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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                                D E B U G                                 --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--          Copyright (C) 1992-2011, 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.      --

--                                                                          --

------------------------------------------------------------------------------

package body Debug is

   ---------------------------------

   -- Summary of Debug Flag Usage --

   ---------------------------------

   --  Debug flags for compiler (GNAT1)

   --  da   Generate messages tracking semantic analyzer progress

   --  db   Show encoding of type names for debug output

   --  dc   List names of units as they are compiled

   --  dd   Dynamic allocation of tables messages generated

   --  de   List the entity table

   --  df   Full tree/source print (includes withed units)

   --  dg   Print source from tree (generated code only)

   --  dh   Generate listing showing loading of name table hash chains

   --  di   Generate messages for visibility linking/delinking

   --  dj   Suppress "junk null check" for access parameter values

   --  dk   Generate GNATBUG message on abort, even if previous errors

   --  dl   Generate unit load trace messages

   --  dm   Allow VMS features even if not OpenVMS version

   --  dn   Generate messages for node/list allocation

   --  do   Print source from tree (original code only)

   --  dp   Generate messages for parser scope stack push/pops

   --  dq   No auto-alignment of small records

   --  dr   Generate parser resynchronization messages

   --  ds   Print source from tree (including original and generated stuff)

   --  dt   Print full tree

   --  du   Uncheck categorization pragmas

   --  dv   Output trace of overload resolution

   --  dw   Print trace of semantic scope stack

   --  dx   Force expansion on, even if no code being generated

   --  dy   Print tree of package Standard

   --  dz   Print source of package Standard

   --  dA   All entities included in representation information output

   --  dB   Output debug encoding of type names and variants

   --  dC   Output debugging information on check suppression

   --  dD   Delete elaboration checks in inner level routines

   --  dE   Apply elaboration checks to predefined units

   --  dF   Front end data layout enabled

   --  dG   Generate all warnings including those normally suppressed

   --  dH   Hold (kill) call to gigi

   --  dI   Inhibit internal name numbering in gnatG listing

   --  dJ   Output debugging trace info for JGNAT (Java VM version of GNAT)

   --  dK   Kill all error messages

   --  dL   Output trace information on elaboration checking

   --  dM   Assume all variables are modified (no current values)

