[clang] Additional FP classification functions (#69041)

C language standard defined library functions `iszero`, `issignaling`
and `issubnormal`, which did not have counterparts among clang builtin
functions. This change adds new functions:

    __builtin_iszero
    __builtin_issubnormal
    __builtin_issignaling

They provide builtin implementation for the missing standard functions.

Pull request: #69041

clang/docs/ReleaseNotes.rst

@@ -809,6 +809,8 @@ Floating Point Support in Clang
 - Add ``__builtin_exp10``, ``__builtin_exp10f``,
   ``__builtin_exp10f16``, ``__builtin_exp10l`` and
   ``__builtin_exp10f128`` builtins.
+- Add ``__builtin_iszero``, ``__builtin_issignaling`` and
+  ``__builtin_issubnormal``.
 
 AST Matchers
 ------------

clang/include/clang/Basic/Builtins.def

@@ -494,6 +494,9 @@ BUILTIN(__builtin_isinf,      "i.", "FnctE")
 BUILTIN(__builtin_isinf_sign, "i.", "FnctE")
 BUILTIN(__builtin_isnan,      "i.", "FnctE")
 BUILTIN(__builtin_isnormal,   "i.", "FnctE")
+BUILTIN(__builtin_issubnormal,"i.", "FnctE")
+BUILTIN(__builtin_iszero,     "i.", "FnctE")
+BUILTIN(__builtin_issignaling,"i.", "FnctE")
 BUILTIN(__builtin_isfpclass,  "i.", "nctE")
 
 // FP signbit builtins

clang/lib/AST/ExprConstant.cpp

@@ -12398,6 +12398,24 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
            Success(Val.isNormal() ? 1 : 0, E);
   }
 
+  case Builtin::BI__builtin_issubnormal: {
+    APFloat Val(0.0);
+    return EvaluateFloat(E->getArg(0), Val, Info) &&
+           Success(Val.isDenormal() ? 1 : 0, E);
+  }
+
+  case Builtin::BI__builtin_iszero: {
+    APFloat Val(0.0);
+    return EvaluateFloat(E->getArg(0), Val, Info) &&
+           Success(Val.isZero() ? 1 : 0, E);
+  }
+
+  case Builtin::BI__builtin_issignaling: {
+    APFloat Val(0.0);
+    return EvaluateFloat(E->getArg(0), Val, Info) &&
+           Success(Val.isSignaling() ? 1 : 0, E);
+  }
+
   case Builtin::BI__builtin_isfpclass: {
     APSInt MaskVal;
     if (!EvaluateInteger(E->getArg(1), MaskVal, Info))

clang/lib/AST/Interp/Floating.h

@@ -93,6 +93,7 @@ class Floating final {
   bool isMin() const { return F.isSmallest(); }
   bool isMinusOne() const { return F.isExactlyValue(-1.0); }
   bool isNan() const { return F.isNaN(); }
+  bool isSignaling() const { return F.isSignaling(); }
   bool isInf() const { return F.isInfinity(); }
   bool isFinite() const { return F.isFinite(); }
   bool isNormal() const { return F.isNormal(); }

clang/lib/AST/Interp/InterpBuiltin.cpp

@@ -306,6 +306,15 @@ static bool interp__builtin_isnan(InterpState &S, CodePtr OpPC,
   return true;
 }
 
+static bool interp__builtin_issignaling(InterpState &S, CodePtr OpPC,
+                                        const InterpFrame *Frame,
+                                        const Function *F) {
+  const Floating &Arg = S.Stk.peek<Floating>();
+
+  pushInt(S, Arg.isSignaling());
+  return true;
+}
+
 static bool interp__builtin_isinf(InterpState &S, CodePtr OpPC,
                                   const InterpFrame *Frame, const Function *F,
                                   bool CheckSign) {
@@ -337,6 +346,24 @@ static bool interp__builtin_isnormal(InterpState &S, CodePtr OpPC,
   return true;
 }
 
+static bool interp__builtin_issubnormal(InterpState &S, CodePtr OpPC,
+                                        const InterpFrame *Frame,
+                                        const Function *F) {
+  const Floating &Arg = S.Stk.peek<Floating>();
+
+  pushInt(S, Arg.isDenormal());
+  return true;
+}
+
+static bool interp__builtin_iszero(InterpState &S, CodePtr OpPC,
+                                   const InterpFrame *Frame,
+                                   const Function *F) {
+  const Floating &Arg = S.Stk.peek<Floating>();
+
+  pushInt(S, Arg.isZero());
+  return true;
+}
+
 /// First parameter to __builtin_isfpclass is the floating value, the
 /// second one is an integral value.
 static bool interp__builtin_isfpclass(InterpState &S, CodePtr OpPC,
@@ -491,6 +518,10 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
     if (interp__builtin_isnan(S, OpPC, Frame, F))
       return retInt(S, OpPC, Dummy);
     break;
+  case Builtin::BI__builtin_issignaling:
+    if (interp__builtin_issignaling(S, OpPC, Frame, F))
+      return retInt(S, OpPC, Dummy);
+    break;
 
