[Mlir-commits] [mlir] 75751f3 - Reapply "Reapply "[mlir] Add FP software implementation lowering pass: `arith-to-apfloat` (#166618)" (#167431)" (#167436)

llvmlistbot at llvm.org llvmlistbot at llvm.org
Tue Nov 11 08:50:41 PST 2025


Author: Maksim Levental
Date: 2025-11-11T08:50:37-08:00
New Revision: 75751f33a8702d14184d435d544f38149514b63f

URL: https://github.com/llvm/llvm-project/commit/75751f33a8702d14184d435d544f38149514b63f
DIFF: https://github.com/llvm/llvm-project/commit/75751f33a8702d14184d435d544f38149514b63f.diff

LOG: Reapply "Reapply "[mlir] Add FP software implementation lowering pass: `arith-to-apfloat` (#166618)" (#167431)" (#167436)

Reland https://github.com/llvm/llvm-project/pull/166618 by fixing
missing symbol issues by explicitly loading
`--shared-libs=%mlir_apfloat_wrappers` as well as
`--shared-libs=%mlir_c_runner_utils`.

Added: 
    mlir/include/mlir/Conversion/ArithToAPFloat/ArithToAPFloat.h
    mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
    mlir/lib/Conversion/ArithToAPFloat/CMakeLists.txt
    mlir/lib/ExecutionEngine/APFloatWrappers.cpp
    mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir
    mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir

Modified: 
    mlir/include/mlir/Conversion/Passes.h
    mlir/include/mlir/Conversion/Passes.td
    mlir/include/mlir/Dialect/Func/Utils/Utils.h
    mlir/include/mlir/Dialect/LLVMIR/FunctionCallUtils.h
    mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp
    mlir/lib/Conversion/CMakeLists.txt
    mlir/lib/Conversion/VectorToLLVM/ConvertVectorToLLVM.cpp
    mlir/lib/Dialect/Func/Utils/Utils.cpp
    mlir/lib/Dialect/LLVMIR/IR/FunctionCallUtils.cpp
    mlir/lib/ExecutionEngine/CMakeLists.txt
    mlir/test/lit.cfg.py

Removed: 
    


################################################################################
diff  --git a/mlir/include/mlir/Conversion/ArithToAPFloat/ArithToAPFloat.h b/mlir/include/mlir/Conversion/ArithToAPFloat/ArithToAPFloat.h
new file mode 100644
index 0000000000000..64a42a228199e
--- /dev/null
+++ b/mlir/include/mlir/Conversion/ArithToAPFloat/ArithToAPFloat.h
@@ -0,0 +1,21 @@
+//===- ArithToAPFloat.h - Arith 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_ARITHTOAPFLOAT_ARITHTOAPFLOAT_H
+#define MLIR_CONVERSION_ARITHTOAPFLOAT_ARITHTOAPFLOAT_H
+
+#include <memory>
+
+namespace mlir {
+class Pass;
+
+#define GEN_PASS_DECL_ARITHTOAPFLOATCONVERSIONPASS
+#include "mlir/Conversion/Passes.h.inc"
+} // namespace mlir
+
+#endif // MLIR_CONVERSION_ARITHTOAPFLOAT_ARITHTOAPFLOAT_H

diff  --git a/mlir/include/mlir/Conversion/Passes.h b/mlir/include/mlir/Conversion/Passes.h
index 40d866ec7bf10..82bdfd02661a6 100644
--- a/mlir/include/mlir/Conversion/Passes.h
+++ b/mlir/include/mlir/Conversion/Passes.h
@@ -12,6 +12,7 @@
 #include "mlir/Conversion/AMDGPUToROCDL/AMDGPUToROCDL.h"
 #include "mlir/Conversion/AffineToStandard/AffineToStandard.h"
 #include "mlir/Conversion/ArithToAMDGPU/ArithToAMDGPU.h"
+#include "mlir/Conversion/ArithToAPFloat/ArithToAPFloat.h"
 #include "mlir/Conversion/ArithToArmSME/ArithToArmSME.h"
 #include "mlir/Conversion/ArithToEmitC/ArithToEmitCPass.h"
 #include "mlir/Conversion/ArithToLLVM/ArithToLLVM.h"

diff  --git a/mlir/include/mlir/Conversion/Passes.td b/mlir/include/mlir/Conversion/Passes.td
index 70e3e45c225db..79bc380dbcb7a 100644
--- a/mlir/include/mlir/Conversion/Passes.td
+++ b/mlir/include/mlir/Conversion/Passes.td
@@ -186,6 +186,21 @@ def ArithToLLVMConversionPass : Pass<"convert-arith-to-llvm"> {
   ];
 }
 
