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Subject: Re: [PATCHv5] Fix not 8-byte aligned ldrd/strd on ARMv5 (PR 89544)
To: Bernd Edlinger <bernd.edlinger@hotmail.de>, Richard Biener <rguenther@suse.de>
Cc: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>, Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>, Kyrill Tkachov <kyrylo.tkachov@foss.arm.com>, Eric Botcazou <ebotcazou@adacore.com>, Jeff Law <law@redhat.com>, Jakub Jelinek <jakub@redhat.com>
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From: "Richard Earnshaw (lists)" <Richard.Earnshaw@arm.com>
Message-ID: <c4e0d051-5b17-2bfa-d0c9-383fa65f8ae2@arm.com>
Date: Wed, 04 Sep 2019 12:53:00 -0000
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On 15/08/2019 20:47, Bernd Edlinger wrote:
> On 8/15/19 6:29 PM, Richard Biener wrote:
>>>>
>>>> Please split it into the parts for the PR and parts making the
>>>> asserts not trigger.
>>>>
>>>
>>> Yes, will do.
>>>
> 
> Okay, here is the rest of the PR 89544 fix,
> actually just an optimization, making the larger stack alignment
> known to the middle-end, and the test cases.
> 
> 
> Boot-strapped and reg-tested on x86_64-pc-linux-gnu and arm-linux-gnueabihf.
> Is it OK for trunk?
> 
> 
> Thanks
> Bernd.
> 

Index: gcc/testsuite/gcc.target/arm/unaligned-argument-2.c
===================================================================
--- gcc/testsuite/gcc.target/arm/unaligned-argument-2.c	(Revision 0)
+++ gcc/testsuite/gcc.target/arm/unaligned-argument-2.c	(Arbeitskopie)
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_arm_ok } */
+/* { dg-require-effective-target arm_ldrd_strd_ok } */
+/* { dg-options "-marm -mno-unaligned-access -O3" } */
+
+struct s {
+  int a, b;
+} __attribute__((aligned(8)));
+
+struct s f0;
+
+void f(int a, int b, int c, int d, int e, struct s f)
+{
+  f0 = f;
+}
+
+/* { dg-final { scan-assembler-times "ldrd" 0 } } */
+/* { dg-final { scan-assembler-times "strd" 0 } } */
+/* { dg-final { scan-assembler-times "stm" 1 } } */

I don't think this test is right.  While we can't use an LDRD to load 
the argument off the stack, there's nothing wrong with using an STRD to 
then store the value to f0 (as that is 8-byte aligned).  So the second 
and third scan-assembler tests are meaningless.

R.

(sorry, just noticed this).