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POWERPC64_TOC_POINTER_ALIGNMENT

Message ID 20151118023217.GH8120@bubble.grove.modra.org
State New
Headers show

Commit Message

Alan Modra Nov. 18, 2015, 2:32 a.m. UTC 
On Tue, Nov 17, 2015 at 07:53:18PM -0500, Michael Meissner wrote:
> Here is the temporary patch I'm using to get past rs6000.c.  But I suspect the
> TOC alignment should never be 256.

Yes, it should be.  Recent GNU ld aligns .TOC. to a 256 byte boundary.
I have this patch in my tree.

Comments

David Edelsohn Nov. 18, 2015, 3:35 p.m. UTC | #1 
On Tue, Nov 17, 2015 at 9:32 PM, Alan Modra <amodra@gmail.com> wrote:
> On Tue, Nov 17, 2015 at 07:53:18PM -0500, Michael Meissner wrote:
>> Here is the temporary patch I'm using to get past rs6000.c.  But I suspect the
>> TOC alignment should never be 256.
>
> Yes, it should be.  Recent GNU ld aligns .TOC. to a 256 byte boundary.
> I have this patch in my tree.
>
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index abc8eaa..e3ec042 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -8059,12 +8059,17 @@ rs6000_cannot_force_const_mem (machine_mode mode ATTRIBUTE_UNUSED, rtx x)
>  static bool
>  use_toc_relative_ref (rtx sym, machine_mode mode)
>  {
> +  /* Silence complaint that the POWERPC64_TOC_POINTER_ALIGNMENT test
> +     is always true.  */
> +#pragma GCC diagnostic push
> +#pragma GCC diagnostic ignored "-Wtype-limits"
>    return ((constant_pool_expr_p (sym)
>            && ASM_OUTPUT_SPECIAL_POOL_ENTRY_P (get_pool_constant (sym),
>                                                get_pool_mode (sym)))
>           || (TARGET_CMODEL == CMODEL_MEDIUM
>               && SYMBOL_REF_LOCAL_P (sym)
>               && GET_MODE_SIZE (mode) <= POWERPC64_TOC_POINTER_ALIGNMENT));
> +#pragma GCC diagnostic pop
>  }
>
>  /* Our implementation of LEGITIMIZE_RELOAD_ADDRESS.  Returns a value to

I have applied Alan's work-around for now until there is a more robust solution.

Thanks, David
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Patch

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index abc8eaa..e3ec042 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -8059,12 +8059,17 @@  rs6000_cannot_force_const_mem (machine_mode mode ATTRIBUTE_UNUSED, rtx x)
 static bool
 use_toc_relative_ref (rtx sym, machine_mode mode)
 {
+  /* Silence complaint that the POWERPC64_TOC_POINTER_ALIGNMENT test
+     is always true.  */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wtype-limits"
   return ((constant_pool_expr_p (sym)
 	   && ASM_OUTPUT_SPECIAL_POOL_ENTRY_P (get_pool_constant (sym),
 					       get_pool_mode (sym)))
 	  || (TARGET_CMODEL == CMODEL_MEDIUM
 	      && SYMBOL_REF_LOCAL_P (sym)
 	      && GET_MODE_SIZE (mode) <= POWERPC64_TOC_POINTER_ALIGNMENT));
+#pragma GCC diagnostic pop
 }
 
 /* Our implementation of LEGITIMIZE_RELOAD_ADDRESS.  Returns a value to