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Compiler Command-line Options
Restrictions
For every CPU that can be specified with --cpu=name, the compiler permits any
hardware VFP architecture to be specified using --fpu=name, providing that the target
architecture inside the processor core is 5TE or later. Beyond the scope of the compiler,
additional architectural constraints apply. For example, VFPv3 is not supported with
architectures prior to ARMv7.
The combination of --fpu and --cpu options permitted by the compiler does not
necessarily translate to the actual device in use.
If you specify an FPU implicitly using the --cpu option, that is incompatible with an
FPU chosen explicitly using --fpu, the compiler generates an error.
The compiler only generates scalar floating-point operations. If you want to use VFP
vector operations, you must do this using assembly code.
NEON support is disabled for softvfp.
Default
If a VFP coprocessor is present, VFP instructions are generated. If there is no VFP
corprocessor, the compiler generates code that makes calls to the software
floating-point library fplib to carry out floating-point operations.
Note
By default, some choices of processor or architecture imply the selection of a particular
floating-point unit. For example, the option --cpu ARM1136JF-S implies the option --fpu
vfpv2.
See also
• --arm on page 2-8
• --cpu=name on page 2-30
• --thumb on page 2-122
• __softfp on page 4-15
• Using floating-point arithmetic on page 5-31 in the Compiler User Guide
• Floating-point build options on page 2-5 in the Developer Guide.
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