defaults.h (LARGEST_EXPONENT_IS_NORMAL, [...]): New.

	* defaults.h (LARGEST_EXPONENT_IS_NORMAL, ROUND_TOWARDS_ZERO): New.
	(MODE_HAS_NANS, MODE_HAS_INFINITIES): Evaluate to false if
	LARGEST_EXPONENT_IS_NORMAL for the given mode.
	(MODE_HAS_SIGN_DEPENDENT_ROUNDING): False when ROUND_TOWARDS_ZERO.
	* real.c (eadd1): Make rounding dependent on !ROUND_TOWARDS_ZERO.
	(ediv, emul, eldexp, esqrt): Likewise.
	(etoe113, etoe64, etoe53, etoe24, etodec, etoibm, etoc4x): Likewise.
	(e24toe): Only check NaNs & infinities if !LARGEST_EXPONENT_IS_NORMAL.
	(saturate): New function.
	(toe53, toe24): Saturate on overflow if LARGEST_EXPONENT_IS_NORMAL.
	(make_nan): Use a saturation value instead of a NaN if
	LARGEST_EXPONENT_IS_NORMAL.  Warn when this happens.
	* fp-bit.c (pack_d): Saturate on NaN, infinite or overflowing
	inputs if LARGEST_EXPONENT_IS_NORMAL.  Represent subnormals as
	zero if NO_DENORMALS.  Only round to nearest if !ROUND_TOWARDS_ZERO.
	(unpack_d): No NaNs or infinities if LARGEST_EXPONENT_IS_NORMAL.
	(_fpmul_parts, _fpdiv_parts): Only round to nearest if
	!ROUND_TOWARDS_ZERO.
	* doc/tm.texi (LARGEST_EXPONENT_IS_NORMAL): Document.
	(ROUND_TOWARDS_ZERO): Document.

From-SVN: r50569

1 files changed, 61 insertions, 14 deletions

diff --git a/gcc/real.c b/gcc/real.c
index 559cb05..0d3e657 100644
--- a/gcc/real.c
+++ b/gcc/real.c
@@ -336,6 +336,7 @@ static int eiisnan	PARAMS ((const UEMUSHORT *));
 static int eiisneg	PARAMS ((const UEMUSHORT *));
 static void make_nan	PARAMS ((UEMUSHORT *, int, enum machine_mode));
 #endif
+static void saturate	PARAMS ((UEMUSHORT *, int, int, int));
 static void emovi	PARAMS ((const UEMUSHORT *, UEMUSHORT *));
 static void emovo	PARAMS ((const UEMUSHORT *, UEMUSHORT *));
 static void ecleaz	PARAMS ((UEMUSHORT *));
@@ -2871,7 +2872,7 @@ eadd1 (a, b, c)
       esubm (ai, bi);
       subflg = 1;
     }
-  emdnorm (bi, lost, subflg, ltb, 64);
+  emdnorm (bi, lost, subflg, ltb, !ROUND_TOWARDS_ZERO);
 
  done:
   emovo (bi, c);
@@ -2967,7 +2968,7 @@ ediv (a, b, c)
   i = edivm (ai, bi);
   /* calculate exponent */
   lt = ltb - lta + EXONE;
-  emdnorm (bi, i, 0, lt, 64);
+  emdnorm (bi, i, 0, lt, !ROUND_TOWARDS_ZERO);
   emovo (bi, c);
 
  divsign:
@@ -3064,7 +3065,7 @@ emul (a, b, c)
   j = emulm (ai, bi);
   /* calculate exponent */
   lt = lta + ltb - (EXONE - 1);
-  emdnorm (bi, j, 0, lt, 64);
+  emdnorm (bi, j, 0, lt, !ROUND_TOWARDS_ZERO);
   emovo (bi, c);
 
  mulsign:
@@ -3445,7 +3446,7 @@ e24toe (pe, y)
   yy[M] = (r & 0x7f) | 0200;
   r &= ~0x807f;			/* strip sign and 7 significand bits */
 #ifdef INFINITY
-  if (r == 0x7f80)
+  if (!LARGEST_EXPONENT_IS_NORMAL (32) && r == 0x7f80)
     {
 #ifdef NANS
       if (REAL_WORDS_BIG_ENDIAN)
@@ -3536,7 +3537,7 @@ etoe113 (x, e)
   /* round off to nearest or even */
   rndsav = rndprc;
   rndprc = 113;
-  emdnorm (xi, 0, 0, exp, 64);
+  emdnorm (xi, 0, 0, exp, !ROUND_TOWARDS_ZERO);
   rndprc = rndsav;
 #ifdef INFINITY
  nonorm:
@@ -3632,7 +3633,7 @@ etoe64 (x, e)
   /* round off to nearest or even */
   rndsav = rndprc;
   rndprc = 64;
-  emdnorm (xi, 0, 0, exp, 64);
+  emdnorm (xi, 0, 0, exp, !ROUND_TOWARDS_ZERO);
   rndprc = rndsav;
 #ifdef INFINITY
  nonorm:
@@ -3852,7 +3853,7 @@ etoe53 (x, e)
   /* round off to nearest or even */
   rndsav = rndprc;
   rndprc = 53;
-  emdnorm (xi, 0, 0, exp, 64);
+  emdnorm (xi, 0, 0, exp, !ROUND_TOWARDS_ZERO);
   rndprc = rndsav;
 #ifdef INFINITY
  nonorm:
@@ -3877,6 +3878,11 @@ toe53 (x, y)
       return;
     }
 #endif
+  if (LARGEST_EXPONENT_IS_NORMAL (64) && x[1] > 2047)
+    {
+      saturate (y, eiisneg (x), 64, 1);
+      return;
+    }
   p = &x[0];
 #ifdef IEEE
   if (! REAL_WORDS_BIG_ENDIAN)
@@ -4031,7 +4037,7 @@ etoe24 (x, e)
   /* round off to nearest or even */
   rndsav = rndprc;
   rndprc = 24;
-  emdnorm (xi, 0, 0, exp, 64);
+  emdnorm (xi, 0, 0, exp, !ROUND_TOWARDS_ZERO);
   rndprc = rndsav;
 #ifdef INFINITY
  nonorm:
@@ -4056,6 +4062,11 @@ toe24 (x, y)
       return;
     }
 #endif
+  if (LARGEST_EXPONENT_IS_NORMAL (32) && x[1] > 255)
+    {
+      saturate (y, eiisneg (x), 32, 1);
+      return;
+    }
   p = &x[0];
 #ifdef IEEE
   if (! REAL_WORDS_BIG_ENDIAN)
@@ -4070,7 +4081,7 @@ toe24 (x, y)
 
