since not all Armv7-m platform support double-precision floating
operations, so we add an extra option that help those specific platform
could define the single-precision floating operations.
for example, qemu-mps platform(armv7-m) support double-precision
floating operations, so we do not need to open
CONFIG_ARM_FPU_SINGLE_HARDWARE build options;
but for fc7300 platform(armv7-m) only support single-precision floating
operations, so if we pass "-fhard" build option to "ghs" compiler, then
the following instruction will be generated:
vcvt.f64.s32 d9, s18
which will fail to execute on fc7300 platform.
with "-fsingle" build option, the "ghs" compiler will generate hardware
instruction for single-precision floating operation, and generate
software instruction for double-precision floating operation.
Signed-off-by: guoshichao <guoshichao@xiaomi.com>
c2d26988fd