[cfe-dev] __builtin_nan support

[Eli Friedman]

On Mon, May 19, 2008 at 11:02 AM, Nate Begeman <natebegeman at mac.com> wrote:
> Attached patch implements __builtin_nan, __builtin_nanf, and __builtin_nanl.

@@ -58,6 +57,10 @@
     if (SemaBuiltinUnorderedCompare(TheCall.get()))
       return true;
     return TheCall.take();
+  case Builtin::BI__builtin_nan:
+  case Builtin::BI__builtin_nanf:
+  case Builtin::BI__builtin_nanl:
+    return SemaBuiltinNaN(FnInfo->getBuiltinID(), TheCall.get());
   case Builtin::BI__builtin_shufflevector:
     return SemaBuiltinShuffleVector(TheCall.get());
   }

This is unsafe; in the case where SemaBuiltinNaN doesn't find a string
literal, you end up with a dangling pointer.

+      llvm::APInt Val(64, 0x7ff8000000000000ULL, false);
+
+      char *endp = 0;
+      uint64_t Significand = strtoull(data, &endp, 0);

Windows doesn't have strtoull.

-Eli