combine.c (combine_simplify_rtx): Don't create an if_then_else unless both args are...

        * combine.c (combine_simplify_rtx): Don't create an if_then_else
        unless both args are general_operand.  Don't canonicalize plus
        to ior unless it helps.

From-SVN: r34247

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e7f25ce..11cfe53 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,9 @@
 2000-05-29  Richard Henderson  <rth@cygnus.com>
 
+       * combine.c (combine_simplify_rtx): Don't create an if_then_else
+       unless both args are general_operand.  Don't canonicalize plus
+       to ior unless it helps.
+
        * toplev.c (rest_of_compilation): Set no_new_pseudos after flow1;
        instead track register_life_up_to_date.  Toggle no_new_pseudos
        around if_convert.  

diff --git a/gcc/combine.c b/gcc/combine.c
index 8a14d80..d4af90e 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -3589,37 +3589,44 @@ combine_simplify_rtx (x, op0_mode, last, in_dest)
          true = subst (true, pc_rtx, pc_rtx, 0, 0);
          false = subst (false, pc_rtx, pc_rtx, 0, 0);
 
-         /* Restarting if we generate a store-flag expression will cause
-            us to loop.  Just drop through in this case.  */
-
-         /* If the result values are STORE_FLAG_VALUE and zero, we can
-            just make the comparison operation.  */
-         if (true == const_true_rtx && false == const0_rtx)
-           x = gen_binary (cond_code, mode, cond, cop1);
-         else if (true == const0_rtx && false == const_true_rtx)
-           x = gen_binary (reverse_condition (cond_code), mode, cond, cop1);
-
-         /* Likewise, we can make the negate of a comparison operation
-            if the result values are - STORE_FLAG_VALUE and zero.  */
-         else if (GET_CODE (true) == CONST_INT
-                  && INTVAL (true) == - STORE_FLAG_VALUE
-                  && false == const0_rtx)
-           x = gen_unary (NEG, mode, mode,
-                          gen_binary (cond_code, mode, cond, cop1));
-         else if (GET_CODE (false) == CONST_INT
-                  && INTVAL (false) == - STORE_FLAG_VALUE
-                  && true == const0_rtx)
-           x = gen_unary (NEG, mode, mode,
-                          gen_binary (reverse_condition (cond_code), 
-                                      mode, cond, cop1));
-         else
-           return gen_rtx_IF_THEN_ELSE (mode,
-                                        gen_binary (cond_code, VOIDmode,
-                                                    cond, cop1),
-                                        true, false);
+         /* If true and false are not general_operands, an if_then_else
+            is unlikely to be simpler.  */
+         if (general_operand (true, VOIDmode)
+             && general_operand (false, VOIDmode))
+           {
+             /* Restarting if we generate a store-flag expression will cause
+                us to loop.  Just drop through in this case.  */
+
+             /* If the result values are STORE_FLAG_VALUE and zero, we can
+                just make the comparison operation.  */
+             if (true == const_true_rtx && false == const0_rtx)
+               x = gen_binary (cond_code, mode, cond, cop1);
+             else if (true == const0_rtx && false == const_true_rtx)
+               x = gen_binary (reverse_condition (cond_code),
+                               mode, cond, cop1);
+
+             /* Likewise, we can make the negate of a comparison operation
+                if the result values are - STORE_FLAG_VALUE and zero.  */
+             else if (GET_CODE (true) == CONST_INT
+                      && INTVAL (true) == - STORE_FLAG_VALUE
+                      && false == const0_rtx)
+               x = gen_unary (NEG, mode, mode,
+                              gen_binary (cond_code, mode, cond, cop1));
+             else if (GET_CODE (false) == CONST_INT
+                      && INTVAL (false) == - STORE_FLAG_VALUE
+                      && true == const0_rtx)
+               x = gen_unary (NEG, mode, mode,
+                              gen_binary (reverse_condition (cond_code), 
+                                          mode, cond, cop1));
+             else
+               return gen_rtx_IF_THEN_ELSE (mode,
+                                            gen_binary (cond_code, VOIDmode,
+                                                        cond, cop1),
+                                            true, false);
 
-         code = GET_CODE (x);
-         op0_mode = VOIDmode;
+             code = GET_CODE (x);
+             op0_mode = VOIDmode;
+           }
        }
     }
 
@@ -4229,7 +4236,17 @@ combine_simplify_rtx (x, op0_mode, last, in_dest)
       if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
          && (nonzero_bits (XEXP (x, 0), mode)
              & nonzero_bits (XEXP (x, 1), mode)) == 0)
-       return gen_binary (IOR, mode, XEXP (x, 0), XEXP (x, 1));
+       {
+         /* Try to simplify the expression further.  */
+         rtx tor = gen_binary (IOR, mode, XEXP (x, 0), XEXP (x, 1));
+         temp = combine_simplify_rtx (tor, mode, last, in_dest);
+
+         /* If we could, great.  If not, do not go ahead with the IOR
+            replacement, since PLUS appears in many special purpose
+            address arithmetic instructions.  */
+         if (GET_CODE (temp) != CLOBBER && temp != tor)
+           return temp;
+       }
       break;
 
     case MINUS: