> Am 15.02.2026 um 03:07 schrieb Andrew Pinski <[email protected]>:
>
> So a few more restrictions are needed here.
> First we don't need to change if the return statement is already
> a RESULT_DECL nor deference of the RESULT_DECL.
> Second proping a global variable into the return is ok for the most
> part except enumtls does not know how to expand that correctly and things
> go down hill. So restrict to non global vars now.
>
> Bootstrapped and tested on x86_64-linux-gnu.
> Also tested the testcase with TLS turned off so enumtls ran.
Ok
Richard
> PR tree-optimization/124099
>
> gcc/ChangeLog:
>
> * tree-ssa-forwprop.cc (optimize_agr_copyprop_return): Don't do anything
> if the return is already result decl or a deference of result decl.
> Also reject non local var decls.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/torture/tls-return-1.c: New test.
>
> Signed-off-by: Andrew Pinski <[email protected]>
> ---
> gcc/testsuite/gcc.dg/torture/tls-return-1.c | 12 ++++++++++++
> gcc/tree-ssa-forwprop.cc | 15 +++++++++++++--
> 2 files changed, 25 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/torture/tls-return-1.c
>
> diff --git a/gcc/testsuite/gcc.dg/torture/tls-return-1.c
> b/gcc/testsuite/gcc.dg/torture/tls-return-1.c
> new file mode 100644
> index 00000000000..aa56e42904c
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/torture/tls-return-1.c
> @@ -0,0 +1,12 @@
> +/* { dg-do compile } */
> +/* { dg-options "" } */
> +
> +
> +/* PR tree-optimization/124099 */
> +
> +struct s1 { int t[2];};
> +__thread struct s1 t;
> +struct s1 g()
> +{
> + return t;
> +}
> diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
> index c4fde7b4aae..a8a8e296b32 100644
> --- a/gcc/tree-ssa-forwprop.cc
> +++ b/gcc/tree-ssa-forwprop.cc
> @@ -1734,11 +1734,22 @@ optimize_agr_copyprop_return (gimple *defstmt,
> greturn *use,
> || is_gimple_min_invariant (rvalue)
> || TYPE_VOLATILE (TREE_TYPE (rvalue)))
> return;
> +
> + /* `<retval> = t;` is already the best it could be.
> + Likewise `*<retval>_N(D) = t`. */
> + if (TREE_CODE (rvalue) == RESULT_DECL
> + || (TREE_CODE (rvalue) == MEM_REF
> + && TREE_CODE (TREE_OPERAND (rvalue, 0)) == SSA_NAME
> + && TREE_CODE (SSA_NAME_VAR (TREE_OPERAND (rvalue, 0)))
> + == RESULT_DECL))
> + return;
> tree newsrc = new_src_based_on_copy (rvalue, dest, src);
> if (!newsrc)
> return;
> - /* Currently only support decls, could support VCEs too? */
> - if (!DECL_P (newsrc))
> + /* Currently only support non-global vars.
> + See PR 124099 on enumtls not supporting expanding for GIMPLE_RETURN.
> + FIXME: could support VCEs too? */
> + if (!VAR_P (newsrc) || is_global_var (newsrc))
> return;
> if (dump_file && (dump_flags & TDF_DETAILS))
> {
> --
> 2.43.0
>
