re PR target/28146 (-O2 produces invalid code on s390-linux-gnu: gcc-4.1.2 20060608)

PR target/28146
* reload.h (reg_equiv_alt_mem_list): New declaration.
* reload1.c (reg_equiv_alt_mem_list): New definition.
(reload): Initialize it and release it.
(delete_output_reload): Use it.
* reload.c (push_reg_equiv_alt_mem): New function.
(find_reloads_toplev): Call it.
(find_reloads_address, find_reloads_address_1): Likewise.
(find_reloads_subreg_address): Likewise.

From-SVN: r116215

gcc/ChangeLog

+2006-08-17  Alexandre Oliva  <aoliva@redhat.com>
+
+	PR target/28146
+	* reload.h (reg_equiv_alt_mem_list): New declaration.
+	* reload1.c (reg_equiv_alt_mem_list): New definition.
+	(reload): Initialize it and release it.
+	(delete_output_reload): Use it.
+	* reload.c (push_reg_equiv_alt_mem): New function.
+	(find_reloads_toplev): Call it.
+	(find_reloads_address, find_reloads_address_1): Likewise.
+	(find_reloads_subreg_address): Likewise.
+
 2006-08-17  Maxim Kuvyrkov  <mkuvyrkov@ispras.ru>
 
 	PR rtl-optimization/28489

gcc/reload.c

@@ -283,6 +283,23 @@ static int find_inc_amount (rtx, rtx);
 static int refers_to_mem_for_reload_p (rtx);
 static int refers_to_regno_for_reload_p (unsigned int, unsigned int,
 					 rtx, rtx *);
+
+/* Add NEW to reg_equiv_alt_mem_list[REGNO] if it's not present in the
+   list yet.  */
+
+static void
+push_reg_equiv_alt_mem (int regno, rtx mem)
+{
+  rtx it;
+
+  for (it = reg_equiv_alt_mem_list [regno]; it; it = XEXP (it, 1))
+    if (rtx_equal_p (XEXP (it, 0), mem))
+      return;
+
+  reg_equiv_alt_mem_list [regno]
+    = alloc_EXPR_LIST (REG_EQUIV, mem,
+		       reg_equiv_alt_mem_list [regno]);
+}
 
 /* Determine if any secondary reloads are needed for loading (if IN_P is
    nonzero) or storing (if IN_P is zero) X to or from a reload register of
@@ -4553,6 +4570,8 @@ find_reloads_toplev (rtx x, int opnum, enum reload_type type,
 	      x = mem;
 	      i = find_reloads_address (GET_MODE (x), &x, XEXP (x, 0), &XEXP (x, 0),
 					opnum, type, ind_levels, insn);
+	      if (x != mem)
+		push_reg_equiv_alt_mem (regno, x);
 	      if (address_reloaded)
 		*address_reloaded = i;
 	    }
@@ -4761,9 +4780,13 @@ find_reloads_address (enum machine_mode mode, rtx *memrefloc, rtx ad,
 	      tem = make_memloc (ad, regno);
 	      if (! strict_memory_address_p (GET_MODE (tem), XEXP (tem, 0)))
 		{
+		  rtx orig = tem;
+
 		  find_reloads_address (GET_MODE (tem), &tem, XEXP (tem, 0),
 					&XEXP (tem, 0), opnum,
 					ADDR_TYPE (type), ind_levels, insn);
+		  if (tem != orig)
+		    push_reg_equiv_alt_mem (regno, tem);
 		}
 	      /* We can avoid a reload if the register's equivalent memory
 		 expression is valid as an indirect memory address.
@@ -5545,6 +5568,8 @@ find_reloads_address_1 (enum machine_mode mode, rtx x, int context,
 	    if (reg_equiv_address[regno]
 		|| ! rtx_equal_p (tem, reg_equiv_mem[regno]))
 	      {
+		rtx orig = tem;
+
 		/* First reload the memory location's address.
 		    We can't use ADDR_TYPE (type) here, because we need to
 		    write back the value after reading it, hence we actually
@@ -5554,6 +5579,9 @@ find_reloads_address_1 (enum machine_mode mode, rtx x, int context,
 				      RELOAD_OTHER,
 				      ind_levels, insn);
 