+//===----------------------------------------------------------------------===//
+// ArithToAPFloat
+//===----------------------------------------------------------------------===//
+
+def ArithToAPFloatConversionPass
+    : Pass<"convert-arith-to-apfloat", "ModuleOp"> {
+  let summary = "Convert Arith ops to APFloat runtime library calls";
+  let description = [{
+    This pass converts supported Arith ops to APFloat-based runtime library
+    calls (APFloatWrappers.cpp). APFloat is a software implementation of
+    floating-point arithmetic operations.
+  }];
+  let dependentDialects = ["func::FuncDialect"];
+}
+
 //===----------------------------------------------------------------------===//
 // ArithToSPIRV
 //===----------------------------------------------------------------------===//

diff  --git a/mlir/include/mlir/Dialect/Func/Utils/Utils.h b/mlir/include/mlir/Dialect/Func/Utils/Utils.h
index 3576126a487ac..00d50874a2e8d 100644
--- a/mlir/include/mlir/Dialect/Func/Utils/Utils.h
+++ b/mlir/include/mlir/Dialect/Func/Utils/Utils.h
@@ -60,6 +60,13 @@ mlir::FailureOr<std::pair<mlir::func::FuncOp, mlir::func::CallOp>>
 deduplicateArgsOfFuncOp(mlir::RewriterBase &rewriter, mlir::func::FuncOp funcOp,
                         mlir::ModuleOp moduleOp);
 
+/// Look up a FuncOp with signature `resultTypes`(`paramTypes`)` and name
+/// `name`. Return a failure if the FuncOp is found but with a 
diff erent
+/// signature.
+FailureOr<FuncOp> lookupFnDecl(SymbolOpInterface symTable, StringRef name,
+                               FunctionType funcT,
+                               SymbolTableCollection *symbolTables = nullptr);
+
 } // namespace func
 } // namespace mlir
 

diff  --git a/mlir/include/mlir/Dialect/LLVMIR/FunctionCallUtils.h b/mlir/include/mlir/Dialect/LLVMIR/FunctionCallUtils.h
index 8ad9ed18acebd..b09d32022e348 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/FunctionCallUtils.h
+++ b/mlir/include/mlir/Dialect/LLVMIR/FunctionCallUtils.h
@@ -52,6 +52,10 @@ lookupOrCreatePrintF32Fn(OpBuilder &b, Operation *moduleOp,
 FailureOr<LLVM::LLVMFuncOp>
 lookupOrCreatePrintF64Fn(OpBuilder &b, Operation *moduleOp,
                          SymbolTableCollection *symbolTables = nullptr);
+FailureOr<LLVM::LLVMFuncOp>
+lookupOrCreateApFloatPrintFn(OpBuilder &b, Operation *moduleOp,
+                             SymbolTableCollection *symbolTables = nullptr);
+
 /// Declares a function to print a C-string.
 /// If a custom runtime function is defined via `runtimeFunctionName`, it must
 /// have the signature void(char const*). The default function is `printString`.

diff  --git a/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp b/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
new file mode 100644
index 0000000000000..01fd5b278aca4
--- /dev/null
+++ b/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
@@ -0,0 +1,158 @@
+//===- ArithToAPFloat.cpp - Arithmetic 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/ArithToAPFloat/ArithToAPFloat.h"
+
+#include "mlir/Dialect/Arith/IR/Arith.h"
+#include "mlir/Dialect/Arith/Transforms/Passes.h"
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+#include "mlir/Dialect/Func/Utils/Utils.h"
+#include "mlir/IR/PatternMatch.h"
+#include "mlir/IR/Verifier.h"
+#include "mlir/Transforms/WalkPatternRewriteDriver.h"
+
+namespace mlir {
+#define GEN_PASS_DEF_ARITHTOAPFLOATCONVERSIONPASS
+#include "mlir/Conversion/Passes.h.inc"
+} // 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 for a binary arithmetic operation.
+///
+/// Parameter 1: APFloat semantics
+/// Parameter 2: Left-hand side operand
+/// Parameter 3: Right-hand side operand
+///
+/// This function will return a failure if the function is found but has an
+/// unexpected signature.
+///
+static FailureOr<FuncOp>
+lookupOrCreateBinaryFn(OpBuilder &b, SymbolOpInterface symTable, StringRef name,
+                       SymbolTableCollection *symbolTables = nullptr) {
+  auto i32Type = IntegerType::get(symTable->getContext(), 32);
+  auto i64Type = IntegerType::get(symTable->getContext(), 64);
+
+  std::string funcName = (llvm::Twine("_mlir_apfloat_") + name).str();
+  FunctionType funcT =
+      FunctionType::get(b.getContext(), {i32Type, i64Type, i64Type}, {i64Type});
+  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);
+}
+
+/// Rewrite a binary arithmetic operation to an APFloat function call.
+template <typename OpTy, const char *APFloatName>
+struct BinaryArithOpToAPFloatConversion final : OpRewritePattern<OpTy> {
+  BinaryArithOpToAPFloatConversion(MLIRContext *context, PatternBenefit benefit,
+                                   SymbolOpInterface symTable)
+      : OpRewritePattern<OpTy>(context, benefit), symTable(symTable) {};
+
+  LogicalResult matchAndRewrite(OpTy op,
+                                PatternRewriter &rewriter) const override {
+    // Get APFloat function from runtime library.
+    FailureOr<FuncOp> fn =
+        lookupOrCreateBinaryFn(rewriter, symTable, APFloatName);
+    if (failed(fn))
+      return fn;
+
+    rewriter.setInsertionPoint(op);
+    // Cast operands to 64-bit integers.
+    Location loc = op.getLoc();
+    auto floatTy = cast<FloatType>(op.getType());
+    auto intWType = rewriter.getIntegerType(floatTy.getWidth());
+    auto int64Type = rewriter.getI64Type();
+    Value lhsBits = arith::ExtUIOp::create(
+        rewriter, loc, int64Type,
+        arith::BitcastOp::create(rewriter, loc, intWType, op.getLhs()));
+    Value rhsBits = arith::ExtUIOp::create(
+        rewriter, loc, int64Type,
+        arith::BitcastOp::create(rewriter, loc, intWType, op.getRhs()));
+
+    // Call APFloat function.
+    int32_t sem =
+        llvm::APFloatBase::SemanticsToEnum(floatTy.getFloatSemantics());
+    Value semValue = arith::ConstantOp::create(
+        rewriter, loc, rewriter.getI32Type(),
+        rewriter.getIntegerAttr(rewriter.getI32Type(), sem));
+    SmallVector<Value> params = {semValue, lhsBits, rhsBits};
+    auto resultOp =
+        func::CallOp::create(rewriter, loc, TypeRange(rewriter.getI64Type()),
+                             SymbolRefAttr::get(*fn), params);
+
+    // Truncate result to the original width.
+    Value truncatedBits = arith::TruncIOp::create(rewriter, loc, intWType,
+                                                  resultOp->getResult(0));
+    rewriter.replaceOp(
+        op, arith::BitcastOp::create(rewriter, loc, floatTy, truncatedBits));
+    return success();
+  }
+
+  SymbolOpInterface symTable;
+};
+
+namespace {
+struct ArithToAPFloatConversionPass final
+    : impl::ArithToAPFloatConversionPassBase<ArithToAPFloatConversionPass> {
+  using Base::Base;
+
+  void runOnOperation() override {
+    MLIRContext *context = &getContext();
+    RewritePatternSet patterns(context);
+    static const char add[] = "add";
+    static const char subtract[] = "subtract";
+    static const char multiply[] = "multiply";
+    static const char divide[] = "divide";
+    static const char remainder[] = "remainder";
+    patterns.add<BinaryArithOpToAPFloatConversion<arith::AddFOp, add>,
+                 BinaryArithOpToAPFloatConversion<arith::SubFOp, subtract>,
+                 BinaryArithOpToAPFloatConversion<arith::MulFOp, multiply>,
+                 BinaryArithOpToAPFloatConversion<arith::DivFOp, divide>,
+                 BinaryArithOpToAPFloatConversion<arith::RemFOp, remainder>>(
+        context, 1, getOperation());
+    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/Conversion/ArithToAPFloat/CMakeLists.txt b/mlir/lib/Conversion/ArithToAPFloat/CMakeLists.txt
new file mode 100644
index 0000000000000..b5ec49c087163
--- /dev/null
+++ b/mlir/lib/Conversion/ArithToAPFloat/CMakeLists.txt
@@ -0,0 +1,18 @@
+add_mlir_conversion_library(MLIRArithToAPFloat
+  ArithToAPFloat.cpp
+
+  ADDITIONAL_HEADER_DIRS
+  ${MLIR_MAIN_INCLUDE_DIR}/mlir/Conversion/ArithToLLVM
+
+  DEPENDS
+  MLIRConversionPassIncGen
+
+  LINK_COMPONENTS
+  Core
+
+  LINK_LIBS PUBLIC
+  MLIRArithDialect
+  MLIRArithTransforms
+  MLIRFuncDialect
+  MLIRFuncUtils
+  )

diff  --git a/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp b/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp
index b6099902cc337..f2bacc3399144 100644
--- a/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp
+++ b/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp
@@ -14,6 +14,7 @@
 #include "mlir/Conversion/LLVMCommon/VectorPattern.h"
 #include "mlir/Dialect/Arith/IR/Arith.h"
 #include "mlir/Dialect/Arith/Transforms/Passes.h"
+#include "mlir/Dialect/LLVMIR/FunctionCallUtils.h"
 #include "mlir/Dialect/LLVMIR/LLVMAttrs.h"
 #include "mlir/Dialect/LLVMIR/LLVMDialect.h"
 #include "mlir/IR/TypeUtilities.h"

