[Mlir-commits] [mlir] [mlir][math] Add FP software implementation lowering pass: math-to-apfloat (PR #171221)
Maksim Levental
llvmlistbot at llvm.org
Mon Dec 8 15:53:27 PST 2025
https://github.com/makslevental updated https://github.com/llvm/llvm-project/pull/171221
>From 1e43eb136b5ffcc0ef86878ed03212d4f4ca151b Mon Sep 17 00:00:00 2001
From: makslevental <maksim.levental at gmail.com>
Date: Mon, 8 Dec 2025 14:48:11 -0800
Subject: [PATCH] [mlir][math] Add FP software implementation lowering pass:
math-to-apfloat
---
.../Conversion/MathToAPFloat/MathToAPFloat.h | 21 ++++++
mlir/include/mlir/Conversion/Passes.h | 1 +
mlir/include/mlir/Conversion/Passes.td | 15 +++++
mlir/include/mlir/Dialect/Func/Utils/Utils.h | 16 +++++
.../ArithToAPFloat/ArithToAPFloat.cpp | 67 ++++---------------
mlir/lib/Conversion/CMakeLists.txt | 1 +
.../Conversion/MathToAPFloat/CMakeLists.txt | 17 +++++
.../MathToAPFloat/MathToAPFloat.cpp | 52 ++++++++++++++
mlir/lib/Dialect/Func/Utils/Utils.cpp | 38 +++++++++++
9 files changed, 175 insertions(+), 53 deletions(-)
create mode 100644 mlir/include/mlir/Conversion/MathToAPFloat/MathToAPFloat.h
create mode 100644 mlir/lib/Conversion/MathToAPFloat/CMakeLists.txt
create mode 100644 mlir/lib/Conversion/MathToAPFloat/MathToAPFloat.cpp
diff --git a/mlir/include/mlir/Conversion/MathToAPFloat/MathToAPFloat.h b/mlir/include/mlir/Conversion/MathToAPFloat/MathToAPFloat.h
new file mode 100644
index 0000000000000..86179a1611d5e
--- /dev/null
+++ b/mlir/include/mlir/Conversion/MathToAPFloat/MathToAPFloat.h
@@ -0,0 +1,21 @@
+//===- MathToAPFloat.h - Math to APFloat impl conversion ---*- C++ ------*-===//
+//
+// Part of the APFloat Project, under the Apache License v2.0 with APFloat
+// Exceptions. See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH APFloat-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MLIR_CONVERSION_MATHTOAPFLOAT_MATHTOAPFLOAT_H
+#define MLIR_CONVERSION_MATHTOAPFLOAT_MATHTOAPFLOAT_H
+
+#include <memory>
+
+namespace mlir {
+class Pass;
+
+#define GEN_PASS_DECL_MATHTOAPFLOATCONVERSIONPASS
+#include "mlir/Conversion/Passes.h.inc"
+} // namespace mlir
+
+#endif // MLIR_CONVERSION_MATHTOAPFLOAT_MATHTOAPFLOAT_H
diff --git a/mlir/include/mlir/Conversion/Passes.h b/mlir/include/mlir/Conversion/Passes.h
index 82bdfd02661a6..05ec2f8ce2538 100644
--- a/mlir/include/mlir/Conversion/Passes.h
+++ b/mlir/include/mlir/Conversion/Passes.h
@@ -44,6 +44,7 @@
#include "mlir/Conversion/IndexToLLVM/IndexToLLVM.h"
#include "mlir/Conversion/IndexToSPIRV/IndexToSPIRV.h"
#include "mlir/Conversion/LinalgToStandard/LinalgToStandard.h"
+#include "mlir/Conversion/MathToAPFloat/MathToAPFloat.h"
#include "mlir/Conversion/MathToEmitC/MathToEmitCPass.h"
#include "mlir/Conversion/MathToFuncs/MathToFuncs.h"
#include "mlir/Conversion/MathToLLVM/MathToLLVM.h"
diff --git a/mlir/include/mlir/Conversion/Passes.td b/mlir/include/mlir/Conversion/Passes.td
index fcbaf3ccc1486..7f24e58671aab 100644
--- a/mlir/include/mlir/Conversion/Passes.td
+++ b/mlir/include/mlir/Conversion/Passes.td
@@ -775,6 +775,21 @@ def ConvertMathToLibmPass : Pass<"convert-math-to-libm", "ModuleOp"> {
];
}
+//===----------------------------------------------------------------------===//
+// MathToAPFloat
+//===----------------------------------------------------------------------===//
+
+def MathToAPFloatConversionPass
+ : Pass<"convert-math-to-apfloat", "ModuleOp"> {
+ let summary = "Convert Math ops to APFloat runtime library calls";
+ let description = [{
+ This pass converts supported Math ops to APFloat-based runtime library
+ calls (APFloatWrappers.cpp). APFloat is a software implementation of
+ floating-point mathmetic operations.