   --  dN   No file name information in exception messages

   --  dO   Output immediate error messages

   --  dP   Do not check for controlled objects in preelaborable packages

   --  dQ   Do not generate runtime check for duplicated external tag

   --  dR   Bypass check for correct version of s-rpc

   --  dS   Never convert numbers to machine numbers in Sem_Eval

   --  dT   Convert to machine numbers only for constant declarations

   --  dU   Enable garbage collection of unreachable entities

   --  dV   Enable viewing of all symbols in debugger

   --  dW   Disable warnings on calls for IN OUT parameters

   --  dX   Display messages on reads of potentially uninitialized scalars

   --  dY   Enable configurable run-time mode

   --  dZ   Generate listing showing the contents of the dispatch tables

   --  d.a  Force Target_Strict_Alignment mode to True

   --  d.b  Dump backend types

   --  d.c  Generate inline concatenation, do not call procedure

   --  d.d  Disable atomic synchronization

   --  d.e  Enable atomic synchronization

   --  d.f  Inhibit folding of static expressions

   --  d.g  Enable conversion of raise into goto

   --  d.h

   --  d.i  Ignore Warnings pragmas

   --  d.j

   --  d.k

   --  d.l  Use Ada 95 semantics for limited function returns

   --  d.m  For -gnatl, print full source only for main unit

   --  d.n  Print source file names

   --  d.o  Generate .NET listing of CIL code

   --  d.p  Enable the .NET CIL verifier

   --  d.q

   --  d.r  Enable OK_To_Reorder_Components in non-variant records

   --  d.s  Disable expansion of slice move, use memmove

   --  d.t  Disable static allocation of library level dispatch tables

   --  d.u

   --  d.v  Enable OK_To_Reorder_Components in variant records

   --  d.w  Do not check for infinite loops

   --  d.x  No exception handlers

   --  d.y

   --  d.z

   --  d.A  Read/write Aspect_Specifications hash table to tree

   --  d.B

   --  d.C  Generate concatenation call, do not generate inline code

   --  d.D  Strict Alfa mode

   --  d.E  Force Alfa mode for gnat2why

   --  d.F  Alfa mode

   --  d.G  Precondition only mode for gnat2why

   --  d.H  Standard package only mode for gnat2why

   --  d.I  SCIL generation mode

   --  d.J  Disable parallel SCIL generation mode

   --  d.K  Alfa detection only mode for gnat2why

   --  d.L  Depend on back end for limited types in conditional expressions

   --  d.M

   --  d.N

   --  d.O  Dump internal SCO tables

   --  d.P  Previous (non-optimized) handling of length comparisons

   --  d.Q

   --  d.R

   --  d.S  Force Optimize_Alignment (Space)

   --  d.T  Force Optimize_Alignment (Time)

   --  d.U

   --  d.V

   --  d.W  Print out debugging information for Walk_Library_Items

   --  d.X  Use Expression_With_Actions

   --  d.Y  Do not use Expression_With_Actions

   --  d.Z

   --  d1   Error msgs have node numbers where possible

   --  d2   Eliminate error flags in verbose form error messages

   --  d3   Dump bad node in Comperr on an abort

   --  d4   Inhibit automatic krunch of predefined library unit files

   --  d5   Debug output for tree read/write

   --  d6   Default access unconstrained to thin pointers

   --  d7   Do not output version & file time stamp in -gnatv or -gnatl mode

   --  d8   Force opposite endianness in packed stuff

   --  d9

   --  Debug flags for binder (GNATBIND)

   --  da  All links (including internal units) listed if there is a cycle

   --  db  Output information from Better_Choice

   --  dc  List units as they are chosen

   --  dd

   --  de  Elaboration dependencies including system units

   --  df

   --  dg

   --  dh

   --  di  Ignore_Errors mode for reading ali files

   --  dj

   --  dk

   --  dl

   --  dm

   --  dn  List details of manipulation of Num_Pred values

   --  do  Use old preference for elaboration order

   --  dp

   --  dq

   --  dr

   --  ds

   --  dt

   --  du  List units as they are acquired

   --  dv

   --  dw

   --  dx  Force binder to read xref information from ali files

   --  dy

   --  dz

   --  Debug flags used in package Make and its clients (e.g. GNATMAKE)

   --  da

   --  db

   --  dc

   --  dd

   --  de

   --  df  Only output file names, not path names, in log

   --  dg

   --  dh  Generate listing showing loading of name table hash chains

   --  di

   --  dj

   --  dk

   --  dl

   --  dm  Display the number of maximum simultaneous compilations

   --  dn  Do not delete temp files created by gnatmake

   --  do

   --  dp  Prints the contents of the Q used by Make.Compile_Sources

   --  dq  Prints source files as they are enqueued and dequeued

   --  dr

   --  ds

   --  dt  Display time stamps when there is a mismatch

   --  du  List units as their ali files are acquired

   --  dv

   --  dw  Prints the list of units withed by the unit currently explored

   --  dx

   --  dy

   --  dz

   --------------------------------------------

   -- Documentation for Compiler Debug Flags --

   --------------------------------------------

   --  da   Generate messages tracking semantic analyzer progress. A message

   --       is output showing each node as it gets analyzed, expanded,

   --       resolved, or evaluated. This option is useful for finding out

   --       exactly where a bomb during semantic analysis is occurring.

   --  db   In Exp_Dbug, certain type names are encoded to include debugging

   --       information. This debug switch causes lines to be output showing

   --       the encodings used.

   --  dc   List names of units as they are compiled. One line of output will

   --       be generated at the start of compiling each unit (package or

   --       subprogram).

   --  dd   Dynamic allocation of tables messages generated. Each time a

   --       table is reallocated, a line is output indicating the expansion.

   --  de   List the entity table

   --  df   Full tree/source print (includes withed units). Normally the tree

   --       output (dt) or recreated source output (dg,do,ds) includes only

   --       the main unit. If df is set, then the output in either case

   --       includes all compiled units (see also dg,do,ds,dt). Note that to

   --       be effective, this swich must be used in combination with one or

   --       more of dt, dg, do or ds.

   --  dg   Print the source recreated from the generated tree. In the case

   --       where the tree has been rewritten this output includes only the

   --       generated code, not the original code (see also df,do,ds,dz).

