ChangeLog:

	* real.h (struct real_format): New member round_towards_zero.
	* real.c (round_for_format): Respect fmt->round_towards_zero.
	(ieee_single_format, mips_single_format, motorola_single_format,
	spu_single_format, ieee_double_format, mips_double_format,
	motorola_double_format, ieee_extended_motorola_format,
	ieee_extended_intel_96_format, ieee_extended_intel_128_format,
	ieee_extended_intel_96_round_53_format, ibm_extended_format,
	mips_extended_format, ieee_quad_format, mips_quad_format,
	vax_f_format, vax_d_format, vax_g_format): Initialize it.
	* config/pdp11/pdp11.c (pdp11_f_format, pdp11_d_format): Likewise.

	* builtins.s (do_mpfr_arg1): Consider round_towards_zero member of
	real_format to choose rounding mode when calling MPFR functions.
	(do_mpfr_arg2, do_mpfr_arg3, do_mpfr_sincos): Likewise.
	(do_mpfr_bessel_n, do_mpfr_remquo, do_mpfr_lgamma_r): Likewise.

	* real.h (real_to_decimal_for_mode): Add prototype.
	* real.c (real_to_decimal_for_mode): Renames old real_to_decimal.
	Respect target rounding mode when generating decimal representation.
	(real_to_decimal): New stub for backwards compatibility.
	* c-cppbuiltin.c (builtin_define_with_hex_fp_value): Use
	real_to_decimal_for_mode instead of real_to_decimal.

	* config/spu/spu.md ("floatdisf2", "floatunsdisf2"): New.


testsuite/ChangeLog:

	* gcc.c-torture/execute/20031003-1.c (main): Update test to
	accommodate SPU single-precision rounding mode.
	* gcc.c-torture/execute/conversion.c (test_float_to_integer,
	test_float_to_longlong_integer): Likewise.
	* gcc.c-torture/execute/ieee/rbug.c (main): Likewise.
	* gcc.dg/hex-round-1.c: Skip test on SPU.
	* gcc.dg/hex-round-2.c: Likewise.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@139014 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 96 insertions, 24 deletions

diff --git a/gcc/real.c b/gcc/real.c
index 49eb97d740c..806e2f88f36 100644
--- a/gcc/real.c
+++ b/gcc/real.c
@@ -1443,20 +1443,30 @@ rtd_divmod (REAL_VALUE_TYPE *num, REAL_VALUE_TYPE *den)
 /* Render R as a decimal floating point constant.  Emit DIGITS significant
    digits in the result, bounded by BUF_SIZE.  If DIGITS is 0, choose the
    maximum for the representation.  If CROP_TRAILING_ZEROS, strip trailing
-   zeros.  */
+   zeros.  If MODE is VOIDmode, round to nearest value.  Otherwise, round
+   to a string that, when parsed back in mode MODE, yields the same value.  */
 
 #define M_LOG10_2	0.30102999566398119521
 
 void
-real_to_decimal (char *str, const REAL_VALUE_TYPE *r_orig, size_t buf_size,
-		 size_t digits, int crop_trailing_zeros)
+real_to_decimal_for_mode (char *str, const REAL_VALUE_TYPE *r_orig,
+			  size_t buf_size, size_t digits,
+			  int crop_trailing_zeros, enum machine_mode mode)
 {
+  const struct real_format *fmt = NULL;
   const REAL_VALUE_TYPE *one, *ten;
   REAL_VALUE_TYPE r, pten, u, v;
   int dec_exp, cmp_one, digit;
   size_t max_digits;
   char *p, *first, *last;
   bool sign;
+  bool round_up;
+
+  if (mode != VOIDmode)
+   {
+     fmt = REAL_MODE_FORMAT (mode);
+     gcc_assert (fmt);
+   }
 
   r = *r_orig;
   switch (r.cl)
@@ -1672,17 +1682,31 @@ real_to_decimal (char *str, const REAL_VALUE_TYPE *r_orig, size_t buf_size,
   digit = rtd_divmod (&r, &pten);
 
