On Mon, Aug 7, 2017 at 3:12 PM, Luc Van Oostenryck
<luc.vanoostenryck@xxxxxxxxx> wrote:
> This is especially usefull when simplifying code
> accessing bitfields.
>
>
> +static int simplify_lsr(struct instruction *insn, pseudo_t pseudo, long long value)
> +{
> + struct instruction *def;
> + unsigned long long mask;
> +
> + if (!value)
> + return replace_with_pseudo(insn, pseudo);
> + switch (def_opcode(insn->src1)) {
> + case OP_AND:
> + // replace (A & M) >> S
> + // by (A >> S) & (M >> S)
Why (A>>S) & (M >>S) is easier to simplify?
The original has two instruction but the result has three.
Is that that because A>>S is more likely to find match in
the CSE?
What if there is no match found, does that mean it is
not useful to do this transformation?
Chris
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