[ConstantFolding] Add support for llvm.atan in constant folding. (#143416)

Fixes #143360

Author: topperc

llvm/lib/Analysis/ConstantFolding.cpp

@@ -1672,6 +1672,7 @@ bool llvm::canConstantFoldCallTo(const CallBase *Call, const Function *F) {
   case Intrinsic::sincos:
   case Intrinsic::sinh:
   case Intrinsic::cosh:
+  case Intrinsic::atan:
   case Intrinsic::pow:
   case Intrinsic::powi:
   case Intrinsic::ldexp:
@@ -2538,6 +2539,8 @@ static Constant *ConstantFoldScalarCall1(StringRef Name,
         return ConstantFoldFP(sinh, APF, Ty);
       case Intrinsic::cosh:
         return ConstantFoldFP(cosh, APF, Ty);
+      case Intrinsic::atan:
+        return ConstantFoldFP(atan, APF, Ty);
       case Intrinsic::sqrt:
         return ConstantFoldFP(sqrt, APF, Ty);
       case Intrinsic::amdgcn_cos:

llvm/test/Transforms/InstSimplify/ConstProp/atan-intrinsic.ll

@@ -0,0 +1,88 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S -passes=instsimplify < %s | FileCheck %s
+
+define double @test_atan_0() {
+; CHECK-LABEL: define double @test_atan_0() {
+; CHECK-NEXT:    ret double 0.000000e+00
+;
+  %result = call double @llvm.atan.f64(double 0.0)
+  ret double %result
+}
+
+define double @test_atan_one() {
+; CHECK-LABEL: define double @test_atan_one() {
+; CHECK-NEXT:    ret double 0x3FE921FB54442D18
+;
+  %res = call double @llvm.atan.f64(double 1.0)
+  ret double %res
+}
+
+define <2 x double> @test_atan_v2() {
+; CHECK-LABEL: define <2 x double> @test_atan_v2() {
+; CHECK-NEXT:    ret <2 x double> zeroinitializer
+;
+  %result = call <2 x double> @llvm.atan.v2f64(<2 x double> zeroinitializer)
+  ret <2 x double> %result
+}
+
+define double @test_atan_neg0() {
+; CHECK-LABEL: define double @test_atan_neg0() {
+; CHECK-NEXT:    ret double -0.000000e+00
+;
+  %res = call double @llvm.atan.f64(double -0.0)
+  ret double %res
+}
+
+define double @test_atan_poison() {
+; CHECK-LABEL: define double @test_atan_poison() {
+; CHECK-NEXT:    [[RES:%.*]] = call double @llvm.atan.f64(double poison)
+; CHECK-NEXT:    ret double [[RES]]
+;
+  %res = call double @llvm.atan.f64(double poison)
+  ret double %res
+}
+
+define double @test_atan_undef() {
+; CHECK-LABEL: define double @test_atan_undef() {
+; CHECK-NEXT:    [[RES:%.*]] = call double @llvm.atan.f64(double undef)
+; CHECK-NEXT:    ret double [[RES]]
+;
+  %res = call double @llvm.atan.f64(double undef)
+  ret double %res
+}
+
+define double @test_atan_snan() {
+; CHECK-LABEL: define double @test_atan_snan() {
+; CHECK-NEXT:    [[RES:%.*]] = call double @llvm.atan.f64(double 0x7FF0000000000001)
+; CHECK-NEXT:    ret double [[RES]]
+;
+  %res = call double @llvm.atan.f64(double 0x7ff0000000000001)
+  ret double %res
+}
+
+define double @test_atan_qnan() {
+; CHECK-LABEL: define double @test_atan_qnan() {
+; CHECK-NEXT:    [[RES:%.*]] = call double @llvm.atan.f64(double 0x7FF8000000000000)
+; CHECK-NEXT:    ret double [[RES]]
+;
+  %res = call double @llvm.atan.f64(double 0x7ff8000000000000)
+  ret double %res
+}
+
+define double @test_atan_pos_inf() {
+; CHECK-LABEL: define double @test_atan_pos_inf() {
+; CHECK-NEXT:    [[RES:%.*]] = call double @llvm.atan.f64(double 0x7FF0000000000000)
+; CHECK-NEXT:    ret double [[RES]]
+;
+  %res = call double @llvm.atan.f64(double 0x7ff0000000000000)
+  ret double %res
+}
+
+define double @test_atan_neg_inf() {
+; CHECK-LABEL: define double @test_atan_neg_inf() {
+; CHECK-NEXT:    [[RES:%.*]] = call double @llvm.atan.f64(double 0xFFF0000000000000)
+; CHECK-NEXT:    ret double [[RES]]
+;
+  %res = call double @llvm.atan.f64(double 0xfff0000000000000)
+  ret double %res
+}