[Ada] Do not use exponentiation for common bases in floating-point Value

gcc/ada/

	* Makefile.rtl (GNATRTL_NONTASKING_OBJS): Likewise.
	* exp_imgv.adb (Expand_Value_Attribute): Use RE_Value_Long_Float in
	lieu of RE_Value_Long_Long_Float as fallback for fixed-point types.
	Also use it for Long_Long_Float if it has same size as Long_Float.
	* libgnat/s-imgrea.adb: Replace Powten_Table with Powen_LLF.
	* libgnat/s-powflt.ads: New file.
	* libgnat/s-powlfl.ads: Likewise.
	* libgnat/s-powtab.ads: Rename to...
	* libgnat/s-powllf.ads: ...this.
	* libgnat/s-valflt.ads: Add with clause for System.Powten_Flt and
	pass its table as actual parameter to System.Val_Real.
	* libgnat/s-vallfl.ads: Likewise for System.Powten_LFlt.
	* libgnat/s-valllf.ads: Likewise for System.Powten_LLF.
	* libgnat/s-valrea.ads: Add Maxpow and Powten_Address parameters.
	* libgnat/s-valrea.adb: Add pragma Warnings (Off).
	(Need_Extra): New boolean constant.
	(Precision_Limit): Set it according to Need_Extra.
	(Impl): Adjust actual parameter.
	(Integer_to_Rea): Add assertion on the machine radix. Take into
	account the extra digit only if Need_Extra is true.  Reimplement
	the computation of the final value for bases 2, 4, 8, 10 and 16.
	* libgnat/s-valued.adb (Impl): Adjust actual parameter.
	(Scan_Decimal): Add pragma Unreferenced.
	(Value_Decimal): Likewise.
	* libgnat/s-valuef.adb (Impl): Adjust actual parameter.
	* libgnat/s-valuer.ads (Floating): Remove.
	(Round): New formal parameter.
	* libgnat/s-valuer.adb (Round_Extra): New procedure.
	(Scan_Decimal_Digits): Use it to round the extra digit if Round
	is set to True in the instantiation.
	(Scan_Integral_Digits): Likewise.

1 files changed, 85 insertions, 0 deletions

diff --git a/gcc/ada/libgnat/s-powflt.ads b/gcc/ada/libgnat/s-powflt.ads
new file mode 100644
index 0000000..9d58967
--- /dev/null
+++ b/gcc/ada/libgnat/s-powflt.ads
@@ -0,0 +1,85 @@
+------------------------------------------------------------------------------
+--                                                                          --
+--                         GNAT COMPILER COMPONENTS                         --
+--                                                                          --
+--                    S Y S T E M . P O W T E N _ F L T                     --
+--                                                                          --
+--                                 S p e c                                  --
+--                                                                          --
+--             Copyright (C) 2020, Free Software Foundation, Inc.           --
+--                                                                          --
+-- GNAT is free software;  you can  redistribute it  and/or modify it under --
+-- terms of the  GNU General Public License as published  by the Free Soft- --
+-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
+-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
+-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
+-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
+--                                                                          --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception,   --
+-- version 3.1, as published by the Free Software Foundation.               --
+--                                                                          --
+-- You should have received a copy of the GNU General Public License and    --
+-- a copy of the GCC Runtime Library Exception along with this program;     --
+-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
+-- <http://www.gnu.org/licenses/>.                                          --
+--                                                                          --
+-- GNAT was originally developed  by the GNAT team at  New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc.      --
+--                                                                          --
+------------------------------------------------------------------------------
+
+--  This package provides a powers of ten table used for real conversions
+
+package System.Powten_Flt is
+   pragma Pure;
+
+   Maxpow : constant := 38;
+   --  Largest power of ten representable with Float
+
+   Maxpow_Exact : constant := 10;
+   --  Largest power of ten exactly representable with Float. It is equal to
+   --  floor (M * log 2 / log 5), when M is the size of the mantissa (24).
+
+   Powten : constant array (0 .. Maxpow) of Float :=
+      (00 => 1.0E+00,
+       01 => 1.0E+01,
+       02 => 1.0E+02,
+       03 => 1.0E+03,
+       04 => 1.0E+04,
+       05 => 1.0E+05,
+       06 => 1.0E+06,
+       07 => 1.0E+07,
+       08 => 1.0E+08,
+       09 => 1.0E+09,
+       10 => 1.0E+10,
+       11 => 1.0E+11,
+       12 => 1.0E+12,
+       13 => 1.0E+13,
+       14 => 1.0E+14,
+       15 => 1.0E+15,
+       16 => 1.0E+16,
+       17 => 1.0E+17,
+       18 => 1.0E+18,
+       19 => 1.0E+19,
+       20 => 1.0E+20,
+       21 => 1.0E+21,
+       22 => 1.0E+22,
+       23 => 1.0E+23,
+       24 => 1.0E+24,
+       25 => 1.0E+25,
+       26 => 1.0E+26,
+       27 => 1.0E+27,
+       28 => 1.0E+28,
+       29 => 1.0E+29,
+       30 => 1.0E+30,
+       31 => 1.0E+31,
+       32 => 1.0E+32,
+       33 => 1.0E+33,
+       34 => 1.0E+34,
+       35 => 1.0E+35,
+       36 => 1.0E+36,
+       37 => 1.0E+37,
+       38 => 1.0E+38);
+
+end System.Powten_Flt;