1. A processor comprising: an execution unit having a plurality of channels to execute control flow instructions including fused control flow instructions comprising two or more consecutive control flow instructions fused into a single fused control flow instruction; and a branch unit to process the control flow instructions and to maintain a global counter indicating a nesting level of the control flow instructions, wherein to process a fused control flow instruction, the branch unit is to store a value N in a stack indicating a number of control flow instructions fused into the fused control flow instruction, the branch unit to subsequently read the value N from the stack upon execution of the fused control flow instruction and decrement the global counter by a value of N responsive to execution of the fused control flow instruction.