When the Natural Optimizer has been activated, you can specify checks by setting the options explained in this section.
The options cannot be used for specifying statements to be optimized.
This document covers the following topics:
The following table lists and describes the Natural Optimizer Compiler options. Default values are underlined (this is the value that will be assumed if the option is not present).
A Natural Optimizer Compiler option consists of a string
surrounded by brackets or single quotation marks (except in the Natural
OPTIONS statement),
with options separated by commas. Some options have values, while the very
existence of some options in the option string is sufficient to modify the
environment.
The following rules apply:
Optional clauses are surrounded by square brackets [ ].
Choices are surrounded by curly braces { }.
Each choice is separated by vertical lines "|".
Only one of these choices can be specified;
ON is equivalent to Y (Yes),
OFF to N (No).
Options specified without the optional clause ON
or OFF (if applicable), or their equivalent values, are
interpreted as set to ON. For example, OVFLW is
identical to OVFLW=ON.
Except for the option OFF, any specified option
switches on optimizing (as if ON was specified) and the default
values apply. For example, INDEX is identical to
ON,INDEX.
| Option | Explanation |
|---|---|
ABEND |
Forces the Natural Optimizer Compiler to generate code
which causes Natural to be abnormally terminated immediately when the
ABEND option is encountered by the Natural Optimizer Compiler
during compilation. The option must appear by itself or it will be ignored.
Other parameters are not changed or reset by this option. This option can be
useful for debugging purposes.
|
ARCH |
Specifies the architecture level to be used for code generation: see ARCH Option in the following section. |
ARROPT |
Specifies
the generation to be used for array assignments of the type
A(*):=scalar. See
ARROPT Option
in the following section.
|
CACHE[={ON| OFF |Y|N}] |
Switches variable caching on or off. See also Variable Caching in the section Performance Considerations. |
CPU= /370 |
Specifies the target architecture. |
DIGTCHCK[={ON| OFF |Y|N}] |
Specifies whether the
digits of packed and unpacked numeric fields (formats P and N) are to be
checked when moving to another variable of the same type and precision. For
example, if DIGTCHCK is ON and an
unpacked numeric variable (format N) contains an invalid digit, such as
X'FA', moving to another unpacked numeric variable with the same
precision will generate a S0C7 (or NAT0954) error. If
DIGTCHCK is OFF, no error is generated but the
generated code is much faster.
|
ERRDUMP[={ON| OFF |Y|N}] |
Specifies whether NOC should abend if an error condition is detected during the compile phase. This is useful for debugging the Natural Optimizer Compiler itself. |
INDEX[={ON| OFF |Y|N}] |
Specifies whether array indexes will be checked for
out-of-bound values in the optimized code.
See also the following Note. |
INDX[={ON| OFF |Y|N}] |
Specifies whether array indexes will be checked for
out-of-bound values in the optimized code.
Additionally, See also the following Note. |
IO[={ON| OFF|Y|N}] |
Provided for compatibility reasons only. No effect. |
LOOPS[={ON| OFF |Y|N}] |
Provided for compatibility reasons only. No effect. |
MIX[={ON| OFF |Y|N}] |
Provided for compatibility reasons only. No effect. |
NODBG[={ON|
OFF|Y|N}] |
If NODBG=OFF/N (default), the Natural
Debugger can be used to debug optimized code (then, additional code is
generated to check whether TEST mode has been set on).
If See also |
NOSGNTR[={ON| OFF |Y|N}] |
Applies to packed numbers only.
If |
ON |
Switches on optimizing. If no additional option is
specified, the default value defined for each option is in effect. As indicated
in the following Note, this may cause
unintended results, in particular regarding the options INDEX, INDX,
OVFLW, and RANGE.
|
OFF |
Switches off optimizing. |
OPTLEV={ 2|3} |
Specifies optimization level - roughly equivalent to
the number of passes through the program.
|
OVFLW[={ON| OFF |Y|N}] |
Specifies whether checks for overflow in arithmetic
operations or assignments will be included in the optimized code.
