[gcc(refs/vendors/AWS/heads/Arm64/gcc-7-branch)] [AArch64] Don't split 64-bit constant stores to volatile location

[Sebastian Pop]

https://gcc.gnu.org/g:aa09a1939811fdc4b0df5fc4c63eec7a4553dcbd

commit aa09a1939811fdc4b0df5fc4c63eec7a4553dcbd
Author: Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Date:   Tue Oct 1 10:37:55 2019 +0000

    [AArch64] Don't split 64-bit constant stores to volatile location
    
    2019-10-01  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
    
            Backport from mainline
            2019-09-24  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
    
            * config/aarch64/aarch64.md (mov<mode>): Don't call
            aarch64_split_dimode_const_store on volatile MEM.
    
            * gcc.target/aarch64/nosplit-di-const-volatile_1.c: New test.
    
    (cherry picked from commit 38bf71d294ea2a2fee6372e1d10f19a28197b7e3)

Diff:
---
 gcc/config/aarch64/aarch64.md                             |  4 ++--
 .../gcc.target/aarch64/nosplit-di-const-volatile_1.c      | 15 +++++++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 90f9ee658c5..3562010b3c4 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -1007,8 +1007,8 @@
 	(match_operand:GPI 1 "general_operand" ""))]
   ""
   "
-    if (MEM_P (operands[0]) && CONST_INT_P (operands[1])
-	&& <MODE>mode == DImode
+    if (MEM_P (operands[0]) && !MEM_VOLATILE_P (operands[0])
+	&& CONST_INT_P (operands[1]) && <MODE>mode == DImode
 	&& aarch64_split_dimode_const_store (operands[0], operands[1]))
       DONE;
 
diff --git a/gcc/testsuite/gcc.target/aarch64/nosplit-di-const-volatile_1.c b/gcc/testsuite/gcc.target/aarch64/nosplit-di-const-volatile_1.c
new file mode 100644
index 00000000000..da5975ad165
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/nosplit-di-const-volatile_1.c
@@ -0,0 +1,15 @@
+/* Check that storing the 64-bit immediate to a volatile location is done
+   with a single store.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+typedef unsigned long long u64;
+
+void bar (u64 *x)
+{
+  *(volatile u64 *)x = 0xabcdef10abcdef10ULL;
+}
+
+/* { dg-final { scan-assembler-times "str\tx..?, .*" 1 } } */
+/* { dg-final { scan-assembler-not "str\tw..?, .*" } } */