[flang-commits] [flang] [flang] Implement `acospi` (PR #150234)

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https://github.com/c8ef updated https://github.com/llvm/llvm-project/pull/150234

>From 9a58d28eb8c865ff722ea860170b54cc16d74f39 Mon Sep 17 00:00:00 2001
From: c8ef <c8ef at outlook.com>
Date: Wed, 23 Jul 2025 15:05:18 +0000
Subject: [PATCH] [flang] Implement `acospi`

---
 .../flang/Optimizer/Builder/IntrinsicCall.h   |  1 +
 flang/lib/Evaluate/intrinsics.cpp             |  1 +
 flang/lib/Optimizer/Builder/IntrinsicCall.cpp | 16 ++++++++++++
 flang/test/Lower/Intrinsics/acospi.f90        | 26 +++++++++++++++++++
 4 files changed, 44 insertions(+)
 create mode 100644 flang/test/Lower/Intrinsics/acospi.f90

diff --git a/flang/include/flang/Optimizer/Builder/IntrinsicCall.h b/flang/include/flang/Optimizer/Builder/IntrinsicCall.h
index ab08415fe32c8..a93b397240576 100644
--- a/flang/include/flang/Optimizer/Builder/IntrinsicCall.h
+++ b/flang/include/flang/Optimizer/Builder/IntrinsicCall.h
@@ -174,6 +174,7 @@ struct IntrinsicLibrary {
   /// real and to the `hypot` math routine if the argument is of complex type.
   mlir::Value genAbs(mlir::Type, llvm::ArrayRef<mlir::Value>);
   mlir::Value genAcosd(mlir::Type, llvm::ArrayRef<mlir::Value>);
+  mlir::Value genAcospi(mlir::Type, llvm::ArrayRef<mlir::Value>);
   template <void (*CallRuntime)(fir::FirOpBuilder &, mlir::Location loc,
                                 mlir::Value, mlir::Value)>
   fir::ExtendedValue genAdjustRtCall(mlir::Type,
diff --git a/flang/lib/Evaluate/intrinsics.cpp b/flang/lib/Evaluate/intrinsics.cpp
index 9c6d49dfda3e8..97e87935c02b0 100644
--- a/flang/lib/Evaluate/intrinsics.cpp
+++ b/flang/lib/Evaluate/intrinsics.cpp
@@ -340,6 +340,7 @@ static const IntrinsicInterface genericIntrinsicFunction[]{
     {"acos", {{"x", SameFloating}}, SameFloating},
     {"acosd", {{"x", SameFloating}}, SameFloating},
     {"acosh", {{"x", SameFloating}}, SameFloating},
+    {"acospi", {{"x", SameFloating}}, SameFloating},
     {"adjustl", {{"string", SameChar}}, SameChar},
     {"adjustr", {{"string", SameChar}}, SameChar},
     {"aimag", {{"z", SameComplex}}, SameReal},
diff --git a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
index ba298298be675..f3af423b24685 100644
--- a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
+++ b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
@@ -246,6 +246,7 @@ static constexpr IntrinsicHandler handlers[]{
     {"abs", &I::genAbs},
     {"achar", &I::genChar},
     {"acosd", &I::genAcosd},
+    {"acospi", &I::genAcospi},
     {"adjustl",
      &I::genAdjustRtCall<fir::runtime::genAdjustL>,
      {{{"string", asAddr}}},
@@ -2676,6 +2677,21 @@ mlir::Value IntrinsicLibrary::genAcosd(mlir::Type resultType,
   return mlir::arith::MulFOp::create(builder, loc, result, factor);
 }
 
+// ACOSPI
+mlir::Value IntrinsicLibrary::genAcospi(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()});
+  mlir::Value acos = getRuntimeCallGenerator("acos", ftype)(builder, loc, args);
+  llvm::APFloat inv_pi = llvm::APFloat(llvm::numbers::inv_pi);
+  mlir::Value dfactor =
+      builder.createRealConstant(loc, mlir::Float64Type::get(context), inv_pi);
+  mlir::Value factor = builder.createConvert(loc, resultType, dfactor);
+  return mlir::arith::MulFOp::create(builder, loc, acos, factor);
+}
+
 // ADJUSTL & ADJUSTR
 template <void (*CallRuntime)(fir::FirOpBuilder &, mlir::Location loc,
                               mlir::Value, mlir::Value)>
diff --git a/flang/test/Lower/Intrinsics/acospi.f90 b/flang/test/Lower/Intrinsics/acospi.f90
new file mode 100644
index 0000000000000..dcacd25bca480
--- /dev/null
+++ b/flang/test/Lower/Intrinsics/acospi.f90
@@ -0,0 +1,26 @@
+! RUN: bbc -emit-fir -hlfir=false %s -o - | FileCheck %s --check-prefixes="CHECK,CHECK-FAST"
+! RUN: bbc --math-runtime=precise -emit-fir -hlfir=false %s -o - | FileCheck %s --check-prefixes="CHECK,CHECK-PRECISE"
+! RUN: %flang_fc1 -emit-fir -flang-deprecated-no-hlfir %s -o - | FileCheck %s --check-prefixes="CHECK,CHECK-FAST"
+
+function test_real4(x)
+  real :: x, test_real4
+  test_real4 = acospi(x)
+end function
+
+! CHECK-LABEL: @_QPtest_real4
+! CHECK-PRECISE: %[[acos:.*]] = fir.call @acosf({{%[A-Za-z0-9._]+}}) fastmath<contract> : (f32) -> f32
+! CHECK-FAST: %[[acos:.*]] = math.acos %{{.*}} : f32
+! CHECK: %[[dpi:.*]] = arith.constant 0.31830988618379069 : f64
+! CHECK: %[[inv_pi:.*]] = fir.convert %[[dpi]] : (f64) -> f32
+! CHECK: %{{.*}} = arith.mulf %[[acos]], %[[inv_pi]] fastmath<contract> : f32
+
+function test_real8(x)
+  real(8) :: x, test_real8
+  test_real8 = acospi(x)
+end function
+
+! CHECK-LABEL: @_QPtest_real8
+! CHECK-PRECISE: %[[acos:.*]] = fir.call @acos({{%[A-Za-z0-9._]+}}) fastmath<contract> : (f64) -> f64
+! CHECK-FAST: %[[acos:.*]] = math.acos %{{.*}} : f64
+! CHECK: %[[inv_pi:.*]] = arith.constant 0.31830988618379069 : f64
+! CHECK: %{{.*}} = arith.mulf %[[acos]], %[[inv_pi]] fastmath<contract> : f64