CGEN:PATCH:RFA: Extracting from the entire insn int

[Dave Brolley]

Hi,

The attached patch extends the capability of
-gen-ifld-extract-base so that it can extract all of the fields
of an instruction when adata-integral-insn? is true. This changes
generated code in decode.c like:

    /* Contents of trailing part of insn.  */
    UINT word_1;
    word_1 = GETIMEMUHI (current_cpu, pc + 2);
    f_imm16 = (0|(EXTRACT_MSB0_UINT (word_1, 16, 0, 16) << 0));
    f_Rn1 = EXTRACT_MSB0_UINT (insn, 32, 12, 4);

into:

    f_imm16 = EXTRACT_MSB0_UINT (insn, 32, 16, 16);
    f_Rn1 = EXTRACT_MSB0_UINT (insn, 32, 12, 4);

which is a-good-thing(tm) because:

o It takes advantage of the fact that the entire insn is already
in 'insn'
o I avoids a redundant core access

OK to commit?

Dave
2000-10-05  Dave Brolley  <brolley@redhat.com>

	* utils-gen.scm (-gen-ifld-extract-base): Compute start position as
	ifld-start + ifld-word-offset.
	(gen-ifld-extract): Check adata-integral-insn? before checking whether
	the field is beyond the base number of bits.
	(gen-define-ifields): Use a base-length of 32 if adata-integral-insn?.
	(gen-extract-ifields): Ditto.