On Wed, Mar 22, 2017 at 6:53 PM, Luc Van Oostenryck
<luc.vanoostenryck@xxxxxxxxx> wrote:
> Patch 11b1a83b1 solved an issue with dangling PSEUDO_PHI
> by killing it's use after a branch rewrite.
>
> However, the change didn't took in account the fact that,
> even after the branch rewrite, some other paths may exist
> where this pseudo was needed.
>
> Fix this by cheking that no such path exist before killing
> the (usage of the) pseudo.
>
> Fixes: 11b1a83b1 "fix OP_PHI usage in try_to_simplify_bb()"
> Reported-by: Dibyendu Majumdar <mobile@xxxxxxxxxxxxxxx>
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
> ---
> flow.c | 35 ++++++++++++++++++++++++++++++++++-
> validation/kill-phi-ttsbb2.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 74 insertions(+), 1 deletion(-)
> create mode 100644 validation/kill-phi-ttsbb2.c
>
> diff --git a/flow.c b/flow.c
> index a5332203f..c12bc0716 100644
> --- a/flow.c
> +++ b/flow.c
> @@ -79,6 +79,39 @@ static int bb_depends_on(struct basic_block *target, struct basic_block *src)
> return 0;
> }
>
> +/*
> + * Return 1 if 'pseudo' is needed in some parent of 'bb'.
> + * Need liveness info.
> + */
> +static int needed_phisrc(struct instruction *phi, struct basic_block *curr, unsigned long generation)
> +{
> + pseudo_t target = phi->target;
> + struct basic_block *bb;
> + int rc = 0;
> +
> + curr->generation = generation;
> + FOR_EACH_PTR(curr->children, bb) {
> + if (bb->generation == generation)
> + continue;
> + if (bb == phi->bb)
> + continue;
> + if (pseudo_in_list(bb->defines, target)) {
> + continue;
> + }
For just one line continue, there is no need for {}
> + if (pseudo_in_list(bb->needs, target)) {
> + rc = 1;
> + goto ret;
Can this simplify as "return 1;"
> + }
> + rc = needed_phisrc(phi, bb, generation);
> + if (rc)
> + goto ret;
needed_phisrc(phi, bb, generation)
And "return 1;" here
> +
> + } END_FOR_EACH_PTR(bb);
> +
> +ret:
> + return rc;
"return 0" here.
There is no need for rc variable.
Chris
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