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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
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Benefits of reducing debug information in objects
Methods of reducing debug information in objects a
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Functions that return multiple values through regi
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Comparison of pure and impure functions
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Inline functions
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Compiler support for floating-point arithmetic
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Limitations on hardware handling of floating-point
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Compiler and library support for half-precision fl
Half-precision floating-point number format
Compiler support for floating-point computations a
Types of floating-point linkage
Compiler options for floating-point linkage and co
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Processors and their implicit Floating-Point Units
Integer division-by-zero errors in C code
About trapping integer division-by-zero errors wit
About trapping integer division-by-zero errors wit
Identification of integer division-by-zero errors
Examining parameters when integer division-by-zero
Software floating-point division-by-zero errors in
About trapping software floating-point division-by
Identification of software floating-point division
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 state
_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 <inttyp
<fenv.h> floating-point environment access i
<stdio.h> snprintf family of functions in C9
<tgmath.h> type-generic math macros in C99
<wchar.h> wide character I/O functions in C9
How to prevent uninitialized data from being initi
Compiler Diagnostic Messages
Using the Inline and Embedded Assemblers of the AR
Compiler User Guide
Compiler optimization for code size versus speed
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| Home > Compiler Coding Practices > Compiler optimization for code size versus speed | |||
The compiler provides two options for optimizing for code size and performance:
-OspaceThis option causes the compiler to optimize mainly for code size. This is the default option.
-OtimeThis option causes the compiler to optimize mainly for speed.
For best results, you must build your application using the most appropriate command-line option.
Note
These command-line options instruct the compiler to use optimizations
that deliver the effect wanted in the vast majority of cases. However,
it is not guaranteed that -Otime always generates faster
code, or that -Ospace always generates smaller
code.
See also| Copyright © 2007-2008, 2011-2012 ARM. All rights reserved. | ARM DUI 0375D |
| Non-Confidential | ID062912 |
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