On 06/05/2026 10:13, Soumya AR wrote:
> The narrow_gp_writes pass uses RTL-SSA and updates DF state via
> df_insn_rescan / df_insn_delete. Both routines look up the insn's bb via
> BLOCK_FOR_INSN to mark it dirty after a change, but pass_free_cfg has already
> cleared those per-insn pointers by the time narrow_gp_writes runs. When
> BLOCK_FOR_INSN returns NULL, the dirty-marking step is silently skipped,
> leaving the DF stale.
>
> Move the pass to run before pass_free_cfg.
>
> Bootstrapped and regtested on aarch64-linux-gnu.
> SPEC CPU 2017 shows no codegen differences (compared to previous placement).
> OK for trunk?
>
> Signed-off-by: Soumya AR <[email protected]>
>
> PR target/124895
>
> gcc/ChangeLog:
>
> * config/aarch64/aarch64-passes.def (INSERT_PASS_BEFORE): Move pass
I think the text in parens here should be pass_narrow_gp_writes.
LGTM with that change, but please give others 24 hours to comment.
Thanks,
Alex
> before pass_free_cfg.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/aarch64/narrow-gp-writes-8.c: New test.
> ---
> gcc/config/aarch64/aarch64-passes.def | 2 +-
> gcc/testsuite/gcc.target/aarch64/narrow-gp-writes-8.c | 10 ++++++++++
> 2 files changed, 11 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/aarch64/narrow-gp-writes-8.c
>
> diff --git a/gcc/config/aarch64/aarch64-passes.def
> b/gcc/config/aarch64/aarch64-passes.def
> index f4307aab551..2df7459af92 100644
> --- a/gcc/config/aarch64/aarch64-passes.def
> +++ b/gcc/config/aarch64/aarch64-passes.def
> @@ -26,4 +26,4 @@ INSERT_PASS_BEFORE (pass_late_thread_prologue_and_epilogue,
> 1, pass_late_track_s
> INSERT_PASS_BEFORE (pass_shorten_branches, 1, pass_insert_bti);
> INSERT_PASS_BEFORE (pass_early_remat, 1, pass_ldp_fusion);
> INSERT_PASS_BEFORE (pass_peephole2, 1, pass_ldp_fusion);
> -INSERT_PASS_BEFORE (pass_cleanup_barriers, 1, pass_narrow_gp_writes);
> +INSERT_PASS_BEFORE (pass_free_cfg, 1, pass_narrow_gp_writes);
> diff --git a/gcc/testsuite/gcc.target/aarch64/narrow-gp-writes-8.c
> b/gcc/testsuite/gcc.target/aarch64/narrow-gp-writes-8.c
> new file mode 100644
> index 00000000000..94ef761e801
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/narrow-gp-writes-8.c
> @@ -0,0 +1,10 @@
> +/* PR target/124895 */
> +/* { dg-do compile } */
> +/* { dg-options "-Os -fpath-coverage -fno-tree-ccp -fprofile-generate
> -mnarrow-gp-writes" } */
> +
> +void
> +foo (unsigned u)
> +{
> + while (u)
> + ;
> +}
> --
> 2.43.0
