On Fri, 19 Nov 2021, Jan Hubicka wrote:
> Hi,
> this patch removes test for function not having call chain guarding
> modref use in ref_maybe_used_by_call_p_1. It never made sense since
> modref treats call chain accesses explicitly. It was however copied from
> earlier check for ECF_CONST (which seems dubious too, but I would like
> to discuss it independelty).
>
> This enables us to detect that memory pointed to static chain (or parts of it)
> are unused by the function.
>
> lto-bootstrapped-regtested all lanugages on x86_64-linux. OK?
OK.
> gcc/ChangeLog:
>
> 2021-11-19 Jan Hubicka
>
> * tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Do not guard modref
> by !gimple_call_chain.
>
> gcc/testsuite/ChangeLog:
>
> 2021-11-19 Jan Hubicka
>
> * gcc.dg/tree-ssa/modref-dse-6.c: New test.
>
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-6.c
> b/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-6.c
> new file mode 100644
> index 000..d1e45a893ad
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-6.c
> @@ -0,0 +1,23 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +int
> +main()
> +{
> + int a,b;
> + __attribute__ ((noinline))
> + void kill_me()
> + {
> +a=1234;
> +b=2234;
> + }
> + a=0;
> + b=1234;
> + __attribute__ ((noinline))
> + int reta()
> + {
> +return a;
> + }
> + return reta();
> +}
> +/* { dg-final { scan-tree-dump-not "kill_me" "optimized" } } */
> +/* { dg-final { scan-tree-dump-not "1234" "optimized" } } */
> diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
> index 02bbc87b597..cd6a0b2f67b 100644
> --- a/gcc/tree-ssa-alias.c
> +++ b/gcc/tree-ssa-alias.c
> @@ -2755,7 +2755,7 @@ ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *ref,
> bool tbaa_p)
>
>callee = gimple_call_fndecl (call);
>
> - if (!gimple_call_chain (call) && callee != NULL_TREE)
> + if (callee != NULL_TREE)
> {
>struct cgraph_node *node = cgraph_node::get (callee);
>/* We can not safely optimize based on summary of calle if it does
>
--
Richard Biener
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)
