ARM Compiler toolchain Using the Linker - ARM Information Center

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5.12 Working with RW data compression 5.12.1 See also When working with RW data compression: Using linker optimizations • Use the linker option --map to see where compression has been applied to regions in your code. • The linker in RealView Compilation Tools (RVCT) v4.0 and later turns off RW compression if there is a reference from a compressed region to a linker-defined symbol that uses a load address. • If you are using an ARM processor with on-chip cache, enable the cache after decompression to avoid code coherency problems. Compressed data sections are automatically decompressed at run time, providing __main is executed, using code from the ARM libraries. This code must be placed in a root region. This is best done using InRoot$$Sections in a scatter file. If you are using a scatter file, you can specify that a load or execution region is not to be compressed by adding the NOCOMPRESS attribute. Concepts • Optimization with RW data compression on page 5-13 • How the linker chooses a compressor on page 5-14 • How compression is applied on page 5-16 • Load$$ execution region symbols on page 7-7 • Chapter 8 Using scatter files. Developing Software for ARM ® Processors: • Chapter 3 Embedded Software Development. Tasks • Overriding the compression algorithm used by the linker on page 5-15. Reference Linker Reference: • --map, --no_map on page 2-108 • Chapter 4 Formal syntax of the scatter file. ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 5-17 ID080411 Non-Confidential
5.13 Inlining functions with the linker 5.13.1 See also Using linker optimizations The linker can inline small functions in place of a branch instruction to that function. For the linker to be able to do this, the function (without the return instruction) must fit in the four bytes of the branch instruction. Use the --inline and --no_inline command-line options to control branch inlining. If branch inlining optimization is enabled, the linker scans each function call in the image and then inlines as appropriate. When the linker finds a suitable function to inline, it replaces the function call with the instruction from the function that is being called. The linker applies branch inlining optimization before any unused sections are eliminated so that inlined sections can also be removed if they are no longer called. Note The linker can inline two 16-bit instructions in place of the 32-bit Thumb BL instruction. Use the --info=inline command-line option to list all the inlined functions. Reference • Factors that influence function inlining on page 5-19 • Elimination of unused sections on page 5-4. Linker Reference: • --info=topic[,topic,...] on page 2-80 • --inline, --no_inline on page 2-85. ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 5-18 ID080411 Non-Confidential
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® ARM Copyright © 2010-2011 ARM.
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Contents ARM Compiler toolchain Usi
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Contents 7.15 Creating a symdefs fi
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Chapter 1 Conventions and feedback
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Chapter 2 Overview of the linker Th
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Concepts • Demand paging on page
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2.3 Linker command-line options lis
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• --keep_protected_symbols on pag
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• --eager_load_debug, --no_eager_
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2.5 What the linker outputs 2.5.1 S
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Chapter 3 Linking models supported
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3.2 Bare-metal linking model 3.2.1
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Linking models supported by armlink
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3.5.1 See also • There are restri
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3.7 Concepts common to both BPABI a
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Image structure and generation •
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4.1.1 See also Image structure and
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Page 37 and 38: 4.4 Methods of specifying an image
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Page 49 and 50: 4.11.2 Example 4.11.3 See also The
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Page 53 and 54: Reference Linker Reference: • --a
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Page 57 and 58: 4.18 Veneer types 4.18.1 See also I
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Page 63 and 64: BL init_foo ;Rest of code END 4.22.
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Page 81 and 82: 3. Creates the output image. 5.7.3
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Page 89 and 90: Reference Assembler Reference: •
Page 91 and 92: 5.16 About reordering of tail calli
Page 93 and 94: 5.18 About merging comment sections
Page 95 and 96: 6.1 Linker options for getting info
Page 97 and 98: 6.3 Example of using the --info lin
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Page 101 and 102: • Load$$LR$$ load region symbols
Page 103 and 104: 7.2 Accessing linker-defined symbol
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Page 109 and 110: 7.7 Region name values when not sca
Page 111 and 112: 7.9 Importing linker-defined symbol
Page 113 and 114: 7.11 Section-related symbols 7.11.1
Page 115 and 116: 7.13 Input section symbols 7.13.1 S
Page 117 and 118: 7.15 Creating a symdefs file 7.15.1
Page 119 and 120: 7.17 Reading a symdefs file 7.17.1
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Page 125 and 126: 7.22 Steering file format 7.22.1 Se
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Page 129 and 130: Using scatter files • Images with
Page 131 and 132: 8.2 When to use scatter-loading 8.2
Page 133 and 134: • --startup=symbol, --no_startup
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8.5.1 See also } SRAM 0x8000 0x8000
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8.7 Specifying stack and heap using
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8.9 Creating root execution regions
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8.9.2 See also Tasks • Using the
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8.11 Placing functions and data at
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Using scatter files RAM 0x200000 (0
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Using scatter files • Using __at
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Developing Software for ARM ® Proc
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} } .ANY1(+RO) ; evenly distributed
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8.14 Examples of using placement al
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Using scatter files 8.15 Example of
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8.16 Examples of using sorting algo
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8.17 Selecting veneer input section
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Compiler Reference: • __attribute
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8.20 Restrictions on placing __at s
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8.21.1 See also Using scatter files
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8.23 Placing a key in flash memory
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8.25 Placement of sections with ove
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8.25.1 See also Using scatter files
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8.27 Example of placing code in a r
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8.29 Example of placing ARM C++ lib
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8.31 Reserving an empty region Usin
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8.32 About creating regions on page
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8.33 Overalignment of execution reg
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8.35 Expression evaluation in scatt
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8.37 Equivalent scatter-loading des
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Using scatter files Example 8-23 Po
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Using scatter files Example 8-25 Po
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Using scatter files • The ER_ZI e
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Using scatter files Example 8-29 Sc
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Chapter 9 GNU ld script support in
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9.2 Typical use cases for using ld
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Reference Linker Reference: • --l
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9.5 Recommendations for using ld sc
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.data : { __data_start = .; *(.data
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9.6.4 See also .got 0 : { *(.got.pl
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9.7.1 See also } .dynamic : { *(.dy
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9.8.1 See also { *(.bss .bss.*) . =
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Chapter 10 BPABI and SysV shared li
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BPABI and SysV shared libraries and
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10.3 Concepts common to all BPABI m
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10.5 Symbol visibility for BPABI mo
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10.6 Automatic import and export fo
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10.8 Symbol versioning for BPABI mo
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10.10 Linker options for SysV model
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10.13 Addressing modes in the SysV
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10.17 Linker options for bare metal
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10.21 Addressing modes in the BPABI
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10.23 About symbol versioning 10.23
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10.25 Example of creating versioned
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10.27 Linker options for enabling i
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Chapter 11 Features of the Base Pla
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Features of the Base Platform linki
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11.2 Example scatter file for the B
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Features of the Base Platform linki
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Change Topics affected Revisions fo
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