[Bug target/59799] New: aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[Bug target/59799] New: aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[michael.hudson at linaro dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

            Bug ID: 59799
           Summary: aarch64_pass_by_reference never passes arrays by
                    value, contrary to ABI documentation
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: michael.hudson at linaro dot org

It's always possible I'm totally misunderstanding something here, but it seems
that this code:

      /* Arrays always passed by reference.  */
      if (TREE_CODE (type) == ARRAY_TYPE)
    return true;

in gcc/config/aarch64/aarch64.c does not agree with the rules from "Procedure
Call Standard for the ARM 64-bit Architecture"
(http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055b/IHI0055B_aapcs64.pdf).
 As far as I can see the rules on page 18 and 19 make no distinction between
arrays and structs and they can both be passed in registers when small enough.

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
"It should be noted that the above algorithm makes provision for languages
other than C and C++ in that it provides 
for passing arrays by value and for passing arguments of dynamic size."

Note the other than C/C++ part here.  This means it only effects non C/C++
languages.

Does go or Ada allow passing arrays by value?

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #1)
> Does go or Ada allow passing arrays by value?

I know fortran does not at least directly.  In that the front-end creates a
structure for the argument instead.

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[ian at airs dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

Ian Lance Taylor <ian at airs dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ian at airs dot com

--- Comment #3 from Ian Lance Taylor <ian at airs dot com> ---
Go supports passing arrays by value.  That's where Michael ran into this issue
(http://golang.org/issue/7120).

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-01-15
     Ever confirmed|0                           |1

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ebotcazou at gcc dot gnu.org

--- Comment #5 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> Does go or Ada allow passing arrays by value?

Yes for Ada as well.

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[michael.hudson at linaro dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

--- Comment #6 from Michael Hudson-Doyle <michael.hudson at linaro dot org> ---
Created attachment 31861
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31861&action=edit
Simple fix

This very simple patch (just deleting the offending lines) makes the go test
case that was failing pass.  I'm running a complete test suite run now, will
update on how it looks when it's done.

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[michael.hudson at linaro dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

--- Comment #7 from Michael Hudson-Doyle <michael.hudson at linaro dot org> ---
There are no additional failures with this patch (and the only additional pass
is libgo's reflect test).

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[ian at airs dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

--- Comment #8 from Ian Lance Taylor <ian at airs dot com> ---
You'll need to send the patch to gcc-patches for approval, if you haven't
already done so.

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[yufeng at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

Yufeng Zhang <yufeng at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |yufeng at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |michael.hudson at linaro dot org

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[yroux at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

--- Comment #9 from yroux at gcc dot gnu.org ---
Author: yroux
Date: Wed Feb 19 15:32:54 2014
New Revision: 207908

URL: http://gcc.gnu.org/viewcvs?rev=207908&root=gcc&view=rev
Log:
2014-02-19  Michael Hudson-Doyle  <michael.hudson@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.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/aarch64/aarch64.c

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[ramana at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

Ramana Radhakrishnan <ramana at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
                 CC|                            |ramana at gcc dot gnu.org
         Resolution|---                         |FIXED
   Target Milestone|---                         |5.0

--- Comment #10 from Ramana Radhakrishnan <ramana at gcc dot gnu.org> ---
This is fixed for 5.0 - we aren't taking ABI changes back into release branches
AFAIK.

[Bug target/59799] aarch64_pass_by_reference never passes arrays by value, contrary to ABI documentation

[michael.hudson at linaro dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59799

--- Comment #11 from Michael Hudson-Doyle <michael.hudson at linaro dot org> ---
Er yes, this was fixed before 4.9.0.