[clang] [CIR] Upstream Builtin Exp2Op (PR #169152)

[Letu Ren via cfe-commits]

https://github.com/FantasqueX created https://github.com/llvm/llvm-project/pull/169152

None

>From 43d1ffab8b5a9067499a3ad6a047adb822bdedee Mon Sep 17 00:00:00 2001
From: Letu Ren <fantasquex at gmail.com>
Date: Sat, 22 Nov 2025 15:29:00 +0800
Subject: [PATCH] [CIR] Upstream Builtin Exp2Op

---
 clang/include/clang/CIR/Dialect/IR/CIROps.td  | 10 +++++++++
 clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp       | 11 ++++++++++
 .../CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp |  8 +++++++
 .../CIR/CodeGen/builtins-floating-point.c     | 21 +++++++++++++++++++
 4 files changed, 50 insertions(+)

diff --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td b/clang/include/clang/CIR/Dialect/IR/CIROps.td
index a19c4f951fff9..777b49434f119 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIROps.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIROps.td
@@ -4612,6 +4612,16 @@ def CIR_ExpOp : CIR_UnaryFPToFPBuiltinOp<"exp", "ExpOp"> {
   }];
 }
 
+def CIR_Exp2Op : CIR_UnaryFPToFPBuiltinOp<"exp2", "Exp2Op"> {
+  let summary = "Computes the floating-point base-2 exponential value";
+  let description = [{
+    `cir.exp2` computes the base-2 exponential 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 0c1f842829686..104bf541b345f 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
@@ -298,6 +298,17 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl &gd, unsigned builtinID,
     assert(!cir::MissingFeatures::fastMathFlags());
     return emitUnaryMaybeConstrainedFPBuiltin<cir::ExpOp>(*this, *e);
 
+  case Builtin::BIexp2:
+  case Builtin::BIexp2f:
+  case Builtin::BIexp2l:
+  case Builtin::BI__builtin_exp2:
+  case Builtin::BI__builtin_exp2f:
+  case Builtin::BI__builtin_exp2f16:
+  case Builtin::BI__builtin_exp2l:
+  case Builtin::BI__builtin_exp2f128:
+    assert(!cir::MissingFeatures::fastMathFlags());
+    return emitUnaryMaybeConstrainedFPBuiltin<cir::Exp2Op>(*this, *e);
+
   case Builtin::BIfabs:
   case Builtin::BIfabsf:
   case Builtin::BIfabsl:
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
index 6136d48204e0c..cd923a15af132 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
@@ -202,6 +202,14 @@ mlir::LogicalResult CIRToLLVMExpOpLowering::matchAndRewrite(
   return mlir::success();
 }
 
+mlir::LogicalResult CIRToLLVMExp2OpLowering::matchAndRewrite(
+    cir::Exp2Op op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  mlir::Type resTy = typeConverter->convertType(op.getType());
+  rewriter.replaceOpWithNewOp<mlir::LLVM::Exp2Op>(op, resTy, adaptor.getSrc());
+  return mlir::success();
+}
+
 static mlir::Value getLLVMIntCast(mlir::ConversionPatternRewriter &rewriter,
                                   mlir::Value llvmSrc, mlir::Type llvmDstIntTy,
                                   bool isUnsigned, uint64_t cirSrcWidth,
diff --git a/clang/test/CIR/CodeGen/builtins-floating-point.c b/clang/test/CIR/CodeGen/builtins-floating-point.c
index 1b7de650662c7..a4307c57b04b6 100644
--- a/clang/test/CIR/CodeGen/builtins-floating-point.c
+++ b/clang/test/CIR/CodeGen/builtins-floating-point.c
@@ -46,3 +46,24 @@ long double expl(long double f) {
   // LLVM: %{{.*}} = call fp128 @llvm.exp.f128(fp128 %{{.*}})
   // OGCG: %{{.*}} = call fp128 @llvm.exp.f128(fp128 %{{.*}})
 }
+
+float exp2f(float f) {
+  return __builtin_exp2f(f);
+  // CIR: %{{.*}} = cir.exp2 {{.*}} : !cir.float
+  // LLVM: %{{.*}} = call float @llvm.exp2.f32(float %{{.*}})
+  // OGCG: %{{.*}} = call float @llvm.exp2.f32(float %{{.*}})
+}
+
+double my_exp2(double f) {
+  return __builtin_exp2(f);
+  // CIR: %{{.*}} = cir.exp2 {{.*}} : !cir.double
+  // LLVM: %{{.*}} = call double @llvm.exp2.f64(double %{{.*}})
+  // OGCG: %{{.*}} = call double @llvm.exp2.f64(double %{{.*}})
+}
+
+long double my_exp2l(long double f) {
+  return __builtin_exp2l(f);
+  // CIR: %{{.*}} = cir.exp2 {{.*}} : !cir.long_double<!cir.f128>
+  // LLVM: %{{.*}} = call fp128 @llvm.exp2.f128(fp128 %{{.*}})
+  // OGCG: %{{.*}} = call fp128 @llvm.exp2.f128(fp128 %{{.*}})
+}