* loop.h (struct induction): Add no_const_addval.

        * loop.c (the_movables, reg_address_cost): New variables.
        (init_loop): Init reg_address_cost.
        (loop_optimize): Call end_alias_analysis.
        (scan_loop): Init the_movables.
        (record_giv): Init induction->no_const_addval.
        (basic_induction_var) [PLUS]: Use rtx_equal_p instead of ==.
        [REG]: Rearrange loop search test to catch more cases.
        (general_induction_var): Return success not benefit; take an extra
        argument for that.  Change all callers.
        (simplify_giv_expr) [PLUS]: Always combine invariants.  Use sge_plus.
        [MULT]: Use rtx_equal_p instead of ==.  Combine simple invariants.
        [default]: Search the_movables for additional combinations.
        (sge_plus_constant, sge_plus): New functions.
        (express_from_1): New function.
        (express_from): Always define.  Rewrite using express_from_1.
        (combine_givs_p): Handle more cases.  Ignore address cost.
        (cmp_combine_givs_stats): New function.
        (combine_givs_used_once, combine_givs_benefit_from): New functions.
        (combine_givs): Rewrite to do best-fit combination.
        * fold-const.c (operand_equal_p): Handle RTL_EXPR.
        (fold): Do a complete (A*C)+(B*C) association check.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@21263 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 35 insertions, 12 deletions

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 8849608795a..4fe68994454 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -1928,6 +1928,11 @@ operand_equal_p (arg0, arg1, only_const)
 	default:
 	  return 0;
 	}
+
+    case 'e':
+      if (TREE_CODE (arg0) == RTL_EXPR)
+	return rtx_equal_p (RTL_EXPR_RTL (arg0), RTL_EXPR_RTL (arg1));
+      return 0;
       
     default:
       return 0;
@@ -4413,18 +4418,36 @@ fold (expr)
 	      goto bit_ior;
 	    }
 
-	  /* (A * C) + (B * C) -> (A+B) * C.  Since we are most concerned
-	     about the case where C is a constant, just try one of the
-	     four possibilities.  */
-
-	  if (TREE_CODE (arg0) == MULT_EXPR && TREE_CODE (arg1) == MULT_EXPR
-	      && operand_equal_p (TREE_OPERAND (arg0, 1),
-				  TREE_OPERAND (arg1, 1), 0))
-	    return fold (build (MULT_EXPR, type,
-				fold (build (PLUS_EXPR, type,
-					     TREE_OPERAND (arg0, 0),
-					     TREE_OPERAND (arg1, 0))),
-				TREE_OPERAND (arg0, 1)));
+	  if (TREE_CODE (arg0) == MULT_EXPR && TREE_CODE (arg1) == MULT_EXPR)
+	    {
+	      tree arg00, arg01, arg10, arg11;
+	      tree alt0, alt1, same;
+
+	      /* (A * C) + (B * C) -> (A+B) * C.
+		 We are most concerned about the case where C is a constant,
+		 but other combinations show up during loop reduction.  Since
+		 it is not difficult, try all four possibilities.  */
+
+	      arg00 = TREE_OPERAND (arg0, 0);
+	      arg01 = TREE_OPERAND (arg0, 1);
+	      arg10 = TREE_OPERAND (arg1, 0);
+	      arg11 = TREE_OPERAND (arg1, 1);
+	      same = NULL_TREE;
+
+	      if (operand_equal_p (arg01, arg11, 0))
+		same = arg01, alt0 = arg00, alt1 = arg10;
+	      else if (operand_equal_p (arg00, arg10, 0))
+		same = arg00, alt0 = arg01, alt1 = arg11;
+	      else if (operand_equal_p (arg00, arg11, 0))
+		same = arg00, alt0 = arg01, alt1 = arg10;
+	      else if (operand_equal_p (arg01, arg10, 0))
+		same = arg01, alt0 = arg00, alt1 = arg11;
+
+	      if (same)
+	        return fold (build (MULT_EXPR, type,
+				    fold (build (PLUS_EXPR, type, alt0, alt1)),
+				    same));
+	    }
 	}
       /* In IEEE floating point, x+0 may not equal x.  */
       else if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT