* combine.c (combine_simplify_rtx): Simplify using

	(float_truncate (float x)) is (float x)
	(float_extend (float_extend x)) is (float_extend x).

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@62624 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8cdbe92..4b08a63 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+Mon Feb 10 11:40:18 CET 2003  Jan Hubicka  <jh@suse.cz>
+
+       * combine.c (combine_simplify_rtx): Simplify using
+       (float_truncate (float x)) is (float x)
+       (float_extend (float_extend x)) is (float_extend x).
+
 2003-02-10  Alan Modra  <amodra@bigpond.net.au>
 
        * calls.c (try_to_integrate): Tidy stack_usage_map access.

diff --git a/gcc/combine.c b/gcc/combine.c
index ad56e85..d33f280 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -4167,6 +4167,36 @@ combine_simplify_rtx (x, op0_mode, last, in_dest)
          && GET_MODE (XEXP (XEXP (x, 0), 0)) == mode)
        return XEXP (XEXP (x, 0), 0);
 
+      /* (float_truncate:SF (float_truncate:DF foo:XF)) 
+         = (float_truncate:SF foo:XF). 
+        This may elliminate double rounding, so it is unsafe.
+
+         (float_truncate:SF (float_extend:XF foo:DF)) 
+         = (float_truncate:SF foo:DF). 
+
+         (float_truncate:DF (float_extend:XF foo:SF)) 
+         = (float_extend:SF foo:DF). */
+      if ((GET_CODE (XEXP (x, 0)) == FLOAT_TRUNCATE
+          && flag_unsafe_math_optimizations)
+         || GET_CODE (XEXP (x, 0)) == FLOAT_EXTEND)
+       return simplify_gen_unary (GET_MODE_SIZE (GET_MODE (XEXP (XEXP (x, 0),
+                                                           0)))
+                                  > GET_MODE_SIZE (mode)
+                                  ? FLOAT_TRUNCATE : FLOAT_EXTEND,
+                                  mode,
+                                  XEXP (XEXP (XEXP (x, 0), 0), 0), mode);
+
+      /*  (float_truncate (float x)) is (float x)  */
+      if (GET_CODE (XEXP (x, 0)) == FLOAT
+         && (flag_unsafe_math_optimizations
+             || ((unsigned)significand_size (GET_MODE (XEXP (x, 0)))
+                 >= (GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (x, 0), 0)))
+                     - num_sign_bit_copies (XEXP (XEXP (x, 0), 0),
+                                            GET_MODE (XEXP (XEXP (x, 0), 0)))))))
+       return simplify_gen_unary (FLOAT, mode,
+                                  XEXP (XEXP (x, 0), 0),
+                                  GET_MODE (XEXP (XEXP (x, 0), 0)));
+
       /* (float_truncate:SF (OP:DF (float_extend:DF foo:sf))) is
         (OP:SF foo:SF) if OP is NEG or ABS.  */
       if ((GET_CODE (XEXP (x, 0)) == ABS
@@ -4183,7 +4213,23 @@ combine_simplify_rtx (x, op0_mode, last, in_dest)
          && GET_CODE (SUBREG_REG (XEXP (x, 0))) == FLOAT_TRUNCATE)
        return SUBREG_REG (XEXP (x, 0));
       break;
+    case FLOAT_EXTEND:
+      /*  (float_extend (float_extend x)) is (float_extend x)
+        
+         (float_extend (float x)) is (float x) assuming that double
+         rounding can't happen. 
+          */
+      if (GET_CODE (XEXP (x, 0)) == FLOAT_EXTEND
+         || (GET_CODE (XEXP (x, 0)) == FLOAT
+             && ((unsigned)significand_size (GET_MODE (XEXP (x, 0)))
+                 >= (GET_MODE_BITSIZE (GET_MODE (XEXP (XEXP (x, 0), 0)))
+                     - num_sign_bit_copies (XEXP (XEXP (x, 0), 0),
+                                            GET_MODE (XEXP (XEXP (x, 0), 0)))))))
+       return simplify_gen_unary (GET_CODE (XEXP (x, 0)), mode,
+                                  XEXP (XEXP (x, 0), 0),
+                                  GET_MODE (XEXP (XEXP (x, 0), 0)));
 
+      break;
 #ifdef HAVE_cc0
     case COMPARE:
       /* Convert (compare FOO (const_int 0)) to FOO unless we aren't