util/u_printf: support printing fp16 values

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34053>

src/util/u_printf.c

@@ -36,6 +36,8 @@
 #include "u_math.h"
 #include "u_printf.h"
 
+#include "util/half_float.h"
+
 #define XXH_INLINE_ALL
 #include "util/xxhash.h"
 
@@ -241,7 +243,11 @@ u_printf_impl(FILE *out, const char *buffer, size_t buffer_size,
                case 2: {
                   uint16_t v;
                   memcpy(&v, &buffer[elmt_buf_pos], elmt_size);
-                  fprintf(out, print_str, v);
+                  if (is_float) {
+                     fprintf(out, print_str, _mesa_half_to_float(v));
+                  } else {
+                     fprintf(out, print_str, v);
+                  }
                   break;
                }
                case 4: {