Compiler/MSP430F5131: Simple C question

Tool/software: TI C/C++ Compiler

I still struggle with seldom-used C "logical" statements -

for speed faster than using an ISR, I want to spin on an interrupt flag for port P1.2 until it becomes a "1"

What's the proper syntax;  While (~P1IV & 0x40) doesn't seem to do it - do I need a semicolon, braces, or some other inversion like ! or what?

Thx for some add'l education!