Packing 32bit floats into 30 bits (c++)

Here are the goals I'm trying to achieve:

I need to pack 32 bit IEEE floats into 30 bits.
I want to do this by decreasing the size of mantissa by 2 bits.
The operation itself should be as fast as possible.
I'm aware that some precision will be lost, and this is acceptable.
It would be an advantage, if this operation would not ruin special cases like SNaN, QNaN, infinities, etc. But I'm ready to sacrifice this over speed.

I guess this questions consists of two parts:

1) Can I just simply clear the least significant bits of mantissa? I've tried this, and so far it works, but maybe I'm asking for trouble... Something like:

float f;
int packed = (*(int*)&f) & ~3;
// later
f = *(float*)&packed;

2) If there are cases where 1) will fail, then what would be the fastest way to achieve this?

Thanks in advance

Solution

I can't select any of the answers as the definite one, because most of them have valid information, but not quite what I was looking for. So I'll just summarize my conclusions.

The method for conversion I've posted in my question's part 1) is clearly wrong by C++ standard, so other methods to extract float's bits should be used.

And most important... as far as I understand from reading the responses and other sources about IEEE754 floats, it's ok to drop the least significant bits from mantissa. It will mostly affect only precision, with one exception: sNaN. Since sNaN is represented by exponent set to 255, and mantissa != 0, there can be situation where mantissa would be <= 3, and dropping last two bits would convert sNaN to +/-Infinity. But since sNaN are not generated during floating point operations on CPU, its safe under controlled environment.