See also the following Note. |
PGEN[={ON| OFF |Y|N}] |
Specifies whether a disassembly of the optimized code should be output. This option also enables all other tracing options: see PGEN Option in the following section. |
RANGE[={ON| OFF |Y|N}] |
Specifies whether range checks will be performed in
operations with arrays. This ensures that array ranges will have an equal
number of elements in corresponding dimensions of all operands.
See also the following Note. |
SIGNCHCK[={
ON|OFF|Y|N}] |
Specifies whether the result of a multiplication with
a packed or unpacked numeric multiplier should be checked for a negative zero.
If zero is multiplied by a negative number, the MP machine instruction
generates a negative zero result. If SIGNCHCK is on, this negative
zero is converted to a positive zero. The check for a negative zero is done for
every multiplication with a packed or unpacked numeric multiplier.
|
TRENTRY |
For internal use by Software AG only. Do not change the setting of this parameter. |
UNICC |
Specifies
whether optimized code is generated for IF and DECIDE
statements with Unicode operands: see UNICC Option in the
following section.
|
ZD[={
ON|OFF|Y|N}] |
Specifies whether divisors should be checked for zero.
If this option is specified, then code is inserted, so that the program behaves
according to the ZD profile parameter of
Natural, that is, Natural error NAT1302 is issued or the result is
zero. If this option is not specified, Natural error NAT0954
occurs if the divisor is zero.
See also ZD - Zero-Division Check in the Natural Parameter Reference documentation. |
Note for INDEX, INDX, OVFLW and RANGE:
If the option INDEX, INDX,
OVFLW or RANGE is set, extra instructions are added
to the generated code to detect data overflow and index-out-of-range situations
should they occur during program execution. Although the use of these options
slightly increases the generated code, we recommend to use them to guarantee
that erroneous programs are detected and cannot lead to unpredictable results,
storage corruptions or abnormal program terminations.
Below is information on:
DEFINE DATA LOCAL ... 1 P1 (P1/9) ... 1 P3 (P3/9) ... 1 I (I4) 1 J (I4) 1 K (I4) 1 L (I4) END-DEFINE ... P1(I:J) := P3(K:L) ... END
With INDX=ON or INDEX=ON set, code is
generated to verify that I, J, K and
L are within the ranges defined for P1 and
P3 respectively.
With INDX=ON or RANGE=ON set, code is
generated to verify that I:J and K:L denote ranges of
the same length.
With OVFLW=ON set, code is generated to verify that
the value of P3 fits into the corresponding P1
variable.
For example: Value 100 would cause an overflow
here.
Example Error Situation:
If one of the occurrences of P3 contains the value
100, with OVFLW=OFF set, the value assigned to the
corresponding P1 occurrence will be zero. If the index variable
I is zero or greater than 9, with
INDX=OFF set, storage areas that do not belong to Array
P1 will be corrupted. If these options (OVFLW and
INDX) are set to ON, a Natural error occurs like it
does in standard Natural runtime.
For the NOC option specified above, additional code is generated. However, this is well compensated for by the advantage of a check that, for example, protects against hard-to-debug errors. Undetected errors can, of course, lead to unpredictable results.
To assure that the least amount of code is generated and thus achieve optimum performance, use:
OPT='NODBG,NOSGNTR,SIGNCHCK=OFF,ZD=OFF'
However, only apply this setting to objects that have been thoroughly debugged; see also Note for INDEX, INDX, OVFLW and RANGE.
The ARCH option specifies the hardware architecture
level to be used for generating code for executable Natural objects.
When you specify an ARCH value, the Natural Optimizer
Compiler generates newer and faster machine instructions that can improve the
performance of the generated code. You cannot specify a value that is higher
than the architecture level of your current machine. An executable Natural
object cataloged with an ARCH level can only run on a machine with
the same or a higher architecture level. Therefore, we recommend not to use the
ARCH option if the cataloged objects are intended to execute on
any machine, especially on a machine with a lower architecture level.
For detailed information on architecture levels, see the related literature from IBM (z/Architecture, Principles of Operation).
The following architecture levels are supported by the
ARCH option of the Natural Optimizer Compiler:
| Architecture Level | IBM Hardware Facility Required |
|---|---|
0 |
Specifies that no architecture level is used. This is the default setting for compatibility with all mainframe platforms supported by Natural. |
1 to
4 |
These values are not evaluated and
treated as ARCH=0.
|
5 to
6 |
|
7 |
|
8 |
|
9 |
|
10 |
|
11 |
|
Note:
With an ARCH value greater zero, the Natural
Optimizer Compiler generates instructions up to the facility level described in
the table above. An ARCH value higher than the architecture level
of the underlying machine is rejected at compile time. The attempt to start a
program compiled with an ARCH level on a machine with a lower
architecture level, causes a NAT1394 runtime error. You
can display information on the current machine by using the
TECH
system command.
This section covers the following topics:
When ARCH=10 is set, the Natural Optimizer Compiler
generates instructions provided by the Decimal-Floating-Point (DFP)
Zoned-Conversion Facility for the numeric operations described in the following
section. This can significantly improve the execution speed for statements that
use these operations.
- Operations Optimized by ARCH=10
The following arithmetic operations on variables of the Natural data formats I (integer), N (numeric unpacked) and P (packed numeric) benefit from
ARCH=10:
Value assignments:
P:=I
P:=N
N:=I
N:=N
N:=Ponly if the number of packed digits is less than or equal to 15.
I:=NArithmetic operations, such as
ADD,SUBTRACT,DIVIDEandMULTIPLYstatements, but only if both of the following conditions apply:At least one of the operands used is in the format N or I.
The operation result does not exceed 34 (integer + precision) digits.Comparisons, such as
IFandDECIDEstatements, but only if both of the following conditions apply:At least one of the operands used is in the format N.
Both operands are in different formats.
When ARCH=11 is set, the Natural Optimizer Compiler
uses machine instructions introduced with the DFP Packed-Conversion Facility.
In addition to the numeric operations optimized with
ARCH=10,
ARCH=11 also optimizes operations that use packed variables
only.
When ARCH=10 is used, the Natural Optimizer
Compiler generates machine instructions introduced with the
Decimal-Floating-Point (DFP) Zoned-Conversion Facility, DFP Packed-Conversion
Facility or the Vector Packed-Decimal Facility (VPD). These instructions
execute faster than the standard machine code instructions for arithmetic
operations, but they do not accept data which is improper in terms of the zoned
numeric data type (N).
This may cause runtime errors, when an N-field is defined within
a REDEFINE section of an alpha or binary variable and the N-field
is not properly initialized before used in an arithmetic operation.
A numeric zoned field carries one digit in one byte. Usually, each byte contains x’F’ in the left halfbyte (Zone bits) and the digit value (0-9) in the right halfbyte (Numeric bits). This applies for all bytes, except for the last one, which contains (A-F) in the left halfbyte (Sign bits).
A sign halfbyte (C,A,F,E) represents a positive value, whereas (B,D) stands for a negative value. A value other than (0-9) inside the numeric halfbytes (N) and a value other than (A-F) inside the sign halfbyte (S) is considered invalid. The data inside the zone halfbytes (Z) is not regarded by arithmetic conversion instructions and can have any value (0-F).
Example for a variable defined as (N6):
| ZN | ZN | ZN | ZN | ZN | SN | Sign is | Value is | Works with ARCH<=9
|
Works with
ARCH>=10 |
|---|---|---|---|---|---|---|---|---|---|
| F1 | F2 | F3 | F4 | F5 | F6 | F=positive | 123456, ok | yes | yes |
| F3 | F2 | F6 | F3 | F3 | D2 | D=negative | 323662, ok | yes | yes |
| 40 | 40 | 40 | 40 | 40 | 40 | 4=invalid | 000000, ok | yes | NAT7024 |
| 00 | 00 | 00 | 00 | 00 | 00 | 0=invalid | 000000, ok | yes | NAT7024 |
| 12 | 13 | 14 | 15 | 16 | 17 | 1=invalid | 234567, ok | yes | NAT7024 |
| 51 | 6B | 72 | 7A | 12 | F1 | F=positive | 1B2A21, invalid | NAT0954 | NAT7024 |
When ARCH=9 (or lower) is used, invalid sign
halfbytes (0-9) are automatically corrected by the generated code to a positive
sign (F). This turns N-fields with a blank contents into valid data with value
zero. The same applies for Hexa zero data.
When ARCH=10 (or higher) is used, invalid sign
halfbytes (0-9) remain unchanged and lead to a program check (Data exception)
when accessed by a DFP or VPD instruction. If such an abend occurs, Natural
issues a NAT7024
error instead of a NAT0954
to clearly indicate that the error is caused by an N-variable that does not
contain valid numeric data.
If a numeric halfbyte (N) contains a value other than (0-9), a program check (Data exception) happens regardless of the ARCH level used.
Do not use ARCH=10 (or higher) to catalog a program
which operates unclean numeric data, with a sign value other than (A-F).
For example:
OPTIONS MCG=(PGEN,ARCH=9) DEFINE DATA LOCAL 1 #A (A6) 1 REDEFINE #A 2 #N (N6) END-DEFINE /* ARCH=9 ARCH=10 #A := H'F1F2F3F4F5F6' ADD 1 TO #N WRITE #N /* ok ok #A := H'F3F2F6F3F3D2' ADD 1 TO #N WRITE #N /* ok ok #A := H'404040404040' ADD 1 TO #N WRITE #N /* ok NAT7024 #A := H'000000000000' ADD 1 TO #N WRITE #N /* ok NAT7024 #A := H'121314151617' ADD 1 TO #N WRITE #N /* ok NAT7024 #A := H'516B727A12F1' ADD 1 TO #N WRITE #N /* NAT0954 NAT7024 END
Moreover, when ARCH=10 (or higher) is used, Natural
can issue a NAT1305
(truncated numeric value) instead of a
NAT1301
error (intermediate result too large) for the following reason: The DFP or VPD
numeric format is used for calculating intermediate results and an overflow is
only detected at the end of the arithmetic operation when the DFP is converted
into the format of the result.
The ARROPT option determines the generation algorithm
to be used for array assignments of the type
A(*):=scalar.
Valid values for ARROPT are:
| Value | Explanation |
|---|---|
ON |
Recommended setting for arrays with a
minimum of 50 occurrences.
|
OFF |
Recommended setting for arrays with less than 50 occurrences. |
The PGEN option causes the Natural Optimizer Compiler
to output the generated code and internal Natural structures. Thus, code and
structures can be examined, for example, for bug fixing, performance review and
support issues.
An understanding of IBM's /370 assembler is required to interpret
the results produced by the PGEN option.
We recommend that you use this option with the assistance of your local Software AG representative.
Below is information on:
To use the PGEN facility, set the PGEN
option when activating on the Optimizer Compiler.
Since the buffer is kept in memory, it is possible that the user
thread will not be big enough to hold the trace information. In this case, try
setting PGEN on only for the portion of the program which is to be
traced, for example:
OPTIONS
MCG=(PGEN=ON,TRGPT=ON)or OPTIONS MCG=+PGEN,TRGPT |
Turns tracing on, including tracing of the GPT entries |
OPTIONS MCG=(PGEN=OFF)or OPTIONS MCG=-PGEN |
Turns tracing off |
Various options affect the content of the output. The basic
PGEN option causes a formatted listing of Natural source lines and
a disassembly of the corresponding code to be generated and kept in memory for
extraction by the NOCSHOW utility as described below, under
Output of the PGEN
Option.
The TRSTMT, TRGPT, TRMPT
and TRVDT options cause hex dumps of internal data structures
associated with each line to be output.
The TRBASES and TRCACHE options cause
information on base registers and cache variables to be printed out.
The following table describes the options when
PGEN=ON. For an explanation of the syntax used see the
introduction to List of
Options above.
| Option | Explanation |
|---|---|
LPP={5|..| 55 |..|255} |
Lines-per-page for the trace output, only used when
TREXT=ON.
|
NOsrcE[={ON| OFF |Y|N}] |
If NOsrcE=OFF, the Natural source
statement is included in the output.
|
TRACELEV={ 0 |..|255} |
Specifies the trace level. Each bit in this one byte
value specifies a buffer type to trace; these bits can be set on by using the
TRxxx options as well.
|
TRBASES[={ON| OFF |Y|N}] |
Specifies whether base register allocations are traced. |
TRCACHE[={ON|
OFF|Y|N}] |
Specifies whether CACHE entries are
traced.
|
TREXT[={ON| OFF |Y|N}] |
If TREXT=ON, trace is directed to the
user exit NOCPRINT as described
below.
|
TRGPT[={ON| OFF |Y|N}] |
Specifies whether GPT entries are
traced.
|
TRMPT[=ON| OFF |Y|N}] |
Specifies whether MPT entries are
traced.
|
TRSTMT[={ON| OFF |Y|N}] |
Specifies whether STMT entries are
traced.
|
TRVDT[={ON| OFF |Y|N}] |
Specifies whether VDT entries are
traced.
|
See also the examples below.
There are two places to where the Natural Optimizer Compiler can
direct the output of PGEN:
The contents of this buffer is overwritten each time a
CHECK, CAT,
STOW or RUN command is
executed. A system utility NOCSHOW is provided whereby the
contents of this buffer can be viewed, searched or printed.
To invoke the NOCSHOW utility
Enter the direct command
NOCSHOW after a CHECK,
STOW, CAT or
RUN where the Natural Optimizer Compiler has been
active.
The following PF keys are available on the screen:
| PF Key | Function |
|---|---|
| PF2 | Position to top of output |
| PF4 | Position one line backward |
| PF5 | Position one line forward |
| PF6 | Print to report (1) |
| PF7 | Position one page backward |
| PF8 | Position one page forward |
| PF9 | Print via Entire Connection to report (7) |
| PF10 | Scan for text string |
| PF11 | Repeat scan |
If TREXT=ON is specified, the Natural Optimizer
Compiler passes every output line to the user exit NOCPRINT
instead of adding it to the trace buffer.
NOCPRINT is invoked following normal OS register
conventions. Register 1 points to a full word containing the address of the 81
byte print line with ANSI carriage control characters in position 1. Register
13 points to an area of 18*4 bytes which may be used as a save area. Register
14 contains the return address and Register 15 contains the entry address of
NOCPRINT.
The user exit NOCPRINT can be written in any
language which supports the register conventions described above. It must be
linked to the Natural nucleus together with the Natural Optimizer Compiler
nucleus.
This section provides hints and explanations on how to interpret
the output created with the PGEN option.
At the top of the PGEN output are some
disassembled lines which do not appear to belong to any source line. These are
the instructions which make up the prologue, which is executed whenever control
passes from non-optimized to optimized code. Permanent base registers are
loaded and control is passed to the correct point in the prologue. See
Example Section
A below.
Sometimes a lot of source lines are printed without any code. This is because the Natural compiler puts a single line number in the object of statements which may span more than one line. See Example Section B below.
If the NODBG=OFF (default) has been specified,
a sequence of instructions is generated at the start of each Natural
statement:
BALR R9,R11 DC X'....'
This sequence sets the line number (in case of error) and
checks whether the TEST mode is switched ON. Without
this sequence, debugging of NOC-compiled statements by the Natural
Debugger is not
possible. See Example Section
C below.
Sometimes there is a line break between disassembled lines. This break indicates an internal statement separation. It happens because often a single Natural statement will generate multiple internal (pseudo-code) statements.
