On Wed, Aug 9, 2017 at 3:38 PM, Luc Van Oostenryck
<luc.vanoostenryck@xxxxxxxxx> wrote:
> This is especially usefull when simplifying code
> accessing bitfields.
>
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
> ---
> simplify.c | 29 ++++++++++++++++++++++++++++-
> validation/bitfield-size.c | 4 +---
> 2 files changed, 29 insertions(+), 4 deletions(-)
>
> diff --git a/simplify.c b/simplify.c
> index 40d4f0068..e8bf1c171 100644
> --- a/simplify.c
> +++ b/simplify.c
> @@ -411,6 +411,32 @@ static int simplify_asr(struct instruction *insn, pseudo_t pseudo, long long val
> return 0;
> }
>
> +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)
A little bit suggestion base on my previous reading and question ask on
this. When I first read the comment without reading the code, then I would
wondering why (A>>S) & (M>>S) is simpler. The following code actually
explain the constant mask very well. So the comment best understand if
the code was read. Adding some comment on M is constant will help a
lot in the comment.
Not a reason to object the patch of course. Just suggestions.
Chris
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