[mlir][arith] Add support for `sitofp`, `uitofp` to `ArithToAPFloat` #169284

matthias-springer · 2025-11-24T07:03:50Z

Add support for arith.sitofp and arith.uitofp.

llvmbot · 2025-11-24T07:04:20Z

@llvm/pr-subscribers-mlir-arith

@llvm/pr-subscribers-mlir

Author: Matthias Springer (matthias-springer)

Changes

Add support for arith.sitofp and arith.uitofp.

Full diff: https://github.com/llvm/llvm-project/pull/169284.diff

4 Files Affected:

(modified) mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp (+70)
(modified) mlir/lib/ExecutionEngine/APFloatWrappers.cpp (+12)
(modified) mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir (+24)
(modified) mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir (+13)

diff --git a/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp b/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
index 1fe698f1c8902..0a37688246537 100644
--- a/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
+++ b/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
@@ -239,6 +239,72 @@ struct FpToIntConversion final : OpRewritePattern<OpTy> {
   bool isUnsigned;
 };
 
+template <typename OpTy>
+struct IntToFpConversion final : OpRewritePattern<OpTy> {
+  IntToFpConversion(MLIRContext *context, SymbolOpInterface symTable,
+                    bool isUnsigned, PatternBenefit benefit = 1)
+      : OpRewritePattern<OpTy>(context, benefit), symTable(symTable),
+        isUnsigned(isUnsigned){};
+
+  LogicalResult matchAndRewrite(OpTy op,
+                                PatternRewriter &rewriter) const override {
+    // Get APFloat function from runtime library.
+    auto i1Type = IntegerType::get(symTable->getContext(), 1);
+    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});
+    if (failed(fn))
+      return fn;
+
+    rewriter.setInsertionPoint(op);
+    // Cast operands to 64-bit integers.
+    Location loc = op.getLoc();
+    auto inIntTy = cast<IntegerType>(op.getOperand().getType());
+    auto int64Type = rewriter.getI64Type();
+    Value operandBits = op.getOperand();
+    if (operandBits.getType().getIntOrFloatBitWidth() < 64) {
+      if (isUnsigned) {
+        operandBits =
+            arith::ExtUIOp::create(rewriter, loc, int64Type, operandBits);
+      } else {
+        operandBits =
+            arith::ExtSIOp::create(rewriter, loc, int64Type, operandBits);
+      }
+    } else if (operandBits.getType().getIntOrFloatBitWidth() > 64) {
+      return rewriter.notifyMatchFailure(
+          loc, "integer bitwidth > 64 is not supported");
+    }
+
+    // Call APFloat function.
+    auto outFloatTy = cast<FloatType>(op.getType());
+    Value outSemValue = getSemanticsValue(rewriter, loc, outFloatTy);
+    Value inWidthValue = arith::ConstantOp::create(
+        rewriter, loc, i32Type,
+        rewriter.getIntegerAttr(i32Type, inIntTy.getWidth()));
+    Value isUnsignedValue = arith::ConstantOp::create(
+        rewriter, loc, i1Type, rewriter.getIntegerAttr(i1Type, isUnsigned));
+    SmallVector<Value> params = {outSemValue, inWidthValue, isUnsignedValue,
+                                 operandBits};
+    auto resultOp =
+        func::CallOp::create(rewriter, loc, TypeRange(rewriter.getI64Type()),
+                             SymbolRefAttr::get(*fn), params);
+
+    // Truncate result to the original width.
+    auto outIntWType = rewriter.getIntegerType(outFloatTy.getWidth());
+    Value truncatedBits = arith::TruncIOp::create(rewriter, loc, outIntWType,
+                                                  resultOp->getResult(0));
+    Value result =
+        arith::BitcastOp::create(rewriter, loc, outFloatTy, truncatedBits);
+    rewriter.replaceOp(op, result);
+    return success();
+  }
+
+  SymbolOpInterface symTable;
