RealView Compilation Tools - ARM Information Center

Compiler Command-line Options
A number of transformations might be performed, including:
• Double-precision math functions might be converted to single
precision equivalents if all floating-point arguments can be exactly
represented as single precision values, and the result is immediately
converted to a single-precision value.
This transformation is only performed when the selected library
contains the single-precision equivalent functions, for example,
when the selected library is rvct or aeabi_glibc.
For example:
float f(float a)
{
return sqrt(a);
}
is transformed to
float f(float a)
{
return sqrtf(a);
}.
• Double-precision floating-point expressions that are narrowed to
single-precision are evaluated in single-precision when it is
beneficial to do so. For example, float y = (float)(x + 1.0) is
evaluated as float y = (float)x + 1.0f.
• Division by a floating-point constant is replaced by multiplication
with the inverse. For example, x / 3.0 is evaluated as x * (1.0 /
3.0).
• It is not guaranteed that the value of errno is compliant with the ISO
C or C++ standard after math functions have been called. This
enables the compiler to inline the VFP square root instructions in
place of calls to sqrt() or sqrtf().
Note
Initialization code might be required to enable the VFP. See VFP support on page 5-34
in the Compiler User Guide for more information.
See also
• ARM Application Note 133 - Using VFP with RVDS in
install_directory\RVDS\Examples\...\vfpsupport.
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