diff mbox series

[v2] Print padding size when aligning struct member

Message ID 20230224072835.12177-1-vit.kabele@sysgo.com
State New
Headers
Series [v2] Print padding size when aligning struct member |

Commit Message

Vit Kabele Feb. 24, 2023, 7:28 a.m. UTC 
  Hello,

I changed the tested pattern to match even on targets with different
alignment.

BR,
VK

-- >8 --

Announce the size of introduced padding when compiling
with -Wpadded.

gcc/ChangeLog:

	* stor-layout.cc (place_field): Change warning message format

gcc/testsuite/ChangeLog:

	* c-c++-common/Wpadded.c: Add new testcase
	* gcc.dg/Wpadded.c: Update the expected warning message

Signed-off-by: Vít Kabele <vit.kabele@sysgo.com>
---
 gcc/stor-layout.cc                   | 2 +-
 gcc/testsuite/c-c++-common/Wpadded.c | 1 +
 gcc/testsuite/gcc.dg/Wpadded.c       | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

Comments

Jeff Law March 11, 2023, 3:35 p.m. UTC | #1 
On 2/24/23 00:28, Vít Kabele wrote:
> Hello,
> 
> I changed the tested pattern to match even on targets with different
> alignment.
So this needs to wait for stage1 development to open -- we're in 
regression bugfixing phase only right now.  I would expect that to 
happen in April/May.

You might consider changing the other similar message you added last 
year to finalize_record_size to use the same format as this message for 
the sake of consistency.

Jeff
Vit Kabele March 28, 2023, 2:24 p.m. UTC | #2 
Hello,

On Sat, Mar 11, 2023 at 08:35:53AM -0700, Jeff Law wrote:
> On 2/24/23 00:28, Vít Kabele wrote:
> You might consider changing the other similar message you added last year to
> finalize_record_size to use the same format as this message for the sake of
> consistency.
For example like this?

- padding struct with %d bytes to align %q+D
+ padding struct to align %q+D with %d bytes

to be consistent with:

padding struct size to alignment boundary with %E bytes
diff mbox series

Patch

diff --git a/gcc/stor-layout.cc b/gcc/stor-layout.cc
index 45bf2d18639..1d2bd61eeae 100644
--- a/gcc/stor-layout.cc
+++ b/gcc/stor-layout.cc
@@ -1346,7 +1346,7 @@  place_field (record_layout_info rli, tree field)
       if (!targetm.ms_bitfield_layout_p (rli->t)
 	  && DECL_SOURCE_LOCATION (field) != BUILTINS_LOCATION
 	  && !TYPE_ARTIFICIAL (rli->t))
-	warning (OPT_Wpadded, "padding struct to align %q+D", field);
+	warning (OPT_Wpadded, "padding struct with %d bytes to align %q+D", (desired_align - known_align)/8, field);
 
       /* If the alignment is still within offset_align, just align
 	 the bit position.  */
diff --git a/gcc/testsuite/c-c++-common/Wpadded.c b/gcc/testsuite/c-c++-common/Wpadded.c
index c5be4686822..0818ea03690 100644
--- a/gcc/testsuite/c-c++-common/Wpadded.c
+++ b/gcc/testsuite/c-c++-common/Wpadded.c
@@ -11,4 +11,5 @@ 
  * 4 byte fields to 2 byte boundary.
  */
 struct S { __UINT32_TYPE__ i; char c; } __attribute__((aligned(4))); /* { dg-warning "padding struct size to alignment boundary with 3 bytes" } */
+struct R { char c; __UINT32_TYPE__ i; } __attribute__((aligned(4))); /* { dg-warning "padding struct with" } */
 
diff --git a/gcc/testsuite/gcc.dg/Wpadded.c b/gcc/testsuite/gcc.dg/Wpadded.c
index 70fcd79a6d4..218b37d1abc 100644
--- a/gcc/testsuite/gcc.dg/Wpadded.c
+++ b/gcc/testsuite/gcc.dg/Wpadded.c
@@ -10,5 +10,5 @@ 
 
 struct foo {
   char bar;
-  long baz; /* { dg-warning "padding struct to align" ""  { target { ! default_packed } } } */
+  long baz; /* { dg-warning "padding struct with" ""  { target { ! default_packed } } } */
 } futz;