+		if (tem != orig)
+		  push_reg_equiv_alt_mem (regno, tem);
+
 		/* Then reload the memory location into a base
 		   register.  */
 		reloadnum = push_reload (tem, tem, &XEXP (x, 0),
@@ -5609,6 +5637,8 @@ find_reloads_address_1 (enum machine_mode mode, rtx x, int context,
 	      if (reg_equiv_address[regno]
 		  || ! rtx_equal_p (tem, reg_equiv_mem[regno]))
 		{
+		  rtx orig = tem;
+
 		  /* First reload the memory location's address.
 		     We can't use ADDR_TYPE (type) here, because we need to
 		     write back the value after reading it, hence we actually
@@ -5616,6 +5646,8 @@ find_reloads_address_1 (enum machine_mode mode, rtx x, int context,
 		  find_reloads_address (GET_MODE (tem), &tem, XEXP (tem, 0),
 					&XEXP (tem, 0), opnum, type,
 					ind_levels, insn);
+		  if (tem != orig)
+		    push_reg_equiv_alt_mem (regno, tem);
 		  /* Put this inside a new increment-expression.  */
 		  x = gen_rtx_fmt_e (GET_CODE (x), GET_MODE (x), tem);
 		  /* Proceed to reload that, as if it contained a register.  */
@@ -5806,6 +5838,8 @@ find_reloads_address_1 (enum machine_mode mode, rtx x, int context,
 		find_reloads_address (GET_MODE (x), &x, XEXP (x, 0),
 				      &XEXP (x, 0), opnum, ADDR_TYPE (type),
 				      ind_levels, insn);
+		if (x != tem)
+		  push_reg_equiv_alt_mem (regno, x);
 	      }
 	  }
 
@@ -5993,6 +6027,7 @@ find_reloads_subreg_address (rtx x, int force_replace, int opnum,
 	      unsigned outer_size = GET_MODE_SIZE (GET_MODE (x));
 	      unsigned inner_size = GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)));
 	      int offset;
+	      rtx orig = tem;
 
 	      /* For big-endian paradoxical subregs, SUBREG_BYTE does not
 		 hold the correct (negative) byte offset.  */
@@ -6028,6 +6063,9 @@ find_reloads_subreg_address (rtx x, int force_replace, int opnum,
 	      find_reloads_address (GET_MODE (tem), &tem, XEXP (tem, 0),
 				    &XEXP (tem, 0), opnum, type,
 				    ind_levels, insn);
+	      /* ??? Do we need to handle nonzero offsets somehow?  */
+	      if (!offset && tem != orig)
+		push_reg_equiv_alt_mem (regno, tem);
 
 	      /* If this is not a toplevel operand, find_reloads doesn't see
 		 this substitution.  We have to emit a USE of the pseudo so

gcc/reload.h

@@ -161,6 +161,7 @@ extern rtx *reg_equiv_invariant;
 extern rtx *reg_equiv_memory_loc;
 extern rtx *reg_equiv_address;
 extern rtx *reg_equiv_mem;
+extern rtx *reg_equiv_alt_mem_list;
 
 /* Element N is the list of insns that initialized reg N from its equivalent
    constant or memory slot.  */

gcc/reload1.c

@@ -123,6 +123,10 @@ rtx *reg_equiv_address;
    or zero if pseudo reg N is not equivalent to a memory slot.  */
 rtx *reg_equiv_mem;
 
+/* Element N is an EXPR_LIST of REG_EQUIVs containing MEMs with
+   alternate representations of the location of pseudo reg N.  */
+rtx *reg_equiv_alt_mem_list;
+
 /* Widest width in which each pseudo reg is referred to (via subreg).  */
 static unsigned int *reg_max_ref_width;
 
@@ -703,6 +707,7 @@ reload (rtx first, int global)
   reg_equiv_constant = XCNEWVEC (rtx, max_regno);
   reg_equiv_invariant = XCNEWVEC (rtx, max_regno);
   reg_equiv_mem = XCNEWVEC (rtx, max_regno);
+  reg_equiv_alt_mem_list = XCNEWVEC (rtx, max_regno);
   reg_equiv_address = XCNEWVEC (rtx, max_regno);
   reg_max_ref_width = XCNEWVEC (unsigned int, max_regno);
   reg_old_renumber = XCNEWVEC (short, max_regno);
@@ -1260,6 +1265,11 @@ reload (rtx first, int global)
   if (offsets_at)
     free (offsets_at);
 
+  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
+    if (reg_equiv_alt_mem_list[i])
+      free_EXPR_LIST_list (&reg_equiv_alt_mem_list[i]);
+  free (reg_equiv_alt_mem_list);
+
   free (reg_equiv_mem);
   reg_equiv_init = 0;
   free (reg_equiv_address);
@@ -7849,6 +7859,11 @@ delete_output_reload (rtx insn, int j, int last_reload_reg)
     n_occurrences += count_occurrences (PATTERN (insn),
 					eliminate_regs (substed, 0,
 							NULL_RTX), 0);
+  for (i1 = reg_equiv_alt_mem_list [REGNO (reg)]; i1; i1 = XEXP (i1, 1))
+    {
+      gcc_assert (!rtx_equal_p (XEXP (i1, 0), substed));
+      n_occurrences += count_occurrences (PATTERN (insn), XEXP (i1, 0), 0);
+    }
   if (n_occurrences > n_inherited)
     return;