RE: Parsing mnemonic suffixes

RE: Parsing mnemonic suffixes

[Will Newton]

 
>  > I'm having a little trouble with getting a cgen generated 
> assembler to  > parse multiple suffixes on a mnemonic. The 
> instruction is specified like  > this:
>  >
>  > "add$sc$cond $reg,$reg,$reg"
>  >
>  > The operand "sc" can have a value of "S" or "" depending 
> on whether this  > instruction sets condition flags.
>  > The operand "cond" can have one of a number of values 
> ("Z", "EQ", "NE",  > "", etc.) depending on whether this 
> instruction is conditional or not.
>  >
>  > When either $sc or $cond is used in isolation (e.g. 
> "ADDS", "ADDEQ") the  > mnemonic is parsed correctly, when 
> the two are used together (e.g.
>  > "ADDSEQ") the parse fails. Is it possible to parse an 
> instruction like  > this with a cgen description?
> 
> I would expect this to work.  I'll look into it.

Cgen/cpu/arm7.cpu does this, but I have no idea if it works. It seems
that what happens is that the mnemonic is parsed, and the trailing
suffixes as one big block are passed to cgen_parse_keyword with the
keyword table for the first suffix, e.g.:

ADDSNE -> cgen_parse_keyword is called with "SNE" and keyword table for
$sc ("", "S").

Cgen_parse_keyword then calls cgen_keyword_lookup_name with the keyword
table, which does a hash lookup of "SNE" in the keyword table. This
fails and returns the null keyword as you would expect.
Cgen_parse_keyword is then called again with "SNE" and the keyword table
for $cond ("NE", ...) which doesn't match either.

My current plan is to write a custom parse handler that doesn't use a
hash table and parses as greedily as possible.

Parsing mnemonic suffixes

[Doug Evans]

Will Newton writes:
 > 
 > I'm having a little trouble with getting a cgen generated assembler to
 > parse multiple suffixes on a mnemonic. The instruction is specified like
 > this:
 > 
 > "add$sc$cond $reg,$reg,$reg"
 > 
 > The operand "sc" can have a value of "S" or "" depending on whether this
 > instruction sets condition flags.
 > The operand "cond" can have one of a number of values ("Z", "EQ", "NE",
 > "", etc.) depending on whether this instruction is conditional or not.
 > 
 > When either $sc or $cond is used in isolation (e.g. "ADDS", "ADDEQ") the
 > mnemonic is parsed correctly, when the two are used together (e.g.
 > "ADDSEQ") the parse fails. Is it possible to parse an instruction like
 > this with a cgen description?

I would expect this to work.  I'll look into it.

Parsing mnemonic suffixes

[Will Newton]

I'm having a little trouble with getting a cgen generated assembler to
parse multiple suffixes on a mnemonic. The instruction is specified like
this:

"add$sc$cond $reg,$reg,$reg"

The operand "sc" can have a value of "S" or "" depending on whether this
instruction sets condition flags.
The operand "cond" can have one of a number of values ("Z", "EQ", "NE",
"", etc.) depending on whether this instruction is conditional or not.

When either $sc or $cond is used in isolation (e.g. "ADDS", "ADDEQ") the
mnemonic is parsed correctly, when the two are used together (e.g.
"ADDSEQ") the parse fails. Is it possible to parse an instruction like
this with a cgen description?

Thanks,