   --       This flag differs from -gnatG in that the output also includes

   --       non-source generated null statements, and freeze nodes, which

   --       are normally omitted in -gnatG mode.

   --  dh   Generates a table at the end of a compilation showing how the hash

   --       table chains built by the Namet package are loaded. This is useful

   --       in ensuring that the hashing algorithm (in Namet.Hash) is working

   --       effectively with typical sets of program identifiers.

   --  di   Generate messages for visibility linking/delinking

   --  dj   Suppress "junk null check" for access parameters. This flag permits

   --       Ada programs to pass null parameters to access parameters, and to

   --       explicitly check such access values against the null literal.

   --       Neither of these is valid Ada, but both were allowed in versions of

   --       GNAT before 3.10, so this switch can ease the transition process.

   --  dk   Immediate kill on abort. Normally on an abort (i.e. a call to

   --       Comperr.Compiler_Abort), the GNATBUG message is not given if

   --       there is a previous error. This debug switch bypasses this test

   --       and gives the message unconditionally (useful for debugging).

   --  dl   Generate unit load trace messages. A line of traceback output is

   --       generated each time a request is made to the library manager to

   --       load a new unit.

   --  dm   Some features are permitted only in OpenVMS ports of GNAT (e.g.

   --       the specification of passing by descriptor). Normally any use

   --       of these features will be flagged as an error, but this debug

   --       flag allows acceptance of these features in non OpenVMS ports.

   --       Of course they may not have any useful effect, and in particular

   --       attempting to generate code with this flag set may blow up.

   --       The flag also forces the use of 64-bits for Long_Integer.

   --  dn   Generate messages for node/list allocation. Each time a node or

   --       list header is allocated, a line of output is generated. Certain

   --       other basic tree operations also cause a line of output to be

   --       generated. This option is useful in seeing where the parser is

   --       blowing up.

   --  do   Print the source recreated from the generated tree. In the case

   --       where the tree has been rewritten, this output includes only the

   --       original code, not the generated code (see also df,dg,ds,dz).

   --  dp   Generate messages for parser scope stack push/pops. A line of

   --       output by the parser each time the parser scope stack is either

   --       pushed or popped. Useful in debugging situations where the

   --       parser scope stack ends up incorrectly synchronized

   --  dq   In layout version 1.38, 2002/01/12, a circuit was implemented

   --       to give decent default alignment to short records that had no

   --       specific alignment set. This debug option restores the previous

   --       behavior of giving such records poor alignments, typically 1.

   --       This may be useful in dealing with transition.

   --  dr   Generate parser resynchronization messages. Normally the parser

   --       resynchronizes quietly. With this debug option, two messages

   --       are generated, one when the parser starts a resynchronization

   --       skip, and another when it resumes parsing. Useful in debugging

   --       inadequate error recovery situations.

   --  ds   Print the source recreated from the generated tree. In the case

   --       where the tree has been rewritten this output includes both the

   --       generated code and the original code with the generated code

   --       being enlosed in curly brackets (see also df,do,ds,dz)

   --  dt   Print full tree. The generated tree is output (see also df,dy)

   --  du   Uncheck categorization pragmas. This debug switch causes the

   --       categorization pragmas (Pure, Preelaborate etc) to be ignored

   --       so that normal checks are not made (this is particularly useful

   --       for adding temporary debugging code to units that have pragmas

   --       that are inconsistent with the debugging code added.

   --  dv   Output trace of overload resolution. Outputs messages for

   --       overload attempts that involve cascaded errors, or where

   --       an interepretation is incompatible with the context.

   --  dw   Write semantic scope stack messages. Each time a scope is created

   --       or removed, a message is output (see the Sem_Ch8.Push_Scope and

   --       Sem_Ch8.Pop_Scope subprograms).

   --  dx   Force expansion on, even if no code being generated. Normally the

   --       expander is inhibited if no code is generated. This switch forces

   --       expansion to proceed normally even if the backend is not being

   --       called. This is particularly useful for debugging purposes when

   --       using the front-end only version of the compiler (which normally

   --       would never do any expansion).

   --  dy   Print tree of package Standard. Normally the tree print out does

   --       not include package Standard, even if the -df switch is set. This

   --       switch forces output of the internal tree built for Standard.

