private boolean canMapReg(RegisterSpec ssaSpec, int ropReg) {
    int category = ssaSpec.getCategory();
    return !(spansParamRange(ropReg, category) || mapper.interferes(ssaSpec, ropReg));
  }
Checks to see if {@code ssaSpec} can be mapped to {@code ropReg}. Checks interference graph and
ensures the range does not cross the parameter range.

@param ssaSpec {@code non-null;} SSA spec
@param ropReg prosepctive new-namespace reg
@return {@code true} if mapping is possible
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/back/FirstFitLocalCombiningAllocator.java