hew stack analysis using call walker - renesas e … training... · -use call walker to view and...

© 2008, Renesas Technology America, Inc., All Rights Reserved

Introduction

�Purpose

-The course explains stack analysis using Call Walker in the HighPerformance Embedded Workshop (HEW), which speeds up the development of software for embedded systems.

�Objectives

-Understand the use of the Call Walker utility

-Learn how to create and view the stack information and profile information files

Content

-19 pages

-3 questions

Learning Time

-30 minutes


Importance of Stack Analysis

Ensuring adequate stack size is vital

- Over-allocating resources wastes valuable RAM

- Allocating too few resources puts program at risk

of stack overflow

HEW simplifies stack analysis- Eliminates manual calculations

- Automates process with Call Walker

- Presents results in graphical format

To get started- Create stack and profile information files

- Use Call Walker to view and edit code


Two Types of Input Files

Stack Use Quantity Information (.sni) files

Profile Information (.pro) files

HEW

Call Walker


Creating Stack Information Files

� Follow sequence: Toolchain � Link/Library � Category � Other

� Click on: Stack information output


Creating Profile Information

� Switch to Simulator Session

� Open Profile window

� Enable Profiler

� Execute the program

� Save “Output Profile Information Files”

Profile Window


� Invoke the Call Walker from Windows® start menu

� Click File � Import Stack fileto import .sni or .pro file

Using Call Walker

Editing file

Assembler label

C/C++ function

Recursive call function or a circulating function

RTOS function

Functions that the reference source is unknown

Omitted symbol


Changing Linked-level Structure

Note: Symbols cannot be moved to a recursive call, a cyclic (circulating) function, or an omitted function

Recursive Call Function

- When a function itself is referred to within the function

Cyclic Function

- When a function refers to a function itself indirectly

• “shortway” stack size is 6

• “recur” stack size is 12

• Drag “recur” symbol to “shortway”

• After drag, “shortway” stack usage is increased from 6 to 18 as “recur” is added to its branches


Viewing and Omitting Symbols

� Two levels of symbols available

- “Show All Symbols” gives detailed view

- “Show Simple Symbols” gives summary view

Click: View � Show Simple SymbolsClick: View � Show All Symbols

All symbols are displayed Some symbols are omitted


Stack Size Displays

� Call Walker Window provides two optional views of stack size

- Each view shows a different interpretation of the information

Show Required Stack Displays stack size required to execute the symbol attached to it

Show Used Stack Displays total stack needed to execute the symbol at that particular level


Interpreting Stack Size Displays

Individual Stack Size

Optional view: “Show Required Stack” formatMain (stack)

= max (sub1, sub2), wheremax sub2 = 4+max (sub21,sub22)

= 14

= max (16, 14+max[sub21,sub22])

= max (16, 14+10)

= 24

sub1 = 8+16 = 24

sub2 = 8+4 = 12

sub21 = 8+4+6 = 18

sub22 = 8+4+10 = 22

Optional view: “Show Used Stack” format

Stack sizes of recursive call or circulating functions

are not displayed

8

PROPERTIES

On passing, 'Finish' button: Goes to Next Slide

On failing, 'Finish' button: Goes to Slide

Allow user to leave quiz: After user has completed quiz

User may view slides after quiz: After passing quiz

User may attempt quiz: Unlimited times


Symbol Detail View

AdvantageDescription

Summary

Click the Summary button for a summary of all six columns in the Call

Walker Window.


Symbol Detail View

Shows clearly how section data are allocated in the memory area after linking

Displays symbol address Address

Provides an instant view of every symbol function type without having to look through all the code

Displays symbol

attributes

Attributes

Gives you a clear view of the selected symbol’s calling symbols and functions

Displays calling symbols that are same as those displayed in call information view

Symbol



Symbol Detail View

Lets you know the calling function or symbol’s source file, so you spend less time searching for it— a valuable time saver in large programs with many source files

Displays source file name that stores the symbol

Source

Tells you how much stack size is used to execute each symbol, without requiring you to manually trace or monitor every symbol’s stack size

(Changes are shown in the stack register and register R7 for H8-series microcontrollers, and in R15 for SH-series devices).

Displays stack size that is used only by the symbol attached to it

Stack size

Allows you to focus program optimization on larger code-size symbols

Displays symbol size Size



Points to Remember

When Call Walker is used to perform stack analysis . . .

Stack amount calculated in the stack information file may be larger than the actual amount will be when the optimization option is used

� Stack amount for interrupt function doesn’t include the stack size the interrupt controller uses for saving context-switches when an interrupt occurs

- Refer to the device hardware manual to get the requisite data, then calculate the required amount

� Stack amount for the interrupt function doesn’t include the saved extended register (EXR)

PROPERTIES







Stack Calculation in HEW

� Is set in the Compiler during project generation

� Has no direct link with Call Walker

� Can be set to Small, Medium, or Large

� - “Medium” is recommended

in most cases

� Determines the stack access area


Changing the Setting

� Change stack calculation settings for loaded project from menu bar section

� Select: Options � H8 Toolchain � CPU tab


Selection Implications

All 4 bytes of the stack register are operated on,

allowing

a stack size of 4G bytes

Large

Least significant two bytes of the stack register are

operated on, allowing a stack size of 64K bytes

Medium

Least significant byte of the stack register is

operated on, allowing a stack size of 255 bytes

Small

Example:

stack=small

Align the stack-section start address so that the entire stack area fits in a single H’100-byte page

H’FE00

STACK SectionH’FEFF

Address at which the stack pointer is initialized is very important,

because subsequent operations cannot cross a “page” boundary

PROPERTIES







Generate stack use quantity information (.sni) and profile information (.pro) files

Import information files into Call Walker for stack analysis

Interpret stack analysis data to optimize system stack usage

Understand stack calculation control settings

Course Summary

Download a free evaluation copy of HEW at:

www.renesas.com/hew

hew stack analysis using call walker - renesas e … training... · -use call walker to view and...

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