+ }];
+ let dependentDialects = ["math::MathDialect", "func::FuncDialect"];
+}
+
//===----------------------------------------------------------------------===//
// MathToLLVM
//===----------------------------------------------------------------------===//
diff --git a/mlir/include/mlir/Dialect/Func/Utils/Utils.h b/mlir/include/mlir/Dialect/Func/Utils/Utils.h
index 00d50874a2e8d..c04f61c869c49 100644
--- a/mlir/include/mlir/Dialect/Func/Utils/Utils.h
+++ b/mlir/include/mlir/Dialect/Func/Utils/Utils.h
@@ -67,6 +67,22 @@ FailureOr<FuncOp> lookupFnDecl(SymbolOpInterface symTable, StringRef name,
FunctionType funcT,
SymbolTableCollection *symbolTables = nullptr);
+/// Create a FuncOp decl and insert it into `symTable` operation. If
+/// `symbolTables` is provided, then the decl will be inserted into the
+/// SymbolTableCollection.
+FuncOp createFnDecl(OpBuilder &b, SymbolOpInterface symTable, StringRef name,
+ FunctionType funcT, bool setPrivate,
+ SymbolTableCollection *symbolTables = nullptr);
+
+/// Helper function to look up or create the symbol for a runtime library
+/// function with the given parameter types. Returns an int64_t, unless a
+/// different result type is specified.
+FailureOr<FuncOp>
+lookupOrCreateFn(OpBuilder &b, SymbolOpInterface symTable, StringRef name,
+ TypeRange paramTypes,
+ SymbolTableCollection *symbolTables = nullptr,
+ Type resultType = {});
+
} // namespace func
} // namespace mlir
diff --git a/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp b/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
index 79816fc6e3bf1..103a9529eab44 100644
--- a/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
+++ b/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
@@ -25,47 +25,6 @@ namespace mlir {
using namespace mlir;
using namespace mlir::func;
-static FuncOp createFnDecl(OpBuilder &b, SymbolOpInterface symTable,
- StringRef name, FunctionType funcT, bool setPrivate,
- SymbolTableCollection *symbolTables = nullptr) {
- OpBuilder::InsertionGuard g(b);
- assert(!symTable->getRegion(0).empty() && "expected non-empty region");
- b.setInsertionPointToStart(&symTable->getRegion(0).front());
- FuncOp funcOp = FuncOp::create(b, symTable->getLoc(), name, funcT);
- if (setPrivate)
- funcOp.setPrivate();
- if (symbolTables) {
- SymbolTable &symbolTable = symbolTables->getSymbolTable(symTable);
- symbolTable.insert(funcOp, symTable->getRegion(0).front().begin());
- }
- return funcOp;
-}
-
-/// Helper function to look up or create the symbol for a runtime library
-/// function with the given parameter types. Returns an int64_t, unless a
-/// different result type is specified.
-static FailureOr<FuncOp>
-lookupOrCreateApFloatFn(OpBuilder &b, SymbolOpInterface symTable,
- StringRef name, TypeRange paramTypes,
- SymbolTableCollection *symbolTables = nullptr,
- Type resultType = {}) {
- if (!resultType)
- resultType = IntegerType::get(symTable->getContext(), 64);
- std::string funcName = (llvm::Twine("_mlir_apfloat_") + name).str();
- auto funcT = FunctionType::get(b.getContext(), paramTypes, {resultType});
- FailureOr<FuncOp> func =
- lookupFnDecl(symTable, funcName, funcT, symbolTables);
- // Failed due to type mismatch.
- if (failed(func))
- return func;
- // Successfully matched existing decl.
- if (*func)
- return *func;
-
- return createFnDecl(b, symTable, funcName, funcT,
- /*setPrivate=*/true, symbolTables);
-}
-
/// Helper function to look up or create the symbol for a runtime library
/// function for a binary arithmetic operation.
///
@@ -81,8 +40,9 @@ lookupOrCreateBinaryFn(OpBuilder &b, SymbolOpInterface symTable, StringRef name,
SymbolTableCollection *symbolTables = nullptr) {
auto i32Type = IntegerType::get(symTable->getContext(), 32);
auto i64Type = IntegerType::get(symTable->getContext(), 64);
- return lookupOrCreateApFloatFn(b, symTable, name, {i32Type, i64Type, i64Type},
- symbolTables);
+ std::string funcName = (llvm::Twine("_mlir_apfloat_") + name).str();
+ return lookupOrCreateFn(b, symTable, funcName, {i32Type, i64Type, i64Type},
+ symbolTables);
}
static Value getSemanticsValue(OpBuilder &b, Location loc, FloatType floatTy) {
@@ -231,8 +191,9 @@ struct FpToFpConversion final : OpRewritePattern<OpTy> {
// Get APFloat function from runtime library.
