rs6000: Make lwa_operand use any_memory_operand

Testcase from comex, see https://lwn.net/Articles/793932/ .


	* config/rs6000/predicates.md (lwa_operand): Allow volatile memory.

gcc/testsuite/
	* gcc.target/powerpc/volatile-mem.c: New testcase.

From-SVN: r273631

gcc/ChangeLog

 2019-07-20  Segher Boessenkool  <segher@kernel.crashing.org>
 
+	* config/rs6000/predicates.md (lwa_operand): Allow volatile memory.
+
+2019-07-20  Segher Boessenkool  <segher@kernel.crashing.org>
+
 	* config/rs6000/predicates.md (volatile_mem_operand): Modernize syntax.
 	(any_memory_operand): New predicate.
 	(reg_or_mem_operand): Use it.

gcc/config/rs6000/predicates.md

@@ -929,7 +929,7 @@
 
   if (gpc_reg_operand (inner, mode))
     return true;
-  if (!memory_operand (inner, mode))
+  if (!any_memory_operand (inner, mode))
     return false;
 
   addr = XEXP (inner, 0);

gcc/testsuite/ChangeLog

+2019-07-20  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	* gcc.target/powerpc/volatile-mem.c: New testcase.
+
 2019-07-20  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/91204

gcc/testsuite/gcc.target/powerpc/volatile-mem.c

+/* { dg-options "-O2 -std=c11" } */
+/* { dg-require-effective-target lp64 } */
+
+/* This tests if the instructions used for C atomic are optimised properly
+   as atomic by the target code, too.  */
+
+#include <stdatomic.h>
+
+int load(_Atomic int *ptr)
+{
+        return atomic_load_explicit(ptr, memory_order_relaxed);
+}
+
+/* There should be only two machine instructions, an lwa and a blr: */
+/* { dg-final { scan-assembler-times {(?n)^\s+[a-z]} 2 } } */
+/* { dg-final { scan-assembler-times {\mlwa\M} 1 } } */