RealView Compiler Reference Guide
Home Products Events Support	Search Keil.com for:

Technical Support

On-Line Manuals

RealView Compiler Reference Guide

Compiler Command-line Options

Language Extensions

Compiler-specific Features

Keywords and operators

__svc_indirect_r7

__value_in_regs

__declspec attributes

__declspec(dllexport)

__declspec(dllimport)

__declspec(noinline)

__declspec(noreturn)

__declspec(nothrow)

__declspec(notshared)

__declspec(thread)

Function attributes

__attribute__((alias))

__attribute__((always_inline))

__attribute__((const))

__attribute__((deprecated))

__attribute__((malloc))

__attribute__((noinline))

__attribute__((no_instrument_function))

__attribute__((nomerge))

__attribute__((nonnull))

__attribute__((noreturn))

__attribute__((notailcall))

__attribute__((pure))

__attribute__((section("name")))

__attribute__((unused))

__attribute__((used))

__attribute__((visibility("visibility_type")))

__attribute__((weak))

Type attributes

__attribute__((bitband))

__attribute__((aligned))

__attribute((packed))

__attribute__((transparent_union))

Variable attributes

__attribute__((alias))

__attribute__((at(address)))

__attribute__((aligned))

__attribute__((deprecated))

__attribute__((packed))

__attribute__((section("name")))

__attribute__((transparent_union))

__attribute__((unused))

__attribute__((used))

__attribute__((visibility("visibility_type")))

__attribute__((weak))

__attribute__((zero_init))

#pragma anon_unions, #pragma no_anon_unions

#pragma arm section [section_sort_list]

#pragma diag_default tag[,tag,...]

#pragma diag_error tag[,tag,...]

#pragma diag_remark tag[,tag,...]

#pragma diag_suppress tag[,tag,...]

#pragma diag_warning tag[, tag, ...]

#pragma exceptions_unwind, #pragma no_exceptions_u

#pragma hdrstop

#pragma import symbol_name

#pragma import(__use_full_stdio)

#pragma inline, #pragma no_inline

#pragma pack(n)

#pragma softfp_linkage, #pragma no_softfp_linkage

#pragma unroll [(n)]

#pragma unroll_completely

Instruction intrinsics

__memory_changed

__return_address

__schedule_barrier

ARMv6 SIMD intrinsics

ETSI basic operations

C55x intrinsics

Named register variables

VFP status intrinsic

GNU builtin functions

Nonstandard functions

C99 functions in the C90 reserved namespace

C99 floating-point functions

Other builtin functions

Compiler predefines

Predefined macros

C and C++ Implementation Details

Via File Syntax

Standard C Implementation Definition

Standard C++ Implementation Definition

C and C++ Compiler Implementation Limits

attribute((pure))

RealView Compilation Tools for µVision Compiler Reference Guide

Version 4.0

Home > Compiler-specific Features > Function attributes > __attribute__((pure))

4.3.12. `attribute((pure))`

Many functions have no effects except to return a value, and that the return value depends only on the parameters and global variables. Functions of this kind can be subject to data flow analysis and might be eliminated.

Note

This function attribute is a GNU compiler extension that is supported by the ARM compiler.

Although related, this function attribute is not equivalent to the __pure keyword. The function attribute equivalent to __pure is __attribute__((const)).

Example

int Function_Attributes_pure_0(int b) __attribute__ ((pure));
int Function_Attributes_pure_0(int b)
{
    static int aStatic;
    aStatic++;
    return b++;
}

int Function_Attributes_pure_2(int b)
{
    int aLocal=0;
    aLocal += Function_Attributes_pure_0(b);
    return 0;
}

The call to Function_Attributes_pure_0 in this example might be eliminated because its result is not used.

Copyright © 2007, 2008 ARM Limited. All rights reserved.	ARM DUI 0376B
Non-Confidential	Unrestricted Access
PDF version

Home > Compiler-specific Features > Function attributes > __attribute__((pure))