   --  dz   Print source of package Standard. Normally the source print out

   --       does not include package Standard, even if the -df switch is set.

   --       This switch forces output of the source recreated from the internal

   --       tree built for Standard. Note that this differs from -gnatS in

   --       that it prints from the actual tree using the normal Sprint

   --       circuitry for printing trees.

   --  dA   Forces output of representation information, including full

   --       information for all internal type and object entities, as well

   --       as all user defined type and object entities including private

   --       and incomplete types. This debug switch also automatically sets

   --       the equivalent of -gnatR3m.

   --  dB   Output debug encodings for types and variants. See Exp_Dbug for

   --       exact form of the generated output.

   --  dC   Output trace information showing the decisions made during

   --       check suppression activity in unit Checks.

   --  dD   Delete new elaboration checks. This flag causes GNAT to return

   --       to the 3.13a elaboration semantics, and to suppress the fixing

   --       of two bugs. The first is in the context of inner routines in

   --       dynamic elaboration mode, when the subprogram we are in was

   --       called at elaboration time by a unit that was also compiled with

   --       dynamic elaboration checks. In this case, if A calls B calls C,

   --       and all are in different units, we need an elaboration check at

   --       each call. These nested checks were only put in recently (see

   --       version 1.80 of Sem_Elab) and we provide this debug flag to

   --       revert to the previous behavior in case of regressions. The

   --       other behavior reverted by this flag is the treatment of the

   --       Elaborate_Body pragma in static elaboration mode. This used to

   --       be treated as not needing elaboration checking, but in fact in

   --       general Elaborate_All is still required because of nested calls.

   --  dE   Apply compile time elaboration checking for with relations between

   --       predefined units. Normally no checks are made (it seems that at

   --       least on the SGI, such checks run into trouble).

   --  dF   Front end data layout enabled. Normally front end data layout

   --       is only enabled if the target parameter Backend_Layout is False.

   --       This debugging switch enables it unconditionally.

   --  dG   Generate all warnings. Normally Errout suppresses warnings on

   --       units that are not part of the main extended source, and also

   --       suppresses warnings on instantiations in the main extended

   --       source that duplicate warnings already posted on the template.

   --       This switch stops both kinds of deletion and causes Errout to

   --       post all warnings sent to it.

   --  dH   Inhibit call to gigi. This is useful for testing front end data

   --       layout, and may be useful in other debugging situations where

   --       you do not want gigi to intefere with the testing.

   --  dI   Inhibit internal name numbering in gnatDG listing. Any sequence of

   --       the form <uppercase-letter><digits><lowercase-letter> appearing in

   --       a name is replaced by <uppercase-letter>...<lowercase-letter>. This

   --       is used in the fixed bugs run to minimize system and version

   --       dependency in filed -gnatD or -gnatG output.

   --  dJ   Generate debugging trace output for the JGNAT back end. This

   --       consists of symbolic Java Byte Code sequences for all generated

   --       classes plus additional information to indicate local variables

   --       and methods.

   --  dK   Kill all error messages. This debug flag suppresses the output

   --       of all error messages. It is used in regression tests where the

   --       error messages are target dependent and irrelevant.

   --  dL   Output trace information on elaboration checking. This debug

   --       switch causes output to be generated showing each call or

   --       instantiation as it is checked, and the progress of the recursive

   --       trace through calls at elaboration time.

   --  dM   Assume all variables have been modified, and ignore current value

   --       indications. This debug flag disconnects the tracking of constant

   --       values (see Exp_Ch2.Expand_Current_Value).

   --  dN   Do not generate file name information in exception messages

   --  dO   Output immediate error messages. This causes error messages to

   --       be output as soon as they are generated (disconnecting several

   --       circuits for improvement of messages, deletion of duplicate

   --       messages etc). Useful to diagnose compiler bombs caused by

   --       erroneous handling of error situations

   --  dP   Do not check for controlled objects in preelaborable packages.

   --       RM 10.2.1(9) forbids the use of library level controlled objects

   --       in preelaborable packages, but this restriction is a huge pain,

   --       especially in the predefined library units.

   --  dQ   Eliminate check for duplicate external tags. This check was added

   --       as per AI 0113, and causes some backward compatibility problems.

