gcc/ada/

	Reapply reverted change:

        2007-09-06  Eric Botcazou  <ebotcazou@adacore.com>

        * trans.c (convert_with_check): Update call to real_2expN.

gcc/
	config/m68k/m68k.c (floating_exact_log2): Update call to real_2expN.
	config/s390/s390.md (fixuns_trunc<BFP:mode><GPR:mode>2): Ditto.

	Reapply reverted changes:

 	2007-09-06  Jan Hubicka  <jh@suse.cz>
 
	* config/i386.c (ix86_expand_lround, ix86_expand_round): Update call of
	real_2expN.

	2007-09-06  Richard Sandiford  <richard@codesourcery.com>

	* config/mips/mips.md (fixuns_truncdfsi2, fixuns_truncdfdi2)
	(fixuns_truncsfsi2, fixuns_truncsfdi2): Update calls to real_2expN.

	2007-09-05  Janis Johnson  <janis187@us.ibm.com>

	* optabs.c (expand_float): Convert unsigned integer as signed only
	if it provides sufficient accuracy; add mode argument to real_2expN.
	(expand_fix): Fix comment typos; extend binary float into mode
	wider than destination for converion to unsigned integer; add mode
	argument to real_2expN.
	* real.c (real_2expN): Add mode argument to special-case decimal
	float values.
	* real.h (real_2expN): Ditto.
	* fixed-value.c (check_real_for_fixed_mode): Add mode argument to
	real_2expN.
	(fixed_from_string): Ditto.
	(fixed_to_decimal): Ditto.
	(fixed_convert_from_real): Ditto.
	(real_convert_from_fixed): Ditto.
	* config/rs6000/rs6000.md (FP): Include DD and TD modes.
	* config/rs6000/dfp.md (extendddtd2, adddd3, addtd3, subdd3, subtd3,
	muldd3, multd3, divdd3, divtd3, cmpdd_internal1, cmptd_internal1,
	floatditd2, ftruncdd2, fixdddi2, ftrunctd2, fixddi2): New.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@128247 138bc75d-0d04-0410-961f-82ee72b054a4

13 files changed, 231 insertions, 29 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a76df2a2665..04922ebca13 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,41 @@
+2007-09-07  Janis Johnson  <janis187@us.ibm.com>
+
+	config/m68k/m68k.c (floating_exact_log2): Update call to real_2expN.
+	config/s390/s390.md (fixuns_trunc<BFP:mode><GPR:mode>2): Ditto.
+
+	Reapply reverted changes:
+
+ 	2007-09-06  Jan Hubicka  <jh@suse.cz>
+ 
+	* config/i386.c (ix86_expand_lround, ix86_expand_round): Update call of
+	real_2expN.
+
+	2007-09-06  Richard Sandiford  <richard@codesourcery.com>
+
+	* config/mips/mips.md (fixuns_truncdfsi2, fixuns_truncdfdi2)
+	(fixuns_truncsfsi2, fixuns_truncsfdi2): Update calls to real_2expN.
+
+	2007-09-05  Janis Johnson  <janis187@us.ibm.com>
+
+	* optabs.c (expand_float): Convert unsigned integer as signed only
+	if it provides sufficient accuracy; add mode argument to real_2expN.
+	(expand_fix): Fix comment typos; extend binary float into mode
+	wider than destination for converion to unsigned integer; add mode
+	argument to real_2expN.
+	* real.c (real_2expN): Add mode argument to special-case decimal
+	float values.
+	* real.h (real_2expN): Ditto.
+	* fixed-value.c (check_real_for_fixed_mode): Add mode argument to
+	real_2expN.
+	(fixed_from_string): Ditto.
+	(fixed_to_decimal): Ditto.
+	(fixed_convert_from_real): Ditto.
+	(real_convert_from_fixed): Ditto.
+	* config/rs6000/rs6000.md (FP): Include DD and TD modes.
+	* config/rs6000/dfp.md (extendddtd2, adddd3, addtd3, subdd3, subtd3,
+	muldd3, multd3, divdd3, divtd3, cmpdd_internal1, cmptd_internal1,
+	floatditd2, ftruncdd2, fixdddi2, ftrunctd2, fixddi2): New.
+
 2007-09-07  Diego Novillo  <dnovillo@google.com>
 
