[clang] [CIR] Upstream FPToFPBuiltin ATanOp (PR #157496)

[Amr Hesham via cfe-commits]

https://github.com/AmrDeveloper created https://github.com/llvm/llvm-project/pull/157496

Upstream support for FPToFPBuiltin ATanOp

>From baccdc42c8c4046788fa364dcc71780bfd6c9ab0 Mon Sep 17 00:00:00 2001
From: AmrDeveloper <amr96 at programmer.net>
Date: Sun, 7 Sep 2025 22:30:39 +0200
Subject: [PATCH] [CIR] Upstream FPToFPBuiltin ATanOp

---
 clang/include/clang/CIR/Dialect/IR/CIROps.td  | 10 +++++++
 clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp       |  2 ++
 .../CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp | 10 +++++++
 .../CIR/Lowering/DirectToLLVM/LowerToLLVM.h   |  9 +++++++
 clang/test/CIR/CodeGen/builtins-elementwise.c | 26 +++++++++++++++++++
 5 files changed, 57 insertions(+)

diff --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td b/clang/include/clang/CIR/Dialect/IR/CIROps.td
index 4592078af966b..cd63f0ea63f46 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIROps.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIROps.td
@@ -3808,6 +3808,16 @@ def CIR_ACosOp : CIR_UnaryFPToFPBuiltinOp<"acos", "ACosOp"> {
   }];
 }
 
+def CIR_ATanOp : CIR_UnaryFPToFPBuiltinOp<"atan", "ATanOp"> {
+  let summary = "Computes the floating-point arcus tangent value";
+  let description = [{
+    `cir.atan` computes the arcus tangent of a floating-point operand
+    and returns a result of the same type.
+
+    Floating-point exceptions are ignored, and it does not set `errno`.
+  }];
+}
+
 def CIR_FAbsOp : CIR_UnaryFPToFPBuiltinOp<"fabs", "FAbsOp"> {
   let summary = "Computes the floating-point absolute value";
   let description = [{
diff --git a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
index b68e91f64dc84..2d14850b4440d 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
@@ -360,6 +360,8 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl &gd, unsigned builtinID,
 
   case Builtin::BI__builtin_elementwise_acos:
     return emitUnaryFPBuiltin<cir::ACosOp>(*this, *e);
+  case Builtin::BI__builtin_elementwise_atan:
+    return emitUnaryFPBuiltin<cir::ATanOp>(*this, *e);
   }
 
   // If this is an alias for a lib function (e.g. __builtin_sin), emit
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
index ee9f58c829ca9..4599e39c1b6b7 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
@@ -1050,6 +1050,15 @@ mlir::LogicalResult CIRToLLVMBaseClassAddrOpLowering::matchAndRewrite(
   return mlir::success();
 }
 
+mlir::LogicalResult CIRToLLVMATanOpLowering::matchAndRewrite(
+    cir::ATanOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  mlir::Type resTy = typeConverter->convertType(op.getType());
+  rewriter.replaceOpWithNewOp<mlir::LLVM::ATanOp>(op, resTy,
+                                                  adaptor.getOperands()[0]);
+  return mlir::success();
+}
+
 mlir::LogicalResult CIRToLLVMAllocaOpLowering::matchAndRewrite(
     cir::AllocaOp op, OpAdaptor adaptor,
     mlir::ConversionPatternRewriter &rewriter) const {
@@ -2431,6 +2440,7 @@ void ConvertCIRToLLVMPass::runOnOperation() {
                CIRToLLVMAssumeAlignedOpLowering,
                CIRToLLVMAssumeSepStorageOpLowering,
                CIRToLLVMBaseClassAddrOpLowering,
+               CIRToLLVMATanOpLowering,
                CIRToLLVMBinOpLowering,
                CIRToLLVMBitClrsbOpLowering,
                CIRToLLVMBitClzOpLowering,
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h
index 2c2aede09b0b2..3c2bcfc978589 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h
@@ -736,6 +736,15 @@ class CIRToLLVMACosOpLowering : public mlir::OpConversionPattern<cir::ACosOp> {
                   mlir::ConversionPatternRewriter &) const override;
 };
 
+class CIRToLLVMATanOpLowering : public mlir::OpConversionPattern<cir::ATanOp> {
+public:
+  using mlir::OpConversionPattern<cir::ATanOp>::OpConversionPattern;
+
+  mlir::LogicalResult
+  matchAndRewrite(cir::ATanOp op, OpAdaptor,
+                  mlir::ConversionPatternRewriter &) const override;
+};
+
 class CIRToLLVMInlineAsmOpLowering
     : public mlir::OpConversionPattern<cir::InlineAsmOp> {
   mlir::DataLayout const &dataLayout;
diff --git a/clang/test/CIR/CodeGen/builtins-elementwise.c b/clang/test/CIR/CodeGen/builtins-elementwise.c
index 1898f56a33628..2555c47e76757 100644
--- a/clang/test/CIR/CodeGen/builtins-elementwise.c
+++ b/clang/test/CIR/CodeGen/builtins-elementwise.c
@@ -36,3 +36,29 @@ void test_builtin_elementwise_acos(float f, double d, vfloat4 vf4,
   vd4 = __builtin_elementwise_acos(vd4);
 }
 
+void test_builtin_elementwise_atan(float f, double d, vfloat4 vf4,
+  vdouble4  vd4) {
+  // CIR-LABEL: test_builtin_elementwise_atan
+  // LLVM-LABEL: test_builtin_elementwise_atan
+  // OGCG-LABEL: test_builtin_elementwise_atan
+
+  // CIR: %{{.*}} = cir.atan %{{.*}} : !cir.float
+  // LLVM: %{{.*}} = call float @llvm.atan.f32(float %{{.*}})
+  // OGCG: %{{.*}} = call float @llvm.atan.f32(float %{{.*}})
+  f = __builtin_elementwise_atan(f);
+
+  // CIR: %{{.*}} = cir.atan %{{.*}} : !cir.double
+  // LLVM: %{{.*}} = call double @llvm.atan.f64(double %{{.*}})
+  // OGCG: %{{.*}} = call double @llvm.atan.f64(double %{{.*}})
+  d = __builtin_elementwise_atan(d);
+
+  // CIR: %{{.*}} = cir.atan %{{.*}} : !cir.vector<4 x !cir.float>
+  // LLVM: %{{.*}} = call <4 x float> @llvm.atan.v4f32(<4 x float> %{{.*}})
+  // OGCG: %{{.*}} = call <4 x float> @llvm.atan.v4f32(<4 x float> %{{.*}})
+  vf4 = __builtin_elementwise_atan(vf4);
+
+  // CIR: %{{.*}} = cir.atan %{{.*}} : !cir.vector<4 x !cir.double>
+  // LLVM: %{{.*}} = call <4 x double> @llvm.atan.v4f64(<4 x double> %{{.*}})
+  // OGCG: %{{.*}} = call <4 x double> @llvm.atan.v4f64(<4 x double> %{{.*}})
+  vd4 = __builtin_elementwise_atan(vd4);
+}