The issue of doing tiny passes is not so much efficiency or the lack thereof; it's that combining passes can allow for better decisions to be made. This can result in better code quality than could be achieved independently. The classic example is the combination of register allocation and scheduling - scheduling can benefit from knowing what the actual operations are (e.g. will this thing be a load or will it be in a register) while register allocation can benefit from not having scheduling make overly aggressive movements of code that generate more live ranges than can be successfully allocated to registers.
Integrating register allocation and instruction scheduling for RISCs (1991) by D G Bradlee, S J Eggers, R R Henry
That being said, many quite successful compilers manage to get by with simpler passes, sometimes using heuristics or multiple passes or just plain trickery. It's nice to be able to keep things simple. Especially nice for pedagogy, as above.
Compilers are lousy with 'phase ordering problems' where there's no clear-cut superior order in which to make certain decisions...
Lots of papers on this sort of topic - the one I remember was (probably outdated): http://portal.acm.org/citation.cfm?id=106986
Integrating register allocation and instruction scheduling for RISCs (1991) by D G Bradlee, S J Eggers, R R Henry
That being said, many quite successful compilers manage to get by with simpler passes, sometimes using heuristics or multiple passes or just plain trickery. It's nice to be able to keep things simple. Especially nice for pedagogy, as above.
Compilers are lousy with 'phase ordering problems' where there's no clear-cut superior order in which to make certain decisions...