Where possible GNAT will store the binary representation of a record aggregate in memory for space and performance reasons. This configuration pragma changes this behaviour so that record aggregates are instead always converted into individual assignment statements.
The following package pack.ads:
-- pack.ads
pragma Aggregate_Individually_Assign;
pragma Restrictions (No_Multiple_Elaboration);
package Pack is
type A_Rec is record
A, B, C, D : Boolean;
end record;
A : A_Rec := (True, False, True, True);
end Pack;
when compiled with
gcc -c -gnatdg pack.ads
should produce the following output:
Source recreated from tree for Pack (spec)
------------------------------------------
pragma aggregate_individually_assign;
pragma restrictions (no_multiple_elaboration);
package pack is
type pack__a_rec is record
a : boolean;
b : boolean;
c : boolean;
d : boolean;
end record;
freeze pack__a_rec [
procedure pack__a_recIP (_init : out pack__a_rec) is
begin
%push_constraint_error_label ()
%push_program_error_label ()
%push_storage_error_label ()
null;
%pop_constraint_error_label
%pop_program_error_label
%pop_storage_error_label
return;
end pack__a_recIP;
]
pack__a : pack__a_rec := (
a => true,
b => false,
c => true,
d => true);
pack__a.a := true;
pack__a.b := false;
pack__a.c := true;
pack__a.d := true;
null;
end pack;
Tested on x86_64-pc-linux-gnu, committed on trunk
2019-08-20 Patrick Bernardi <berna...@adacore.com>
gcc/ada/
* exp_aggr.adb (Expand_Record_Aggregate): Always convert a
record Aggregate to assignment statements if the option
Aggregate_Individually_Assign is set.
* opt.ads (Aggregate_Individually_Assign): New option.
* par-prag.adb (Prag): Add Pragma_Aggregate_Individually_Assign.
* sem_prag.adb (Analyze_Pragma): Likewise.
* snames.ads-tmpl: Add Pragma_Aggregate_Individually_Assign and
Name_Aggregate_Individually_Assign.
* doc/gnat_rm/implementation_defined_pragmas.rst: Document
pragma Aggregate_Individually_Assign.
* gnat_rm.texi: Regenerate.
patch.diff.gz
Description: application/gzip