 	* tree-flow.h (const_block_stmt_iterator): Remove.
diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 7ec2c1d2cdd..8de9c577d15 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,11 @@
+2007-09-07  Janis Johnson  <janis187@us.ibm.com>
+
+	Reapply reverted change:
+
+        2007-09-06  Eric Botcazou  <ebotcazou@adacore.com>
+
+        * trans.c (convert_with_check): Update call to real_2expN.
+
 2007-09-06  Janis Johnson  <janis187@us.ibm.com>
 
 	Revert:
diff --git a/gcc/ada/trans.c b/gcc/ada/trans.c
index 4d79cb3f9b6..24797753fd8 100644
--- a/gcc/ada/trans.c
+++ b/gcc/ada/trans.c
@@ -5893,7 +5893,7 @@ convert_with_check (Entity_Id gnat_type, tree gnu_expr, bool overflowp,
 
       /* Compute the exact value calc_type'Pred (0.5) at compile time. */
       fmt = REAL_MODE_FORMAT (TYPE_MODE (calc_type));
-      real_2expN (&half_minus_pred_half, -(fmt->p) - 1);
+      real_2expN (&half_minus_pred_half, -(fmt->p) - 1, TYPE_MODE (calc_type));
       REAL_ARITHMETIC (pred_half, MINUS_EXPR, dconsthalf,
                        half_minus_pred_half);
       gnu_pred_half = build_real (calc_type, pred_half);
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index dba72dfa737..f6f80a05969 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -23144,7 +23144,7 @@ ix86_expand_lround (rtx op0, rtx op1)
 
   /* load nextafter (0.5, 0.0) */
   fmt = REAL_MODE_FORMAT (mode);
-  real_2expN (&half_minus_pred_half, -(fmt->p) - 1);
+  real_2expN (&half_minus_pred_half, -(fmt->p) - 1, mode);
   REAL_ARITHMETIC (pred_half, MINUS_EXPR, dconsthalf, half_minus_pred_half);
 
   /* adj = copysign (0.5, op1) */
@@ -23555,7 +23555,7 @@ ix86_expand_round (rtx operand0, rtx operand1)
 
   /* load nextafter (0.5, 0.0) */
   fmt = REAL_MODE_FORMAT (mode);
-  real_2expN (&half_minus_pred_half, -(fmt->p) - 1);
+  real_2expN (&half_minus_pred_half, -(fmt->p) - 1, mode);
   REAL_ARITHMETIC (pred_half, MINUS_EXPR, dconsthalf, half_minus_pred_half);
 
   /* xa = xa + 0.5 */
diff --git a/gcc/config/m68k/m68k.c b/gcc/config/m68k/m68k.c
index 76d765e7252..cd7f493815c 100644
--- a/gcc/config/m68k/m68k.c
+++ b/gcc/config/m68k/m68k.c
@@ -3571,7 +3571,7 @@ floating_exact_log2 (rtx x)
     return 0;
 
   exp = real_exponent (&r);
-  real_2expN (&r1, exp);
+  real_2expN (&r1, exp, DFmode);
   if (REAL_VALUES_EQUAL (r1, r))
     return exp;
 
diff --git a/gcc/config/mips/mips.md b/gcc/config/mips/mips.md
index 2006f920600..76dde25fc9c 100644
--- a/gcc/config/mips/mips.md
+++ b/gcc/config/mips/mips.md
@@ -2805,7 +2805,7 @@
   rtx label2 = gen_label_rtx ();
   REAL_VALUE_TYPE offset;
 
-  real_2expN (&offset, 31);
+  real_2expN (&offset, 31, DFmode);
 
   if (reg1)			/* Turn off complaints about unreached code.  */
     {
@@ -2850,7 +2850,7 @@
   rtx label2 = gen_label_rtx ();
   REAL_VALUE_TYPE offset;
 
-  real_2expN (&offset, 63);
+  real_2expN (&offset, 63, DFmode);
 
   mips_emit_move (reg1, CONST_DOUBLE_FROM_REAL_VALUE (offset, DFmode));
   do_pending_stack_adjust ();
@@ -2892,7 +2892,7 @@
   rtx label2 = gen_label_rtx ();
   REAL_VALUE_TYPE offset;
 
-  real_2expN (&offset, 31);
+  real_2expN (&offset, 31, SFmode);
 
   mips_emit_move (reg1, CONST_DOUBLE_FROM_REAL_VALUE (offset, SFmode));
   do_pending_stack_adjust ();
@@ -2934,7 +2934,7 @@
   rtx label2 = gen_label_rtx ();
   REAL_VALUE_TYPE offset;
 
-  real_2expN (&offset, 63);
+  real_2expN (&offset, 63, SFmode);
 
   mips_emit_move (reg1, CONST_DOUBLE_FROM_REAL_VALUE (offset, SFmode));
   do_pending_stack_adjust ();
diff --git a/gcc/config/rs6000/dfp.md b/gcc/config/rs6000/dfp.md
index 0bc405a3f54..fa20f7d0652 100644
--- a/gcc/config/rs6000/dfp.md
+++ b/gcc/config/rs6000/dfp.md
@@ -405,3 +405,151 @@
 { rs6000_split_multireg_move (operands[0], operands[1]); DONE; }
   [(set_attr "length" "8,8,8,20,20,16")])
 
+;; Hardware support for decimal floating point operations.
+
+(define_insn "extendddtd2"
+  [(set (match_operand:TD 0 "gpc_reg_operand" "=f")
+	(float_extend:TD (match_operand:DD 1 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dctqpq %0,%1"
+  [(set_attr "type" "fp")])
+
+;; The result of drdpq is an even/odd register pair with the converted
+;; value in the even register and zero in the odd register.
+;; FIXME: Avoid the register move by using a reload constraint to ensure
+;; that the result is the first of the pair receiving the result of drdpq.
+
+(define_insn "trunctddd2"
+  [(set (match_operand:DD 0 "gpc_reg_operand" "=f")
+	(float_truncate:DD (match_operand:TD 1 "gpc_reg_operand" "f")))
+   (clobber (match_scratch:TD 2 "=f"))]
+  "TARGET_DFP"
+  "drdpq %2,%1\;fmr %0,%2"
+  [(set_attr "type" "fp")])
+
+(define_insn "adddd3"
+  [(set (match_operand:DD 0 "gpc_reg_operand" "=f")
+	(plus:DD (match_operand:DD 1 "gpc_reg_operand" "%f")
+		 (match_operand:DD 2 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dadd %0,%1,%2"
+  [(set_attr "type" "fp")])
+
+(define_insn "addtd3"
+  [(set (match_operand:TD 0 "gpc_reg_operand" "=f")
+	(plus:TD (match_operand:TD 1 "gpc_reg_operand" "%f")
+		 (match_operand:TD 2 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "daddq %0,%1,%2"
+  [(set_attr "type" "fp")])
+
+(define_insn "subdd3"
+  [(set (match_operand:DD 0 "gpc_reg_operand" "=f")
+	(minus:DD (match_operand:DD 1 "gpc_reg_operand" "f")
+		  (match_operand:DD 2 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dsub %0,%1,%2"
+  [(set_attr "type" "fp")])
+
+(define_insn "subtd3"
+  [(set (match_operand:TD 0 "gpc_reg_operand" "=f")
+	(minus:TD (match_operand:TD 1 "gpc_reg_operand" "f")
+		  (match_operand:TD 2 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dsubq %0,%1,%2"
+  [(set_attr "type" "fp")])
+
+(define_insn "muldd3"
+  [(set (match_operand:DD 0 "gpc_reg_operand" "=f")
+	(mult:DD (match_operand:DD 1 "gpc_reg_operand" "%f")
+		 (match_operand:DD 2 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dmul %0,%1,%2"
+  [(set_attr "type" "fp")])
+
+(define_insn "multd3"
+  [(set (match_operand:TD 0 "gpc_reg_operand" "=f")
+	(mult:TD (match_operand:TD 1 "gpc_reg_operand" "%f")
+		 (match_operand:TD 2 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dmulq %0,%1,%2"
+  [(set_attr "type" "fp")])
+
+(define_insn "divdd3"
+  [(set (match_operand:DD 0 "gpc_reg_operand" "=f")
+	(div:DD (match_operand:DD 1 "gpc_reg_operand" "f")
+		(match_operand:DD 2 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "ddiv %0,%1,%2"
+  [(set_attr "type" "fp")])
+
+(define_insn "divtd3"
+  [(set (match_operand:TD 0 "gpc_reg_operand" "=f")
+	(div:TD (match_operand:TD 1 "gpc_reg_operand" "f")
+		(match_operand:TD 2 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "ddivq %0,%1,%2"
+  [(set_attr "type" "fp")])
+
+(define_insn "*cmpdd_internal1"
+  [(set (match_operand:CCFP 0 "cc_reg_operand" "=y")
+	(compare:CCFP (match_operand:DD 1 "gpc_reg_operand" "f")
+		      (match_operand:DD 2 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dcmpu %0,%1,%2"
+  [(set_attr "type" "fpcompare")])
+
+(define_insn "*cmptd_internal1"
+  [(set (match_operand:CCFP 0 "cc_reg_operand" "=y")
+	(compare:CCFP (match_operand:TD 1 "gpc_reg_operand" "f")
+		      (match_operand:TD 2 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dcmpuq %0,%1,%2"
+  [(set_attr "type" "fpcompare")])
+
+(define_insn "floatditd2"
+  [(set (match_operand:TD 0 "gpc_reg_operand" "=f")
+	(float:TD (match_operand:DI 1 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dcffixq %0,%1"
+  [(set_attr "type" "fp")])
+
+;; Convert a decimal64 to a decimal64 whose value is an integer.
+;; This is the first stage of converting it to an integer type.
+
+(define_insn "ftruncdd2"
+  [(set (match_operand:DD 0 "gpc_reg_operand" "=f")
+	(fix:DD (match_operand:DD 1 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "drintn. 0,%0,%1,1"
+  [(set_attr "type" "fp")])
+
+;; Convert a decimal64 whose value is an integer to an actual integer.
+;; This is the second stage of converting decimal float to integer type.
+
+(define_insn "fixdddi2"
+  [(set (match_operand:DI 0 "gpc_reg_operand" "=f")
+	(fix:DI (match_operand:DD 1 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dctfix %0,%1"
+  [(set_attr "type" "fp")])
+
+;; Convert a decimal128 to a decimal128 whose value is an integer.
+;; This is the first stage of converting it to an integer type.
+
+(define_insn "ftrunctd2"
+  [(set (match_operand:TD 0 "gpc_reg_operand" "=f")
+	(fix:TD (match_operand:TD 1 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "drintnq. 0,%0,%1,1"
+  [(set_attr "type" "fp")])
+
+;; Convert a decimal128 whose value is an integer to an actual integer.
+;; This is the second stage of converting decimal float to integer type.
+
+(define_insn "fixtddi2"
+  [(set (match_operand:DI 0 "gpc_reg_operand" "=f")
+	(fix:DI (match_operand:TD 1 "gpc_reg_operand" "f")))]
+  "TARGET_DFP"
+  "dctfixq %0,%1"
+  [(set_attr "type" "fp")])
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index e3505d1e5ae..debacdc74b4 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -204,7 +204,9 @@
   (TF "!TARGET_IEEEQUAD
    && TARGET_HARD_FLOAT
    && (TARGET_FPRS || TARGET_E500_DOUBLE)
-   && TARGET_LONG_DOUBLE_128")])
+   && TARGET_LONG_DOUBLE_128")
+  (DD "TARGET_DFP")
+  (TD "TARGET_DFP")])
 
