Improve address offset range computation

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@163081 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 22 insertions, 16 deletions

diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c
index 1d65b4aadfa..c940d413de8 100644
--- a/gcc/tree-ssa-loop-ivopts.c
+++ b/gcc/tree-ssa-loop-ivopts.c
@@ -3241,9 +3241,8 @@ get_address_cost (bool symbol_present, bool var_present,
   if (!data)
     {
       HOST_WIDE_INT i;
-      HOST_WIDE_INT start = BIGGEST_ALIGNMENT / BITS_PER_UNIT;
-      HOST_WIDE_INT rat, off;
-      int old_cse_not_expected;
+      HOST_WIDE_INT rat, off = 0;
+      int old_cse_not_expected, width;
       unsigned sym_p, var_p, off_p, rat_p, add_c;
       rtx seq, addr, base;
       rtx reg0, reg1;
@@ -3252,33 +3251,40 @@ get_address_cost (bool symbol_present, bool var_present,
 
       reg1 = gen_raw_REG (address_mode, LAST_VIRTUAL_REGISTER + 1);
 
+      width = GET_MODE_BITSIZE (address_mode) - 1;
+      if (width > (HOST_BITS_PER_WIDE_INT - 1))
+	width = HOST_BITS_PER_WIDE_INT - 1;
       addr = gen_rtx_fmt_ee (PLUS, address_mode, reg1, NULL_RTX);
-      for (i = start; i <= 1 << 20; i <<= 1)
+
+      for (i = width; i >= 0; i--)
 	{
-	  XEXP (addr, 1) = gen_int_mode (i, address_mode);
-	  if (!memory_address_addr_space_p (mem_mode, addr, as))
+	  off = -((HOST_WIDE_INT) 1 << i);
+	  XEXP (addr, 1) = gen_int_mode (off, address_mode);
+	  if (memory_address_addr_space_p (mem_mode, addr, as))
 	    break;
 	}
-      data->max_offset = i == start ? 0 : i >> 1;
-      off = data->max_offset;
+      data->min_offset = (i == -1? 0 : off);
 
-      for (i = start; i <= 1 << 20; i <<= 1)
+      for (i = width; i >= 0; i--)
 	{
-	  XEXP (addr, 1) = gen_int_mode (-i, address_mode);
-	  if (!memory_address_addr_space_p (mem_mode, addr, as))
+	  off = ((HOST_WIDE_INT) 1 << i) - 1;
+	  XEXP (addr, 1) = gen_int_mode (off, address_mode);
+	  if (memory_address_addr_space_p (mem_mode, addr, as))
 	    break;
 	}
-      data->min_offset = i == start ? 0 : -(i >> 1);
+      if (i == -1)
+        off = 0;
+      data->max_offset = off;
 
       if (dump_file && (dump_flags & TDF_DETAILS))
 	{
 	  fprintf (dump_file, "get_address_cost:\n");
-	  fprintf (dump_file, "  min offset %s %d\n",
+	  fprintf (dump_file, "  min offset %s " HOST_WIDE_INT_PRINT_DEC "\n",
 		   GET_MODE_NAME (mem_mode),
-		   (int) data->min_offset);
-	  fprintf (dump_file, "  max offset %s %d\n",
+		   data->min_offset);
+	  fprintf (dump_file, "  max offset %s " HOST_WIDE_INT_PRINT_DEC "\n",
 		   GET_MODE_NAME (mem_mode),
-		   (int) data->max_offset);
+		   data->max_offset);
 	}
 
       rat = 1;