   /* Round the result.  */
-  if (digit == 5)
+  if (fmt && fmt->round_towards_zero)
     {
-      /* Round to nearest.  If R is nonzero there are additional
-	 nonzero digits to be extracted.  */
+      /* If the format uses round towards zero when parsing the string
+	 back in, we need to always round away from zero here.  */
       if (cmp_significand_0 (&r))
 	digit++;
-      /* Round to even.  */
-      else if ((p[-1] - '0') & 1)
-	digit++;
+      round_up = digit > 0;
     }
-  if (digit > 5)
+  else
+    {
+      if (digit == 5)
+	{
+	  /* Round to nearest.  If R is nonzero there are additional
+	     nonzero digits to be extracted.  */
+	  if (cmp_significand_0 (&r))
+	    digit++;
+	  /* Round to even.  */
+	  else if ((p[-1] - '0') & 1)
+	    digit++;
+	}
+
+      round_up = digit > 5;
+    }
+
+  if (round_up)
     {
       while (p > first)
 	{
@@ -1716,6 +1740,26 @@ real_to_decimal (char *str, const REAL_VALUE_TYPE *r_orig, size_t buf_size,
 
   /* Append the exponent.  */
   sprintf (last, "e%+d", dec_exp);
+
+#ifdef ENABLE_CHECKING
+  /* Verify that we can read the original value back in.  */
+  if (mode != VOIDmode)
+    {
+      real_from_string (&r, str);
+      real_convert (&r, mode, &r);
+      gcc_assert (real_identical (&r, r_orig));
+    }
+#endif
+}
+
+/* Likewise, except always uses round-to-nearest.  */
+
+void
+real_to_decimal (char *str, const REAL_VALUE_TYPE *r_orig, size_t buf_size,
+		 size_t digits, int crop_trailing_zeros)
+{
+  real_to_decimal_for_mode (str, r_orig, buf_size,
+			    digits, crop_trailing_zeros, VOIDmode);
 }
 
 /* Render R as a hexadecimal floating point constant.  Emit DIGITS
@@ -2389,9 +2433,8 @@ static void
 round_for_format (const struct real_format *fmt, REAL_VALUE_TYPE *r)
 {
   int p2, np2, i, w;
-  unsigned long sticky;
-  bool guard, lsb;
   int emin2m1, emax2;
+  bool round_up = false;
 
   if (r->decimal)
     {
@@ -2463,21 +2506,28 @@ round_for_format (const struct real_format *fmt, REAL_VALUE_TYPE *r)
 	}
     }
 
-  /* There are P2 true significand bits, followed by one guard bit,
-     followed by one sticky bit, followed by stuff.  Fold nonzero
-     stuff into the sticky bit.  */
+  if (!fmt->round_towards_zero)
+    {
+      /* There are P2 true significand bits, followed by one guard bit,
+         followed by one sticky bit, followed by stuff.  Fold nonzero
+         stuff into the sticky bit.  */
+      unsigned long sticky;
+      bool guard, lsb;
 
-  sticky = 0;
-  for (i = 0, w = (np2 - 1) / HOST_BITS_PER_LONG; i < w; ++i)
-    sticky |= r->sig[i];
-  sticky |=
-    r->sig[w] & (((unsigned long)1 << ((np2 - 1) % HOST_BITS_PER_LONG)) - 1);
+      sticky = 0;
+      for (i = 0, w = (np2 - 1) / HOST_BITS_PER_LONG; i < w; ++i)
+	sticky |= r->sig[i];
+      sticky |= r->sig[w]
+		& (((unsigned long)1 << ((np2 - 1) % HOST_BITS_PER_LONG)) - 1);
 
-  guard = test_significand_bit (r, np2 - 1);
-  lsb = test_significand_bit (r, np2);
+      guard = test_significand_bit (r, np2 - 1);
+      lsb = test_significand_bit (r, np2);
 
