[gcc r14-9081] bpf: Add documentation for the -mcpu option

[Jose E. Marchesi <jemarch@gcc.gnu.org>]

https://gcc.gnu.org/g:97f34ad10da8f46a4a1c17af6fdb950b132e1abc

commit r14-9081-g97f34ad10da8f46a4a1c17af6fdb950b132e1abc
Author: Will Hawkins <hawkinsw@obs.cr>
Date:   Tue Feb 20 13:33:38 2024 +0100

    bpf: Add documentation for the -mcpu option
    
    Add documentation describing the meaning and values for the -mcpu
    command-line option.
    
    Tested for bpf-unknown-none on x86_64-linux-gnu host.
    
    gcc/ChangeLog:
    
            * config/bpf/bpf.opt: Add help information for -mcpu.
    
    Signed-off-by: Will Hawkins <hawkinsw@obs.cr>

Diff:
---
 gcc/config/bpf/bpf.opt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/gcc/config/bpf/bpf.opt b/gcc/config/bpf/bpf.opt
index bc5b2220116c..acfddebdad71 100644
--- a/gcc/config/bpf/bpf.opt
+++ b/gcc/config/bpf/bpf.opt
@@ -77,9 +77,11 @@ Enable signed move and memory load instructions.
 
 mcpu=
 Target RejectNegative Joined Var(bpf_isa) Enum(bpf_isa) Init(ISA_V4)
+Select the eBPF ISA version to target in code generation.
 
 Enum
 Name(bpf_isa) Type(enum bpf_isa_version)
+Valid ISA versions (for use with the -mcpu= option)
 
 EnumValue
 Enum(bpf_isa) String(v1) Value(ISA_V1)