diff  --git a/mlir/lib/Conversion/CMakeLists.txt b/mlir/lib/Conversion/CMakeLists.txt
index bebf1b8fff3f9..613dc6d242ceb 100644
--- a/mlir/lib/Conversion/CMakeLists.txt
+++ b/mlir/lib/Conversion/CMakeLists.txt
@@ -2,6 +2,7 @@ add_subdirectory(AffineToStandard)
 add_subdirectory(AMDGPUToROCDL)
 add_subdirectory(ArithCommon)
 add_subdirectory(ArithToAMDGPU)
+add_subdirectory(ArithToAPFloat)
 add_subdirectory(ArithToArmSME)
 add_subdirectory(ArithToEmitC)
 add_subdirectory(ArithToLLVM)

diff  --git a/mlir/lib/Conversion/VectorToLLVM/ConvertVectorToLLVM.cpp b/mlir/lib/Conversion/VectorToLLVM/ConvertVectorToLLVM.cpp
index 69a317ecd101f..c747e1b59558a 100644
--- a/mlir/lib/Conversion/VectorToLLVM/ConvertVectorToLLVM.cpp
+++ b/mlir/lib/Conversion/VectorToLLVM/ConvertVectorToLLVM.cpp
@@ -1654,6 +1654,20 @@ class VectorPrintOpConversion : public ConvertOpToLLVMPattern<vector::PrintOp> {
           return failure();
         }
       }
+    } else if (auto floatTy = dyn_cast<FloatType>(printType)) {
+      // Print other floating-point types using the APFloat runtime library.
+      int32_t sem =
+          llvm::APFloatBase::SemanticsToEnum(floatTy.getFloatSemantics());
+      Value semValue = LLVM::ConstantOp::create(
+          rewriter, loc, rewriter.getI32Type(),
+          rewriter.getIntegerAttr(rewriter.getI32Type(), sem));
+      Value floatBits =
+          LLVM::ZExtOp::create(rewriter, loc, rewriter.getI64Type(), value);
+      printer =
+          LLVM::lookupOrCreateApFloatPrintFn(rewriter, parent, symbolTables);
+      emitCall(rewriter, loc, printer.value(),
+               ValueRange({semValue, floatBits}));
+      return success();
     } else {
       return failure();
     }

diff  --git a/mlir/lib/Dialect/Func/Utils/Utils.cpp b/mlir/lib/Dialect/Func/Utils/Utils.cpp
index b4cb0932ef631..d6dfd0229963c 100644
--- a/mlir/lib/Dialect/Func/Utils/Utils.cpp
+++ b/mlir/lib/Dialect/Func/Utils/Utils.cpp
@@ -254,3 +254,28 @@ func::deduplicateArgsOfFuncOp(RewriterBase &rewriter, func::FuncOp funcOp,
 
   return std::make_pair(*newFuncOpOrFailure, newCallOp);
 }
+
+FailureOr<func::FuncOp>
+func::lookupFnDecl(SymbolOpInterface symTable, StringRef name,
+                   FunctionType funcT, SymbolTableCollection *symbolTables) {
+  FuncOp func;
+  if (symbolTables) {
+    func = symbolTables->lookupSymbolIn<FuncOp>(
+        symTable, StringAttr::get(symTable->getContext(), name));
+  } else {
+    func = llvm::dyn_cast_or_null<FuncOp>(
+        SymbolTable::lookupSymbolIn(symTable, name));
+  }
+
+  if (!func)
+    return func;
+
+  mlir::FunctionType foundFuncT = func.getFunctionType();
+  // Assert the signature of the found function is same as expected
+  if (funcT != foundFuncT) {
+    return func.emitError("matched function '")
+           << name << "' but with 
diff erent type: " << foundFuncT
+           << " (expected " << funcT << ")";
+  }
+  return func;
+}

diff  --git a/mlir/lib/Dialect/LLVMIR/IR/FunctionCallUtils.cpp b/mlir/lib/Dialect/LLVMIR/IR/FunctionCallUtils.cpp
index feaffa34897b6..160b6ae89215c 100644
--- a/mlir/lib/Dialect/LLVMIR/IR/FunctionCallUtils.cpp
+++ b/mlir/lib/Dialect/LLVMIR/IR/FunctionCallUtils.cpp
@@ -30,6 +30,7 @@ static constexpr llvm::StringRef kPrintF16 = "printF16";
 static constexpr llvm::StringRef kPrintBF16 = "printBF16";
 static constexpr llvm::StringRef kPrintF32 = "printF32";
 static constexpr llvm::StringRef kPrintF64 = "printF64";
+static constexpr llvm::StringRef kPrintApFloat = "printApFloat";
 static constexpr llvm::StringRef kPrintString = "printString";
 static constexpr llvm::StringRef kPrintOpen = "printOpen";
 static constexpr llvm::StringRef kPrintClose = "printClose";
@@ -160,6 +161,16 @@ mlir::LLVM::lookupOrCreatePrintF64Fn(OpBuilder &b, Operation *moduleOp,
       LLVM::LLVMVoidType::get(moduleOp->getContext()), symbolTables);
 }
 