-  /* Round to even.  */
-  if (guard && (sticky || lsb))
+      /* Round to even.  */
+      round_up = guard && (sticky || lsb);
+    }
+
+  if (round_up)
     {
       REAL_VALUE_TYPE u;
       get_zero (&u, 0);
@@ -2817,6 +2867,7 @@ const struct real_format ieee_single_format =
     128,
     31,
     31,
+    false,
     true,
     true,
     true,
@@ -2836,6 +2887,7 @@ const struct real_format mips_single_format =
     128,
     31,
     31,
+    false,
     true,
     true,
     true,
@@ -2855,6 +2907,7 @@ const struct real_format motorola_single_format =
     128,
     31,
     31,
+    false,
     true,
     true,
     true,
@@ -2885,6 +2938,7 @@ const struct real_format spu_single_format =
     129,
     31,
     31,
+    true,
     false,
     false,
     true,
@@ -3092,6 +3146,7 @@ const struct real_format ieee_double_format =
     1024,
     63,
     63,
+    false,
     true,
     true,
     true,
@@ -3111,6 +3166,7 @@ const struct real_format mips_double_format =
     1024,
     63,
     63,
+    false,
     true,
     true,
     true,
@@ -3130,6 +3186,7 @@ const struct real_format motorola_double_format =
     1024,
     63,
     63,
+    false,
     true,
     true,
     true,
@@ -3467,6 +3524,7 @@ const struct real_format ieee_extended_motorola_format =
     16384,
     95,
     95,
+    false,
     true,
     true,
     true,
@@ -3486,6 +3544,7 @@ const struct real_format ieee_extended_intel_96_format =
     16384,
     79,
     79,
+    false,
     true,
     true,
     true,
@@ -3505,6 +3564,7 @@ const struct real_format ieee_extended_intel_128_format =
     16384,
     79,
     79,
+    false,
     true,
     true,
     true,
@@ -3526,6 +3586,7 @@ const struct real_format ieee_extended_intel_96_round_53_format =
     16384,
     79,
     79,
+    false,
     true,
     true,
     true,
@@ -3612,6 +3673,7 @@ const struct real_format ibm_extended_format =
     1024,
     127,
     -1,
+    false,
     true,
     true,
     true,
@@ -3631,6 +3693,7 @@ const struct real_format mips_extended_format =
     1024,
     127,
     -1,
+    false,
     true,
     true,
     true,
@@ -3892,6 +3955,7 @@ const struct real_format ieee_quad_format =
     16384,
     127,
     127,
+    false,
     true,
     true,
     true,
@@ -3911,6 +3975,7 @@ const struct real_format mips_quad_format =
     16384,
     127,
     127,
+    false,
     true,
     true,
     true,
@@ -4214,6 +4279,7 @@ const struct real_format vax_f_format =
     false,
     false,
     false,
+    false,
     false
   };
 
@@ -4233,6 +4299,7 @@ const struct real_format vax_d_format =
     false,
     false,
     false,
+    false,
     false
   };
 
@@ -4252,6 +4319,7 @@ const struct real_format vax_g_format =
     false,
     false,
     false,
+    false,
     false
   };
 
@@ -4321,6 +4389,7 @@ const struct real_format decimal_single_format =
     96,
     31,
     31,
+    false,
     true,
     true,
     true,
@@ -4341,6 +4410,7 @@ const struct real_format decimal_double_format =
     384,
     63,
     63,
+    false,
     true,
     true,
     true,
@@ -4361,6 +4431,7 @@ const struct real_format decimal_quad_format =
     6144,
     127,
     127,
+    false,
     true,
     true,
     true, 
@@ -4404,6 +4475,7 @@ const struct real_format real_internal_format =
     MAX_EXP,
     -1,
     -1,
+    false,
     true,
     true,
     false,