+  bool isUnsigned;
+};
+
 namespace {
 struct ArithToAPFloatConversionPass final
     : impl::ArithToAPFloatConversionPassBase<ArithToAPFloatConversionPass> {
@@ -266,6 +332,10 @@ void ArithToAPFloatConversionPass::runOnOperation() {
                                                    /*isUnsigned=*/false);
   patterns.add<FpToIntConversion<arith::FPToUIOp>>(context, getOperation(),
                                                    /*isUnsigned=*/true);
+  patterns.add<IntToFpConversion<arith::SIToFPOp>>(context, getOperation(),
+                                                   /*isUnsigned=*/false);
+  patterns.add<IntToFpConversion<arith::UIToFPOp>>(context, getOperation(),
+                                                   /*isUnsigned=*/true);
   LogicalResult result = success();
   ScopedDiagnosticHandler scopedHandler(context, [&result](Diagnostic &diag) {
     if (diag.getSeverity() == DiagnosticSeverity::Error) {
diff --git a/mlir/lib/ExecutionEngine/APFloatWrappers.cpp b/mlir/lib/ExecutionEngine/APFloatWrappers.cpp
index 632fe9cf2269d..2fbcc26200540 100644
--- a/mlir/lib/ExecutionEngine/APFloatWrappers.cpp
+++ b/mlir/lib/ExecutionEngine/APFloatWrappers.cpp
@@ -115,4 +115,16 @@ MLIR_APFLOAT_WRAPPERS_EXPORT uint64_t _mlir_apfloat_convert_to_int(
   val.convertToInteger(result, llvm::RoundingMode::NearestTiesToEven, &isExact);
   return result.getZExtValue();
 }
+
+MLIR_APFLOAT_WRAPPERS_EXPORT uint64_t _mlir_apfloat_convert_from_int(
+    int32_t semantics, int32_t inputWidth, bool isUnsigned, uint64_t a) {
+  llvm::APInt val(inputWidth, a, /*isSigned=*/!isUnsigned);
+  const llvm::fltSemantics &sem = llvm::APFloatBase::EnumToSemantics(
+      static_cast<llvm::APFloatBase::Semantics>(semantics));
+  llvm::APFloat result(sem);
+  // TODO: Custom rounding modes are not supported yet.
+  result.convertFromAPInt(val, /*IsSigned=*/!isUnsigned,
+                          llvm::RoundingMode::NearestTiesToEven);
+  return result.bitcastToAPInt().getZExtValue();
+}
 }
diff --git a/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir b/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir
index f1acfd5e5618a..d71d81dddcd4f 100644
--- a/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir
+++ b/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir
@@ -174,3 +174,27 @@ func.func @fptoui(%arg0: f16) {
   %0 = arith.fptoui %arg0 : f16 to i4
   return
 }
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_convert_from_int(i32, i32, i1, i64) -> i64
+// CHECK: %[[sem_out:.*]] = arith.constant 18 : i32
+// CHECK: %[[in_width:.*]] = arith.constant 32 : i32
+// CHECK: %[[is_unsigned:.*]] = arith.constant false
+// CHECK: %[[res:.*]] = call @_mlir_apfloat_convert_from_int(%[[sem_out]], %[[in_width]], %[[is_unsigned]], %{{.*}}) : (i32, i32, i1, i64) -> i64
+func.func @sitofp(%arg0: i32) {
+  %0 = arith.sitofp %arg0 : i32 to f4E2M1FN
+  return
+}
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_convert_from_int(i32, i32, i1, i64) -> i64
+// CHECK: %[[sem_out:.*]] = arith.constant 18 : i32
+// CHECK: %[[in_width:.*]] = arith.constant 32 : i32
+// CHECK: %[[is_unsigned:.*]] = arith.constant true
+// CHECK: %[[res:.*]] = call @_mlir_apfloat_convert_from_int(%[[sem_out]], %[[in_width]], %[[is_unsigned]], %{{.*}}) : (i32, i32, i1, i64) -> i64
+func.func @uitofp(%arg0: i32) {
+  %0 = arith.uitofp %arg0 : i32 to 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
index 5e93945c3eb60..8046610d479a8 100644
--- a/mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir
+++ b/mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir
@@ -53,5 +53,18 @@ func.func @entry() {
   %cvt_int_unsigned = arith.fptoui %cvt : f8E4M3FN to i2
   vector.print %cvt_int_unsigned : i2
 
