* [PATCH][V4][middle-end/104550]Suppress uninitialized warnings for new created uses from __builtin_clear_padding folding
@ 2022-02-26 0:21 Qing Zhao
2022-02-28 9:50 ` Richard Biener
0 siblings, 1 reply; 2+ messages in thread
From: Qing Zhao @ 2022-02-26 0:21 UTC (permalink / raw)
To: jakub Jelinek, richard Biener; +Cc: gcc-patches Paul A Clarke via
Hi,
This is the 4th version based on the discussion so far.
The major change is:
> SET_EXPR_LOCATION (tmp_dst, UNKNOWN_LOCATION);
> suppress_warning (tmp_dst, OPT_Wuninitialized);
> with a comment explaing why we do that.
The patch has been bootstrapped and regress tested on both x86 and aarch64.
Okay for trunk?
Thanks.
Qing
=====================
From 276975e60827942f0dd4043ce5f52e600327d6a8 Mon Sep 17 00:00:00 2001
From: Qing Zhao <qing.zhao@oracle.com>
Date: Thu, 24 Feb 2022 22:38:38 +0000
Subject: [PATCH] Suppress uninitialized warnings for new created uses from
__builtin_clear_padding folding [PR104550]
__builtin_clear_padding(&object) will clear all the padding bits of the object.
actually, it doesn't involve any use of an user variable. Therefore, users do
not expect any uninitialized warning from it. It's reasonable to suppress
uninitialized warnings for all new created uses from __builtin_clear_padding
folding.
PR middle-end/104550
gcc/ChangeLog:
* gimple-fold.cc (clear_padding_flush): Suppress warnings for new
created uses.
gcc/testsuite/ChangeLog:
* gcc.dg/auto-init-pr104550-1.c: New test.
* gcc.dg/auto-init-pr104550-2.c: New test.
* gcc.dg/auto-init-pr104550-3.c: New test.
---
gcc/gimple-fold.cc | 12 +++++++++++-
gcc/testsuite/gcc.dg/auto-init-pr104550-1.c | 10 ++++++++++
gcc/testsuite/gcc.dg/auto-init-pr104550-2.c | 11 +++++++++++
gcc/testsuite/gcc.dg/auto-init-pr104550-3.c | 11 +++++++++++
4 files changed, 43 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/auto-init-pr104550-1.c
create mode 100644 gcc/testsuite/gcc.dg/auto-init-pr104550-2.c
create mode 100644 gcc/testsuite/gcc.dg/auto-init-pr104550-3.c
diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index 16f02c2d098d..c9179abb27ed 100644
--- a/gcc/gimple-fold.cc
+++ b/gcc/gimple-fold.cc
@@ -4379,7 +4379,17 @@ clear_padding_flush (clear_padding_struct *buf, bool full)
else
{
src = make_ssa_name (type);
- g = gimple_build_assign (src, unshare_expr (dst));
+ tree tmp_dst = unshare_expr (dst);
+ /* The folding introduces a read from the tmp_dst, we should
+ prevent uninitialized warning analysis from issuing warning
+ for such fake read. In order to suppress warning only for
+ this expr, we should set the location of tmp_dst to
+ UNKNOWN_LOCATION first, then suppress_warning will call
+ set_no_warning_bit to set the no_warning flag only for
+ tmp_dst. */
+ SET_EXPR_LOCATION (tmp_dst, UNKNOWN_LOCATION);
+ suppress_warning (tmp_dst, OPT_Wuninitialized);
+ g = gimple_build_assign (src, tmp_dst);
gimple_set_location (g, buf->loc);
gsi_insert_before (buf->gsi, g, GSI_SAME_STMT);
tree mask = native_interpret_expr (type,
diff --git a/gcc/testsuite/gcc.dg/auto-init-pr104550-1.c b/gcc/testsuite/gcc.dg/auto-init-pr104550-1.c
new file mode 100644
index 000000000000..a08110c3a170
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/auto-init-pr104550-1.c
@@ -0,0 +1,10 @@
+/* PR 104550*/