   --       It is never legitimate to have duplicate external tags, so the

   --       check is certainly valid, but this debug switch can be useful for

   --       enabling previous behavior of ignoring this problem.

   --  dR   Bypass the check for a proper version of s-rpc being present

   --       to use the -gnatz? switch. This allows debugging of the use

   --       of stubs generation without needing to have GLADE (or some

   --       other PCS  installed).

   --  dS   Omit conversion of fpt numbers to exact machine numbers in

   --       non-static evaluation contexts (see Check_Non_Static_Context).

   --       This is intended for testing out timing problems with this

   --       conversion circuit.

   --  dT   Similar to dS, but omits the conversions only in the case where

   --       the parent is not a constant declaration.

   --  dU   Enable garbage collection of unreachable entities. This enables

   --       both the reachability analysis and changing the Is_Public and

   --       Is_Eliminated flags.

   --  dV   Enable viewing of all symbols in debugger. Causes debug information

   --       to be generated for all symbols, including internal symbols. This

   --       is enabled by default for -gnatD, but this switch allows this to

   --       be enabled without generating modified source files. Note that the

   --       use of -gnatdV ensures in the dwarf/elf case that all symbols that

   --       are present in the elf tables are also in the dwarf tables (which

   --       seems to be required by some tools). Another effect of dV is to

   --       generate full qualified names, including internal names generated

   --       for blocks and loops.

   --  dW   Disable warnings when a possibly uninitialized scalar value is

   --       passed to an IN OUT parameter of a procedure. This usage is a

   --       quite improper bounded error [erroneous in Ada 83] situation,

   --       and would normally generate a warning. However, to ease the

   --       task of transitioning incorrect legacy code, we provide this

   --       undocumented feature for suppressing these warnings.

   --  dY   Enable configurable run-time mode, just as though the System file

   --       had Configurable_Run_Time_Mode set to True. This is useful in

   --       testing high integrity mode.

   --  dZ   Generate listing showing the contents of the dispatch tables. Each

   --       line has an internally generated number used for references between

   --       tagged types and primitives. For each primitive the output has the

   --       following fields:

   --

   --         - Letter 'P' or letter 's': The former indicates that this

   --           primitive will be located in a primary dispatch table. The

   --           latter indicates that it will be located in a secondary

   --           dispatch table.

   --

   --         - Name of the primitive. In case of predefined Ada primitives

   --           the text "(predefined)" is added before the name, and these

   --           acronyms are used: SR (Stream_Read), SW (Stream_Write), SI

   --           (Stream_Input), SO (Stream_Output), DA (Deep_Adjust), DF

   --           (Deep_Finalize). In addition Oeq identifies the equality

   --           operator, and "_assign" the assignment.

   --

   --         - If the primitive covers interface types, two extra fields

   --           referencing other primitives are generated: "Alias" references

   --           the primitive of the tagged type that covers an interface

   --           primitive, and "AI_Alias" references the covered interface

   --           primitive.

   --

   --         - The expression "at #xx" indicates the slot of the dispatch

   --           table occupied by such primitive in its corresponding primary

   --           or secondary dispatch table.

   --

   --         - In case of abstract subprograms the text "is abstract" is

   --           added at the end of the line.

   --  d.a  Force Target_Strict_Alignment to True, even on targets where it

   --       would normally be false. Can be used for testing strict alignment

   --       circuitry in the compiler.

   --  d.b  Dump back end types. During Create_Standard, the back end is

   --       queried for all available types. This option shows them.

   --  d.c  Generate inline concatenation, instead of calling one of the

   --       System.Concat_n.Str_Concat_n routines in cases where the latter

   --       routines would normally be called.

   --  d.d  Disable atomic synchronization for all atomic variable references.

   --       Pragma Enable_Atomic_Synchronization is ignored.

   --  d.e  Enable atomic synchronization for all atomic variable references.

   --       Pragma Disable_Atomic_Synchronization is ignored, and also the

   --       compiler switch -gnated is ignored.

   --  d.f  Suppress folding of static expressions. This of course results

   --       in seriously non-conforming behavior, but is useful sometimes

   --       when tracking down handling of complex expressions.

   --  d.g  Enables conversion of a raise statement into a goto when the

   --       relevant handler is statically determinable. For now we only try

   --       this if this debug flag is set. Later we will enable this more

   --       generally by default.