+  // CHECK-NEXT: -6
+  // Bit pattern: 1...11110111, interpreted as signed: -9
+  // Closest f4E2M1FN value: -6.0
+  %c9 = arith.constant -9 : i16
+  %cvt_from_signed_int = arith.sitofp %c9 : i16 to f4E2M1FN
+  vector.print %cvt_from_signed_int : f4E2M1FN
+
+  // CHECK-NEXT: 6
+  // Bit pattern: 1...11110111, interpreted as unsigned: 65527
+  // Closest f4E2M1FN value: 6.0
+  %cvt_from_unsigned_int = arith.uitofp %c9 : i16 to f4E2M1FN
+  vector.print %cvt_from_unsigned_int : f4E2M1FN
+
   return
 }

llvmbot · 2025-11-24T07:04:20Z

@llvm/pr-subscribers-mlir-execution-engine

Author: Matthias Springer (matthias-springer)

Changes

Add support for arith.sitofp and arith.uitofp.

Full diff: https://github.com/llvm/llvm-project/pull/169284.diff

4 Files Affected:

(modified) mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp (+70)
(modified) mlir/lib/ExecutionEngine/APFloatWrappers.cpp (+12)
(modified) mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir (+24)
(modified) mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir (+13)

diff --git a/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp b/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
index 1fe698f1c8902..0a37688246537 100644
--- a/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
+++ b/mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp
@@ -239,6 +239,72 @@ struct FpToIntConversion final : OpRewritePattern<OpTy> {
   bool isUnsigned;
 };
 