auto i32Type = IntegerType::get(symTable->getContext(), 32);
auto i64Type = IntegerType::get(symTable->getContext(), 64);
- FailureOr<FuncOp> fn = lookupOrCreateApFloatFn(
- rewriter, symTable, "convert", {i32Type, i32Type, i64Type});
+ FailureOr<FuncOp> fn =
+ lookupOrCreateFn(rewriter, symTable, "_mlir_apfloat_convert",
+ {i32Type, i32Type, i64Type});
if (failed(fn))
return fn;
@@ -289,8 +250,8 @@ struct FpToIntConversion final : OpRewritePattern<OpTy> {
auto i32Type = IntegerType::get(symTable->getContext(), 32);
auto i64Type = IntegerType::get(symTable->getContext(), 64);
FailureOr<FuncOp> fn =
- lookupOrCreateApFloatFn(rewriter, symTable, "convert_to_int",
- {i32Type, i32Type, i1Type, i64Type});
+ lookupOrCreateFn(rewriter, symTable, "_mlir_apfloat_convert_to_int",
+ {i32Type, i32Type, i1Type, i64Type});
if (failed(fn))
return fn;
@@ -351,8 +312,8 @@ struct IntToFpConversion final : OpRewritePattern<OpTy> {
auto i32Type = IntegerType::get(symTable->getContext(), 32);
auto i64Type = IntegerType::get(symTable->getContext(), 64);
FailureOr<FuncOp> fn =
- lookupOrCreateApFloatFn(rewriter, symTable, "convert_from_int",
- {i32Type, i32Type, i1Type, i64Type});
+ lookupOrCreateFn(rewriter, symTable, "_mlir_apfloat_convert_from_int",
+ {i32Type, i32Type, i1Type, i64Type});
if (failed(fn))
return fn;
@@ -421,8 +382,8 @@ struct CmpFOpToAPFloatConversion final : OpRewritePattern<arith::CmpFOp> {
auto i32Type = IntegerType::get(symTable->getContext(), 32);
auto i64Type = IntegerType::get(symTable->getContext(), 64);
FailureOr<FuncOp> fn =
- lookupOrCreateApFloatFn(rewriter, symTable, "compare",
- {i32Type, i64Type, i64Type}, nullptr, i8Type);
+ lookupOrCreateFn(rewriter, symTable, "_mlir_apfloat_compare",
+ {i32Type, i64Type, i64Type}, nullptr, i8Type);
if (failed(fn))
return fn;
@@ -569,8 +530,8 @@ struct NegFOpToAPFloatConversion final : OpRewritePattern<arith::NegFOp> {
// Get APFloat function from runtime library.
auto i32Type = IntegerType::get(symTable->getContext(), 32);
auto i64Type = IntegerType::get(symTable->getContext(), 64);
- FailureOr<FuncOp> fn =
- lookupOrCreateApFloatFn(rewriter, symTable, "neg", {i32Type, i64Type});
+ FailureOr<FuncOp> fn = lookupOrCreateFn(
+ rewriter, symTable, "_mlir_apfloat_neg", {i32Type, i64Type});
if (failed(fn))
return fn;
diff --git a/mlir/lib/Conversion/CMakeLists.txt b/mlir/lib/Conversion/CMakeLists.txt
index 613dc6d242ceb..3c59fbda6810a 100644
--- a/mlir/lib/Conversion/CMakeLists.txt
+++ b/mlir/lib/Conversion/CMakeLists.txt
@@ -35,6 +35,7 @@ add_subdirectory(IndexToLLVM)
add_subdirectory(IndexToSPIRV)
add_subdirectory(LinalgToStandard)
add_subdirectory(LLVMCommon)
+add_subdirectory(MathToAPFloat)
add_subdirectory(MathToEmitC)
add_subdirectory(MathToFuncs)
add_subdirectory(MathToLibm)
diff --git a/mlir/lib/Conversion/MathToAPFloat/CMakeLists.txt b/mlir/lib/Conversion/MathToAPFloat/CMakeLists.txt
new file mode 100644
index 0000000000000..454b71b1ef160
--- /dev/null
+++ b/mlir/lib/Conversion/MathToAPFloat/CMakeLists.txt
@@ -0,0 +1,17 @@
+add_mlir_conversion_library(MLIRMathToAPFloat
+ MathToAPFloat.cpp
+
+ ADDITIONAL_HEADER_DIRS
+ ${MLIR_MAIN_INCLUDE_DIR}/mlir/Conversion/MathToLLVM
+
+ DEPENDS
+ MLIRConversionPassIncGen
+
+ LINK_COMPONENTS
+ Core
+
+ LINK_LIBS PUBLIC
+ MLIRMathDialect
+ MLIRFuncDialect
+ MLIRFuncUtils
+ )
diff --git a/mlir/lib/Conversion/MathToAPFloat/MathToAPFloat.cpp b/mlir/lib/Conversion/MathToAPFloat/MathToAPFloat.cpp
