Ping. Updated patch attached.
Also, retested for arm-none-linux-gnueabihf with native bootstrap and make
check and for arm-none-eabi with cross compiled make check.
On 02/07/15 14:15, Matthew Wahab wrote:
This patch backports the changes made to strengthen the barriers emitted for
the __sync compare-and-swap builtins.
The trunk patch submission is at
https://gcc.gnu.org/ml/gcc-patches/2015-06/msg01411.html
The commit is at https://gcc.gnu.org/ml/gcc-cvs/2015-06/msg01236.html
Tested the series for arm-none-linux-gnueabihf with check-gcc
Ok for the branch?
Matthew
2015-07-02 Matthew Wahab <matthew.wa...@arm.com>
Backport from trunk:
2015-06-29 Matthew Wahab <matthew.wa...@arm.com>
PR target/65697
* config/armc/arm.c (arm_split_compare_and_swap): For ARMv8,
replace an initial acquire barrier with final barrier.
>From fdcde1aa0b852f2a01bb45115e28f694b0225fcf Mon Sep 17 00:00:00 2001
From: mwahab <mwahab@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Mon, 29 Jun 2015 16:09:10 +0000
Subject: [PATCH 2/4] 2015-07-01 Matthew Wahab <matthew.wa...@arm.com>
Backport
PR target/65697
* config/armc/arm.c (arm_split_compare_and_swap): For ARMv8, replace an
initial acquire barrier with final barrier.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@225133 138bc75d-0d04-0410-961f-82ee72b054a4
Conflicts:
gcc/ChangeLog
Change-Id: Ifab505d792d6227c7d2231813dfb2e7826f0f450
---
gcc/config/arm/arm.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index f694e74..1e67a73 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -27757,6 +27757,8 @@ arm_split_compare_and_swap (rtx operands[])
scratch = operands[7];
mode = GET_MODE (mem);
+ bool is_armv8_sync = arm_arch8 && is_mm_sync (mod_s);
+
bool use_acquire = TARGET_HAVE_LDACQ
&& !(is_mm_relaxed (mod_s) || is_mm_consume (mod_s)
|| is_mm_release (mod_s));
@@ -27765,6 +27767,11 @@ arm_split_compare_and_swap (rtx operands[])
&& !(is_mm_relaxed (mod_s) || is_mm_consume (mod_s)
|| is_mm_acquire (mod_s));
+ /* For ARMv8, the load-acquire is too weak for __sync memory orders. Instead,
+ a full barrier is emitted after the store-release. */
+ if (is_armv8_sync)
+ use_acquire = false;
+
/* Checks whether a barrier is needed and emits one accordingly. */
if (!(use_acquire || use_release))
arm_pre_atomic_barrier (mod_s);
@@ -27805,7 +27812,8 @@ arm_split_compare_and_swap (rtx operands[])
emit_label (label2);
/* Checks whether a barrier is needed and emits one accordingly. */
- if (!(use_acquire || use_release))
+ if (is_armv8_sync
+ || !(use_acquire || use_release))
arm_post_atomic_barrier (mod_s);
if (is_mm_relaxed (mod_f))
--
1.9.1