+template <typename OpTy>
+struct IntToFpConversion final : OpRewritePattern<OpTy> {
+  IntToFpConversion(MLIRContext *context, SymbolOpInterface symTable,
+                    bool isUnsigned, PatternBenefit benefit = 1)
+      : OpRewritePattern<OpTy>(context, benefit), symTable(symTable),
+        isUnsigned(isUnsigned){};
+
+  LogicalResult matchAndRewrite(OpTy op,
+                                PatternRewriter &rewriter) const override {
+    // Get APFloat function from runtime library.
+    auto i1Type = IntegerType::get(symTable->getContext(), 1);
+    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});
+    if (failed(fn))
+      return fn;
+
+    rewriter.setInsertionPoint(op);
+    // Cast operands to 64-bit integers.
+    Location loc = op.getLoc();
+    auto inIntTy = cast<IntegerType>(op.getOperand().getType());
+    auto int64Type = rewriter.getI64Type();
+    Value operandBits = op.getOperand();
+    if (operandBits.getType().getIntOrFloatBitWidth() < 64) {
+      if (isUnsigned) {
+        operandBits =
+            arith::ExtUIOp::create(rewriter, loc, int64Type, operandBits);
+      } else {
+        operandBits =
+            arith::ExtSIOp::create(rewriter, loc, int64Type, operandBits);
+      }
+    } else if (operandBits.getType().getIntOrFloatBitWidth() > 64) {
+      return rewriter.notifyMatchFailure(
+          loc, "integer bitwidth > 64 is not supported");
+    }
+
+    // Call APFloat function.
+    auto outFloatTy = cast<FloatType>(op.getType());
+    Value outSemValue = getSemanticsValue(rewriter, loc, outFloatTy);
+    Value inWidthValue = arith::ConstantOp::create(
+        rewriter, loc, i32Type,
+        rewriter.getIntegerAttr(i32Type, inIntTy.getWidth()));
+    Value isUnsignedValue = arith::ConstantOp::create(
+        rewriter, loc, i1Type, rewriter.getIntegerAttr(i1Type, isUnsigned));
+    SmallVector<Value> params = {outSemValue, inWidthValue, isUnsignedValue,
+                                 operandBits};
+    auto resultOp =
+        func::CallOp::create(rewriter, loc, TypeRange(rewriter.getI64Type()),
+                             SymbolRefAttr::get(*fn), params);
+
+    // Truncate result to the original width.
+    auto outIntWType = rewriter.getIntegerType(outFloatTy.getWidth());
+    Value truncatedBits = arith::TruncIOp::create(rewriter, loc, outIntWType,
+                                                  resultOp->getResult(0));
+    Value result =
+        arith::BitcastOp::create(rewriter, loc, outFloatTy, truncatedBits);
+    rewriter.replaceOp(op, result);
+    return success();
+  }
+
+  SymbolOpInterface symTable;
+  bool isUnsigned;
+};
+
 namespace {
 struct ArithToAPFloatConversionPass final
     : impl::ArithToAPFloatConversionPassBase<ArithToAPFloatConversionPass> {
@@ -266,6 +332,10 @@ void ArithToAPFloatConversionPass::runOnOperation() {
                                                    /*isUnsigned=*/false);
   patterns.add<FpToIntConversion<arith::FPToUIOp>>(context, getOperation(),
                                                    /*isUnsigned=*/true);
+  patterns.add<IntToFpConversion<arith::SIToFPOp>>(context, getOperation(),
+                                                   /*isUnsigned=*/false);
+  patterns.add<IntToFpConversion<arith::UIToFPOp>>(context, getOperation(),
+                                                   /*isUnsigned=*/true);
   LogicalResult result = success();
   ScopedDiagnosticHandler scopedHandler(context, [&result](Diagnostic &diag) {
     if (diag.getSeverity() == DiagnosticSeverity::Error) {
diff --git a/mlir/lib/ExecutionEngine/APFloatWrappers.cpp b/mlir/lib/ExecutionEngine/APFloatWrappers.cpp
index 632fe9cf2269d..2fbcc26200540 100644
--- a/mlir/lib/ExecutionEngine/APFloatWrappers.cpp
+++ b/mlir/lib/ExecutionEngine/APFloatWrappers.cpp
@@ -115,4 +115,16 @@ MLIR_APFLOAT_WRAPPERS_EXPORT uint64_t _mlir_apfloat_convert_to_int(
   val.convertToInteger(result, llvm::RoundingMode::NearestTiesToEven, &isExact);
   return result.getZExtValue();
 }
+
+MLIR_APFLOAT_WRAPPERS_EXPORT uint64_t _mlir_apfloat_convert_from_int(
+    int32_t semantics, int32_t inputWidth, bool isUnsigned, uint64_t a) {
+  llvm::APInt val(inputWidth, a, /*isSigned=*/!isUnsigned);
+  const llvm::fltSemantics &sem = llvm::APFloatBase::EnumToSemantics(
+      static_cast<llvm::APFloatBase::Semantics>(semantics));
+  llvm::APFloat result(sem);
+  // TODO: Custom rounding modes are not supported yet.
+  result.convertFromAPInt(val, /*IsSigned=*/!isUnsigned,
+                          llvm::RoundingMode::NearestTiesToEven);
+  return result.bitcastToAPInt().getZExtValue();
+}
 }
diff --git a/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir b/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir
index f1acfd5e5618a..d71d81dddcd4f 100644
--- a/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir
+++ b/mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir
@@ -174,3 +174,27 @@ func.func @fptoui(%arg0: f16) {
   %0 = arith.fptoui %arg0 : f16 to i4
   return
 }
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_convert_from_int(i32, i32, i1, i64) -> i64
+// CHECK: %[[sem_out:.*]] = arith.constant 18 : i32
+// CHECK: %[[in_width:.*]] = arith.constant 32 : i32
+// CHECK: %[[is_unsigned:.*]] = arith.constant false
+// CHECK: %[[res:.*]] = call @_mlir_apfloat_convert_from_int(%[[sem_out]], %[[in_width]], %[[is_unsigned]], %{{.*}}) : (i32, i32, i1, i64) -> i64
+func.func @sitofp(%arg0: i32) {
+  %0 = arith.sitofp %arg0 : i32 to f4E2M1FN
+  return
+}
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_convert_from_int(i32, i32, i1, i64) -> i64
+// CHECK: %[[sem_out:.*]] = arith.constant 18 : i32
+// CHECK: %[[in_width:.*]] = arith.constant 32 : i32
+// CHECK: %[[is_unsigned:.*]] = arith.constant true
+// CHECK: %[[res:.*]] = call @_mlir_apfloat_convert_from_int(%[[sem_out]], %[[in_width]], %[[is_unsigned]], %{{.*}}) : (i32, i32, i1, i64) -> i64
+func.func @uitofp(%arg0: i32) {
+  %0 = arith.uitofp %arg0 : i32 to 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
index 5e93945c3eb60..8046610d479a8 100644
--- a/mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir
+++ b/mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir
@@ -53,5 +53,18 @@ func.func @entry() {
   %cvt_int_unsigned = arith.fptoui %cvt : f8E4M3FN to i2
   vector.print %cvt_int_unsigned : i2
 
