[PATCH v2] x86: Add comment with ISA level for all targets support by GCC12.1

[Noah Goldstein <goldstein.w.n@gmail.com>]

This is just a quality of life change to make it easier to see how the
ISA level will effect a given build.
---
 sysdeps/x86/isa-level.h | 67 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 2 deletions(-)

diff --git a/sysdeps/x86/isa-level.h b/sysdeps/x86/isa-level.h
index e1a30ed83e..f14ae5cc00 100644
--- a/sysdeps/x86/isa-level.h
+++ b/sysdeps/x86/isa-level.h
@@ -64,8 +64,71 @@
 #define MINIMUM_X86_ISA_LEVEL                                                 \
   (__X86_ISA_V1 + __X86_ISA_V2 + __X86_ISA_V3 + __X86_ISA_V4)
 
-
-/*
+/* ISA levels for known GCC targets as of GCC12.1:
+ *
+ * amdfam10       -> 1
+ * athlon-fx      -> 1
+ * athlon64       -> 1
+ * athlon64-sse3  -> 1
+ * atom           -> 1
+ * barcelona      -> 1
+ * bonnell        -> 1
+ * btver1         -> 1
+ * core2          -> 1
+ * eden-x2        -> 1
+ * eden-x4        -> 1
+ * k8             -> 1
+ * k8-sse3        -> 1
+ * nano           -> 1
+ * nano-1000      -> 1
+ * nano-2000      -> 1
+ * nano-3000      -> 1
+ * nano-x2        -> 1
+ * nano-x4        -> 1
+ * nocona         -> 1
+ * opteron        -> 1
+ * opteron-sse3   -> 1
+ * x86-64         -> 1
+ * bdver1         -> 2
+ * bdver2         -> 2
+ * bdver3         -> 2
+ * btver2         -> 2
+ * core-avx-i     -> 2
+ * corei7         -> 2
+ * corei7-avx     -> 2
+ * goldmont       -> 2
+ * goldmont-plus  -> 2
+ * ivybridge      -> 2
+ * nehalem        -> 2
+ * sandybridge    -> 2
+ * silvermont     -> 2
+ * slm            -> 2
+ * tremont        -> 2
+ * westmere       -> 2
+ * x86-64-v2      -> 2
+ * alderlake      -> 3
+ * bdver4         -> 3
+ * broadwell      -> 3
+ * core-avx2      -> 3
+ * haswell        -> 3
+ * knl            -> 3
+ * knm            -> 3
+ * skylake        -> 3
+ * x86-64-v3      -> 3
+ * znver1         -> 3
+ * znver2         -> 3
+ * znver3         -> 3
+ * cannonlake     -> 4
+ * cascadelake    -> 4
+ * cooperlake     -> 4
+ * icelake-client -> 4
+ * icelake-server -> 4
+ * rocketlake     -> 4
+ * sapphirerapids -> 4
+ * skylake-avx512 -> 4
+ * tigerlake      -> 4
+ * x86-64-v4      -> 4
+ *
  * CPU Features that are hard coded as enabled/disabled depending on
  * ISA build level.
  *    - Values > 0 features are always ENABLED if:
-- 
2.34.1