 ; Various instructions that come in SI and DI forms.
 ; A generic w/d attribute, for things like cmpw/cmpd.
diff --git a/gcc/config/s390/s390.md b/gcc/config/s390/s390.md
index 66cf5612da6..b1350336e18 100644
--- a/gcc/config/s390/s390.md
+++ b/gcc/config/s390/s390.md
@@ -3295,8 +3295,8 @@
   REAL_VALUE_TYPE cmp, sub;
   
   operands[1] = force_reg (<BFP:MODE>mode, operands[1]);
-  real_2expN (&cmp, GET_MODE_BITSIZE(<GPR:MODE>mode) - 1);
-  real_2expN (&sub, GET_MODE_BITSIZE(<GPR:MODE>mode));
+  real_2expN (&cmp, GET_MODE_BITSIZE(<GPR:MODE>mode) - 1, <BFP:mode>mode);
+  real_2expN (&sub, GET_MODE_BITSIZE(<GPR:MODE>mode), <BFP:mode>mode);
   
   emit_insn (gen_cmp<BFP:mode> (operands[1],
 	CONST_DOUBLE_FROM_REAL_VALUE (cmp, <BFP:MODE>mode)));
diff --git a/gcc/fixed-value.c b/gcc/fixed-value.c
index aca386a6d9c..8c8d3719044 100644
--- a/gcc/fixed-value.c
+++ b/gcc/fixed-value.c
@@ -64,8 +64,8 @@ check_real_for_fixed_mode (REAL_VALUE_TYPE *real_value, enum machine_mode mode)
 {
   REAL_VALUE_TYPE max_value, min_value, epsilon_value;
 
