ARM Compiler toolchain Using the Compiler: Compiler Coding Practices

Compiler Coding Practices

The compiler, armcc, is a mature, industrial-strength ISO C and C++ compiler capable of producing highly optimized, high quality machine code. By using programming practices and techniques that work well on RISC processors such as ARM cores, you can increase the portability, efficiency and robustness of your C and C++ source code. The following topics describe some of these programming practices, together with some programming techniques that are specific to ARM processors:

The compiler as an optimizing compiler
Compiler optimization for code size versus speed
Compiler optimization levels and the debug view
Selecting the target CPU at compile time
Optimization of loop termination in C code
Loop unrolling in C code
Compiler optimization and the volatile keyword
Code metrics
Code metrics for measurement of code size and data size
Stack use in C and C++
Benefits of reducing debug information in objects and libraries
Methods of reducing debug information in objects and libraries
Guarding against multiple inclusion of header files
Methods of minimizing function parameter passing overhead
Functions that return multiple values through registers
Functions that return the same result when called with the same arguments
Comparison of pure and impure functions
Recommendation of postfix syntax when qualifying functions with ARM function modifiers
Inline functions
Compiler decisions on function inlining
Automatic function inlining and static functions
Inline functions and removal of unused out-of-line functions at link time
Automatic function inlining and multifile compilation
Restriction on overriding compiler decisions about function inlining
Compiler modes and inline functions
Inline functions in C++ and C90 mode
Inline functions in C99 mode
Inline functions and debugging
Types of data alignment
Advantages of natural data alignment
Compiler storage of data objects by natural byte alignment
Relevance of natural data alignment at compile time
Unaligned data access in C and C++ code
The __packed qualifier and unaligned data access in C and C++ code
Unaligned fields in structures
Performance penalty associated with marking whole structures as packed
Unaligned pointers in C and C++ code
Unaligned Load Register (LDR) instructions generated by the compiler
Detailed comparison of an unpacked struct, a __packed struct, and a struct with individually __packed fields
Compiler support for floating-point arithmetic
Default selection of hardware or software floating-point support
Example of hardware and software support differences for floating-point arithmetic
Vector Floating-Point (VFP) architectures
Limitations on hardware handling of floating-point arithmetic
Implementation of Vector Floating-Point (VFP) support code
Compiler and library support for half-precision floating-point numbers
Half-precision floating-point number format
Compiler support for floating-point computations and linkage
Types of floating-point linkage
Compiler options for floating-point linkage and computations
Integer division-by-zero errors in C code
About trapping integer division-by-zero errors with __aeabi_idiv0()
About trapping integer division-by-zero errors with __rt_raise()
Identification of integer division-by-zero errors in C code
Examining parameters when integer division-by-zero errors occur in C code
Software floating-point division-by-zero errors in C code
About trapping software floating-point division-by-zero errors
Identification of software floating-point division-by-zero errors
Software floating-point division-by-zero debugging
New language features of C99
New library features of C99
// comments in C99 and C90
Compound literals in C99
Designated initializers in C99
Hexadecimal floating-point numbers in C99
Flexible array members in C99
__func__ predefined identifier in C99
inline functions in C99
long long data type in C99 and C90
Macros with a variable number of arguments in C99
Mixed declarations and statements in C99
New block scopes for selection and iteration statements in C99
_Pragma preprocessing operator in C99
Restricted pointers in C99
Additional <math.h> library functions in C99
Complex numbers in C99
Boolean type and <stdbool.h> in C99
Extended integer types and functions in <inttypes.h> and <stdint.h> in C99
<fenv.h> floating-point environment access in C99
<stdio.h> snprintf family of functions in C99
<tgmath.h> type-generic math macros in C99
<wchar.h> wide character I/O functions in C99
How to prevent uninitialized data from being initialized to zero.

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