[PATCH] x86: Add a test for PR tree-optimization/42587

[H.J. Lu via Gcc-patches]

        PR tree-optimization/42587
        * gcc.target/i386/pr42587.c: New test.
---
 gcc/testsuite/gcc.target/i386/pr42587.c | 35 +++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr42587.c

diff --git a/gcc/testsuite/gcc.target/i386/pr42587.c 
b/gcc/testsuite/gcc.target/i386/pr42587.c
new file mode 100644
index 00000000000..d4b5143eb6d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr42587.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-store-merging" } */
+
+typedef unsigned char u8;
+typedef unsigned int u32;
+union __anonunion_out_195
+{
+  u32 value;
+  u8 bytes[4];
+};
+union __anonunion_in_196
+{
+  u32 value;
+  u8 bytes[4];
+};
+extern void acpi_ut_track_stack_ptr (void);
+u32 acpi_ut_dword_byte_swap (u32 value);
+u32
+acpi_ut_dword_byte_swap (u32 value)
+{
+  union __anonunion_out_195 out;
+  union __anonunion_in_196 in;
+
+  {
+    acpi_ut_track_stack_ptr ();
+    in.value = value;
+    out.bytes[0] = in.bytes[3];
+    out.bytes[1] = in.bytes[2];
+    out.bytes[2] = in.bytes[1];
+    out.bytes[3] = in.bytes[0];
+    return (out.value);
+  }
+}
+
+/* { dg-final { scan-tree-dump "32 bit bswap implementation found at" 
"store-merging" } } */
-- 
2.31.1