Re: [pushed] Darwin, PPC: Fix struct layout with pragma pack [PR110044].

[Richard Biener via Gcc-patches]

> Am 02.06.2023 um 21:12 schrieb Iain Sandoe via Gcc-patches 
> <gcc-patches@gcc.gnu.org>:
> 
> @David: I am not sure what sets the ABI on AIX (for Darwin, it is effectively
> "whatever the system compiler [Apple gcc-4] does") but from an inspection of
> the code, it seems that (if the platform should honour #pragma pack) a similar
> effect could be present there too.
> 
> Tested on powerpc-apple-darwin9, powerpc64-linux-gnu and on i686 and x86_64
> Darwin.  Checked that the testcases also pass for Apple gcc-4.2.1.
> pushed to trunk, thanks
> Iain
> 
> --- 8< ---
> 
> This bug was essentially that darwin_rs6000_special_round_type_align()
> was ignoring externally-imposed capping of field alignment.
> 
> Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
> 
>    PR target/110044
> 
> gcc/ChangeLog:
> 
>    * config/rs6000/rs6000.cc (darwin_rs6000_special_round_type_align):
>    Make sure that we do not have a cap on field alignment before altering
>    the struct layout based on the type alignment of the first entry.
> 
> gcc/testsuite/ChangeLog:
> 
>    * gcc.target/powerpc/darwin-abi-13-0.c: New test.
>    * gcc.target/powerpc/darwin-abi-13-1.c: New test.
>    * gcc.target/powerpc/darwin-abi-13-2.c: New test.
>    * gcc.target/powerpc/darwin-structs-0.h: New test.
> ---
> gcc/config/rs6000/rs6000.cc                   |  3 +-
> .../gcc.target/powerpc/darwin-abi-13-0.c      | 23 +++++++++++++++
> .../gcc.target/powerpc/darwin-abi-13-1.c      | 27 +++++++++++++++++
> .../gcc.target/powerpc/darwin-abi-13-2.c      | 27 +++++++++++++++++
> .../gcc.target/powerpc/darwin-structs-0.h     | 29 +++++++++++++++++++
> 5 files changed, 108 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/powerpc/darwin-abi-13-0.c
> create mode 100644 gcc/testsuite/gcc.target/powerpc/darwin-abi-13-1.c
> create mode 100644 gcc/testsuite/gcc.target/powerpc/darwin-abi-13-2.c
> create mode 100644 gcc/testsuite/gcc.target/powerpc/darwin-structs-0.h
> 
> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
> index 5b3b8b52e7e..42f49e4a56b 100644
> --- a/gcc/config/rs6000/rs6000.cc
> +++ b/gcc/config/rs6000/rs6000.cc
> @@ -8209,7 +8209,8 @@ darwin_rs6000_special_round_type_align (tree type, 
> unsigned int computed,
>       type = TREE_TYPE (type);
>   } while (AGGREGATE_TYPE_P (type));
> 
> -  if (! AGGREGATE_TYPE_P (type) && type != error_mark_node)
> +  if (type != error_mark_node && ! AGGREGATE_TYPE_P (type)
> +      && ! TYPE_PACKED (type) && maximum_field_alignment == 0)

Just noticed while browsing mail.  ‚Maximum_field_alignment‘ sounds like
Something that should be factored in when 
Computing align but as written there’s no adjustment done instead?  Is there a 
way to get that to more than BITS_PER_UNIT?

