docs: add caveat for __builtin_cpu_supports

Document that the function does not work correctly for old
VIA processors.

	PR target/100758

gcc/ChangeLog:

	* doc/extend.texi: Document that the function
	does not work correctly for old VIA processors.

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 5a026c4b48cee57e361c1d34bfd3b582149bb2fa..66a9d8898815567289a83dbc2436aa022701896f 100644 (file)
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -22071,6 +22071,9 @@ else
      count = generic_countbits (n); //generic implementation.
   @}
 @end smallexample
+
+Caveat: This built-in function does not work correctly on old VIA
+processors (Centaur family).
 @end deftypefn
 
 The following built-in functions are made available by @option{-mmmx}.