RealView Compilation Tools Compiler Reference Guide - ARM ...

Language Extensions
• New features of C99 on page 1-5 in the Compiler User Guide.
3.3.2 long long
The ARM compiler supports 64-bit integer types through the type specifiers long long
and unsigned long long. They behave analogously to long and unsigned long with
respect to the usual arithmetic conversions. __int64 is a synonym for long long.
Integer constants can have:
• an ll suffix to force the type of the constant to long long, if it fits, or to unsigned
long long if it does not fit
• a ull or llu suffix to force the type of the constant to unsigned long long.
Format specifiers for printf() and scanf() can include ll to specify that the following
conversion applies to a long long argument, as7 in %lld or %llu.
Also, a plain integer constant is of type long long or unsigned long long if its value is
large enough. There is a warning message from the compiler indicating the change. For
example, in strict 1990 ISO Standard C 2147483648 has type unsigned long. In ARM
C and C++ it has the type long long. One consequence of this is the value of an
expression such as:
2147483648 > –1
This expression evaluates to 0 in strict C and C++, and to 1 in ARM C and C++.
The long long types are accommodated in the usual arithmetic conversions.
See also
• __int64 on page 4-9.
3.3.3 restrict
The restrict keyword is a C99 feature that enables you to ensure that different object
pointer types and function parameter arrays do not point to overlapping regions of
memory. Therefore, the compiler performs optimizations that can be otherwise
prevented because of possible aliasing.
Restrictions
To enable the restrict keyword in C90 or C++, you must specify the --restrict option.
The keywords __restrict and __restrict__ are supported as synonyms for restrict and
are always available, regardless of whether --restrict is specified.
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