   --  d.i  Ignore all occurrences of pragma Warnings in the sources. This can

   --       be used in particular to disable Warnings (Off) to check if any of

   --       these statements are inappropriate.

   --  d.l  Use Ada 95 semantics for limited function returns. This may be

   --       used to work around the incompatibility introduced by AI-318-2.

   --       It is useful only in -gnat05 mode.

   --  d.m  When -gnatl is used, the normal output includes full listings of

   --       all files in the extended main source (body/spec/subunits). If this

   --       debug switch is used, then the full listing is given only for the

   --       main source (this corresponds to a previous behavior of -gnatl and

   --       is used for running the ACATS tests).

   --  d.n  Print source file names as they are loaded. This is useful if the

   --       compiler has a bug -- these are the files that need to be included

   --       in a bug report.

   --  d.o  Generate listing showing the IL instructions generated by the .NET

   --       compiler for each subprogram.

   --  d.p  Enable the .NET CIL verifier. During development the verifier is

   --       disabled by default and this flag is used to enable it. In the

   --       future we will reverse this functionality.

   --  d.r  Forces the flag OK_To_Reorder_Components to be set in all record

   --       base types that have no discriminants.

   --  d.s  Normally the compiler expands slice moves into loops if overlap

   --       might be possible. This debug flag inhibits that expansion, and

   --       the back end is expected to use an appropriate routine to handle

   --       overlap, based on Forward_OK and Backwards_OK flags.

   --  d.t  The compiler has been modified (a fairly extensive modification)

   --       to generate static dispatch tables for library level tagged types.

   --       This debug switch disables this modification and reverts to the

   --       previous dynamic construction of tables. It is there as a possible

   --       work around if we run into trouble with the new implementation.

   --  d.v  Forces the flag OK_To_Reorder_Components to be set in all record

   --       base types that have at least one discriminant (v = variant).

   --  d.w  This flag turns off the scanning of loops to detect possible

   --       infinite loops.

   --  d.A  There seems to be a problem with ASIS if we activate the circuit

   --       for reading and writing the aspect specification hash table, so

   --       for now, this is controlled by the debug flag d.A. The hash table

   --       is only written and read if this flag is set.

   --  d.x  No exception handlers in generated code. This causes exception

   --       handlers to be eliminated from the generated code. They are still

   --       fully compiled and analyzed, they just get eliminated from the

   --       code generation step.

   --  d.C  Generate call to System.Concat_n.Str_Concat_n routines in cases

   --       where we would normally generate inline concatenation code.

   --  d.D  Strict Alfa mode. Interpret compiler permissions as strictly as

   --       possible in Alfa mode.

   --  d.E  Force Alfa mode for gnat2why. In this mode, errors are issued for

   --       all violations of Alfa in user code, and warnings are issued for

   --       constructs not yet implemented in gnat2why.

   --  d.F  Alfa mode. Generate AST in a form suitable for formal verification,

   --       as well as additional cross reference information in ALI files to

   --       compute effects of subprograms.

   --  d.G  Precondition only mode for gnat2why. In this mode, gnat2why will

   --       only generate Why code that checks for the well-guardedness of

   --       preconditions.

   --  d.H  Standard package only mode for gnat2why. In this mode, gnat2why

   --       will only generate Why code for package Standard. Any given input

   --       file will be ignored.

   --  d.I  Generate SCIL mode. Generate intermediate code for the sake of

   --       of static analysis tools, and ensure additional tree consistency

   --       between different compilations of specs.

   --  d.J  Disable parallel SCIL generation. Normally SCIL file generation is

   --       done in parallel to speed processing. This switch disables this

   --       behavior.

   --  d.K  Alfa detection only mode for gnat2why. In this mode, gnat2why

   --       will only generate the .alfa file, but no Why code.

   --  d.L  Normally the front end generates special expansion for conditional

   --       expressions of a limited type. This debug flag removes this special

   --       case expansion, leaving it up to the back end to handle conditional

   --       expressions correctly.

   --  d.O  Dump internal SCO tables. Before outputting the SCO information to

   --       the ALI file, the internal SCO tables (SCO_Table/SCO_Unit_Table)

   --       are dumped for debugging purposes.