+FailureOr<LLVM::LLVMFuncOp>
+mlir::LLVM::lookupOrCreateApFloatPrintFn(OpBuilder &b, Operation *moduleOp,
+                                         SymbolTableCollection *symbolTables) {
+  return lookupOrCreateReservedFn(
+      b, moduleOp, kPrintApFloat,
+      {IntegerType::get(moduleOp->getContext(), 32),
+       IntegerType::get(moduleOp->getContext(), 64)},
+      LLVM::LLVMVoidType::get(moduleOp->getContext()), symbolTables);
+}
+
 static LLVM::LLVMPointerType getCharPtr(MLIRContext *context) {
   return LLVM::LLVMPointerType::get(context);
 }

diff  --git a/mlir/lib/ExecutionEngine/APFloatWrappers.cpp b/mlir/lib/ExecutionEngine/APFloatWrappers.cpp
new file mode 100644
index 0000000000000..0a05f7369e556
--- /dev/null
+++ b/mlir/lib/ExecutionEngine/APFloatWrappers.cpp
@@ -0,0 +1,89 @@
+//===- APFloatWrappers.cpp - Software Implementation of FP Arithmetics --- ===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file exposes the APFloat infrastructure to MLIR programs as a runtime
+// library. APFloat is a software implementation of floating point arithmetics.
+//
+// On the MLIR side, floating-point values must be bitcasted to 64-bit integers
+// before calling a runtime function. If a floating-point type has less than
+// 64 bits, it must be zero-extended to 64 bits after bitcasting it to an
+// integer.
+//
+// Runtime functions receive the floating-point operands of the arithmeic
+// operation in the form of 64-bit integers, along with the APFloat semantics
+// in the form of a 32-bit integer, which will be interpreted as an
+// APFloatBase::Semantics enum value.
+//
+#include "llvm/ADT/APFloat.h"
+
+#ifdef _WIN32
+#ifndef MLIR_APFLOAT_WRAPPERS_EXPORT
+#ifdef mlir_apfloat_wrappers_EXPORTS
+// We are building this library
+#define MLIR_APFLOAT_WRAPPERS_EXPORT __declspec(dllexport)
+#else
+// We are using this library
+#define MLIR_APFLOAT_WRAPPERS_EXPORT __declspec(dllimport)
+#endif // mlir_apfloat_wrappers_EXPORTS
+#endif // MLIR_APFLOAT_WRAPPERS_EXPORT
+#else
+// Non-windows: use visibility attributes.
+#define MLIR_APFLOAT_WRAPPERS_EXPORT __attribute__((visibility("default")))
+#endif // _WIN32
+
+/// Binary operations without rounding mode.
+#define APFLOAT_BINARY_OP(OP)                                                  \
+  MLIR_APFLOAT_WRAPPERS_EXPORT int64_t _mlir_apfloat_##OP(                     \
+      int32_t semantics, uint64_t a, uint64_t b) {                             \
+    const llvm::fltSemantics &sem = llvm::APFloatBase::EnumToSemantics(        \
+        static_cast<llvm::APFloatBase::Semantics>(semantics));                 \
+    unsigned bitWidth = llvm::APFloatBase::semanticsSizeInBits(sem);           \
+    llvm::APFloat lhs(sem, llvm::APInt(bitWidth, a));                          \
+    llvm::APFloat rhs(sem, llvm::APInt(bitWidth, b));                          \
+    lhs.OP(rhs);                                                               \
+    return lhs.bitcastToAPInt().getZExtValue();                                \
+  }
+
+/// Binary operations with rounding mode.
+#define APFLOAT_BINARY_OP_ROUNDING_MODE(OP, ROUNDING_MODE)                     \
+  MLIR_APFLOAT_WRAPPERS_EXPORT int64_t _mlir_apfloat_##OP(                     \
+      int32_t semantics, uint64_t a, uint64_t b) {                             \
+    const llvm::fltSemantics &sem = llvm::APFloatBase::EnumToSemantics(        \
+        static_cast<llvm::APFloatBase::Semantics>(semantics));                 \
+    unsigned bitWidth = llvm::APFloatBase::semanticsSizeInBits(sem);           \
+    llvm::APFloat lhs(sem, llvm::APInt(bitWidth, a));                          \
+    llvm::APFloat rhs(sem, llvm::APInt(bitWidth, b));                          \
+    lhs.OP(rhs, ROUNDING_MODE);                                                \
+    return lhs.bitcastToAPInt().getZExtValue();                                \
+  }
+
+extern "C" {
+
+#define BIN_OPS_WITH_ROUNDING(X)                                               \
+  X(add, llvm::RoundingMode::NearestTiesToEven)                                \
+  X(subtract, llvm::RoundingMode::NearestTiesToEven)                           \
+  X(multiply, llvm::RoundingMode::NearestTiesToEven)                           \
+  X(divide, llvm::RoundingMode::NearestTiesToEven)
+
+BIN_OPS_WITH_ROUNDING(APFLOAT_BINARY_OP_ROUNDING_MODE)
+#undef BIN_OPS_WITH_ROUNDING
+#undef APFLOAT_BINARY_OP_ROUNDING_MODE
+
+APFLOAT_BINARY_OP(remainder)
+
+#undef APFLOAT_BINARY_OP
+
+MLIR_APFLOAT_WRAPPERS_EXPORT void printApFloat(int32_t semantics, uint64_t a) {
+  const llvm::fltSemantics &sem = llvm::APFloatBase::EnumToSemantics(
+      static_cast<llvm::APFloatBase::Semantics>(semantics));
+  unsigned bitWidth = llvm::APFloatBase::semanticsSizeInBits(sem);
+  llvm::APFloat x(sem, llvm::APInt(bitWidth, a));
+  double d = x.convertToDouble();
+  fprintf(stdout, "%lg", d);
+}
+}

