Automatic Performance Improvement for Legacy COBOL

1. Automatic Performance
Improvement for Legacy COBOL
Session 1810

2. Notices and Disclaimers
1
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IBM products and services are warranted according to the terms and conditions ofthe agreements under which they are provided.
Any statements regarding IBM's future direction, intent or product plans are subject to change or withdrawalwithout notice.
Performance data contained herein was generallyobtained in a controlled,isolated environments. Customer examples are presented as illustrations ofhow those customers
have used IBM products and the results they may have achieved. Actual performance,cost,savings or other results in other operating environments mayvary.
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3. Notices and Disclaimers Con’t.
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4. Please Note:
3
• IBM’s statements regarding its plans, directions, and intent are subject to change or withdrawal without notice at IBM’s sole
discretion.
• Information regarding potential future products is intended to outline our general product direction and it should not be relied on in
making a purchasing decision.
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• Performance is based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual
throughput or performance that any user will experience will vary depending upon many factors, including considerations such as the
amount of multiprogramming in the user’s job stream, the I/O configuration, the storage configuration, and the workload processed.
Therefore, no assurance can be given that an individual user will achieve results similar to those stated here.

5. IBM Automatic Binary Optimizer (ABO) for z/OS
Overview: z/OS 2.2 Release Nov. 2015; z/OS 2.1: Feb. 19, 2016
• ABO improves performance of already compiled COBOL V3 & V4 programs
• Optimize directly from the compiled program
• No source level migration or recompilation or options tuning required
• Leverage latest advanced COBOL optimization technology
• Generate code to target latest z Systems (e.g. zEC12, zBC12, z13 & z13s)
• Support in z/OS® 2.2 to automatically load optimized modules to target latest z
Systems
4
ABO
Original Program Binaries
(Base ESA390)
Optimized Program Binaries
(Latest z Systems)

6. ABO and COBOL Compiler:
Complementary Tools
5
Use Case ABO COBOL
Compiler
Significant Performance Improvement*
*No Source, Migration or Options Tuning Required 
Interoperability/Legacy Compatibility: PDS supported, pre-Enterprise COBOL etc.

Built in Support for Targeting Multiple Hardware Levels At Deployment

No need to downgrade ARCH setting to match DR* machine
Original compiled program always available for DR 
New COBOL development and new features

Maintenance on existing COBOL programs

Maximum Performance Improvement*
*Source, Migration and Options Tuning Required

*DR  Disaster Recovery Machine : Down level machine used for emergency situations. Usually 1 or 2 revisions old so puts limits
on Compiler ARCH setting (and performance improvements possible) based on this older level

7. Compatibility and Testing
6
ABO consumes the original
binary so the exact behavior
of the original program is
known vs the documented
“correct” behavior when
compiling from source
No compiler options
(performance or otherwise)
are changing
The optimized program
looks/behaves as the
original program from the
outside (but faster!) so no
interoperability concerns
with other programs
Strong compatibility guarantee for the modules produced by ABO
InteroperabilityUnchanged
Options
Binary As
Input
If something goes wrong using the optimized module revert to using original
program and call IBM
Failure
Scenario
The recommendedtesting focus should be on performance and scalability (less
on business logic)Testing

8. Tooling Support
• IBM Problem Determination Tools for z/OS
support includes:
– Fault Analyzer (FA) for z/OS
– Debug Tool (DT) for z/OS
– Application Performance Analyzer (APA) for
z/OS
• Several 3rd party tooling vendors were
involved in our beta program this year
– Please contact your tools vendor directly to
ask about support for ABO
7
APA
FA
DT

