diff mbox series

aarch64: Move pass_narrow_gp_writes above pass_free_cfg [PR124895]

Message ID 5980B89D-C6F9-438C-B1D6-89DE4966096A@nvidia.com
State Committed
Headers
Series aarch64: Move pass_narrow_gp_writes above pass_free_cfg [PR124895] |

Commit Message

Soumya AR May 6, 2026, 10:13 a.m. UTC 
  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 <soumyaa@nvidia.com>

	PR target/124895

gcc/ChangeLog:

	* config/aarch64/aarch64-passes.def (INSERT_PASS_BEFORE): Move pass
	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

Comments

Alex Coplan May 6, 2026, 12:56 p.m. UTC | #1 
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 <soumyaa@nvidia.com>
> 
> 	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
Soumya AR May 8, 2026, 7:01 a.m. UTC | #2 
Committed: cefcc09723c

Thanks!

> On 6 May 2026, at 6:26 PM, Alex Coplan <alex.coplan@arm.com> wrote:
> 
> External email: Use caution opening links or attachments
> 
> 
> 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 <soumyaa@nvidia.com>
>> 
>>      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
diff mbox series

Patch

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)
+    ;
+}