   case Builtin::BI__builtin_isinf:
     if (interp__builtin_isinf(S, OpPC, Frame, F, /*Sign=*/false))
@@ -510,6 +541,14 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
     if (interp__builtin_isnormal(S, OpPC, Frame, F))
       return retInt(S, OpPC, Dummy);
     break;
+  case Builtin::BI__builtin_issubnormal:
+    if (interp__builtin_issubnormal(S, OpPC, Frame, F))
+      return retInt(S, OpPC, Dummy);
+    break;
+  case Builtin::BI__builtin_iszero:
+    if (interp__builtin_iszero(S, OpPC, Frame, F))
+      return retInt(S, OpPC, Dummy);
+    break;
   case Builtin::BI__builtin_isfpclass:
     if (interp__builtin_isfpclass(S, OpPC, Frame, F, Call))
       return retInt(S, OpPC, Dummy);

clang/lib/CodeGen/CGBuiltin.cpp

@@ -3356,6 +3356,14 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
                            ConvertType(E->getType())));
   }
 
+  case Builtin::BI__builtin_issignaling: {
+    CodeGenFunction::CGFPOptionsRAII FPOptsRAII(*this, E);
+    Value *V = EmitScalarExpr(E->getArg(0));
+    return RValue::get(
+        Builder.CreateZExt(Builder.createIsFPClass(V, FPClassTest::fcSNan),
+                           ConvertType(E->getType())));
+  }
+
   case Builtin::BI__builtin_isinf: {
     CodeGenFunction::CGFPOptionsRAII FPOptsRAII(*this, E);
     Value *V = EmitScalarExpr(E->getArg(0));
@@ -3390,6 +3398,22 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
                            ConvertType(E->getType())));
   }
 
+  case Builtin::BI__builtin_issubnormal: {
+    CodeGenFunction::CGFPOptionsRAII FPOptsRAII(*this, E);
+    Value *V = EmitScalarExpr(E->getArg(0));
+    return RValue::get(
+        Builder.CreateZExt(Builder.createIsFPClass(V, FPClassTest::fcSubnormal),
+                           ConvertType(E->getType())));
+  }
+
+  case Builtin::BI__builtin_iszero: {
+    CodeGenFunction::CGFPOptionsRAII FPOptsRAII(*this, E);
+    Value *V = EmitScalarExpr(E->getArg(0));
+    return RValue::get(
+        Builder.CreateZExt(Builder.createIsFPClass(V, FPClassTest::fcZero),
+                           ConvertType(E->getType())));
+  }
+
   case Builtin::BI__builtin_isfpclass: {
     Expr::EvalResult Result;
     if (!E->getArg(1)->EvaluateAsInt(Result, CGM.getContext()))

clang/lib/Sema/SemaChecking.cpp

@@ -2255,7 +2255,10 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
   case Builtin::BI__builtin_isinf:
   case Builtin::BI__builtin_isinf_sign:
   case Builtin::BI__builtin_isnan:
+  case Builtin::BI__builtin_issignaling:
   case Builtin::BI__builtin_isnormal:
+  case Builtin::BI__builtin_issubnormal:
+  case Builtin::BI__builtin_iszero:
   case Builtin::BI__builtin_signbit:
   case Builtin::BI__builtin_signbitf:
   case Builtin::BI__builtin_signbitl:

clang/test/AST/Interp/builtin-functions.cpp

@@ -130,6 +130,8 @@ namespace nan {
                                              // expected-error {{must be initialized by a constant expression}} \
                                              // expected-note {{read of dereferenced one-past-the-end pointer}} \
                                              // expected-note {{in call to}}
+  static_assert(!__builtin_issignaling(__builtin_nan("")), "");
+  static_assert(__builtin_issignaling(__builtin_nans("")), "");
 }
 
 namespace fmin {
@@ -153,6 +155,17 @@ namespace inf {
 
   static_assert(__builtin_isnormal(1.0), "");
   static_assert(!__builtin_isnormal(__builtin_inf()), "");
+
+#ifndef __AVR__
+  static_assert(__builtin_issubnormal(0x1p-1070), "");
+#endif
+  static_assert(!__builtin_issubnormal(__builtin_inf()), "");
+
+  static_assert(__builtin_iszero(0.0), "");
+  static_assert(!__builtin_iszero(__builtin_inf()), "");
+
+  static_assert(__builtin_issignaling(__builtin_nans("")), "");
+  static_assert(!__builtin_issignaling(__builtin_inf()), "");
 }
 
 namespace isfpclass {

clang/test/CodeGen/builtins.c

@@ -64,6 +64,9 @@ int main(void) {
   P(isinf_sign, (1.));
   P(isnan, (1.));
   P(isfinite, (1.));
+  P(iszero, (1.));
+  P(issubnormal, (1.));
+  P(issignaling, (1.));
   P(isfpclass, (1., 1));
 
   // Bitwise & Numeric Functions
@@ -270,6 +273,18 @@ void test_float_builtins(__fp16 *H, float F, double D, long double LD) {
   // CHECK: [[TMP:%.*]] = call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 264)
   // CHECK: zext i1 [[TMP]] to i32
 