+  // CHECK-NEXT: -6
+  // Bit pattern: 1...11110111, interpreted as signed: -9
+  // Closest f4E2M1FN value: -6.0
+  %c9 = arith.constant -9 : i16
+  %cvt_from_signed_int = arith.sitofp %c9 : i16 to f4E2M1FN
+  vector.print %cvt_from_signed_int : f4E2M1FN
+
+  // CHECK-NEXT: 6
+  // Bit pattern: 1...11110111, interpreted as unsigned: 65527
+  // Closest f4E2M1FN value: 6.0
+  %cvt_from_unsigned_int = arith.uitofp %c9 : i16 to f4E2M1FN
+  vector.print %cvt_from_unsigned_int : f4E2M1FN
+
   return
 }

github-actions · 2025-11-24T07:05:33Z

✅ With the latest revision this PR passed the C/C++ code formatter.

mlir/lib/ExecutionEngine/APFloatWrappers.cpp

makslevental

LGTM!

…lvm#169284) Add support for `arith.sitofp` and `arith.uitofp`.

matthias-springer requested a review from makslevental November 24, 2025 07:03

matthias-springer requested a review from kuhar as a code owner November 24, 2025 07:03

llvmbot added mlir mlir:arith mlir:execution-engine labels Nov 24, 2025

makslevental reviewed Nov 24, 2025

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makslevental approved these changes Nov 25, 2025

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matthias-springer force-pushed the users/matthias-springer/apfloat_fp_to_int branch 3 times, most recently from eb5759f to 790e4bc Compare November 25, 2025 01:50

Base automatically changed from users/matthias-springer/apfloat_fp_to_int to main November 25, 2025 01:50

matthias-springer force-pushed the users/matthias-springer/apfloat_from_int branch from 3ab9d96 to 727c97c Compare November 25, 2025 01:51

[mlir][arith] Add support for sitofp, uitofp to ArithToAPFloat

0737431

matthias-springer force-pushed the users/matthias-springer/apfloat_from_int branch from 727c97c to 0737431 Compare November 25, 2025 01:53

matthias-springer merged commit 6ec6867 into main Nov 25, 2025
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matthias-springer deleted the users/matthias-springer/apfloat_from_int branch November 25, 2025 02:31

aadeshps-mcw pushed a commit to aadeshps-mcw/llvm-project that referenced this pull request Nov 26, 2025

[mlir][arith] Add support for sitofp, uitofp to ArithToAPFloat (l…

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[mlir][arith] Add support for `sitofp`, `uitofp` to `ArithToAPFloat` #169284

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