diff  --git a/mlir/lib/ExecutionEngine/CMakeLists.txt b/mlir/lib/ExecutionEngine/CMakeLists.txt
index fdeb4dacf9278..8c09e50e4de7b 100644
--- a/mlir/lib/ExecutionEngine/CMakeLists.txt
+++ b/mlir/lib/ExecutionEngine/CMakeLists.txt
@@ -2,6 +2,7 @@
 # is a big dependency which most don't need.
 
 set(LLVM_OPTIONAL_SOURCES
+  APFloatWrappers.cpp
   ArmRunnerUtils.cpp
   ArmSMEStubs.cpp
   AsyncRuntime.cpp
@@ -167,6 +168,15 @@ if(LLVM_ENABLE_PIC)
   set_property(TARGET mlir_float16_utils PROPERTY CXX_STANDARD 17)
   target_compile_definitions(mlir_float16_utils PRIVATE mlir_float16_utils_EXPORTS)
 
+  add_mlir_library(mlir_apfloat_wrappers
+    SHARED
+    APFloatWrappers.cpp
+
+    EXCLUDE_FROM_LIBMLIR
+    )
+  set_property(TARGET mlir_apfloat_wrappers PROPERTY CXX_STANDARD 17)
+  target_compile_definitions(mlir_apfloat_wrappers PRIVATE mlir_apfloat_wrappers_EXPORTS)
+
   add_subdirectory(SparseTensor)
 
   add_mlir_library(mlir_c_runner_utils
@@ -177,6 +187,7 @@ if(LLVM_ENABLE_PIC)
     EXCLUDE_FROM_LIBMLIR
 
     LINK_LIBS PUBLIC
+    mlir_apfloat_wrappers
     mlir_float16_utils
     MLIRSparseTensorEnums
     MLIRSparseTensorRuntime
@@ -191,6 +202,7 @@ if(LLVM_ENABLE_PIC)
     EXCLUDE_FROM_LIBMLIR
 
     LINK_LIBS PUBLIC
+    mlir_apfloat_wrappers
     mlir_float16_utils
   )
   target_compile_definitions(mlir_runner_utils PRIVATE mlir_runner_utils_EXPORTS)