new file mode 100644
index 0000000000000..35a4f94e4be24
--- /dev/null
+++ b/mlir/lib/Conversion/MathToAPFloat/MathToAPFloat.cpp
@@ -0,0 +1,52 @@
+//===- MathToAPFloat.cpp - Mathmetic to APFloat Conversion ----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Conversion/MathToAPFloat/MathToAPFloat.h"
+
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+#include "mlir/Dialect/Func/Utils/Utils.h"
+#include "mlir/Dialect/Math/IR/Math.h"
+#include "mlir/Dialect/Math/Transforms/Passes.h"
+#include "mlir/Dialect/Vector/IR/VectorOps.h"
+#include "mlir/IR/PatternMatch.h"
+#include "mlir/IR/Verifier.h"
+#include "mlir/Transforms/WalkPatternRewriteDriver.h"
+
+namespace mlir {
+#define GEN_PASS_DEF_MATHTOAPFLOATCONVERSIONPASS
+#include "mlir/Conversion/Passes.h.inc"
+} // namespace mlir
+
+using namespace mlir;
+using namespace mlir::func;
+
+namespace {
+struct MathToAPFloatConversionPass final
+ : impl::MathToAPFloatConversionPassBase<MathToAPFloatConversionPass> {
+ using Base::Base;
+
+ void runOnOperation() override;
+};
+
+void MathToAPFloatConversionPass::runOnOperation() {
+ MLIRContext *context = &getContext();
+ RewritePatternSet patterns(context);
+ LogicalResult result = success();
+ ScopedDiagnosticHandler scopedHandler(context, [&result](Diagnostic &diag) {
+ if (diag.getSeverity() == DiagnosticSeverity::Error) {
+ result = failure();
+ }
+ // NB: if you don't return failure, no other diag handlers will fire (see
+ // mlir/lib/IR/Diagnostics.cpp:DiagnosticEngineImpl::emit).
+ return failure();
+ });
+ walkAndApplyPatterns(getOperation(), std::move(patterns));
+ if (failed(result))
+ return signalPassFailure();
+}
+} // namespace
diff --git a/mlir/lib/Dialect/Func/Utils/Utils.cpp b/mlir/lib/Dialect/Func/Utils/Utils.cpp
index d6dfd0229963c..d7dc89bb8c050 100644
--- a/mlir/lib/Dialect/Func/Utils/Utils.cpp
+++ b/mlir/lib/Dialect/Func/Utils/Utils.cpp
@@ -279,3 +279,41 @@ func::lookupFnDecl(SymbolOpInterface symTable, StringRef name,
}
return func;
}
+
+func::FuncOp func::createFnDecl(OpBuilder &b, SymbolOpInterface symTable,
+ StringRef name, FunctionType funcT,
+ bool setPrivate,
+ SymbolTableCollection *symbolTables) {
+ OpBuilder::InsertionGuard g(b);
+ assert(!symTable->getRegion(0).empty() && "expected non-empty region");
+ b.setInsertionPointToStart(&symTable->getRegion(0).front());
+ func::FuncOp funcOp =
+ func::FuncOp::create(b, symTable->getLoc(), name, funcT);
+ if (setPrivate)
+ funcOp.setPrivate();
+ if (symbolTables) {
+ SymbolTable &symbolTable = symbolTables->getSymbolTable(symTable);
+ symbolTable.insert(funcOp, symTable->getRegion(0).front().begin());
+ }
+ return funcOp;
+}
+
+FailureOr<func::FuncOp>
+func::lookupOrCreateFn(OpBuilder &b, SymbolOpInterface symTable,
+ StringRef funcName, TypeRange paramTypes,
+ SymbolTableCollection *symbolTables, Type resultType) {
+ if (!resultType)
+ resultType = IntegerType::get(symTable->getContext(), 64);
+ auto funcT = FunctionType::get(b.getContext(), paramTypes, {resultType});
+ FailureOr<func::FuncOp> func =
+ lookupFnDecl(symTable, funcName, funcT, symbolTables);
+ // Failed due to type mismatch.
+ if (failed(func))
+ return func;
+ // Successfully matched existing decl.
+ if (*func)
+ return *func;
+
+ return createFnDecl(b, symTable, funcName, funcT,
+ /*setPrivate=*/true, symbolTables);
+}
\ No newline at end of file
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