+  res = __builtin_issubnormal(F);
+  // CHECK: [[TMP:%.*]] = call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 144)
+  // CHECK: zext i1 [[TMP]] to i32
+
+  res = __builtin_iszero(F);
+  // CHECK: [[TMP:%.*]] = call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 96)
+  // CHECK: zext i1 [[TMP]] to i32
+
+  res = __builtin_issignaling(F);
+  // CHECK: [[TMP:%.*]] = call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 1)
+  // CHECK: zext i1 [[TMP]] to i32
+
   res = __builtin_flt_rounds();
   // CHECK: call i32 @llvm.get.rounding(
 }

clang/test/Sema/constant-builtins-2.c

@@ -124,6 +124,45 @@ char isnormal_inf_neg[!__builtin_isnormal(-__builtin_inf()) ? 1 : -1];
 char isnormal_nan    [!__builtin_isnormal(__builtin_nan("")) ? 1 : -1];
 char isnormal_snan   [!__builtin_isnormal(__builtin_nans("")) ? 1 : -1];
 
+char iszero_inf_pos[!__builtin_iszero(__builtin_inf()) ? 1 : -1];
+char iszero_pos    [!__builtin_iszero(1.0) ? 1 : -1];
+char iszero_normf  [!__builtin_iszero(1e-37f) ? 1 : -1];
+char iszero_denormf[!__builtin_iszero(1e-38f) ? 1 : -1];
+char iszero_norm   [!__builtin_iszero(1e-307) ? 1 : -1];
+char iszero_denorm [!__builtin_iszero(1e-308) ? 1 : -1];
+char iszero_zero   [__builtin_iszero(0.0) ? 1 : -1];
+char iszero_negzero[__builtin_iszero(-0.0) ? 1 : -1];
+char iszero_neg    [!__builtin_iszero(-1.0) ? 1 : -1];
+char iszero_inf_neg[!__builtin_iszero(-__builtin_inf()) ? 1 : -1];
+char iszero_nan    [!__builtin_iszero(__builtin_nan("")) ? 1 : -1];
+char iszero_snan   [!__builtin_iszero(__builtin_nans("")) ? 1 : -1];
+
+char issubnormal_inf_pos[!__builtin_issubnormal(__builtin_inf()) ? 1 : -1];
+char issubnormal_pos    [!__builtin_issubnormal(1.0) ? 1 : -1];
+char issubnormal_normf  [!__builtin_issubnormal(1e-37f) ? 1 : -1];
+char issubnormal_denormf[__builtin_issubnormal(1e-38f) ? 1 : -1];
+char issubnormal_norm   [!__builtin_issubnormal(1e-307) ? 1 : -1];
+char issubnormal_denorm [__builtin_issubnormal(1e-308) ? 1 : -1];
+char issubnormal_zero   [!__builtin_issubnormal(0.0) ? 1 : -1];
+char issubnormal_negzero[!__builtin_issubnormal(-0.0) ? 1 : -1];
+char issubnormal_neg    [!__builtin_issubnormal(-1.0) ? 1 : -1];
+char issubnormal_inf_neg[!__builtin_issubnormal(-__builtin_inf()) ? 1 : -1];
+char issubnormal_nan    [!__builtin_issubnormal(__builtin_nan("")) ? 1 : -1];
+char issubnormal_snan   [!__builtin_issubnormal(__builtin_nans("")) ? 1 : -1];
+
+char issignaling_inf_pos[!__builtin_issignaling(__builtin_inf()) ? 1 : -1];
+char issignaling_pos    [!__builtin_issignaling(1.0) ? 1 : -1];
+char issignaling_normf  [!__builtin_issignaling(1e-37f) ? 1 : -1];
+char issignaling_denormf[!__builtin_issignaling(1e-38f) ? 1 : -1];
+char issignaling_norm   [!__builtin_issignaling(1e-307) ? 1 : -1];
+char issignaling_denorm [!__builtin_issignaling(1e-308) ? 1 : -1];
+char issignaling_zero   [!__builtin_issignaling(0.0) ? 1 : -1];
+char issignaling_negzero[!__builtin_issignaling(-0.0) ? 1 : -1];
+char issignaling_neg    [!__builtin_issignaling(-1.0) ? 1 : -1];
+char issignaling_inf_neg[!__builtin_issignaling(-__builtin_inf()) ? 1 : -1];
+char issignaling_nan    [!__builtin_issignaling(__builtin_nan("")) ? 1 : -1];
+char issignaling_snan   [__builtin_issignaling(__builtin_nans("")) ? 1 : -1];
+
 char isfpclass_inf_pos_0[__builtin_isfpclass(__builtin_inf(), 0x0200) ? 1 : -1]; // fcPosInf
 char isfpclass_inf_pos_1[!__builtin_isfpclass(__builtin_inff(), 0x0004) ? 1 : -1]; // fcNegInf
 char isfpclass_inf_pos_2[__builtin_isfpclass(__builtin_infl(), 0x0207) ? 1 : -1]; // fcSNan|fcQNan|fcNegInf|fcPosInf