FPGA Floating-point to Unsigned 32bits

Question

Regarding something I read in a Xilinx manual saying this:

Because floating-point operations use considerable resources relative to integer/fixed point operations, the Vivado HLS tool utilizes those resources as efficiently as possible.

I was thinking about the following option:

If that is true about floating-point cores utilizing more resources, why can't we convert every float we have to u32 with a union like this:

union converter{
     float f32;
     unsigned int u32;
}

do the operations always with the u32 and then in the end convert everything back to float?

I saw some examples of people doing this in really small designs, but never in big ones with lots of float operations.

Answer 1

Just because they use the same number of bits, doesn't mean that you can perform operations on them in the same way.

Look at how a float is actually constructed internally - how the bits are used (sign, exponent, fraction) and then think about what would happen if you simply did integer operations on it.

Answer 2

You can, but if you do, you cannot perform any floating point operations, so it wouldn't help you in calculations. Floating point calculations are time consuming. Load/Store operations aren't.