On October 16, 2021 2:47:51 PM GMT+02:00, Jan Hubicka via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>Hi,
>while updating compute_points_to_sets I missed that the code not only
>sets the nonlocal/escaped flags but also initializes pt. With my
>previous change if uses_global_memory is false pt is not updated
>correctly which may lead to wrong code.
>
>This is fixed by the following patch I comitted to avoid strange
>misoptimizations.
>
>Bootstrapped/regtested x86_64-linux and also tested with LTO.
OK.
Richard.
>Honza
>
>gcc/ChangeLog:
>
> PR tree-optimization/102720
> * tree-ssa-structalias.c (compute_points_to_sets): Fix producing
> of call used and clobbered sets.
>
>diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
>index 6f12a66ee0d..2e6513bb72a 100644
>--- a/gcc/tree-ssa-structalias.c
>+++ b/gcc/tree-ssa-structalias.c
>@@ -7541,17 +7541,18 @@ compute_points_to_sets (void)
> determine_global_memory_access (stmt, NULL,
> &reads_global_memory,
> &uses_global_memory);
>- if (!uses_global_memory)
>- ;
>- else if ((vi = lookup_call_use_vi (stmt)) != NULL)
>+ if ((vi = lookup_call_use_vi (stmt)) != NULL)
> {
> *pt = find_what_var_points_to (cfun->decl, vi);
> /* Escaped (and thus nonlocal) variables are always
> implicitly used by calls. */
> /* ??? ESCAPED can be empty even though NONLOCAL
> always escaped. */
>- pt->nonlocal = uses_global_memory;
>- pt->escaped = uses_global_memory;
>+ if (uses_global_memory)
>+ {
>+ pt->nonlocal = uses_global_memory;
>+ pt->escaped = uses_global_memory;
>+ }
> }
> else if (uses_global_memory)
> {
>@@ -7572,17 +7573,18 @@ compute_points_to_sets (void)
> determine_global_memory_access (stmt, &writes_global_memory,
> NULL, NULL);
>
>- if (!writes_global_memory)
>- ;
>- else if ((vi = lookup_call_clobber_vi (stmt)) != NULL)
>+ if ((vi = lookup_call_clobber_vi (stmt)) != NULL)
> {
> *pt = find_what_var_points_to (cfun->decl, vi);
> /* Escaped (and thus nonlocal) variables are always
> implicitly clobbered by calls. */
> /* ??? ESCAPED can be empty even though NONLOCAL
> always escaped. */
>- pt->nonlocal = writes_global_memory;
>- pt->escaped = writes_global_memory;
>+ if (writes_global_memory)
>+ {
>+ pt->nonlocal = writes_global_memory;
>+ pt->escaped = writes_global_memory;
>+ }
> }
> else if (writes_global_memory)
> {
