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Arm Compiler User Guide

Arm® Compiler User Guide

Version 6.14

Table of Contents

About this book
Using this book
Typographic conventions
Other information
1 Getting Started
1.1 Introduction to Arm® Compiler 6
1.2 About the Arm® Compiler toolchain assemblers
1.3 Installing Arm® Compiler
1.4 Accessing Arm® Compiler from Arm® Development Studio
1.5 Accessing Arm® Compiler from the Arm® Keil® µVision® IDE
1.6 Compiling a Hello World example
1.7 Using the integrated assembler
1.8 Running bare-metal images
1.9 Architectures supported by Arm® Compiler
1.10 Using Arm® Compiler securely in a shared environment
2 Using Common Compiler Options
2.1 Mandatory armclang options
2.2 Common Arm® Compiler toolchain options
2.3 Selecting source language options
2.4 Selecting optimization options
2.5 Building to aid debugging
2.6 Linking object files to produce an executable
2.7 Linker options for mapping code and data to target memory
2.8 Passing options from the compiler to the linker
2.9 Controlling diagnostic messages
2.10 Selecting floating-point options
2.11 Compilation tools command-line option rules
3 Writing Optimized Code
3.1 Effect of the volatile keyword on compiler optimization
3.2 Optimizing loops
3.3 Inlining functions
3.4 Stack use in C and C++
3.5 Packing data structures
3.6 Optimizing for code size or performance
3.7 Methods of minimizing function parameter passing overhead
3.8 Optimizing across modules with Link-Time Optimization
3.8.1 Enabling Link-Time Optimization
3.8.2 Restrictions with Link-Time Optimization
3.8.3 Removing unused code across multiple object files
3.9 Scatter file section or object placement with Link-Time Optimization
3.10 How optimization affects the debug experience
4 Assembling Assembly Code
4.1 Assembling armasm and GNU syntax assembly code
4.2 Preprocessing assembly code
5 Using Assembly and Intrinsics in C or C++ Code
5.1 Using intrinsics
5.2 Writing inline assembly code
5.3 Calling assembly functions from C and C++
6 Mapping Code and Data to the Target
6.1 What the linker does to create an image
6.1.1 What you can control with a scatter file
6.2 Placing data items for target peripherals with a scatter file
6.3 Placing the stack and heap with a scatter file
6.4 Root region
6.4.1 Effect of the ABSOLUTE attribute on a root region
6.4.2 Effect of the FIXED attribute on a root region
6.5 Placing functions and data in a named section
6.6 Placing functions and data at specific addresses
6.6.1 Placing __at sections at a specific address
6.6.2 Restrictions on placing __at sections
6.6.3 Automatically placing __at sections
6.6.4 Manually placing __at sections
6.6.5 Placing a key in flash memory with an __at section
6.6.6 Placing constants at fixed locations
6.6.7 Placing jump tables in ROM
6.6.8 Placing a variable at a specific address without scatter-loading
6.6.9 Placing a variable at a specific address with scatter-loading
6.7 Bare-metal Position Independent Executables
6.8 Placement of Arm® C and C++ library code
6.8.1 Placing code in a root region
6.8.2 Placing Arm® C library code
6.8.3 Placing Arm® C++ library code
6.9 Placement of unassigned sections
6.9.1 Default rules for placing unassigned sections
6.9.2 Command-line options for controlling the placement of unassigned sections
6.9.3 Prioritizing the placement of unassigned sections
6.9.4 Specify the maximum region size permitted for placing unassigned sections
6.9.5 Examples of using placement algorithms for .ANY sections
6.9.6 Example of next_fit algorithm showing behavior of full regions, selectors, and priority
6.9.7 Examples of using sorting algorithms for .ANY sections
6.9.8 Behavior when .ANY sections overflow because of linker-generated content
6.10 Placing veneers with a scatter file
6.11 Preprocessing a scatter file
6.11.1 Default behavior for armclang -E in a scatter file
6.11.2 Using other preprocessors in a scatter file
6.12 Reserving an empty block of memory
6.12.1 Characteristics of a reserved empty block of memory
6.12.2 Example of reserving an empty block of memory
6.13 Aligning regions to page boundaries
6.14 Aligning execution regions and input sections
7 Overlays
7.1 Overlay support in Arm® Compiler