>     align = MAX (align, TYPE_ALIGN (type));
> 
>   return align;
> diff --git a/gcc/testsuite/gcc.target/powerpc/darwin-abi-13-0.c 
> b/gcc/testsuite/gcc.target/powerpc/darwin-abi-13-0.c
> new file mode 100644
> index 00000000000..d8d3c63a083
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/darwin-abi-13-0.c
> @@ -0,0 +1,23 @@
> +/* { dg-do compile { target powerpc*-*-darwin* } } */
> +/* { dg-require-effective-target ilp32 } */
> +/* { dg-options "-Wno-long-long" } */
> +
> +#include "darwin-structs-0.h"
> +
> +int tcd[sizeof(cd) != 12 ? -1 : 1];
> +int acd[__alignof__(cd) != 4 ? -1 : 1];
> +
> +int sdc[sizeof(dc) != 16 ? -1 : 1];
> +int adc[__alignof__(dc) != 8 ? -1 : 1];
> +
> +int scL[sizeof(cL) != 12 ? -1 : 1];
> +int acL[__alignof__(cL) != 4 ? -1 : 1];
> +
> +int sLc[sizeof(Lc) != 16 ? -1 : 1];
> +int aLc[__alignof__(Lc) != 8 ? -1 : 1];
> +
> +int scD[sizeof(cD) != 32 ? -1 : 1];
> +int acD[__alignof__(cD) != 16 ? -1 : 1];
> +
> +int sDc[sizeof(Dc) != 32 ? -1 : 1];
> +int aDc[__alignof__(Dc) != 16 ? -1 : 1];
> diff --git a/gcc/testsuite/gcc.target/powerpc/darwin-abi-13-1.c 
> b/gcc/testsuite/gcc.target/powerpc/darwin-abi-13-1.c
> new file mode 100644
> index 00000000000..4d888d383fa
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/darwin-abi-13-1.c
> @@ -0,0 +1,27 @@
> +/* { dg-do compile { target powerpc*-*-darwin* } } */
> +/* { dg-require-effective-target ilp32 } */
> +/* { dg-options "-Wno-long-long" } */
> +
> +#pragma pack(push, 1)
> +
> +#include "darwin-structs-0.h"
> +
> +int tcd[sizeof(cd) != 9 ? -1 : 1];
> +int acd[__alignof__(cd) != 1 ? -1 : 1];
> +
> +int sdc[sizeof(dc) != 9 ? -1 : 1];
> +int adc[__alignof__(dc) != 1 ? -1 : 1];
> +
> +int scL[sizeof(cL) != 9 ? -1 : 1];
> +int acL[__alignof__(cL) != 1 ? -1 : 1];
> +
> +int sLc[sizeof(Lc) != 9 ? -1 : 1];
> +int aLc[__alignof__(Lc) != 1 ? -1 : 1];
> +
> +int scD[sizeof(cD) != 17 ? -1 : 1];
> +int acD[__alignof__(cD) != 1 ? -1 : 1];
> +
> +int sDc[sizeof(Dc) != 17 ? -1 : 1];
> +int aDc[__alignof__(Dc) != 1 ? -1 : 1];
> +
> +#pragma pack(pop)
> diff --git a/gcc/testsuite/gcc.target/powerpc/darwin-abi-13-2.c 
> b/gcc/testsuite/gcc.target/powerpc/darwin-abi-13-2.c
> new file mode 100644
> index 00000000000..3bd52c0a8f8
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/darwin-abi-13-2.c
> @@ -0,0 +1,27 @@
> +/* { dg-do compile { target powerpc*-*-darwin* } } */
> +/* { dg-require-effective-target ilp32 } */
> +/* { dg-options "-Wno-long-long" } */
> +
> +#pragma pack(push, 2)
> +
> +#include "darwin-structs-0.h"
> +
> +int tcd[sizeof(cd) != 10 ? -1 : 1];
> +int acd[__alignof__(cd) != 2 ? -1 : 1];
> +
> +int sdc[sizeof(dc) != 10 ? -1 : 1];
> +int adc[__alignof__(dc) != 2 ? -1 : 1];
> +
> +int scL[sizeof(cL) != 10 ? -1 : 1];
> +int acL[__alignof__(cL) != 2 ? -1 : 1];
> +
> +int sLc[sizeof(Lc) != 10 ? -1 : 1];
> +int aLc[__alignof__(Lc) != 2 ? -1 : 1];
> +
> +int scD[sizeof(cD) != 18 ? -1 : 1];
> +int acD[__alignof__(cD) != 2 ? -1 : 1];
> +
> +int sDc[sizeof(Dc) != 18 ? -1 : 1];
> +int aDc[__alignof__(Dc) != 2 ? -1 : 1];
> +
> +#pragma pack(pop)
> diff --git a/gcc/testsuite/gcc.target/powerpc/darwin-structs-0.h 
> b/gcc/testsuite/gcc.target/powerpc/darwin-structs-0.h
> new file mode 100644
> index 00000000000..1db44f7a808
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/darwin-structs-0.h
> @@ -0,0 +1,29 @@
> +typedef struct _cd {
> + char c;
> + double d;
> +} cd;
> +
> +typedef struct _dc {
> + double d;
> + char c;
> +} dc;
> +
> +typedef struct _cL {
> + char c;
> + long long L;
> +} cL;
> +
> +typedef struct _Lc {
> + long long L;
> + char c;
> +} Lc;
> +
> +typedef struct _cD {
> + char c;
> + long double D;
> +} cD;
> +
> +typedef struct _Dc {
> + long double D;
> + char c;
> +} Dc;
> -- 
> 2.39.2 (Apple Git-143)
>