-  real_2expN (&max_value, GET_MODE_IBIT (mode));
-  real_2expN (&epsilon_value, -GET_MODE_FBIT (mode));
+  real_2expN (&max_value, GET_MODE_IBIT (mode), mode);
+  real_2expN (&epsilon_value, -GET_MODE_FBIT (mode), mode);
 
   if (SIGNED_FIXED_POINT_MODE_P (mode))
     min_value = REAL_VALUE_NEGATE (max_value);
@@ -102,7 +102,7 @@ fixed_from_string (FIXED_VALUE_TYPE *f, const char *str, enum machine_mode mode)
       || (temp == FIXED_MAX_EPS && ALL_ACCUM_MODE_P (f->mode)))
     warning (OPT_Woverflow,
 	     "large fixed-point constant implicitly truncated to fixed-point type");
-  real_2expN (&base_value, fbit);
+  real_2expN (&base_value, fbit, mode);
   real_arithmetic (&fixed_value, MULT_EXPR, &real_value, &base_value);
   real_to_integer2 ((HOST_WIDE_INT *)&f->data.low, &f->data.high,
 		    &fixed_value);
@@ -132,7 +132,7 @@ fixed_to_decimal (char *str, const FIXED_VALUE_TYPE *f_orig,
 {
   REAL_VALUE_TYPE real_value, base_value, fixed_value;
 
-  real_2expN (&base_value, GET_MODE_FBIT (f_orig->mode));
+  real_2expN (&base_value, GET_MODE_FBIT (f_orig->mode), f_orig->mode);
   real_from_integer (&real_value, VOIDmode, f_orig->data.low, f_orig->data.high,
 		     UNSIGNED_FIXED_POINT_MODE_P (f_orig->mode));
   real_arithmetic (&fixed_value, RDIV_EXPR, &real_value, &base_value);
@@ -1067,7 +1067,7 @@ fixed_convert_from_real (FIXED_VALUE_TYPE *f, enum machine_mode mode,
 
   real_value = *a;
   f->mode = mode;
-  real_2expN (&base_value, fbit);
+  real_2expN (&base_value, fbit, mode);
   real_arithmetic (&fixed_value, MULT_EXPR, &real_value, &base_value);
   real_to_integer2 ((HOST_WIDE_INT *)&f->data.low, &f->data.high, &fixed_value);
   temp = check_real_for_fixed_mode (&real_value, mode);
@@ -1116,7 +1116,7 @@ real_convert_from_fixed (REAL_VALUE_TYPE *r, enum machine_mode mode,
 {
   REAL_VALUE_TYPE base_value, fixed_value, real_value;
 
-  real_2expN (&base_value, GET_MODE_FBIT (f->mode));
+  real_2expN (&base_value, GET_MODE_FBIT (f->mode), f->mode);
   real_from_integer (&fixed_value, VOIDmode, f->data.low, f->data.high,
 		     UNSIGNED_FIXED_POINT_MODE_P (f->mode));
   real_arithmetic (&real_value, RDIV_EXPR, &fixed_value, &base_value);
diff --git a/gcc/optabs.c b/gcc/optabs.c
index b1b32efb441..32b195c2a5c 100644
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -5135,10 +5135,11 @@ expand_float (rtx to, rtx from, int unsignedp)
 	  }
       }
 
-  /* Unsigned integer, and no way to convert directly.  For binary
-     floating point modes, convert as signed, then conditionally adjust
-     the result.  */
-  if (unsignedp && can_do_signed && !DECIMAL_FLOAT_MODE_P (GET_MODE (to)))
+  /* Unsigned integer, and no way to convert directly.  Convert as signed,
+     then unconditionally adjust the result.  For decimal float values we
+     do this only if we have already determined that a signed conversion
+     provides sufficient accuracy.  */
+  if (unsignedp && (can_do_signed || !DECIMAL_FLOAT_MODE_P (GET_MODE (to))))
     {
       rtx label = gen_label_rtx ();
       rtx temp;
@@ -5229,7 +5230,7 @@ expand_float (rtx to, rtx from, int unsignedp)
 			       0, label);
 
 
-      real_2expN (&offset, GET_MODE_BITSIZE (GET_MODE (from)));
+      real_2expN (&offset, GET_MODE_BITSIZE (GET_MODE (from)), fmode);
       temp = expand_binop (fmode, add_optab, target,
 			   CONST_DOUBLE_FROM_REAL_VALUE (offset, fmode),
 			   target, 0, OPTAB_LIB_WIDEN);
@@ -5340,14 +5341,16 @@ expand_fix (rtx to, rtx from, int unsignedp)
      anything with a wider integer mode.
 
