Index: testsuite/gcc.dg/tree-ssa/alias_bug.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/alias_bug.c	(revision 0)
+++ testsuite/gcc.dg/tree-ssa/alias_bug.c	(revision 0)
@@ -0,0 +1,61 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-strict-aliasing -fdump-tree-optimized" } */
+
+typedef unsigned u32;
+typedef unsigned short u16;
+typedef unsigned char u8;
+struct biosregs {
+ union {
+  struct {
+   u32 edi;
+   u32 esi;
+   u32 ebp;
+   u32 _esp;
+   u32 ebx;
+   u32 edx;
+   u32 ecx;
+   u32 eax;
+   u32 _fsgs;
+   u32 _dses;
+   u32 eflags;
+  };
+  struct {
+   u16 di, hdi;
+   u16 si, hsi;
+   u16 bp, hbp;
+   u16 _sp, _hsp;
+   u16 bx, hbx;
+   u16 dx, hdx;
+   u16 cx, hcx;
+   u16 ax, hax;
+   u16 gs, fs;
+   u16 es, ds;
+   u16 flags, hflags;
+  };
+  struct {
+   u8 dil, dih, edi2, edi3;
+   u8 sil, sih, esi2, esi3;
+   u8 bpl, bph, ebp2, ebp3;
+   u8 _spl, _sph, _esp2, _esp3;
+   u8 bl, bh, ebx2, ebx3;
+   u8 dl, dh, edx2, edx3;
+   u8 cl, ch, ecx2, ecx3;
+   u8 al, ah, eax2, eax3;
+  };
+ };
+};
+void initregs(struct biosregs *regs);
+void intcall(u8 int_no, const struct biosregs *ireg, struct biosregs *oreg);
+static u32 *const gp = (u32*) 0x32;
+void keyboard_set_repeat(void)
+{
+ struct biosregs ireg;
+ *gp = 10;
+ initregs(&ireg);
+ ireg.ax = 0x0305;
+ intcall(0x16, &ireg, ((void *)0));
+}
+
+/* { dg-final { scan-tree-dump-times "ireg.*ax" 1 "optimized"} } */
+ 
+/* { dg-final { cleanup-tree-dump "optimized" } } */