpl.h (+21-6) - (modified) mlir/lib/AsmParser/Parser.cpp (+6-10) - (added) mlir/test/IR/custom-float-attr-roundtrip.mlir (+57) - (modified) mlir/test/IR/parser.mlir (+24) - (modified) mlir/test/lib/Dialect/Test/TestAttrDefs.td (+11) - (modified) mlir/test/lib/Dialect/Test/TestAttributes.cpp (+41) ``````````diff diff --git a/mlir/include/mlir/IR/OpImplementation.h b/mlir/include/mlir/IR/OpImplementation.h index 5333d7446df5ca..fa435cb3155ed4 100644 --- a/mlir/include/mlir/IR/OpImplementation.h +++ b/mlir/include/mlir/IR/OpImplementation.h @@ -700,6 +700,10 @@ class AsmParser { /// Parse a floating point value from the stream. virtual ParseResult parseFloat(double &result) = 0; + /// Parse a floating point value into APFloat from the stream. + virtual ParseResult parseFloat(const llvm::fltSemantics &semantics, + APFloat &result) = 0; + /// Parse an integer value from the stream. template ParseResult parseInteger(IntT &result) { diff --git a/mlir/lib/AsmParser/AsmParserImpl.h b/mlir/lib/AsmParser/AsmParserImpl.h index 30c0079cda0861..8b88a3a6650a3e 100644 --- a/mlir/lib/AsmParser/AsmParserImpl.h +++ b/mlir/lib/AsmParser/AsmParserImpl.h @@ -269,8 +269,11 @@ class AsmParserImpl : public BaseT { return success(); } - /// Parse a floating point value from the stream. - ParseResult parseFloat(double &result) override { + /// Parse a floating point value with given semantics from the stream. Since + /// this implementation parses the string as double precision and just than + /// converts the value to the requested semantic, precision may be lost. + ParseResult parseFloat(const llvm::fltSemantics &semantics, + APFloat &result) override { bool isNegative = parser.consumeIf(Token::minus); Token curTok = parser.getToken(); SMLoc loc = curTok.getLoc(); @@ -281,7 +284,9 @@ class AsmParserImpl : public BaseT { if (!val) return emitError(loc, "floating point value too large"); parser.consumeToken(Token::floatliteral); - result = isNegative ? -*val : *val; + result = APFloat(isNegative ? -*val : *val); + bool losesInfo; + result.convert(semantics, APFloat::rmNearestTiesToEven, &losesInfo); return success(); } @@ -289,18 +294,28 @@ class AsmParserImpl : public BaseT { if (curTok.is(Token::integer)) { std::optional apResult; if (failed(parser.parseFloatFromIntegerLiteral( - apResult, curTok, isNegative, APFloat::IEEEdouble(), - /*typeSizeInBits=*/64))) + apResult, curTok, isNegative, semantics, + APFloat::semanticsSizeInBits(semantics)))) return failure(); + result = *apResult; parser.consumeToken(Token::integer); - result = apResult->convertToDouble(); return success(); } return emitError(loc, "expected floating point literal"); } + /// Parse a floating point value from the stream. + ParseResult parseFloat(double &result) override { + llvm::APFloat apResult(0.0); + if (parseFloat(APFloat::IEEEdouble(), apResult)) + return failure(); + + result = apResult.convertToDouble(); + return success(); + } + /// Parse an optional integer value from the stream. OptionalParseResult parseOptionalInteger(APInt &result) override { return parser.parseOptionalInteger(result); diff --git a/mlir/lib/AsmParser/Parser.cpp b/mlir/lib/AsmParser/Parser.cpp index 00f2b0c0c2f12f..1b8b4bac1821e9 100644 --- a/mlir/lib/AsmParser/Parser.cpp +++ b/mlir/lib/AsmParser/Parser.cpp @@ -326,19 +326,15 @@ ParseResult Parser::parseFloatFromIntegerLiteral( "leading minus"); } - std::optional value = tok.getUInt64IntegerValue(); - if (!value) + APInt intValue; + tok.getSpelling().getAsInteger(isHex ? 