  Existing exoplanet radial velocity surveys are complete in the planetary
mass-semimajor axis (Mp-a) plane over the range 0.1 AU < a < 2.0 AU where Mp >~
100 M_Earth. We marginalize over mass in this complete domain of parameter
space and demonstrate that the observed semimajor axis distribution is
inconsistent with models of planet formation that use the full Type I migration
rate derived from a linear theory and that do not include the effect of the ice
line on the disk surface density profile. However, the efficiency of Type I
migration can be suppressed by both nonlinear feedback and the barriers
introduced by local maxima in the disk pressure distribution, and we confirm
that the synthesized Mp-a distribution is compatible with the observed data if
we account for both retention of protoplanetary embryos near the ice line and
an order-of-magnitude reduction in the efficiency of Type I migration. The
validity of these assumption can be checked because they also predict a
population of short-period rocky planets with a range of masses comparable to
that of the Earth as well as a "desert" in the Mp-a distribution centered
around Mp ~ 30-50 M_Earth and a < 1 AU. We show that the expected "desert" in
the Mp-a plane will be discernible by a radial velocity survey with 1 m/s
precision and n ~ 700 radial velocity observations of program stars.
