Re: [PATCH] rtlanal: Fix bits/bytes confusion in set_noop_p (PR68814)

[Segher Boessenkool <segher at kernel dot crashing dot org>]

On Fri, Apr 15, 2016 at 01:41:25PM +0200, Jakub Jelinek wrote:
> On Fri, Apr 15, 2016 at 01:37:07PM +0200, Bernd Schmidt wrote:
> > On 04/15/2016 02:35 AM, Segher Boessenkool wrote:
> > >This now also shows up on GCC 5, see PR70672.  It there happens in
> > >the jump1 pass already.
> > >
> > >Is this okay to backport to 5 and 4.9?
> > 
> > Ok.
> 
> Can you please also create a runtime testcase from PR70672 (unless it is
> roughly the same as the other PR) and commit to all branches?

I came up with this.  I'll commit it in an hour or so unless someone
complains; it should work on all targets, BE and LE (tested on
powerpc64-linux and powerpc64le-linux).

So I now need to commit it to one more branch, yay :-)


Segher


gcc/testsuite/
	PR rtl-optimization/70672
	PR rtl-optimization/68814
	* gcc.dg/pr70672.c: New testcase.


diff --git a/gcc/testsuite/gcc.dg/pr70672.c b/gcc/testsuite/gcc.dg/pr70672.c
new file mode 100644
index 0000000..d785124
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr70672.c
@@ -0,0 +1,64 @@
+/* PR rtl-optimization/70672 */
+/* PR rtl-optimization/68814 */
+/* { dg-do run { target { stdint_types } } } */
+/* { dg-options "-O2" } */
+
+#include <stdint.h>
+#include <stdlib.h>
+
+struct pair {
+  uint32_t one;
+  uint32_t two;
+};
+
+union u {
+  struct pair pair;
+  uint64_t num;
+};
+
+uint64_t __attribute__ ((noinline))
+f(uint64_t a)
+{
+  union u x;
+
+  x.num = a;
+
+  x.pair.one = x.pair.two;
+  x.pair.two = 0;
+
+  return x.num;
+}
+
+uint64_t __attribute__ ((noinline))
+g(uint64_t a)
+{
+  union u x;
+
+  x.num = a;
+
+  x.pair.two = x.pair.one;
+  x.pair.one = 0;
+
+  return x.num;
+}
+
+int
+main (void)
+{
+  uint64_t x = 0x123456789abcdef0ULL;
+  uint64_t fx = f(x);
+  uint64_t gx = g(x);
+  uint64_t fgx = f(gx);
+  uint64_t gfx = g(fx);
+
+  if ((fx & gx))
+    abort ();
+
+  if ((fgx & gfx))
+    abort ();
+
+  if ((fgx | gfx) != x)
+    abort ();
+
+  return 0;
+}