0 : 10, intValue); + if (intValue.getActiveBits() > typeSizeInBits) return emitError(loc, "hexadecimal float constant out of range for type"); - if (&semantics == &APFloat::IEEEdouble()) { - result = APFloat(semantics, APInt(typeSizeInBits, *value)); - return success(); - } + APInt truncatedValue(typeSizeInBits, intValue.getNumWords(), + intValue.getRawData()); - APInt apInt(typeSizeInBits, *value); - if (apInt != *value) - return emitError(loc, "hexadecimal float constant out of range for type"); - result = APFloat(semantics, apInt); + result.emplace(semantics, truncatedValue); return success(); } diff --git a/mlir/test/IR/custom-float-attr-roundtrip.mlir b/mlir/test/IR/custom-float-attr-roundtrip.mlir new file mode 100644 index 00000000000000..e0913e58d29538 --- /dev/null +++ b/mlir/test/IR/custom-float-attr-roundtrip.mlir @@ -0,0 +1,57 @@ +// RUN: mlir-opt %s -split-input-file -verify-diagnostics| FileCheck %s + +// CHECK-LABEL: @test_enum_attr_roundtrip +func.func @test_enum_attr_roundtrip() -> () { + // CHECK: attr = #test.custom_float<"float" : 2.000000e+00> + "test.op"() {attr = #test.custom_float<"float" : 2.>} : () -> () + // CHECK: attr = #test.custom_float<"double" : 2.000000e+00> + "test.op"() {attr =#test.custom_float<"double" : 2.>} : () -> () + // CHECK: attr = #test.custom_float<"fp80" : 2.000000e+00> + "test.op"() {attr =#test.custom_float<"fp80" : 2.>} : () -> () + // CHECK: attr = #test.custom_float<"float" : 0x7FC00000> + "test.op"() {attr =#test.custom_float<"float" : 0x7FC00000>} : () -> () + // CHECK: attr = #test.custom_float<"double" : 0x7FF0000001000000> + "test.op"() {attr =#test.custom_float<"double" : 0x7FF0000001000000>} : () -> () + // CHECK: attr = #test.custom_float<"fp80" : 0x7FFFC000000000100000> + "test.op"() {attr =#test.custom_float<"fp80" : 0x7FFFC000000000100000>} : () -> () + return +} + +// ----- + +// Verify literal must be hex or float + +// 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}} +"test.op"() {attr =#test.custom_float<"float" : 42>} : () -> () + +// ----- + +// Integer value must be in the width of the floating point type + +// expected-error @below {{hexadecimal float constant out of range for type}} +"test.op"() {attr =#test.custom_float<"float" : 0x7FC000000>} : () -> () + + +// ----- + +// Integer value must be in the width of the floating point type + +// expected-error @below {{hexadecimal float constant out of range for type}} +"test.op"() {attr =#test.custom_float<"double" : 0x7FC000007FC0000000>} : () -> () + + +// ----- + +// Integer value must be in the width of the floating point type + +// expected-error @below {{hexadecimal float constant out of range for type}} +"test.op"() {attr =#test.custom_float<"fp80" : 0x7FC0000007FC0000007FC000000>} : () -> () + +// ----- + +// Value must be a floating point literal or integer literal + +// expected-error @below {{expected floating point literal}} +"test.op"() {attr =#test.custom_float<"float" : "blabla">} : () -> () + diff --git a/mlir/test/IR/parser.mlir b/mlir/test/IR/parser.mlir index bebbb876391d07..020942e7f4c11b 100644 --- a/mlir/test/IR/parser.mlir +++ b/mlir/test/IR/parser.mlir @@ -1105,6 +1105,30 @@ func.func @bfloat16_special_values() { return } +// CHECK-LABEL: @f80_special_values +func.func @f80_special_values() { + // F80 signaling NaNs. + // CHECK: arith.constant 0x7FFFE000000000000001 : f80 + %0 = arith.constant 0x7FFFE000000000000001 : f80 + // CHECK: arith.constant 0x7FFFB000000000000011 : f80 + %1 = arith.constant 0x7FFFB000000000000011 : f80 + + // F80 quiet