diff  --git a/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir b/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir
new file mode 100644
index 0000000000000..797f42c37a26f
--- /dev/null
+++ b/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir
@@ -0,0 +1,128 @@
+// RUN: mlir-opt %s --convert-arith-to-apfloat -split-input-file -verify-diagnostics | FileCheck %s
+
+// CHECK-LABEL:   func.func private @_mlir_apfloat_add(i32, i64, i64) -> i64
+
+// CHECK-LABEL:   func.func @foo() -> f8E4M3FN {
+// CHECK:           %[[CONSTANT_0:.*]] = arith.constant 2.250000e+00 : f8E4M3FN
+// CHECK:           return %[[CONSTANT_0]] : f8E4M3FN
+// CHECK:         }
+
+// CHECK-LABEL:   func.func @bar() -> f6E3M2FN {
+// CHECK:           %[[CONSTANT_0:.*]] = arith.constant 3.000000e+00 : f6E3M2FN
+// CHECK:           return %[[CONSTANT_0]] : f6E3M2FN
+// CHECK:         }
+
+// Illustrate that both f8E4M3FN and f6E3M2FN calling the same _mlir_apfloat_add is fine
+// because each gets its own semantics enum and gets bitcast/extui/trunci to its own width.
+// CHECK-LABEL:   func.func @full_example() {
+// CHECK:           %[[CONSTANT_0:.*]] = arith.constant 1.375000e+00 : f8E4M3FN
+// CHECK:           %[[VAL_0:.*]] = call @foo() : () -> f8E4M3FN
+// CHECK:           %[[BITCAST_0:.*]] = arith.bitcast %[[CONSTANT_0]] : f8E4M3FN to i8
+// CHECK:           %[[EXTUI_0:.*]] = arith.extui %[[BITCAST_0]] : i8 to i64
+// CHECK:           %[[BITCAST_1:.*]] = arith.bitcast %[[VAL_0]] : f8E4M3FN to i8
+// CHECK:           %[[EXTUI_1:.*]] = arith.extui %[[BITCAST_1]] : i8 to i64
+//                  // fltSemantics semantics for f8E4M3FN
+// CHECK:           %[[CONSTANT_1:.*]] = arith.constant 10 : i32
+// CHECK:           %[[VAL_1:.*]] = call @_mlir_apfloat_add(%[[CONSTANT_1]], %[[EXTUI_0]], %[[EXTUI_1]]) : (i32, i64, i64) -> i64
+// CHECK:           %[[TRUNCI_0:.*]] = arith.trunci %[[VAL_1]] : i64 to i8
+// CHECK:           %[[BITCAST_2:.*]] = arith.bitcast %[[TRUNCI_0]] : i8 to f8E4M3FN
+// CHECK:           vector.print %[[BITCAST_2]] : f8E4M3FN
+
+// CHECK:           %[[CONSTANT_2:.*]] = arith.constant 2.500000e+00 : f6E3M2FN
+// CHECK:           %[[VAL_2:.*]] = call @bar() : () -> f6E3M2FN
+// CHECK:           %[[BITCAST_3:.*]] = arith.bitcast %[[CONSTANT_2]] : f6E3M2FN to i6
+// CHECK:           %[[EXTUI_2:.*]] = arith.extui %[[BITCAST_3]] : i6 to i64
+// CHECK:           %[[BITCAST_4:.*]] = arith.bitcast %[[VAL_2]] : f6E3M2FN to i6
+// CHECK:           %[[EXTUI_3:.*]] = arith.extui %[[BITCAST_4]] : i6 to i64
+//                  // fltSemantics semantics for f6E3M2FN
+// CHECK:           %[[CONSTANT_3:.*]] = arith.constant 16 : i32
+// CHECK:           %[[VAL_3:.*]] = call @_mlir_apfloat_add(%[[CONSTANT_3]], %[[EXTUI_2]], %[[EXTUI_3]]) : (i32, i64, i64) -> i64
+// CHECK:           %[[TRUNCI_1:.*]] = arith.trunci %[[VAL_3]] : i64 to i6
+// CHECK:           %[[BITCAST_5:.*]] = arith.bitcast %[[TRUNCI_1]] : i6 to f6E3M2FN
+// CHECK:           vector.print %[[BITCAST_5]] : f6E3M2FN
+// CHECK:           return
+// CHECK:         }
+
+// Put rhs into separate function so that it won't be constant-folded.
+func.func @foo() -> f8E4M3FN {
+  %cst = arith.constant 2.2 : f8E4M3FN
+  return %cst : f8E4M3FN
+}
+
+func.func @bar() -> f6E3M2FN {
+  %cst = arith.constant 3.2 : f6E3M2FN
+  return %cst : f6E3M2FN
+}
+
+func.func @full_example() {
+  %a = arith.constant 1.4 : f8E4M3FN
+  %b = func.call @foo() : () -> (f8E4M3FN)
+  %c = arith.addf %a, %b : f8E4M3FN
+  vector.print %c : f8E4M3FN
+
+  %d = arith.constant 2.4 : f6E3M2FN
+  %e = func.call @bar() : () -> (f6E3M2FN)
+  %f = arith.addf %d, %e : f6E3M2FN
+  vector.print %f : f6E3M2FN
+  return
+}
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_add(i32, i64, i64) -> i64
+// CHECK: %[[sem:.*]] = arith.constant 18 : i32
+// CHECK: call @_mlir_apfloat_add(%[[sem]], %{{.*}}, %{{.*}}) : (i32, i64, i64) -> i64
+func.func @addf(%arg0: f4E2M1FN, %arg1: f4E2M1FN) {
+  %0 = arith.addf %arg0, %arg1 : f4E2M1FN
+  return
+}
+
+// -----
+
+// Test decl collision (
diff erent type)
+// expected-error at +1{{matched function '_mlir_apfloat_add' but with 
diff erent type: '(i32, i32, f32) -> index' (expected '(i32, i64, i64) -> i64')}}
+func.func private @_mlir_apfloat_add(i32, i32, f32) -> index
+func.func @addf(%arg0: f4E2M1FN, %arg1: f4E2M1FN) {
+  %0 = arith.addf %arg0, %arg1 : f4E2M1FN
+  return
+}
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_subtract(i32, i64, i64) -> i64
+// CHECK: %[[sem:.*]] = arith.constant 18 : i32
+// CHECK: call @_mlir_apfloat_subtract(%[[sem]], %{{.*}}, %{{.*}}) : (i32, i64, i64) -> i64
+func.func @subf(%arg0: f4E2M1FN, %arg1: f4E2M1FN) {
+  %0 = arith.subf %arg0, %arg1 : f4E2M1FN
+  return
+}
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_multiply(i32, i64, i64) -> i64
+// CHECK: %[[sem:.*]] = arith.constant 18 : i32
+// CHECK: call @_mlir_apfloat_multiply(%[[sem]], %{{.*}}, %{{.*}}) : (i32, i64, i64) -> i64
+func.func @subf(%arg0: f4E2M1FN, %arg1: f4E2M1FN) {
+  %0 = arith.mulf %arg0, %arg1 : f4E2M1FN
+  return
+}
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_divide(i32, i64, i64) -> i64
+// CHECK: %[[sem:.*]] = arith.constant 18 : i32
+// CHECK: call @_mlir_apfloat_divide(%[[sem]], %{{.*}}, %{{.*}}) : (i32, i64, i64) -> i64
+func.func @subf(%arg0: f4E2M1FN, %arg1: f4E2M1FN) {
+  %0 = arith.divf %arg0, %arg1 : f4E2M1FN
+  return
+}
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_remainder(i32, i64, i64) -> i64
+// CHECK: %[[sem:.*]] = arith.constant 18 : i32
+// CHECK: call @_mlir_apfloat_remainder(%[[sem]], %{{.*}}, %{{.*}}) : (i32, i64, i64) -> i64
+func.func @remf(%arg0: f4E2M1FN, %arg1: f4E2M1FN) {
+  %0 = arith.remf %arg0, %arg1 : f4E2M1FN
+  return
+}