+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized -ftrivial-auto-var-init=pattern" } */
+struct vx_audio_level {
+ int has_monitor_level : 1;
+};
+
+void vx_set_monitor_level() {
+ struct vx_audio_level info; /* { dg-bogus "info" "is used uninitialized" } */
+}
diff --git a/gcc/testsuite/gcc.dg/auto-init-pr104550-2.c b/gcc/testsuite/gcc.dg/auto-init-pr104550-2.c
new file mode 100644
index 000000000000..2c395b32d322
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/auto-init-pr104550-2.c
@@ -0,0 +1,11 @@
+/* PR 104550 */
+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized -ftrivial-auto-var-init=zero" } */
+struct vx_audio_level {
+ int has_monitor_level : 1;
+};
+
+void vx_set_monitor_level() {
+ struct vx_audio_level info;
+ __builtin_clear_padding (&info); /* { dg-bogus "info" "is used uninitialized" } */
+}
diff --git a/gcc/testsuite/gcc.dg/auto-init-pr104550-3.c b/gcc/testsuite/gcc.dg/auto-init-pr104550-3.c
new file mode 100644
index 000000000000..9893e37f12d8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/auto-init-pr104550-3.c
@@ -0,0 +1,11 @@
+/* PR 104550 */
+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized -ftrivial-auto-var-init=pattern" } */
+struct vx_audio_level {
+ int has_monitor_level : 1;
+};
+
+void vx_set_monitor_level() {
+ struct vx_audio_level info; /* { dg-bogus "info" "is used uninitialized" } */
+ __builtin_clear_padding (&info); /* { dg-bogus "info" "is used uninitialized" } */
+}
--
2.27.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH][V4][middle-end/104550]Suppress uninitialized warnings for new created uses from __builtin_clear_padding folding
2022-02-26 0:21 [PATCH][V4][middle-end/104550]Suppress uninitialized warnings for new created uses from __builtin_clear_padding folding Qing Zhao
@ 2022-02-28 9:50 ` Richard Biener
0 siblings, 0 replies; 2+ messages in thread
From: Richard Biener @ 2022-02-28 9:50 UTC (permalink / raw)
To: Qing Zhao; +Cc: jakub Jelinek, gcc-patches Paul A Clarke via
On Sat, 26 Feb 2022, Qing Zhao wrote:
> Hi,
>
> This is the 4th version based on the discussion so far.
>
> The major change is:
>
> > SET_EXPR_LOCATION (tmp_dst, UNKNOWN_LOCATION);
> > suppress_warning (tmp_dst, OPT_Wuninitialized);
> > with a comment explaing why we do that.
>
>
> The patch has been bootstrapped and regress tested on both x86 and aarch64.
> Okay for trunk?
OK.
Thanks,
Richard.
> Thanks.
>
> Qing
>
> =====================
> From 276975e60827942f0dd4043ce5f52e600327d6a8 Mon Sep 17 00:00:00 2001
> From: Qing Zhao <qing.zhao@oracle.com>
> Date: Thu, 24 Feb 2022 22:38:38 +0000
> Subject: [PATCH] Suppress uninitialized warnings for new created uses from
> __builtin_clear_padding folding [PR104550]
>
> __builtin_clear_padding(&object) will clear all the padding bits of the object.
> actually, it doesn't involve any use of an user variable. Therefore, users do
> not expect any uninitialized warning from it. It's reasonable to suppress
> uninitialized warnings for all new created uses from __builtin_clear_padding
> folding.
>
> PR middle-end/104550
>
> gcc/ChangeLog:
>
> * gimple-fold.cc (clear_padding_flush): Suppress warnings for new
> created uses.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/auto-init-pr104550-1.c: New test.
> * gcc.dg/auto-init-pr104550-2.c: New test.
> * gcc.dg/auto-init-pr104550-3.c: New test.
