Re: [PATCH] Print padding size when aligning struct member

[Vit Kabele]

On Tue, Feb 07, 2023 at 02:08:35PM +0100, Andreas Schwab wrote:
> On Feb 07 2023, Vít Kabele wrote:
> 
> > diff --git a/gcc/testsuite/gcc.dg/Wpadded.c b/gcc/testsuite/gcc.dg/Wpadded.c
> > index 70fcd79a6d4..357e7f61e4a 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 7 bytes to align" ""  { 
> > target { ! default_packed } } } */
> 
> The actual amount of padding is target dependent.
Ah sorry, would removing everything after `with...` be ok?

Like this:
> +  long baz; /* { dg-warning "padding struct with" ""  { target { ! 
> default_packed } } } */

-- 
Best regards,
Vit Kabele

Re: [PATCH] Print padding size when aligning struct member

[Andreas Schwab via Gcc-patches]

On Feb 07 2023, Vít Kabele wrote:

> diff --git a/gcc/testsuite/gcc.dg/Wpadded.c b/gcc/testsuite/gcc.dg/Wpadded.c
> index 70fcd79a6d4..357e7f61e4a 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 7 bytes to align" ""  { 
> target { ! default_packed } } } */

The actual amount of padding is target dependent.

-- 
Andreas Schwab, SUSE Labs, sch...@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

[PATCH] Print padding size when aligning struct member

[Vít Kabele]

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 
---
 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(-)

diff --git a/gcc/stor-layout.cc b/gcc/stor-layout.cc
index 45bf2d18639..fb1948b94af 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..35ff013026f 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 3 bytes to align 'i'" } */
 
diff --git a/gcc/testsuite/gcc.dg/Wpadded.c b/gcc/testsuite/gcc.dg/Wpadded.c
index 70fcd79a6d4..357e7f61e4a 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 7 bytes to align" ""  { 
target { ! default_packed } } } */
 } futz;
-- 
2.30.2