diff  --git a/mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir b/mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir
new file mode 100644
index 0000000000000..2768afe0834b5
--- /dev/null
+++ b/mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir
@@ -0,0 +1,36 @@
+// Case 1: All floating-point arithmetics is lowered through APFloat.
+// RUN: mlir-opt %s --convert-arith-to-apfloat --convert-to-llvm | \
+// RUN: mlir-runner -e entry --entry-point-result=void \
+// RUN:             --shared-libs=%mlir_c_runner_utils \
+// RUN:             --shared-libs=%mlir_apfloat_wrappers | FileCheck %s
+
+// Case 2: Only unsupported arithmetics (f8E4M3FN) is lowered through APFloat.
+//         Arithmetics on f32 is lowered directly to LLVM.
+// RUN: mlir-opt %s --convert-to-llvm --convert-arith-to-apfloat \
+// RUN:          --convert-to-llvm --reconcile-unrealized-casts | \
+// RUN: mlir-runner -e entry --entry-point-result=void \
+// RUN:             --shared-libs=%mlir_c_runner_utils \
+// RUN:             --shared-libs=%mlir_apfloat_wrappers | FileCheck %s
+
+// Put rhs into separate function so that it won't be constant-folded.
+func.func @foo() -> (f8E4M3FN, f32) {
+  %cst1 = arith.constant 2.2 : f8E4M3FN
+  %cst2 = arith.constant 2.2 : f32
+  return %cst1, %cst2 : f8E4M3FN, f32
+}
+
+func.func @entry() {
+  %a1 = arith.constant 1.4 : f8E4M3FN
+  %a2 = arith.constant 1.4 : f32
+  %b1, %b2 = func.call @foo() : () -> (f8E4M3FN, f32)
+  %c1 = arith.addf %a1, %b1 : f8E4M3FN  // not supported by LLVM
+  %c2 = arith.addf %a2, %b2 : f32       // supported by LLVM
+
+  // CHECK: 3.5
+  vector.print %c1 : f8E4M3FN
+
+  // CHECK: 3.6
+  vector.print %c2 : f32
+
+  return
+}

diff  --git a/mlir/test/lit.cfg.py b/mlir/test/lit.cfg.py
index 6ff12d66523f5..4a38ed605be0c 100644
--- a/mlir/test/lit.cfg.py
+++ b/mlir/test/lit.cfg.py
@@ -208,6 +208,7 @@ def find_real_python_interpreter():
     add_runtime("mlir_c_runner_utils"),
     add_runtime("mlir_async_runtime"),
     add_runtime("mlir_float16_utils"),
+    add_runtime("mlir_apfloat_wrappers"),
     "mlir-linalg-ods-yaml-gen",
     "mlir-reduce",
     "mlir-pdll",


        


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