[Ada] Expand integer-only implementation of ordinary fixed-point types

[Pierre-Marie de Rodat]

This change relaxes the conditions under which the implementation of
ordinary fixed-point types uses only underlying integer instructions.

These conditions are on the Small of the ordinary fixed-point types,
which must now be a rational number whose factors are of a magnitude
bounded relatively to the size of the mantissa.

The algorithms of Image and Value are not modified, only that of Fore
is genezalized in a straightforward way.  Two new attributes are added
to the compiler, Small_Denominator and Small_Numerator, in order for
the Text_IO.Fixed_IO package to benefit from the enhancement.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

        * doc/gnat_rm/implementation_defined_attributes.rst (Pool_Address):
        Fix pasto.
        (Small_Denominator): New entry.
        (Small_Numerator): Likewise.
        * doc/gnat_rm/implementation_defined_characteristics.rst (3.5.9):
        Relax conditions on 128-bit smalls and integer-only implementation.
        * gnat_rm.texi: Regenerate.
        * exp_attr.adb (Expand_N_Attribute_Reference) <Attribute_Fore>:
        Relax conditions on integer implementation for ordinary fixed-point
        types and pass a third parameter to the routine.
        <Attribute_Small_Denominator>: Raise Program_Error.
        <Attribute_Small_Numerator>: Likewise.
        * exp_fixd.adb (Expand_Convert_Fixed_To_Fixed): Use a scaled divide
        if the numerator and denominator of the small ratio are sufficiently
        small integers.
        (Expand_Convert_Fixed_To_Integer): Use a scaled divide if numerator
        and denominator of the small value are sufficiently small integers.
        (Expand_Convert_Integer_To_Fixed): Likewise.
        * exp_imgv.adb (Expand_Image_Attribute): Relax the conditions on the
        integer implementation for ordinary fixed-point types.
        (Expand_Value_Attribute): Likewise.
        * freeze.adb (Freeze_Fixed_Point_Type): Relax conditions on 128-bit
        smalls.
        * sem_attr.adb (Analyze_Attribute) <Attribute_Small_Denominator>:
        Check no arguments, fixed-point and set type to Universal_Integer.
        <Attribute_Small_Numerator>: Likewise.
        (Eval_Attribute) <Attribute_Small_Denominator>: Fold statically.
        <Attribute_Small_Numerator>: Likewise.
        * snames.ads-tmpl (Name_Small_Denominator): New attribute name.
        (Name_Small_Numerator): Likewise.
        (Attribute_Id): Add Attribute_Small_{Denominator,Numerator}.
        * libgnat/a-tifiio.adb (Exact): Delete.
        (Need_64): Likewise.
        (OK_Get_32): New boolean constant.
        (OK_Put_32): Likewise.
        (OK_Get_64): Likewise.
        (OK_Put_64): Likewise.
        (E): Adjust.
        (Get procedures): Likewise.
        (Put procedures): Likewise.
        * libgnat/a-tifiio__128.adb (Exact): Delete.
        (Need_64): Likewise.
        (Need_128): Likewise.
        (OK_Get_32): New boolean constant.
        (OK_Put_32): Likewise.
        (OK_Get_64): Likewise.
        (OK_Put_64): Likewise.
        (OK_Get_128): Likewise.
        (OK_Put_128): Likewise.
        (E): Adjust.
        (Get procedures): Likewise.
        (Put procedures): Likewise.
        * libgnat/a-wtfiio.adb (Exact): Delete.
        (Need_64): Likewise.
        (OK_Get_32): New boolean constant.
        (OK_Put_32): Likewise.
        (OK_Get_64): Likewise.
        (OK_Put_64): Likewise.
        (E): Adjust.
        (Get procedures): Likewise.
        (Put procedures): Likewise.
        * libgnat/a-wtfiio__128.adb (Exact): Delete.
        (Need_64): Likewise.
        (Need_128): Likewise.
        (OK_Get_32): New boolean constant.
        (OK_Put_32): Likewise.
        (OK_Get_64): Likewise.
        (OK_Put_64): Likewise.
        (OK_Get_128): Likewise.
        (OK_Put_128): Likewise.
        (E): Adjust.
        (Get procedures): Likewise.
        (Put procedures): Likewise.
        * libgnat/a-ztfiio.adb (Exact): Delete.
        (Need_64): Likewise.
        (OK_Get_32): New boolean constant.
        (OK_Put_32): Likewise.
        (OK_Get_64): Likewise.
        (OK_Put_64): Likewise.
        (E): Adjust.
        (Get procedures): Likewise.
        (Put procedures): Likewise.
        * libgnat/a-ztfiio__128.adb (Exact): Delete.
        (Need_64): Likewise.
        (Need_128): Likewise.
        (OK_Get_32): New boolean constant.
        (OK_Put_32): Likewise.
        (OK_Get_64): Likewise.
        (OK_Put_64): Likewise.
        (OK_Get_128): Likewise.
        (OK_Put_128): Likewise.
        (E): Adjust.
        (Get procedures): Likewise.
        (Put procedures): Likewise.
        * libgnat/s-fore_f.ads (Fore_Fixed): Adjust signature.
        * libgnat/s-fore_f.adb (Fore_Fixed): Reimplement.
        * libgnat/s-fofi32.ads (Fore_Fixed32): Adjust signature.
        * libgnat/s-fofi64.ads (Fore_Fixed64): Likewise.
        * libgnat/s-fofi128.ads (Fore_Fixed128): Likewise.
        * libgnat/s-imagef.ads: Adjust description.
        * libgnat/s-imagef.adb (Maxdigs): Move around.
        (Set_Image_Integer): Remove assertion.
        * libgnat/s-valuef.ads: Adjust description.
        * libgnat/s-valuef.adb (Integer_To_Fixed): Minor tweak.

patch.diff.gz
Description: application/gzip