9. ABO Supports Tooling Infrastructure
8
COBOL v4.2 compiler listing:
000027 COMPUTE
00042C F247 D110 8000 PACK 272(5,13),0(8,8) TS2=0 WS-VAR-1
000432 960F D114 OI 276(13),X'0F' TS2=4
000436 F247 D118 8008 PACK 280(5,13),8(8,8) TS2=8 WS-VAR-2
00043C 960F D11C OI 284(13),X'0F' TS2=12
000440 FA44 D110 D118 AP 272(5,13),280(5,13) TS2=0 TS2=8
000446 F374 8010 D110 UNPK 16(8,8),272(5,13) WS-VAR-3 TS2=0
00044C 96F0 8017 OI 23(8),X'F0' WS-VAR-3+7
Listing Transform:
00042C PACK 272(5,13),0(8,8)
000432 OI 276(13),15
0004C4 ED07 4000 00AA 00042C CDZT FP0,_WSA[0x12c] 0(8,R4),0x0
000436 PACK 280(5,13),8(8,8)
00043C OI 284(13),15
0004CA ED07 4008 10AA 000436 CDZT FP1,_WSA[0x12c] 8(8,R4),0x0
000440 AP 272(5,13),280(5,13)
0004D0 B3D2 1000 000440 ADTR FP0,FP0,FP1
000446 UNPK 16(8,8),272(5,13)
00044C OI 23(8),240
0004D4 ED07 4010 00A8 00044C CZDT FP0, 16(8,R4),0x0
COBOL Program:
000027 COMPUTE WS-VAR-3 = WS-VAR-1 + WS-VAR-2.
Input “source” instructions. Starts at column 1
Optimized Instructions. Starts at column 5
LEGEND:
Source Line number in original program.
CSECT offset of instruction generated by COBOL 4.2
Compiler
CSECT offset of instructions generated by ABO
Each optimized instruction generated is also
annotated with the “source” offset that it was
generated for
Allows tracking as instructions are re-ordered

10. Whole Program Optimization
9
• Unbind
• Binary  IR*
Internal
Verification
• Optimize
• Optimize
• Optimize…
Internal
Verification • IR Binary
• Rebind
Done
Optimized
Executable
CSECT1 … CSECTN
Original
Executable
CSECT1 … CSECTN
*IR - Intermediate Representation

11. User Scenarios
ABO
Optimization
Configuration
z/OS

12. Example 1 : Binary Optimization Process
Optimization, Test and Static Selection
z/OS 2.1/2.2
Selected Compiled Application
Binaries
(e.g. Performance Sensitive)
1) Optimize and Test Application
ABO
2) Static Selection: Load + Run Application
JCL
Generates
Testing*
Validates
Loads + Runs
Optimized Application
Binaries (+debug metadata)
Optimized + Original
Application
Binaries
*Testing focuson performance/scalability
and less on business logic
Modified JCL
Pointing To Optimized +
Original Application Binaries
ChangeManagement

13. Example 2: Binary Optimization Process
Optimization, Test and Dynamic Selection
Selected Compiled Application
Binaries
(e.g. Performance Sensitive)
1) Optimize and Test Application
ABO
2) Load + Run Application
JCL
Generates
Validates
ChangeManagement
Loads + Runs
Optimized + Original
Application
Binaries
Original JCL
Pointing Only to Original
Application Binaries
z/OS 2.2
Optimization
Product
Infrastructure
Optimization
Configuration
*Testing focuson performance/scalability
and less on business logic
Optimized Application
Binaries (+debug metadata)
Testing*
* SMF for tracking changes in Optimization configuration
SMF*

14. Performance:
Internal Benchmark Suite And Early Customer Results
• Early customer results show performance gains of 5%  21% for a mix of v3 and v4
compiled input programs
• On internal benchmarks: 34% improvement.
• Performance gains will vary by application but expected to average 15%
13
*Performance data contained herein was generally obtained in a controlled, isolated environments. Customer examples are
presented as illustrations of how those customers have used IBM products and the results they may have achieved. Actual
performance, cost, savings or other results in other operating environments may vary.

15. Performance Example: Numeric Edited MOVE
2.35x (57%) Faster
14
01 WS-VAR-1 PIC S9(9)V99 COMP-3.
01 WS-VAR-2 PIC ZZZ,ZZZ,ZZ9.99.
MOVE WS-VAR-1 to WS-VAR-2
Automatic Binary Optimizer
Decompose editbehaviorto a longer but
much faster sequence
TP 0(6,R4)
...
UNPK 340(11,R10),0(6,R4)
IIHF R1,1075847200
OI 350(,R10),X'F0'
IILF R1,1797267488
...
ICM R1,X'3',349(,R10)
CDPT FP0,0(6,R4),0x8
STCM R1,X'7',284(,R5)
...
V4 OPT(FULL)
Uses traditional ED (edit)instruction
MVC 272(15,13),103(10)
L 2,300(0,9
ED 272(15,13),0(2)
MVC 8(14,2),273(13)

16. Performance Example: Decimal To Float MOVE
3.97x (75%) Faster
15
01 WS-VAR-1 PIC S9(7)V99.
01 WS-VAR-2 comp-2.
MOVE WS-VAR-1 to WS-VAR-2
Automatic Binary Optimizer
Decimal to floatconversion is inlined usinga
more efficientalgorithm
CVB R0,340(,R10)
LD FP8,256(,R7)
CXFR FP0,R6
DXR FP4,FP8
...
AXR FP4,FP0
LDXR FP0,FP4
V4 OPT(FULL)
LibraryCall for decimalto floatconversion
Runtime path length is > 100 instructions
L 3,92(0,9)
L 15,268(0,3) V(IGZCFPC )
LA 1,227(0,10)
BASR 14,15
MVC 16(8,2),272(13)