7.2 Automatic overlay support
7.2.1 Automatically placing code sections in overlay regions
7.2.2 Overlay veneer
7.2.3 Overlay data tables
7.2.4 Limitations of automatic overlay support
7.2.5 Writing an overlay manager for automatically placed overlays
7.3 Manual overlay support
7.3.1 Manually placing code sections in overlay regions
7.3.2 Writing an overlay manager for manually placed overlays
8 Embedded Software Development
8.1 About embedded software development
8.2 Default compilation tool behavior
8.3 C library structure
8.4 Default memory map
8.5 Application startup
8.6 Tailoring the C library to your target hardware
8.7 Reimplementing C library functions
8.8 Tailoring the image memory map to your target hardware
8.9 About the scatter-loading description syntax
8.10 Root regions
8.11 Placing the stack and heap
8.12 Run-time memory models
8.13 Reset and initialization
8.14 The vector table
8.15 ROM and RAM remapping
8.16 Local memory setup considerations
8.17 Stack pointer initialization
8.18 Hardware initialization
8.19 Execution mode considerations
8.20 Target hardware and the memory map
8.21 Execute-only memory
8.22 Building applications for execute-only memory
8.23 Vector table for ARMv6 and earlier, ARMv7-A and ARMv7-R profiles
8.24 Vector table for M-profile architectures
8.25 Vector Table Offset Register
8.26 Integer division-by-zero errors in C code
9 Building Secure and Non-secure Images Using Arm®v8‑M Security Extensions
9.1 Overview of building Secure and Non-secure images
9.2 Building a Secure image using the Arm®v8‑M Security Extensions
9.3 Building a Non-secure image that can call a Secure image
9.4 Building a Secure image using a previously generated import library
10 Overview of the Linker
10.1 About the linker
10.1.1 Summary of the linker features
10.1.2 What the linker can accept as input
10.1.3 What the linker outputs
10.2 armlink command-line syntax
10.3 What the linker does when constructing an executable image
11 Getting Image Details
11.1 Options for getting information about linker-generated files
11.2 Identifying the source of some link errors
11.3 Example of using the --info linker option
11.4 How to find where a symbol is placed when linking
12 SysV Dynamic Linking
12.1 Build a SysV shared object
12.2 Build a SysV executable
13 Overview of the fromelf Image Converter
13.1 About the fromelf image converter
13.2 fromelf execution modes
13.3 Getting help on the fromelf command
13.4 fromelf command-line syntax
14 Using fromelf
14.1 General considerations when using fromelf
14.2 Examples of processing ELF files in an archive
14.3 Options to protect code in image files with fromelf
14.4 Options to protect code in object files with fromelf
14.5 Option to print specific details of ELF files
14.6 Using fromelf to find where a symbol is placed in an executable ELF image
15 Overview of the Arm® Librarian
15.1 About the Arm® Librarian
15.2 Considerations when working with library files
15.3 armar command-line syntax
15.4 Option to get help on the armar command
16 Overview of the armasm Legacy Assembler
16.1 Key features of the armasm assembler
16.2 How the assembler works
A Supporting reference information
A.1 Support level definitions
A.2 Standards compliance in Arm® Compiler
A.3 Compliance with the ABI for the Arm® Architecture (Base Standard)
A.4 GCC compatibility provided by Arm® Compiler 6
A.5 Locale support in Arm® Compiler
A.6 Toolchain environment variables
A.7 Clang and LLVM documentation
A.8 Further reading

Release Information

Document History
Issue Date Confidentiality Change
0606-00 04 November 2016 Non-Confidential Arm Compiler v6.6 Release
0607-00 05 April 2017 Non-Confidential Arm Compiler v6.7 Release
0608-00 30 July 2017 Non-Confidential Arm Compiler v6.8 Release.
0609-00 25 October 2017 Non-Confidential Arm Compiler v6.9 Release.
0610-00 14 March 2018 Non-Confidential Arm Compiler v6.10 Release.
0611-00 25 October 2018 Non-Confidential Arm Compiler v6.11 Release.
0612-00 27 February 2019 Non-Confidential Arm Compiler v6.12 Release.
0613-00 09 October 2019 Non-Confidential Arm Compiler v6.13 Release.
0614-00 26 February 2020 Non-Confidential Arm Compiler v6.14 Release.

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