Changeset 9821:9e2898b0e9bd
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cpu: allow the fetch buffer to be smaller than a cache line

the current implementation of the fetch buffer in the o3 cpu
is only allowed to be the size of a cache line. some
architectures, e.g., ARM, have fetch buffers smaller than a cache
line, see slide 22 at:
http://www.arm.com/files/pdf/at-exploring_the_design_of_the_cortex-a15.pdf

this patch allows the fetch buffer to be set to values smaller
than a cache line.

ran several of the shorter SPEC CPU2006 benchmarks with test input.
icache.overall_accesses::total stat was validated against real
cortex A15 hardware, the value is much closer now.

regressions pass