The GCC toolchain included within Xilinx SDK allows users to configure the floating point ABI through the mfloat-api option.
SDK 2015.4 and earlier versions:
The default toolchain is Sourcery CodeBench which only includes libraries compiled with the soft-float ABI.
This means that mfloat-api=hard cannot be used and will generate a compilation error.
The default project settings of a created application do not include any specific configuration, so the toolchain makes use of mfloat-abi=softfp by default.
This behavior can be checked by examining the disassembly code of any floating point operation.
SDK 2016.1 and later versions:
The default toolchain is Linaro GCC which includes libraries compiled with both soft-float and hard-float ABI.
The project settings of created applications include the mfloat-abi=hard setting by default, so FPU hardware instruction are used by the toolchain.