IBM Haifa Labs © 2005 IBM Corporation

Performance Tools developed in IBM Haifa

http://www.haifa.il.ibm.com/dept/svt/code_paot.html

Gad Haber(haber@il.ibm.com)

IBM Haifa Labs

© 2005 IBM Corporation2

HRL Performance Tools FDPR-Pro

Feedback-based optimizer operating on binary executable files Part of the AIX 5L Available on Linux on Power via alphaworks Under development for

Mac OS X – to be available soon via alphaworks z/OS

CodeAnalyzer Eclipse plugin tool for analyzing executable files Under development

To be added as part of the Performance Work Bench (PerfWB) BProber

Utility for instrumenting binary executable files Under development

ESTO Utility for identifying the optimal set of optimization options Under development

IBM Haifa Labs © 2005 IBM Corporation

FDPR-Pro

Feedback Directed Program Restructuring

IBM Haifa Labs

© 2005 IBM Corporation4

FDPR-Pro - Feedback Directed Program Restructuring

Using a global view of the entire program Operating on the executable file after linkage These properties enable FDPR-Pro to do:

Global Code ReorderingInter Procedure Boundaries OptimizationsStatic Data RearrangementConstant Area RearrangementData Prefetching

Examples of FDPR-Pro additional optimizations:Usage of Branch TablesUsage of TOC load instructions More..

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Method

Phase 1: Code instrumentationBasic block level

Phase 2: Profile information gatheringSelection of "right" input set (representative workload)Accumulation over several input sets

Phase 3: Global Code & Data OptimizationsComplements the compiler

Instrumentation

executablefile

Instrumentedexecutable

Global Code & Data

Optimizations

Profiling Information

run representativeworkloads

Optimizedexecutable

Dissecting the

executable file into program elements

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FDPR-Pro Optimization Options

-RC Reorder Code -bf Branch folding -bp Branch prediction bit setting -align Code alignment -nop Eliminate nop instructions -uce Unreachable code elimination -hco_resched Hot/Cold instruction scheduling -RD, -build_dcg Static data reordering -tocload, -reduce_toc Tocload optimizations -si, -ipht, -ihf, -isf Aggressive function inlining options -ptrgl_optimization Optimize function calls via pointers -dcbt_optimizationInject data prefetching instructions -link_reg_optimization Eliminate stores/restore of link register -volatile_regs Eliminate stores/restores using available volatile regs -killed_regs Eliminate stores/restores of killed registers -load_after_store Separate between frequent load and store to same address -loop_unroll Loop unrolling -stack_opt Reduce stack frame size of Hot functions -dce Dead code elimination

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CodeAnalyzer

IBM Haifa Labs

© 2005 IBM Corporation8

CodeAnalyzer - Motivation

Architectures are becoming more complex Using only hardware simulators to detect

information about potential performance bottlenecks in a given program is hard

There is a need for performance tools that can statically analyze and visualize programs for a platform design, to be used by: Hardware architects Compiler writers Application developers

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CodeAnalyzer

CodeAnalyzer is an eclipse plugin which performs comprehensive static analysis on given executable files and DLLs Relies on the FDPR-Pro tool for the analysis phase

CodeAnalyzer displays the analyzed information together with profiling data collected by:

tprof FDPR-Pro

The code is then colored according to: Frequency counters - gathered by FDPR-Pro Hardware event ticks - gathered by tprof

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CodeAnalyzer – (continued)

Provides several views of the input binary Assembly instructions Basic blocks Procedures CSECT modules control flow graph Hot loops Call graph Annotated source code Dispatch group formation Pipeline slots and functional units

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CodeAnalyzer – (continued)

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CodeAnalyzer – (continued)

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CodeAnalyzer – (continued)

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CodeAnalyzer – (continued)

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CodeAnalyzer – (continued)

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CodeAnalyzer – (continued)

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CodeAnalyzer – Performance Comments

Performance comments displayed by CodeAnalyzer Comments which do not require profiling

Pipeline stalls for the Power architecture Unreachable code and non-used data

Profile-based comments Non-variant instructions within Hot loops Hot function calls proceeded by overwriting non-volatile registers Hot saves and restores of registers which could be relocated to cold spill areas Hot instructions that could be scheduled to colder areas in the code Removable hot branches Hot direct unconditional branches Hot direct conditional branches that are taken, which have a colder fallthru Hot call sites that are appropriate candidates for function inlining Hot call sites that are appropriate for function specialization Hot loops that are appropriate for loop unrolling Hot TOC load instructions that can be replaced by immediate add instructions

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Performance Workbench (PerfWB)

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© 2005 IBM Corporation21

PerfWB

CodeAnalyzer is part of the Performance Workbench (PerfWB) utility

PerfWB is a collection of eclipse plugins that provide performance monitoring, tuning and analysis

PerfWB consists of the following eclipse plugins:

ProcMon - system-level monitoring tool for displaying system state and for monitoring running processes and threads

E-Tune - visualizer of feedback information produced by tprof

CodeAnalyzer – performance analyzer of executables and DLLs

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ProcMon

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E-Tune with CodeAnalyzer