(subst): When moving operation inside IF_THEN_ELSE, make a new rtx

instead of using SUBST due to sharing.

(simplify_comparison): Correct test for sign extension when trying to
widen comparison.

From-SVN: r1938

diff --git a/gcc/combine.c b/gcc/combine.c
index 5b9b9a446f5c010071187acc42634a91f977272e..2af4949e054fb2eb660adaf4e27efc04c3be61af 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -2616,16 +2616,18 @@ subst (x, from, to, in_dest, unique_copy)
   if ((GET_RTX_CLASS (code) == '2' || GET_RTX_CLASS (code) == 'c')
       && GET_CODE (XEXP (x, 0)) == IF_THEN_ELSE)
     {
-      SUBST (XEXP (XEXP (x, 0), 1),
-            subst (gen_binary (code, mode, XEXP (XEXP (x, 0), 1),
-                               XEXP (x, 1)),
-                   pc_rtx, pc_rtx, 0));
-      SUBST (XEXP (XEXP (x, 0), 2),
-            subst (gen_binary (code, mode, XEXP (XEXP (x, 0), 2),
-                               XEXP (x, 1)),
-                   pc_rtx, pc_rtx, 0));
-
-      x = XEXP (x, 0);
+      /* Don't do this by using SUBST inside X since we might be messing
+        up a shared expression.  */
+      rtx cond = XEXP (XEXP (x, 0), 0);
+      rtx t_arm = subst (gen_binary (code, mode, XEXP (XEXP (x, 0), 1),
+                                    XEXP (x, 1)),
+                        pc_rtx, pc_rtx, 0);
+      rtx f_arm = subst (gen_binary (code, mode, XEXP (XEXP (x, 0), 2),
+                                    XEXP (x, 1)),
+                        pc_rtx, pc_rtx, 0);
+
+
+      x = gen_rtx (IF_THEN_ELSE, mode, cond, t_arm, f_arm);
       goto restart;
     }
 
@@ -2633,14 +2635,13 @@ subst (x, from, to, in_dest, unique_copy)
           && GET_CODE (XEXP (x, 0)) == IF_THEN_ELSE
           && GET_MODE (XEXP (x, 0)) == mode)
     {
-      SUBST (XEXP (XEXP (x, 0), 1),
-            subst (gen_unary (code, mode, XEXP (XEXP (x, 0), 1)),
-                   pc_rtx, pc_rtx, 0));
-      SUBST (XEXP (XEXP (x, 0), 2),
-            subst (gen_unary (code, mode, XEXP (XEXP (x, 0), 2)),
-                   pc_rtx, pc_rtx, 0));
-
-      x = XEXP (x, 0);
+      rtx cond = XEXP (XEXP (x, 0), 0);
+      rtx t_arm = subst (gen_unary (code, mode, XEXP (XEXP (x, 0), 1)),
+                        pc_rtx, pc_rtx, 0);
+      rtx f_arm = subst (gen_unary (code, mode, XEXP (XEXP (x, 0), 2)),
+                        pc_rtx, pc_rtx, 0);
+
+      x = gen_rtx_combine (IF_THEN_ELSE, mode, cond, t_arm, f_arm);
       goto restart;
     }
 
@@ -7956,9 +7957,9 @@ simplify_comparison (code, pop0, pop1)
              || ((code == EQ || code == NE
                   || code == GE || code == GT || code == LE || code == LT)
                  && (num_sign_bit_copies (op0, tmode)
-                     >= GET_MODE_BITSIZE (tmode) - GET_MODE_BITSIZE (mode))
+                     > GET_MODE_BITSIZE (tmode) - GET_MODE_BITSIZE (mode))
                  && (num_sign_bit_copies (op1, tmode)
-                     >= GET_MODE_BITSIZE (tmode) - GET_MODE_BITSIZE (mode))))
+                     > GET_MODE_BITSIZE (tmode) - GET_MODE_BITSIZE (mode))))
            {
              op0 = gen_lowpart_for_combine (tmode, op0);
              op1 = gen_lowpart_for_combine (tmode, op1);