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18. Example 1 In Depth: Binary Optimization Process
Optimization, Test and Static Selection
Selected Compiled
Application
Binaries
1) Optimize and Test Application
ABO Testing
Optimized
Application
Binaries
 Using ABO in the static
selection case is a
matter of selecting
compiled programs to
optimize by using
straightforward new JCL
//OPTIMIZE JOB
//OPT EXEC PGM=BOZOPT,REGION=0M
//STEPLIB DD DSN=$HLQ.BOZ110.SBOZMOD1,DISP=SHR
//SYSPRINT DD DSN=$HLQ.BOZOUT.LISTING,DISP=SHR
//SYSIN DD *
BOPT IN=$HLQ.IN.LOAD(M*) OUT=$HLQ.OUT.LOAD.ZEC12 ARCH=10
BOPT IN=$HLQ.IN.LOAD(M*) OUT=$HLQ.OUT.LOAD.Z13 ARCH=11
JCL to compile all M* members from
IN.LOAD to an OUT.LOAD for zEC12
and one for z13

19. Example 1 In Depth: Binary Optimization Process
Optimization, Test and Static Selection (targeting multiple hardware levels)
z/OS 2.2/2.1
2) Static Selection
JCL
Loads + Runs
Optimized + Original Application
Binaries
Modified JCL
Pointing To Optimized + Original
Application Binaries
 Static selection requires
modifications to all JCL that
contained the original
modules(s) to be updated to
point to new modules(s) for
each architecture being
targeted
...
//STEPLIB DD DSN=$HLQ.OUT.LOAD.ZEC12:$HLQ.IN.LOAD,DISP=SHR
...
...
//STEPLIB DD DSN=$HLQ.OUT.LOAD.Z13:$HLQ.IN.LOAD,DISP=SHR
...
z13
zEC12

20. Example 2 In Depth: Binary Optimization Process
Optimization, Test and Dynamic Selection
Selected Compiled
Application
Binaries
1) Optimize and Test Application
ABO Testing
Optimized Application
Binaries (+debug
metadata)
 Using ABO in the
dynamic selection case
only requires ‘pointing’
to active configuration
by specifying IEFOPZ in
JCL
Optimization
Configuratio
n
OLDNEW (
OWNER(IBM)
OLD( DSNAME (HLQ.IN.LOAD) )
NEW( DSNAME (HLQ.OUT.LOAD.ZEC12) ARCH(10) )
NEW( DSNAME (HLQ.OUT.LOAD.Z13) ARCH(11) )
INCLUDEMEMBERS(M*)
INACTIVE )
//OPTIMIZE JOB
//OPT EXEC PGM=BOZOPT,REGION=0M
//STEPLIB DD DSN=$HLQ.BOZ110.SBOZMOD1,DISP=SHR
//SYSPRINT DD DSN=$HLQ.BOZOUT.LISTING,DISP=SHR
//SYSIN DD *
IEFOPZ

21. Example 2 In Depth: Binary Optimization Process
Optimization, Test and Dynamic Selection (targeting multiple hardware levels)
2) Load + Run Application
JCL
zEC12
 Dynamic selection requires
no modifications to JCL. The
new z/OS infrastructure will
select the highest ARCH
‘NEW’ dataset available for
the current machine
 Configurations
trackable/auditable/viewable
by SMF records and
DISPLAY IEFOPZxx
z/OS 2.2
Optimization
Product
InfrastructureOriginal JCL
Pointing Only to Original Application
Binaries
Optimization
Configuratio
n
OLDNEW (
OWNER(IBM)
OLD( DSNAME (HLQ.IN.LOAD) )
NEW( DSNAME (HLQ.OUT.LOAD.ZEC12) ARCH(10) )
NEW( DSNAME (HLQ.OUT.LOAD.Z13) ARCH(11) )
INCLUDEMEMBERS(M*)
ACTIVE )
Unchanged JCL
SMF*
Optimized + Original Application
Binaries
z13
...
//STEPLIB DD DSN=$HLQ.IN.LOAD,DISP=SHR  e.g. target z13 and zEC12
...
* SMF for tracking changes in Optimization configuration