Re: Alpha assembly language - ldah/lda after jsr

"Timothy Jones" <tim.jones@mail.com> wrote in message
news:03-10-040@comp.compilers...


> I have a problem with some alpha assembly code. Specifically with the
> ldah/lda pair of instructions to load the $gp after a function call.
> Initially the alpha compiler produces this:
>
> jsr $26, ($27), spec_getc!lituse_jsr!468
> ldl $1, ($12)
> ldah $gp, ($26)!gpdisp!469
> cmpeq $10, $0, $2
> cmplt $11, 255, $3
> lda $gp, 4($gp)!gpdisp!469
> ...


(snip)


LDAH Ra.wq,disp.ab(Rb.ab)


The virtual address is computed by adding register Rb to 65536 times the
sign extended 16 bit displacement. The 64 bit result is written to Ra.
With no displacement, it would seem to copy Rb into Ra.


When you add a nop you did make sure that all addresses are still addressing
the right place. (I don't know if you are modifying the object program or
assembly source.)


-- glen

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