   --  d.P  Previous non-optimized handling of length comparisons. Setting this

   --       flag inhibits the effect of Optimize_Length_Comparison in Exp_Ch4.

   --       This is there in case we find a situation where the optimization

   --       malfunctions, to provide a work around.

   --  d.S  Force Optimize_Alignment (Space) mode as the default

   --  d.T  Force Optimize_Alignment (Time) mode as the default

   --  d.W  Print out debugging information for Walk_Library_Items, including

   --       the order in which units are walked. This is primarily for use in

   --       debugging CodePeer mode.

   --  d.X  By default, the compiler uses an elaborate rewriting framework for

   --       short-circuited forms where the right hand condition generates

   --       actions to be inserted. With the gcc backend, we now use the new

   --       N_Expression_With_Actions node for this expansion, but we still use

   --       the old method for other backends and in SCIL mode. This debug flag

   --       forces use of the new N_Expression_With_Actions node in these other

   --       cases and is intended for transitional use.

   --  d.Y  Prevents the use of the N_Expression_With_Actions node even in the

   --       case of the gcc back end. Provided as a back up in case the new

   --       scheme has problems.

   --  d1   Error messages have node numbers where possible. Normally error

   --       messages have only source locations. This option is useful when

   --       debugging errors caused by expanded code, where the source location

   --       does not give enough information.

   --  d2   Suppress output of the error position flags for verbose form error

   --       messages. The messages are still interspersed in the listing, but

   --       without any error flags or extra blank lines. Also causes an extra

   --       <<< to be output at the right margin. This is intended to be the

   --       easiest format for checking conformance of ACATS B tests. This

   --       flag also suppresses the additional messages explaining why a

   --       non-static expression is non-static (see Sem_Eval.Why_Not_Static).

   --       This avoids having to worry about these messages in ACATS testing.

   --  d3   Causes Comperr to dump the contents of the node for which an abort

   --       was detected (normally only the Node_Id of the node is output).

   --  d4   Inhibits automatic krunching of predefined library unit file names.

   --       Normally, as described in the spec of package Krunch, such files

   --       are automatically krunched to 8 characters, with special treatment

   --       of the prefixes Ada, System, and Interfaces. Setting this debug

   --       switch disables this special treatment.

   --  d5   Causes the tree read/write circuit to output detailed information

   --       tracking the data that is read and written element by element.

   --  d6   Normally access-to-unconstrained-array types are represented

   --       using fat (double) pointers. Using this debug flag causes them

   --       to default to thin. This can be used to test the performance

   --       implications of using thin pointers, and also to test that the

   --       compiler functions correctly with this choice.

   --  d7   Normally a -gnatl or -gnatv listing includes the time stamp

   --       of the source file. This debug flag suppresses this output,

   --       and also suppresses the message with the version number.

   --       This is useful in certain regression tests.

   --  d8   This forces the packed stuff to generate code assuming the

   --       opposite endianness from the actual correct value. Useful in

   --       testing out code generation from the packed routines.

   ------------------------------------------

   -- Documentation for Binder Debug Flags --

   ------------------------------------------

   --  da  Normally if there is an elaboration circularity, then in describing

   --      the cycle, links involving internal units are omitted, since they

   --      are irrelevant and confusing. This debug flag causes all links to

   --      be listed, and is useful when diagnosing circularities introduced

   --      by incorrect changes to the run-time library itself.

   --  db  Output debug information from Better_Choice in Binde, which uses

   --      various heuristics to determine elaboration order in cases where

   --      multiple orders are valid.

   --  dc  List units as they are chosen. As units are selected for addition to

   --      the elaboration order, a line of output is generated showing which

   --      unit has been selected.

   --  de  Similar to the effect of -e (output complete list of elaboration

   --      dependencies) except that internal units are included in the

   --      listing.

   --  di  Normally gnatbind calls Read_Ali with Ignore_Errors set to

   --      False, since the binder really needs correct version ALI

   --      files to do its job. This debug flag causes Ignore_Errors

   --      mode to be set for the binder (and is particularly useful

   --      for testing ignore errors mode).

   --  dn  List details of manipulation of Num_Pred values during execution of

   --      the algorithm used to determine a correct order of elaboration. This

   --      is useful in diagnosing any problems in its behavior.

