Fixup __float128 uses and if defined guard in ConstantFolding

Uses of __float128 in (#94944) should be float128. Although ConstantFoldFP128
is not reliant on HAS_LOGF128, it is only used by conditional code controlled
by HAS_LOGF128, and will cause unused errors on buildbots.

llvm/lib/Analysis/ConstantFolding.cpp

@@ -1744,7 +1744,7 @@ Constant *GetConstantFoldFPValue(double V, Type *Ty) {
 }
 
 #if defined(HAS_IEE754_FLOAT128)
-Constant *GetConstantFoldFPValue128(__float128 V, Type *Ty) {
+Constant *GetConstantFoldFPValue128(float128 V, Type *Ty) {
   if (Ty->isFP128Ty())
     return ConstantFP::get(Ty, V);
   llvm_unreachable("Can only constant fold fp128");
@@ -1783,12 +1783,11 @@ Constant *ConstantFoldFP(double (*NativeFP)(double), const APFloat &V,
   return GetConstantFoldFPValue(Result, Ty);
 }
 
-#if defined(HAS_IEE754_FLOAT128)
-LLVM_ATTRIBUTE_UNUSED
+#if defined(HAS_IEE754_FLOAT128) && defined(HAS_LOGF128)
 Constant *ConstantFoldFP128(long double (*NativeFP)(long double),
                             const APFloat &V, Type *Ty) {
   llvm_fenv_clearexcept();
-  __float128 Result = NativeFP(V.convertToQuad());
+  float128 Result = NativeFP(V.convertToQuad());
   if (llvm_fenv_testexcept()) {
     llvm_fenv_clearexcept();
     return nullptr;
@@ -2120,7 +2119,7 @@ static Constant *ConstantFoldScalarCall1(StringRef Name,
 #if defined(HAS_IEE754_FLOAT128) && defined(HAS_LOGF128)
     if (Ty->isFP128Ty()) {
       if (IntrinsicID == Intrinsic::log) {
-        __float128 Result = logf128(Op->getValueAPF().convertToQuad());
+        float128 Result = logf128(Op->getValueAPF().convertToQuad());
         return GetConstantFoldFPValue128(Result, Ty);
       }