   i = *p++;
 /* Handle overflow cases.  */
-  if (i >= 255)
+  if (!LARGEST_EXPONENT_IS_NORMAL (32) && i >= 255)
     {
 #ifdef INFINITY
       *y |= (UEMUSHORT) 0x7f80;
@@ -5628,7 +5639,7 @@ eldexp (x, pwr2, y)
   li = xi[1];
   li += pwr2;
   i = 0;
-  emdnorm (xi, i, i, li, 64);
+  emdnorm (xi, i, i, li, !ROUND_TOWARDS_ZERO);
   emovo (xi, y);
 }
 
@@ -5826,7 +5837,7 @@ etodec (x, d)
   /* Round off to nearest or even.  */
   rndsav = rndprc;
   rndprc = 56;
-  emdnorm (xi, 0, 0, exp, 64);
+  emdnorm (xi, 0, 0, exp, !ROUND_TOWARDS_ZERO);
   rndprc = rndsav;
   todec (xi, d);
 }
@@ -5938,7 +5949,7 @@ etoibm (x, d, mode)
 							/* round off to nearest or even */
   rndsav = rndprc;
   rndprc = 56;
-  emdnorm (xi, 0, 0, exp, 64);
+  emdnorm (xi, 0, 0, exp, !ROUND_TOWARDS_ZERO);
   rndprc = rndsav;
   toibm (xi, d, mode);
 }
@@ -6136,7 +6147,7 @@ etoc4x (x, d, mode)
   /* Round off to nearest or even.  */
   rndsav = rndprc;
   rndprc = mode == QFmode ? 24 : 32;
-  emdnorm (xi, 0, 0, exp, 64);
+  emdnorm (xi, 0, 0, exp, !ROUND_TOWARDS_ZERO);
   rndprc = rndsav;
   toc4x (xi, d, mode);
 }
@@ -6298,7 +6309,15 @@ make_nan (nan, sign, mode)
 {
   int n;
   const UEMUSHORT *p;
+  int size;
 
+  size = GET_MODE_BITSIZE (mode);
+  if (LARGEST_EXPONENT_IS_NORMAL (size))
+    {
+      warning ("%d-bit floats cannot hold NaNs", size);
+      saturate (nan, sign, size, 0);
+      return;
+    }
   switch (mode)
     {
 /* Possibly the `reserved operand' patterns on a VAX can be
@@ -6353,6 +6372,34 @@ make_nan (nan, sign, mode)
 }
 #endif /* NANS */
 
+
+/* Create a saturation value for a SIZE-bit float, assuming that
+   LARGEST_EXPONENT_IS_NORMAL (SIZE).
+
+   If SIGN is true, fill X with the most negative value, otherwise fill
+   it with the most positive value.  WARN is true if the function should
+   warn about overflow.  */
+
+static void
+saturate (x, sign, size, warn)
+     UEMUSHORT *x;
+     int sign, size, warn;
+{
+  int i;
+
+  if (warn && extra_warnings)
+    warning ("value exceeds the range of a %d-bit float", size);
+
+  /* Create the most negative value.  */
+  for (i = 0; i < size / EMUSHORT_SIZE; i++)
+    x[i] = 0xffff;
+
+  /* Make it positive, if necessary.  */
+  if (!sign)
+    x[REAL_WORDS_BIG_ENDIAN? 0 : i - 1] = 0x7fff;
+}
+
+
 /* This is the inverse of the function `etarsingle' invoked by
    REAL_VALUE_TO_TARGET_SINGLE.  */
 
@@ -6876,7 +6923,7 @@ esqrt (x, y)
     k |= (int) num[i];
 
   /* Renormalize and round off.  */
-  emdnorm (sq, k, 0, exp, 64);
+  emdnorm (sq, k, 0, exp, !ROUND_TOWARDS_ZERO);
   emovo (sq, y);
 }
 #endif