Problem in gen_reload(), seeking an explanation

[Franz Sirl]

At 06:59 22.06.99 , Jeffrey A Law wrote:
>   In message < 4.2.0.56.19990621135045.036f9220@mail.lauterbach.com >you write:
>   > The code is not shuffling operands cause it is only special-casing
>   > pseudo-registers, but we enter here with 2 real registers. Something 
> like
>   > below works too:
>Not exactly what I had in mind.  But better.
>
>If you look even earlier, you will find code that looks like this:
>
>       if (op0 != XEXP (in, 0) || op1 != XEXP (in, 1))
>         in = gen_rtx_PLUS (GET_MODE (in), op0, op1);
>
>       insn = emit_insn (gen_rtx_SET (VOIDmode, out, in));
>       code = recog_memoized (insn);
>
>       if (code >= 0)
>         {
>           extract_insn (insn);
>           /* We want constrain operands to treat this insn strictly in
>              its validity determination, i.e., the way it would after reload
>              has completed.  */
>           if (constrain_operands (1))
>             return insn;
>         }
>
>       delete_insns_since (last);
>
>We can do the same thing in the later hunk of code.  ie, try it one way, if
>that does not work, swap the operands and try again.  Something like this
>
>       gen_reload (out, op0, opnum, type);
>
>       /* If OP0 and OP1 are the same, we can use OUT for OP1.
>          This fixes a problem on the 32K where the stack pointer cannot
>          be used as an operand of an add insn.  */
>
>       if (rtx_equal_p (op0, op1))
>         op1 = out;
>
>       insn = emit_insn (gen_rtx_SET ...)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
You are kidding, aren't you? That's exactly what my first patch did.


>       /* If that failed, copy the address register to the reload register.
>          Then add the constant to the reload register.  */
>
>       code = recog_memoized (insn);
>       [ ... check that the operands match the constraints... ]
>       if constraints fail, call delete_all_insns_since (last), swap
>       op0 and op1 and try again.  If it still fails delete the insns and
>       go on to the next method of generating the reload.

Still the same way as I suggested in my first patch.

Now, why didn't you accept my first patch?

Franz.