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 --git a/gcc/config/bpf/bpf.opt b/gcc/config/bpf/bpf.opt
index bc5b2220116cc6bf8b91dbc47ccfa5a96792fd44..acfddebdad718909127b1e1440f58d98944967a8 100644 (file)
--- 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)