   --  do  Use old elaboration order preference. The new preference rules

   --      prefer specs with no bodies to specs with bodies, and between two

   --      specs with bodies, prefers the one whose body is closer to being

   --      able to be elaborated. This is a clear improvement, but we provide

   --      this debug flag in case of regressions.

   --  du  List unit name and file name for each unit as it is read in

   --  dx  Force the binder to read (and then ignore) the xref information

   --      in ali files (used to check that read circuit is working OK).

   --------------------------------------------

   -- Documentation for gnatmake Debug Flags --

   --------------------------------------------

   --  df  Only output file names, not path names, in log

   --  dh  Generate listing showing loading of name table hash chains,

   --      same as for the compiler.

   --  dm  Issue a message indicating the maximum number of simultaneous

   --      compilations.

   --  dn  Do not delete temporary files created by gnatmake at the end

   --      of execution, such as temporary config pragma files, mapping

   --      files or project path files.

   --  dp  Prints the Q used by routine Make.Compile_Sources every time

   --      we go around the main compile loop of Make.Compile_Sources

   --  dq  Prints source files as they are enqueued and dequeued in the Q

   --      used by routine Make.Compile_Sources. Useful to figure out the

   --      order in which sources are recompiled.

   --  dt  When a time stamp mismatch has been found for an ALI file,

   --      display the source file name, the time stamp expected and

   --      the time stamp found.

   --  du  List unit name and file name for each unit as it is read in

   --  dw  Prints the list of units withed by the unit currently explored

   --      during the main loop of Make.Compile_Sources.

   ---------------------------------------------

   -- Documentation for gprbuild Debug Flags  --

   ---------------------------------------------

   --  dn  Do not delete temporary files createed by gprbuild at the end

   --      of execution, such as temporary config pragma files, mapping

   --      files or project path files.

   --  dt  When a time stamp mismatch has been found for an ALI file,

   --      display the source file name, the time stamp expected and

   --      the time stamp found.

   --------------------

   -- Set_Debug_Flag --

   --------------------

   procedure Set_Debug_Flag (C : Character; Val : Boolean := True) is

      subtype Dig  is Character range '1' .. '9';

      subtype LLet is Character range 'a' .. 'z';

      subtype ULet is Character range 'A' .. 'Z';

   begin

      if C in Dig then

         case Dig (C) is

            when '1' => Debug_Flag_1 := Val;

            when '2' => Debug_Flag_2 := Val;

            when '3' => Debug_Flag_3 := Val;

            when '4' => Debug_Flag_4 := Val;

            when '5' => Debug_Flag_5 := Val;

            when '6' => Debug_Flag_6 := Val;

            when '7' => Debug_Flag_7 := Val;

            when '8' => Debug_Flag_8 := Val;

            when '9' => Debug_Flag_9 := Val;

         end case;

      elsif C in ULet then

         case ULet (C) is

            when 'A' => Debug_Flag_AA := Val;

            when 'B' => Debug_Flag_BB := Val;

            when 'C' => Debug_Flag_CC := Val;

            when 'D' => Debug_Flag_DD := Val;

            when 'E' => Debug_Flag_EE := Val;

            when 'F' => Debug_Flag_FF := Val;

            when 'G' => Debug_Flag_GG := Val;

            when 'H' => Debug_Flag_HH := Val;

            when 'I' => Debug_Flag_II := Val;

            when 'J' => Debug_Flag_JJ := Val;

            when 'K' => Debug_Flag_KK := Val;

            when 'L' => Debug_Flag_LL := Val;

            when 'M' => Debug_Flag_MM := Val;

            when 'N' => Debug_Flag_NN := Val;

            when 'O' => Debug_Flag_OO := Val;

            when 'P' => Debug_Flag_PP := Val;

            when 'Q' => Debug_Flag_QQ := Val;

            when 'R' => Debug_Flag_RR := Val;

            when 'S' => Debug_Flag_SS := Val;

            when 'T' => Debug_Flag_TT := Val;

            when 'U' => Debug_Flag_UU := Val;

            when 'V' => Debug_Flag_VV := Val;

            when 'W' => Debug_Flag_WW := Val;

            when 'X' => Debug_Flag_XX := Val;

            when 'Y' => Debug_Flag_YY := Val;

            when 'Z' => Debug_Flag_ZZ := Val;

         end case;

      else