000000 5880 D354 L R8,RTADR+4 000004 5870 D370 L R7,RTADR+32 000008 4810 6006 LH R1,6(,R6) 00000C 1F60 SLR R6,R0 00000E 47F1 A000 BC 15,0(R1,R10)
0010 OPTIONS MCG=(PGEN=ON,TRGPT=ON)
0020 DEFINE DATA LOCAL
0030 1 I(I4)
0040 1 P(P7.2)
0050 1 T(P7.2)
0060 END-DEFINE
0070 *
0080 SETTIME
0090 *
000012 45E0 B040 BAL R14,RETH
000016 0036 DC X'0036'
0100 FOR I=1 TO 100000
000018 059B BALR R9,R11
00001A 003E DC X'003E'
00001C D203 7000 833B MVC I,#VAR033B
000022 059B BALR R9,R11
000024 004C DC X'004C'
000026 47F0 A040 BC 15,64(,R10)
00002A 059B BALR R9,R11
00002C 005A DC X'005A'
00002E BFFF 8343 ICM R15,15,#VAR0343
000032 BF0F 7000 ICM R0,15,I
000036 1A0F AR R0,R15
000038 BE0F 7000 STCM R0,15,I
00003C 059B BALR R9,R11
00003E 006C DC X'006C'
000040 BFFF 833F ICM R15,15,#VAR033F
000044 BF0F 7000 ICM R0,15,I
000048 190F CR R0,R15
00004A 4720 A066 BC 2,102(,R10)
0110 ADD 1.00 TO P
00004E 059B BALR R9,R11
000050 0082 DC X'0082'
000052 FA41 7004 8347 AP P,#VAR0347
000058 DC00 7008 B488 TR P+4(1),PSGNTR
0120 END-FOR
0130 *
00005E 059B BALR R9,R11
000060 0094 DC X'0094'
000062 47F0 A02A BC 15,42(,R10)
0140 T:=*TIMD(0080)
000066 059B BALR R9,R11
000068 009C DC X'009C'
00006A 45E0 B0D8 BAL R14,SYSFUNC
00006E 0330 B881 DC X'0330B881'
000072 F246 7009 8330 PACK T,#VAR0330
000078 F040 7009 0002 SRP T,2,0
00007E DC00 700D B488 TR T+4(1),PSGNTR
0150 T:=T / 10
0160 *
000084 059B BALR R9,R11
000086 00AE DC X'00AE'
000088 F864 D100 7009 ZAP OP1(7),T
00008E F811 D130 8349 ZAP WORK2(2),#VAR0349
000094 45E0 B104 BAL R14,ZDCHECK
000098 F240 7009 B355 PACK T,ZEROZ
00009E 47F0 E01C BC 15,28(,R14)
0000A2 FD61 D100 8349 DP OP1(7),#VAR0349
0000A8 D204 7009 D100 MVC T,OP1
0000AE DC00 700D B488 TR T+4(1),PSGNTR
0170 DISPLAY 'ELAPSED TIME (S)' T
0000B4 45E0 B040 BAL R14,RETH
0000B8 00C0 DC X'00C0'
0180 END
The Natural Optimizer Compiler generates optimized code for Natural statements with Unicode strings if the following requirements are met:
| Statement | Requirement |
|---|---|
| All statements | All operands used in the statement must be of the type Unicode. |
EXAMINE |
The ARCH option must be set to a
value greater than or equal to 6.
|
IF
|
|
MOVE
|
The ARCH option must be set to a
value greater than or equal to 5.
|
The UNICC option controls the generation of optimized
code for IF, DECIDE FOR and DECIDE ON
statements that contain Unicode operands.
Valid values for UNICC are:
| Value | Explanation |
|---|---|
ON |
Generates optimized code and checks
whether COLLATE=OFF is
set (see the CFICU profile parameter in the
Parameter Reference documentation).
If |
FORCE |
Generates optimized code analogous to
ON but without COLLATE=OFF check.
The code optimized with |
OFF |
Optimized code is not generated.
|
The global parameter ZD influences the
behavior of the NOC compiler. See the description of the
ZD option as
described under List of
Options above.
The COMPOPT parameter PSIGNF
(see also the system command COMPOPT in
the Natural System Commands documentation) influences the
behavior by forcing the signs of positive packed decimal numbers to F if
ON, and to C if OFF. The parameter is applied if
NOSGNTR=OFF is specified.
See the chart below for packed data (Format P) ":"
NOSGNTR=OFF |
and | PSIGNF=ON |
All signs are normalized to F (default). |
NOSGNTR=OFF |
and | PSIGNF=OFF |
All signs are normalized to C. |
NOSGNTR=ON |
All signs are left as they were generated by the last operation. | ||
For numeric data (Format N) the signs are always normalized to F,
regardless of the settings of NOSGNTR and
PSIGNF.