address review comments

Author: c8ef

clang/include/clang/Basic/Builtins.td

@@ -199,7 +199,7 @@ def FloorF16F128 : Builtin, F16F128MathTemplate {
 
 def FmaF16F128 : Builtin, F16F128MathTemplate {
   let Spellings = ["__builtin_fma"];
-  let Attributes = [FunctionWithBuiltinPrefix, NoThrow, ConstIgnoringErrnoAndExceptions];
+  let Attributes = [FunctionWithBuiltinPrefix, NoThrow, ConstIgnoringErrnoAndExceptions, Constexpr];
   let Prototype = "T(T, T, T)";
 }
 

clang/lib/AST/ByteCode/Floating.h

@@ -203,6 +203,13 @@ class Floating final {
     return R->F.divide(B.F, RM);
   }
 
+  static APFloat::opStatus fma(const Floating &A, const Floating &B,
+                               const Floating &C, llvm::RoundingMode RM,
+                               Floating *R) {
+    *R = Floating(A.F);
+    return R->F.fusedMultiplyAdd(B.F, C.F, RM);
+  }
+
   static bool neg(const Floating &A, Floating *R) {
     *R = -A;
     return false;

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -571,8 +571,8 @@ static bool interp__builtin_fma(InterpState &S, CodePtr OpPC,
   Floating Result;
 
   llvm::RoundingMode RM = getActiveRoundingMode(S, Call);
-  Floating::mul(X, Y, RM, &Result);
-  Floating::add(Result, Z, RM, &Result);
+  if (!Floating::fma(X, Y, Z, RM, &Result))
+    return false;
 
   S.Stk.push<Floating>(Result);
   return true;

clang/lib/AST/ExprConstant.cpp

@@ -15325,9 +15325,7 @@ bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
       return false;
 
     llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
-    Result.multiply(Y, RM);
-    Result.add(Z, RM);
-    return true;
+    return Result.fusedMultiplyAdd(Y, Z, RM) == APFloat::opOK;
   }
 
   case Builtin::BI__arithmetic_fence:

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

@@ -58,7 +58,7 @@ double g19 = __builtin_fma(1.0, 1.0, 1.0);
 float g20 = __builtin_fmaf(1.0f, 1.0f, 1.0f);
 long double g21 = __builtin_fmal(1.0L, 1.0L, 1.0L);
 #if defined(__FLOAT128__) || defined(__SIZEOF_FLOAT128__)
-__float128 g21_2 = __builtin_fma(1.0q, 1.0q, 1.0q);
+__float128 g21_2 = __builtin_fmaf128(1.0q, 1.0q, 1.0q);
 #endif
 
 char classify_nan     [__builtin_fpclassify(+1, -1, -1, -1, -1, __builtin_nan(""))];