re PR target/16176 (Miscompilation of unaligned data in MIPS backend (SB1 flavor))

	PR target/16176
	* config/mips/mips.c (mips_expand_unaligned_load): Use a temporary
	register for the destination of the lwl or ldl.

From-SVN: r83668

gcc/ChangeLog

+2004-06-25  Richard Sandiford  <rsandifo@redhat.com>
+
+	PR target/16176
+	* config/mips/mips.c (mips_expand_unaligned_load): Use a temporary
+	register for the destination of the lwl or ldl.
+
 2004-06-25  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>
 
 	* tree-cfg.c (verify_expr): Add macro CHECK_OK.

gcc/config/mips/mips.c

@@ -4434,7 +4434,7 @@ mips_get_unaligned_mem (rtx *op, unsigned int width, int bitpos,
 bool
 mips_expand_unaligned_load (rtx dest, rtx src, unsigned int width, int bitpos)
 {
-  rtx left, right;
+  rtx left, right, temp;
 
   /* If TARGET_64BIT, the destination of a 32-bit load will be a
      paradoxical word_mode subreg.  This is the only case in which
@@ -4453,17 +4453,16 @@ mips_expand_unaligned_load (rtx dest, rtx src, unsigned int width, int bitpos)
   if (!mips_get_unaligned_mem (&src, width, bitpos, &left, &right))
     return false;
 
+  temp = gen_reg_rtx (GET_MODE (dest));
   if (GET_MODE (dest) == DImode)
     {
-      emit_insn (gen_mov_ldl (dest, src, left));
-      emit_insn (gen_mov_ldr (copy_rtx (dest), copy_rtx (src),
-			      right, copy_rtx (dest)));
+      emit_insn (gen_mov_ldl (temp, src, left));
+      emit_insn (gen_mov_ldr (dest, copy_rtx (src), right, temp));
     }
   else
     {
-      emit_insn (gen_mov_lwl (dest, src, left));
-      emit_insn (gen_mov_lwr (copy_rtx (dest), copy_rtx (src),
-			      right, copy_rtx (dest)));
+      emit_insn (gen_mov_lwl (temp, src, left));
+      emit_insn (gen_mov_lwr (dest, copy_rtx (src), right, temp));
     }
   return true;
 }

gcc/testsuite/ChangeLog

+2004-06-25  Richard Sandiford  <rsandifo@redhat.com>
+
+	* gcc.c-torture/execute/20040625-1.c: New test.
+
 2004-06-25  Tobias Schlueter  <tobias.schlueter@physik.uni-muenchen.de>
 
 	* gfortran.fortran-torture/execute/der_init_3.f90: Fix syntax error.

gcc/testsuite/gcc.c-torture/execute/20040625-1.c

+/* From PR target/16176 */
+struct __attribute__ ((packed)) s { struct s *next; };
+
+struct s * __attribute__ ((noinline))
+maybe_next (struct s *s, int t)
+{
+  if (t)
+    s = s->next;
+  return s;
+}
+
+int main ()
+{
+  struct s s1, s2;
+
+  s1.next = &s2;
+  if (maybe_next (&s1, 1) != &s2)
+    abort ();
+  exit (0);
+}