I'm trying to figure out just how expensive floating point fundamentally is, at the hardware level. For example, how many more transistors does a 32-bit multiplier cost in floating point compared to integer.
To be specific:
- A 32-bit floating point multiplier, versus a 32-bit integer multiplier.
- Both have a throughput of one clock cycle.
- The FP does not need IEEE semantics; it can make the simplifications typical of GPUs e.g. no exceptions, rounding mode is not configurable, denormals flush to zero.
- The integer multiplier only produces 32 bits of result and throws away the rest.
- If it matters, say the target clock speed is 50 MHz and the implementation technology is CMOS.
- I'm just considering the arithmetic hardware itself, not other issues like control logic, register renaming etc.
Roughly how much more expensive is the floating point circuit? For example, twice as many transistors?