-- Do_Division_Check flag on float exponentiation expressions, for the case
-- where the value is 0.0 and the exponent is negative, although this case
-- does lead to a division check failure. As another special case,
- -- the frontend does not insert a Do_Range_Check on an allocator where
+ -- the front end does not insert a Do_Range_Check on an allocator where
-- the designated type is scalar, and the designated type is more
-- constrained than the type of the initialized allocator value or the type
-- of the default value for an uninitialized allocator.
- -- Note: the expander always takes care of the Do_Range check case,
- -- so this flag will never be set in the expanded tree passed to the
- -- back end code generator.
+ -- Note that the expander always takes care of the Do_Range_Check case, so
+ -- this flag will never be set in the expanded tree passed to the back end.
+ -- For the other two flags, the check can be generated either by the back
+ -- end or by the front end, depending on the setting of a target parameter.
-- Note that this accounts for all nodes that trigger the corresponding
-- checks, except for range checks on subtype_indications, which may be
-- conversion nodes (and set if the conversion requires a check).
-- Do_Division_Check (Flag13-Sem)
- -- This flag is set on a division operator (/ mod rem) to indicate
- -- that a zero divide check is required. The actual check is dealt
- -- with by the backend (all the front end does is to set the flag).
+ -- This flag is set on a division operator (/ mod rem) to indicate that
+ -- a zero divide check is required. The actual check is either dealt with
+ -- by the back end if Backend_Divide_Checks is set to true, or by the
+ -- front end itself if it is set to false.
-- Do_Length_Check (Flag4-Sem)
-- This flag is set in an N_Assignment_Statement, N_Op_And, N_Op_Or,
-- Do_Overflow_Check (Flag17-Sem)
-- This flag is set on an operator where an overflow check is required on
- -- the operation. The actual check is dealt with by the backend (all the
- -- front end does is to set the flag). The other cases where this flag is
- -- used is on a Type_Conversion node and for attribute reference nodes.
+ -- the operation. The actual check is either dealt with by the back end
+ -- if Backend_Overflow_Checks is set to true, or by the front end itself
+ -- if it is set to false. The other cases where this flag is used is on a
+ -- Type_Conversion node as well on if and case expression nodes.
-- For a type conversion, it means that the conversion is from one base
-- type to another, and the value may not fit in the target base type.
- -- See also the description of Do_Range_Check for this case. The only
- -- attribute references which use this flag are Pred and Succ, where it
- -- means that the result should be checked for going outside the base
- -- range. Note that this flag is not set for modular types. This flag is
+ -- See also the description of Do_Range_Check for this case. This flag is
-- also set on if and case expression nodes if we are operating in either
-- MINIMIZED or ELIMINATED overflow checking mode (to make sure that we
-- properly process overflow checking for dependent expressions).
-- range check is required. The target type is clear from the context.
-- The contexts in which this flag can appear are the following:
- -- Right side of an assignment. In this case the target type is
- -- taken from the left side of the assignment, which is referenced
- -- by the Name of the N_Assignment_Statement node.
+ -- Right side of an assignment. In this case the target type is taken
+ -- from the left side of the assignment, which is referenced by the
+ -- Name of the N_Assignment_Statement node.
-- Subscript expressions in an indexed component. In this case the
-- target type is determined from the type of the array, which is
-- listed above (e.g. in a return statement), an additional type
-- conversion node is introduced to represent the required check.
- -- A special case arises for the arguments of the Pred/Succ attributes.
- -- Here the range check needed is against First + 1 .. Last (Pred) or
- -- First .. Last - 1 (Succ) of the corresponding base type. Essentially
- -- these checks are what would be performed within the implicit body of
- -- the functions that correspond to these attributes. In these cases,
- -- the Do_Range check flag is set on the argument to the attribute
- -- function, and the back end must special case the appropriate range
- -- to check against.
-
-- Do_Storage_Check (Flag17-Sem)
-- This flag is set in an N_Allocator node to indicate that a storage
-- check is required for the allocation, or in an N_Subprogram_Body node
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