NaNs. + // CHECK: arith.constant 0x7FFFC000000000100000 : f80 + %2 = arith.constant 0x7FFFC000000000100000 : f80 + // CHECK: arith.constant 0x7FFFE000000001000000 : f80 + %3 = arith.constant 0x7FFFE000000001000000 : f80 + + // F80 positive infinity. + // CHECK: arith.constant 0x7FFF8000000000000000 : f80 + %4 = arith.constant 0x7FFF8000000000000000 : f80 + // F80 negative infinity. + // CHECK: arith.constant 0xFFFF8000000000000000 : f80 + %5 = arith.constant 0xFFFF8000000000000000 : f80 + + return +} + // We want to print floats in exponential notation with 6 significant digits, // but it may lead to precision loss when parsing back, in which case we print // the decimal form instead. diff --git a/mlir/test/lib/Dialect/Test/TestAttrDefs.td b/mlir/test/lib/Dialect/Test/TestAttrDefs.td index 40f035a3e3a4e5..12635e107bd42c 100644 --- a/mlir/test/lib/Dialect/Test/TestAttrDefs.td +++ b/mlir/test/lib/Dialect/Test/TestAttrDefs.td @@ -340,4 +340,15 @@ def TestConditionalAliasAttr : Test_Attr<"TestConditionalAlias"> { }]; } +// Test AsmParser::parseFloat(const fltSemnatics&, APFloat&) API through the +// custom parser and printer. +def TestCustomFloatAttr : Test_Attr<"TestCustomFloat"> { + let mnemonic = "custom_float"; + let parameters = (ins "mlir::StringAttr":$type_str, APFloatParameter<"">:$value); + + let assemblyFormat = [{ + `<` custom($type_str, $value) `>` + }]; +} + #endif // TEST_ATTRDEFS diff --git a/mlir/test/lib/Dialect/Test/TestAttributes.cpp b/mlir/test/lib/Dialect/Test/TestAttributes.cpp index 2cc051e664beec..d7e40d35238d91 100644 --- a/mlir/test/lib/Dialect/Test/TestAttributes.cpp +++ b/mlir/test/lib/Dialect/Test/TestAttributes.cpp @@ -18,6 +18,7 @@ #include "mlir/IR/ExtensibleDialect.h" #include "mlir/IR/Types.h" #include "mlir/Support/LogicalResult.h" +#include "llvm/ADT/APFloat.h" #include "llvm/ADT/Hashing.h" #include "llvm/ADT/StringExtras.h" #include "llvm/ADT/TypeSwitch.h" @@ -240,6 +241,46 @@ static void printConditionalAlias(AsmPrinter &p, StringAttr value) { p.printKeywordOrString(value); } +//===----------------------------------------------------------------------===// +// Custom Float Attribute +//===----------------------------------------------------------------------===// + +static void printCustomFloatAttr(AsmPrinter &p, StringAttr typeStrAttr, + APFloat value) { + p << typeStrAttr << " : " << value; +} + +static ParseResult parseCustomFloatAttr(AsmParser &p, StringAttr &typeStrAttr, + FailureOr &value) { + + std::string str; + if (p.parseString(&str)) + return failure(); + + typeStrAttr = StringAttr::get(p.getContext(), str); + + if (p.parseColon()) + return failure(); + + const llvm::fltSemantics *semantics; + if (str == "float") + semantics = &llvm::APFloat::IEEEsingle(); + else if (str == "double") + semantics = &llvm::APFloat::IEEEdouble(); + else if (str == "fp80") + semantics = &llvm::APFloat::x87DoubleExtended(); + else + return p.emitError(p.getCurrentLocation(), "unknown float type, expected " + "'float', 'double' or 'fp80'"); + + APFloat parsedValue(0.0); + if (p.parseFloat(*semantics, parsedValue)) + return failure(); + + value.emplace(parsedValue); + return success(); +} + //===----------------------------------------------------------------------===// // Tablegen Generated Definitions //===----------------------------------------------------------------------===// ``````````

[orbiri]

Fixed nits. If there are no other objections - I'd appreciate help with committing this to main 🙏

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