[pushed] libiberty, Darwin : Fix simple-object LTO table for cross-endian case.

Hi,

For mach-o, we encapsulate streamed IR for LTO in three special
sections with a table that describes their entries.  The table is expected
to be written with native endianness for the target, but for cross-endian
cross-compilation the swapping was omitted.  Fixed thus.

tested on a cross from x86_64-darwin to powerpc-darwin,
pushed to master, thanks
Iain

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

libiberty/ChangeLog:

	* simple-object-mach-o.c (simple_object_mach_o_write_segment):
	Arrange to swap the LTO index tables where needed.
---
 libiberty/simple-object-mach-o.c | 5 +++++
 1 file changed, 5 insertions(+)

On 8/18/21 20:37, Iain Sandoe wrote:
> Hi,
> 
> For mach-o, we encapsulate streamed IR for LTO in three special
> sections with a table that describes their entries.  The table is expected
> to be written with native endianness for the target, but for cross-endian
> cross-compilation the swapping was omitted.  Fixed thus.

Hello.

I noticed the change produced the following Clang warning:

build/libiberty/simple-object-mach-o.c:1231:10: warning: incompatible pointer types passing 'unsigned int *' to parameter of type 'unsigned char *' [-Wincompatible-pointer-types]

Can you please take a look?
Thanks,
Martin

> 
> tested on a cross from x86_64-darwin to powerpc-darwin,
> pushed to master, thanks
> Iain
> 
> Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
> 
> libiberty/ChangeLog:
> 
> 	* simple-object-mach-o.c (simple_object_mach_o_write_segment):
> 	Arrange to swap the LTO index tables where needed.
> ---
>   libiberty/simple-object-mach-o.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/libiberty/simple-object-mach-o.c b/libiberty/simple-object-mach-o.c
> index aa5e0952faf..72b69d19c21 100644
> --- a/libiberty/simple-object-mach-o.c
> +++ b/libiberty/simple-object-mach-o.c
> @@ -1225,6 +1225,11 @@ simple_object_mach_o_write_segment (simple_object_write *sobj, int descriptor,
>   	index[4 * i] -= index[0];
>         index[0] = 0;
>   
> +      /* Swap the indices, if required.  */
> +
> +      for (i = 0; i < (nsects_in * 4); ++i)
> +	set_32 (&index[i], index[i]);
> +
>         sechdr_offset += sechdrsize;
>   
>         /* Write out the section names.
>

Hi,

> On 23 Aug 2021, at 09:07, Martin Liška <mliska@suse.cz> wrote:
> 
> On 8/18/21 20:37, Iain Sandoe wrote:

>> For mach-o, we encapsulate streamed IR for LTO in three special
>> sections with a table that describes their entries.  The table is expected
>> to be written with native endianness for the target, but for cross-endian
>> cross-compilation the swapping was omitted.  Fixed thus.

> I noticed the change produced the following Clang warning:
> 
> build/libiberty/simple-object-mach-o.c:1231:10: warning: incompatible pointer types passing 'unsigned int *' to parameter of type 'unsigned char *' [-Wincompatible-pointer-types]

thanks for catching that, fixed as below 
tested on x86_64-darwin X powerpc-darwin (with clang and GCC).
pushed to master, thanks
Iain


diff --git a/libiberty/simple-object-mach-o.c b/libiberty/simple-object-mach-o.c
index 72b69d19c21..a8869e7c639 100644
--- a/libiberty/simple-object-mach-o.c
+++ b/libiberty/simple-object-mach-o.c
@@ -1228,7 +1228,7 @@ simple_object_mach_o_write_segment (simple_object_write *sobj, int descriptor,
       /* Swap the indices, if required.  */
 
       for (i = 0; i < (nsects_in * 4); ++i)
-	set_32 (&index[i], index[i]);
+	set_32 ((unsigned char *) &index[i], index[i]);
 
       sechdr_offset += sechdrsize;