Re: Allow passing arrays in registers on AArch64

[Yufeng Zhang]

Hi Michael,

Thanks for the fix.  The patch looks OK to me in general, although I 
have some minor comments below.

On 01/17/14 08:22, Michael Hudson-Doyle wrote:
Hi, as discussed inhttp://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799
GCC currently gets a detail of the AArch64 ABI wrong: arrays are not
always passed by reference.  Fortunately the fix is rather easy...

Can you please indicate what kind of testing you have run, e.g. regtest 
on aarch64-none-abi?

Also can you please try to add some new test(s)?  It may not be that 
straightforward to add non-C/C++ tests, but give it a try.


I guess this is an ABI break but my understand there has been no release
of GCC which supports compiling a language that can pass arrays by value
on AArch64 yet.

Cheers,
mwh

   2014-01-17  Michael Hudson-Doyle<michael.hud...@linaro.org>

             PR target/59799

             * config/aarch64/aarch64.c (aarch64_pass_by_reference):
               The rules for passing arrays in registers are the same as
               for structs, so remove the special case for them.


aarch64-abi-fix.diff


diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index fa53c71..d63da95 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -987,10 +987,7 @@ aarch64_pass_by_reference (cumulative_args_t pcum 
ATTRIBUTE_UNUSED,

    if (type)
      {
-      /* Arrays always passed by reference.  */
-      if (TREE_CODE (type) == ARRAY_TYPE)
-       return true;
-      /* Other aggregates based on their size.  */
+      /* Aggregates based on their size.  */
        if (AGGREGATE_TYPE_P (type))
        size = int_size_in_bytes (type);
      }


You can actually merge the two iffs to have something like:

  /* Aggregates are based on their size.  */
  if (type && AGGREGATE_TYPE_P (type))
    size = int_size_in_bytes (type);

Thanks,
Yufeng