[flang-commits] [flang] [flang] Implement `COSPI` (PR #149343)

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https://github.com/c8ef created https://github.com/llvm/llvm-project/pull/149343

This feature is added in the Fortran 2023 standard.

>From 6b2da588c8a286881fbcc8053f62dba749192445 Mon Sep 17 00:00:00 2001
From: c8ef <c8ef at outlook.com>
Date: Thu, 17 Jul 2025 15:49:22 +0000
Subject: [PATCH] implement cospi for flang

---
 .../flang/Optimizer/Builder/IntrinsicCall.h   |  1 +
 flang/lib/Evaluate/intrinsics.cpp             |  1 +
 flang/lib/Optimizer/Builder/IntrinsicCall.cpp | 16 ++++++++++++++
 flang/test/Lower/Intrinsics/cospi.f90         | 22 +++++++++++++++++++
 4 files changed, 40 insertions(+)
 create mode 100644 flang/test/Lower/Intrinsics/cospi.f90

diff --git a/flang/include/flang/Optimizer/Builder/IntrinsicCall.h b/flang/include/flang/Optimizer/Builder/IntrinsicCall.h
index 01801dbdaffca..acdba7c49e6b3 100644
--- a/flang/include/flang/Optimizer/Builder/IntrinsicCall.h
+++ b/flang/include/flang/Optimizer/Builder/IntrinsicCall.h
@@ -245,6 +245,7 @@ struct IntrinsicLibrary {
   fir::ExtendedValue genCPtrCompare(mlir::Type,
                                     llvm::ArrayRef<fir::ExtendedValue>);
   mlir::Value genCosd(mlir::Type, llvm::ArrayRef<mlir::Value>);
+  mlir::Value genCospi(mlir::Type, llvm::ArrayRef<mlir::Value>);
   void genDateAndTime(llvm::ArrayRef<fir::ExtendedValue>);
   mlir::Value genDim(mlir::Type, llvm::ArrayRef<mlir::Value>);
   fir::ExtendedValue genDotProduct(mlir::Type,
diff --git a/flang/lib/Evaluate/intrinsics.cpp b/flang/lib/Evaluate/intrinsics.cpp
index 4773e136c41cb..9957010684d48 100644
--- a/flang/lib/Evaluate/intrinsics.cpp
+++ b/flang/lib/Evaluate/intrinsics.cpp
@@ -428,6 +428,7 @@ static const IntrinsicInterface genericIntrinsicFunction[]{
     {"conjg", {{"z", SameComplex}}, SameComplex},
     {"cos", {{"x", SameFloating}}, SameFloating},
     {"cosd", {{"x", SameFloating}}, SameFloating},
+    {"cospi", {{"x", SameFloating}}, SameFloating},
     {"cosh", {{"x", SameFloating}}, SameFloating},
     {"coshape", {{"coarray", AnyData, Rank::coarray}, SizeDefaultKIND}, KINDInt,
         Rank::vector, IntrinsicClass::inquiryFunction},
diff --git a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
index 7aa5602d2bc84..d77a656158a37 100644
--- a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
+++ b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
@@ -396,6 +396,7 @@ static constexpr IntrinsicHandler handlers[]{
     {"command_argument_count", &I::genCommandArgumentCount},
     {"conjg", &I::genConjg},
     {"cosd", &I::genCosd},
+    {"cospi", &I::genCospi},
     {"count",
      &I::genCount,
      {{{"mask", asAddr}, {"dim", asValue}, {"kind", asValue}}},
@@ -3623,6 +3624,21 @@ mlir::Value IntrinsicLibrary::genCosd(mlir::Type resultType,
   return getRuntimeCallGenerator("cos", ftype)(builder, loc, {arg});
 }
 
+// COSPI
+mlir::Value IntrinsicLibrary::genCospi(mlir::Type resultType,
+                                       llvm::ArrayRef<mlir::Value> args) {
+  assert(args.size() == 1);
+  mlir::MLIRContext *context = builder.getContext();
+  mlir::FunctionType ftype =
+      mlir::FunctionType::get(context, {resultType}, {args[0].getType()});
+  llvm::APFloat pi = llvm::APFloat(llvm::numbers::pi);
+  mlir::Value dfactor =
+      builder.createRealConstant(loc, mlir::Float64Type::get(context), pi);
+  mlir::Value factor = builder.createConvert(loc, args[0].getType(), dfactor);
+  mlir::Value arg = builder.create<mlir::arith::MulFOp>(loc, args[0], factor);
+  return getRuntimeCallGenerator("cos", ftype)(builder, loc, {arg});
+}
+
 // COUNT
 fir::ExtendedValue
 IntrinsicLibrary::genCount(mlir::Type resultType,
diff --git a/flang/test/Lower/Intrinsics/cospi.f90 b/flang/test/Lower/Intrinsics/cospi.f90
new file mode 100644
index 0000000000000..894002566141b
--- /dev/null
+++ b/flang/test/Lower/Intrinsics/cospi.f90
@@ -0,0 +1,22 @@
+! RUN: %flang_fc1 -emit-fir %s -o - | FileCheck %s --check-prefixes="CHECK"
+
+function test_real4(x)
+  real :: x, test_real4
+  test_real4 = cospi(x)
+end function
+
+! CHECK-LABEL: @_QPtest_real4
+! CHECK: %[[dfactor:.*]] = arith.constant 3.1415926535897931 : f64
+! CHECK: %[[factor:.*]] = fir.convert %[[dfactor]] : (f64) -> f32
+! CHECK: %[[mul:.*]] = arith.mulf %{{.*}}, %[[factor]] fastmath<contract> : f32
+! CHECK: %[[cos:.*]] = math.cos %[[mul]] fastmath<contract> : f32
+
+function test_real8(x)
+  real(8) :: x, test_real8
+  test_real8 = cospi(x)
+end function
+
+! CHECK-LABEL: @_QPtest_real8
+! CHECK: %[[dfactor:.*]] = arith.constant 3.1415926535897931 : f64
+! CHECK: %[[mul:.*]] = arith.mulf %{{.*}}, %[[dfactor]] fastmath<contract> : f64
+! CHECK: %[[cos:.*]] = math.cos %[[mul]] fastmath<contract> : f64