RealView Compilation Tools Compiler Reference Guide - ARM ...

C and C++ Implementation Details
• Bitwise operations on signed integral types follow the rules that arise naturally
from two's complement representation. No sign extension takes place.
• Right shifts on signed quantities are arithmetic.
• For values of type int,
— Shifts outside the range 0 to 127 are undefined.
— Left shifts of more than 31 give a result of zero.
— Right shifts of more than 31 give a result of zero from a shift of an unsigned
value or positive signed value. They yield –1 from a shift of a negative
signed value.
• For values of type long long, shifts outside the range 0 to 63 are undefined.
• The remainder on integer division has the same sign as the divisor, as mandated
by the ISO C99 standard.
• If a value of integral type is truncated to a shorter signed integral type, the result
is obtained by discarding an appropriate number of most significant bits. If the
original number is too large, positive or negative, for the new type, there is no
guarantee that the sign of the result is going to be the same as the original.
• A conversion between integral types does not raise an exception.
• Integer overflow does not raise an exception.
• Integer division by zero returns zero by default.
Operations on floating-point types
The following statements apply to operations on floating-point types:
• Normal IEEE 754 rules apply.
• Rounding is to the nearest representable value by default.
• Floating-point exceptions are disabled by default.
Also, see --fpmode=model on page 2-39.
Note
The IEEE 754 standard for floating-point processing states that the default action to an
exception is to proceed without a trap. You can modify floating-point error handling by
tailoring the functions and definitions in fenv.h. See Tailoring error signaling, error
handling, and program exit on page 2-76 for more information.
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