[flang] Remove blank from NaN string representation

[vdonaldson]

Summary

Flang front end function DumpHexadecimal generates a string representation of a REAL value. When the value is a NaN, the string contains a blank, as in "NaN 0x7fc00000". This function is used by lowering to generate a string that is then passed to llvm Support function ConvertFromStringSpecials, which does not expect a blank in the string. Remove the blank to allow correct recognition of a NaN by this llvm function.

Note that function DumpHexadecimal is not exercised by the front end itself. This functionality is only exercised by code that is not yet present in llvm.

[vdonaldson]

Flang front end function DumpHexadecimal generates a string representation of a REAL value. When the value is a NaN, the string contains a blank, as in "NaN 0x7fc00000". This function is used by lowering to generate a string that is then passed to llvm Support function ConvertFromStringSpecials, which does not expect a blank in the string. Remove the blank to allow correct recognition of a NaN by this llvm function.

[PeteSteinfeld]

All build, tests, and looks good.

flang/lib/Evaluate/real.cpp

 
 template <typename W, int P> std::string Real<W, P>::DumpHexadecimal() const {
   if (IsNotANumber()) {
-    return "NaN 0x"s + word_.Hexadecimal();
+    return "NaN0x"s + word_.Hexadecimal();
   } else if (IsNegative()) {
     return "-"s + Negate().DumpHexadecimal();
   } else if (IsInfinite()) {

flang/unittests/Evaluate/real.cpp

     std::uint64_t raw;
     const char *expected;
   } table[] = {
-      {0x7f876543, "NaN 0x7f876543"},
+      {0x7f876543, "NaN0x7f876543"},
       {0x7f800000, "Inf"},
       {0xff800000, "-Inf"},
       {0x00000000, "0.0"},