      This code used to extend FP value into mode wider than the destination.
-     This is not needed.  Consider, for instance conversion from SFmode
+     This is needed for decimal float modes which cannot accurately
+     represent one plus the highest signed number of the same size, but
+     not for binary modes.  Consider, for instance conversion from SFmode
      into DImode.
 
      The hot path through the code is dealing with inputs smaller than 2^63
      and doing just the conversion, so there is no bits to lose.
 
      In the other path we know the value is positive in the range 2^63..2^64-1
-     inclusive.  (as for other imput overflow happens and result is undefined)
+     inclusive.  (as for other input overflow happens and result is undefined)
      So we know that the most important bit set in mantissa corresponds to
      2^63.  The subtraction of 2^63 should not generate any rounding as it
      simply clears out that bit.  The rest is trivial.  */
@@ -5355,15 +5358,16 @@ expand_fix (rtx to, rtx from, int unsignedp)
   if (unsignedp && GET_MODE_BITSIZE (GET_MODE (to)) <= HOST_BITS_PER_WIDE_INT)
     for (fmode = GET_MODE (from); fmode != VOIDmode;
 	 fmode = GET_MODE_WIDER_MODE (fmode))
-      if (CODE_FOR_nothing != can_fix_p (GET_MODE (to), fmode, 0,
-					 &must_trunc))
+      if (CODE_FOR_nothing != can_fix_p (GET_MODE (to), fmode, 0, &must_trunc)
+	  && (!DECIMAL_FLOAT_MODE_P (fmode)
+	      || GET_MODE_BITSIZE (fmode) > GET_MODE_BITSIZE (GET_MODE (to))))
 	{
 	  int bitsize;
 	  REAL_VALUE_TYPE offset;
 	  rtx limit, lab1, lab2, insn;
 
 	  bitsize = GET_MODE_BITSIZE (GET_MODE (to));
-	  real_2expN (&offset, bitsize - 1);
+	  real_2expN (&offset, bitsize - 1, fmode);
 	  limit = CONST_DOUBLE_FROM_REAL_VALUE (offset, fmode);
 	  lab1 = gen_label_rtx ();
 	  lab2 = gen_label_rtx ();
diff --git a/gcc/real.c b/gcc/real.c
index 9686309cf3d..ec7d56b7b10 100644
--- a/gcc/real.c
+++ b/gcc/real.c
@@ -2304,7 +2304,7 @@ real_maxval (REAL_VALUE_TYPE *r, int sign, enum machine_mode mode)
 /* Fills R with 2**N.  */
 
 void
-real_2expN (REAL_VALUE_TYPE *r, int n)
+real_2expN (REAL_VALUE_TYPE *r, int n, enum machine_mode fmode)
 {
   memset (r, 0, sizeof (*r));
 
@@ -2319,6 +2319,8 @@ real_2expN (REAL_VALUE_TYPE *r, int n)
       SET_REAL_EXP (r, n);
       r->sig[SIGSZ-1] = SIG_MSB;
     }
+  if (DECIMAL_FLOAT_MODE_P (fmode))
+    decimal_real_convert (r, fmode, r);
 }
 
 
diff --git a/gcc/real.h b/gcc/real.h
index e24a0df8a64..1eaabed28c0 100644
--- a/gcc/real.h
+++ b/gcc/real.h
@@ -248,7 +248,7 @@ extern bool real_nan (REAL_VALUE_TYPE *, const char *, int, enum machine_mode);
 
 extern void real_maxval (REAL_VALUE_TYPE *, int, enum machine_mode);
 
-extern void real_2expN (REAL_VALUE_TYPE *, int);
+extern void real_2expN (REAL_VALUE_TYPE *, int, enum machine_mode);
 
 extern unsigned int real_hash (const REAL_VALUE_TYPE *);