> ---
> gcc/gimple-fold.cc | 12 +++++++++++-
> gcc/testsuite/gcc.dg/auto-init-pr104550-1.c | 10 ++++++++++
> gcc/testsuite/gcc.dg/auto-init-pr104550-2.c | 11 +++++++++++
> gcc/testsuite/gcc.dg/auto-init-pr104550-3.c | 11 +++++++++++
> 4 files changed, 43 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.dg/auto-init-pr104550-1.c
> create mode 100644 gcc/testsuite/gcc.dg/auto-init-pr104550-2.c
> create mode 100644 gcc/testsuite/gcc.dg/auto-init-pr104550-3.c
>
> diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
> index 16f02c2d098d..c9179abb27ed 100644
> --- a/gcc/gimple-fold.cc
> +++ b/gcc/gimple-fold.cc
> @@ -4379,7 +4379,17 @@ clear_padding_flush (clear_padding_struct *buf, bool full)
> else
> {
> src = make_ssa_name (type);
> - g = gimple_build_assign (src, unshare_expr (dst));
> + tree tmp_dst = unshare_expr (dst);
> + /* The folding introduces a read from the tmp_dst, we should
> + prevent uninitialized warning analysis from issuing warning
> + for such fake read. In order to suppress warning only for
> + this expr, we should set the location of tmp_dst to
> + UNKNOWN_LOCATION first, then suppress_warning will call
> + set_no_warning_bit to set the no_warning flag only for
> + tmp_dst. */
> + SET_EXPR_LOCATION (tmp_dst, UNKNOWN_LOCATION);
> + suppress_warning (tmp_dst, OPT_Wuninitialized);
> + g = gimple_build_assign (src, tmp_dst);
> gimple_set_location (g, buf->loc);
> gsi_insert_before (buf->gsi, g, GSI_SAME_STMT);
> tree mask = native_interpret_expr (type,
> diff --git a/gcc/testsuite/gcc.dg/auto-init-pr104550-1.c b/gcc/testsuite/gcc.dg/auto-init-pr104550-1.c
> new file mode 100644
> index 000000000000..a08110c3a170
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/auto-init-pr104550-1.c
> @@ -0,0 +1,10 @@
> +/* PR 104550*/
> +/* { dg-do compile } */
> +/* { dg-options "-O -Wuninitialized -ftrivial-auto-var-init=pattern" } */
> +struct vx_audio_level {
> + int has_monitor_level : 1;
> +};
> +
> +void vx_set_monitor_level() {
> + struct vx_audio_level info; /* { dg-bogus "info" "is used uninitialized" } */
> +}
> diff --git a/gcc/testsuite/gcc.dg/auto-init-pr104550-2.c b/gcc/testsuite/gcc.dg/auto-init-pr104550-2.c
> new file mode 100644
> index 000000000000..2c395b32d322
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/auto-init-pr104550-2.c
> @@ -0,0 +1,11 @@
> +/* PR 104550 */
> +/* { dg-do compile } */
> +/* { dg-options "-O -Wuninitialized -ftrivial-auto-var-init=zero" } */
> +struct vx_audio_level {
> + int has_monitor_level : 1;
> +};
> +
> +void vx_set_monitor_level() {
> + struct vx_audio_level info;
> + __builtin_clear_padding (&info); /* { dg-bogus "info" "is used uninitialized" } */
> +}
> diff --git a/gcc/testsuite/gcc.dg/auto-init-pr104550-3.c b/gcc/testsuite/gcc.dg/auto-init-pr104550-3.c
> new file mode 100644
> index 000000000000..9893e37f12d8
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/auto-init-pr104550-3.c
> @@ -0,0 +1,11 @@
> +/* PR 104550 */
> +/* { dg-do compile } */
> +/* { dg-options "-O -Wuninitialized -ftrivial-auto-var-init=pattern" } */
> +struct vx_audio_level {
> + int has_monitor_level : 1;
> +};
> +
> +void vx_set_monitor_level() {
> + struct vx_audio_level info; /* { dg-bogus "info" "is used uninitialized" } */
> + __builtin_clear_padding (&info); /* { dg-bogus "info" "is used uninitialized" } */
> +}
>
--
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)
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