[Mlir-commits] [mlir] [mlir][arith] Add rounding mode support for 'remf' operation (PR #194126)

[llvmlistbot at llvm.org]

https://github.com/worthlane created https://github.com/llvm/llvm-project/pull/194126

None

>From 07c282d8d793eb3894fbc472573efe98b03cca4d Mon Sep 17 00:00:00 2001
From: Artem Maklakov <art.maklakov28 at gmail.com>
Date: Sat, 25 Apr 2026 11:46:49 +0300
Subject: [PATCH] [mlir][arith] Add rounding mode support for 'remf' operation

---
 mlir/include/mlir/Dialect/Arith/IR/ArithOps.td      |  4 +---
 mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp     | 11 ++++++++---
 mlir/test/Conversion/ArithToLLVM/arith-to-llvm.mlir | 11 +++++++++++
 mlir/test/Dialect/Arith/ops.mlir                    |  4 +++-
 4 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/mlir/include/mlir/Dialect/Arith/IR/ArithOps.td b/mlir/include/mlir/Dialect/Arith/IR/ArithOps.td
index ba9ccb6a01d66..375190a07b169 100644
--- a/mlir/include/mlir/Dialect/Arith/IR/ArithOps.td
+++ b/mlir/include/mlir/Dialect/Arith/IR/ArithOps.td
@@ -1273,13 +1273,11 @@ def Arith_DivFOp : Arith_FloatBinaryOpWithRoundingMode<"divf"> {
 // RemFOp
 //===----------------------------------------------------------------------===//
 
-def Arith_RemFOp : Arith_FloatBinaryOp<"remf"> {
+def Arith_RemFOp : Arith_FloatBinaryOpWithRoundingMode<"remf"> {
   let summary = "floating point division remainder operation";
   let description = [{
     Returns the floating point division remainder.
     The remainder has the same sign as the dividend (lhs operand).
-
-    TODO: Add support for rounding modes.
   }];
   let hasFolder = 1;
 }
diff --git a/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp b/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp
index 2624420cf5318..30f32b8e248f4 100644
--- a/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp
+++ b/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp
@@ -170,9 +170,13 @@ using NegFOpLowering =
                                /*FailOnUnsupportedFP=*/true>;
 using OrIOpLowering = VectorConvertToLLVMPattern<arith::OrIOp, LLVM::OrOp>;
 using RemFOpLowering =
-    VectorConvertToLLVMPattern<arith::RemFOp, LLVM::FRemOp,
-                               arith::AttrConvertFastMathToLLVM,
-                               /*FailOnUnsupportedFP=*/true>;
+    ConstrainedVectorConvertToLLVMPattern<arith::RemFOp, LLVM::FRemOp,
+                                          /*HasRoundingMode=*/false,
+                                          arith::AttrConvertFastMathToLLVM,
+                                          /*FailOnUnsupportedFP=*/true>;
+using ConstrainedRemFOpLowering = ConstrainedVectorConvertToLLVMPattern<
+    arith::RemFOp, LLVM::ConstrainedFRemIntr, /*HasRoundingMode=*/true,
+    arith::AttrConverterConstrainedFPToLLVM, /*FailOnUnsupportedFP=*/true>;
 using RemSIOpLowering =
     VectorConvertToLLVMPattern<arith::RemSIOp, LLVM::SRemOp>;
 using RemUIOpLowering =
@@ -760,6 +764,7 @@ void mlir::arith::populateArithToLLVMConversionPatterns(
     NegFOpLowering,
     OrIOpLowering,
     RemFOpLowering,
+    ConstrainedRemFOpLowering,
     RemSIOpLowering,
     RemUIOpLowering,
     SelectOpLowering,
diff --git a/mlir/test/Conversion/ArithToLLVM/arith-to-llvm.mlir b/mlir/test/Conversion/ArithToLLVM/arith-to-llvm.mlir
index df58d4ffcaf51..d1e10ea42d19f 100644
--- a/mlir/test/Conversion/ArithToLLVM/arith-to-llvm.mlir
+++ b/mlir/test/Conversion/ArithToLLVM/arith-to-llvm.mlir
@@ -451,6 +451,17 @@ func.func @experimental_constrained_divf(%arg0 : f64, %arg1 : f64) {
 
 // -----
 
+// CHECK-LABEL: experimental_constrained_remf
+func.func @experimental_constrained_remf(%arg0 : f64, %arg1 : f64) {
+// CHECK-NEXT: = llvm.intr.experimental.constrained.frem %arg0, %arg1 tonearest ignore
+  %0 = arith.remf %arg0, %arg1 to_nearest_even : f64
+// CHECK-NEXT: = llvm.intr.experimental.constrained.frem %arg0, %arg1 tonearestaway ignore
+  %1 = arith.remf %arg0, %arg1 to_nearest_away : f64
+  return
+}
+
+// -----
+
 // Verify that fastmath flags are stripped when lowering to constrained
 // intrinsics (constrained FP and fastmath are contradictory).
 // CHECK-LABEL: constrained_addf_with_fastmath
diff --git a/mlir/test/Dialect/Arith/ops.mlir b/mlir/test/Dialect/Arith/ops.mlir
index 059e35c384dac..21d9cd364f720 100644
--- a/mlir/test/Dialect/Arith/ops.mlir
+++ b/mlir/test/Dialect/Arith/ops.mlir
@@ -1276,8 +1276,10 @@ func.func @roundingmode(%arg0: f32, %arg1: f32) {
   %2 = arith.mulf %arg0, %arg1 upward : f32
 // CHECK: {{.*}} = arith.divf %arg0, %arg1 toward_zero : f32
   %3 = arith.divf %arg0, %arg1 toward_zero : f32
+// CHECK: {{.*}} = arith.remf %arg0, %arg1 toward_zero : f32
+  %4 = arith.remf %arg0, %arg1 toward_zero : f32
 // CHECK: {{.*}} = arith.addf %arg0, %arg1 to_nearest_even fastmath<fast> : f32
-  %4 = arith.addf %arg0, %arg1 to_nearest_even fastmath<fast> : f32
+  %5 = arith.addf %arg0, %arg1 to_nearest_even fastmath<fast> : f32
   return
 }