Hi,
On Fri, Sep 12 2025, Qing Zhao wrote:
> In tree-sra.cc, for the following stmt (initialization in source code):
> s = {};
>
> for the above lhs "s", the field "grp_assignment_write" of the created
> struct access is 1;
>
> however, for the following stmt (compiler added initialization):
> s = .DEFERRED_INIT (size, init_type, &"s"[0]);
>
> for the above lhs "s", the field "grp_assignment_write" of the created
> struct access is 0;
>
> Since the field "grp_assignment_write" of the struct access for the
> corresponding LHS "s" is not set correctly when the RHS is .DEFERRED_INIT,
> SRA phase didn't do a correct transformation for call to .DEFERRED_INIT.
>
> To fix this issue, we should set the field "grp_assignment_write" correctly
> for .DEFERRED_INIT.
>
> PR 121894
>
> gcc/ChangeLog:
>
> * tree-sra.cc (scan_function): Set grp_assignment_write to 1 when
> specially handle call to .DEFERRED_INIT.
>
Thanks,
I cannot approve the change but I think it makes sense.
Martin
> gcc/testsuite/ChangeLog:
>
> * g++.dg/auto-init-sra-pr121894.C: New test.
>
> The patch is bootstrapping and regression testing on both x86 and aarch64,
> Okay for committing if no issue?
>
> Thanks.
>
> Qing
>
> ---
> gcc/testsuite/g++.dg/auto-init-sra-pr121894.C | 22 +++++++++++++++++++
> gcc/tree-sra.cc | 8 ++++++-
> 2 files changed, 29 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/g++.dg/auto-init-sra-pr121894.C
>
> diff --git a/gcc/testsuite/g++.dg/auto-init-sra-pr121894.C
> b/gcc/testsuite/g++.dg/auto-init-sra-pr121894.C
> new file mode 100644
> index 00000000000..b1e5a59ffe7
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/auto-init-sra-pr121894.C
> @@ -0,0 +1,22 @@
> +/* Verify that SRA total scalarization will not be confused by padding
> + and also not confused by auto initialization. */
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fdump-tree-esra -ftrivial-auto-var-init=pattern" } */
> +
> +struct S { int a, b, c, d; };
> +void bar (int, int, int, int);
> +
> +void
> +foo ()
> +{
> + S s;
> + s.a = 1;
> + s.c = 2;
> + s.d = 3;
> + s.a++;
> + s.c++;
> + s.d++;
> + bar (s.a, s.b, s.c, s.d);
> +}
> +
> +/* { dg-final { scan-tree-dump-times "DEFERRED_INIT" 4 "esra" } } */
> diff --git a/gcc/tree-sra.cc b/gcc/tree-sra.cc
> index 921664ef470..cb0f518ff03 100644
> --- a/gcc/tree-sra.cc
> +++ b/gcc/tree-sra.cc
> @@ -1678,7 +1678,13 @@ scan_function (void)
> /* If the STMT is a call to DEFERRED_INIT, avoid setting
> cannot_scalarize_away_bitmap. */
> if (gimple_call_internal_p (stmt, IFN_DEFERRED_INIT))
> - ret |= !!build_access_from_expr_1 (t, stmt, true);
> + {
> + struct access *access
> + = build_access_from_expr_1 (t, stmt, true);
> + if (access)
> + access->grp_assignment_write = 1;
> + ret |= access != NULL;
> + }
> else
> ret |= build_access_from_expr (t, stmt, true);
> }
> --
> 2.31.1
