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authorKevin Lim <ktlim@umich.edu>2005-01-11 19:00:16 -0500
committerKevin Lim <ktlim@umich.edu>2005-01-11 19:00:16 -0500
commit42f3b4ffb3fedcb70e9ff068ed7160dc6020b8c4 (patch)
treeba3d10f448bec63df45dff3bb7f2d6fbd6dcf9c7 /cpu/beta_cpu/2bit_local_pred.hh
parent202758eea20c092bb85d1886898c3816f377d288 (diff)
parent90d4436351620bd3861013333aabd152d5492df7 (diff)
downloadgem5-42f3b4ffb3fedcb70e9ff068ed7160dc6020b8c4.tar.xz
Merge changes.
base/traceflags.py: Merge extra new CPU flags cpu/static_inst.hh: Include all the execute functions in static_inst_impl.hh --HG-- extra : convert_revision : 78eb753bf709d37400e7c2418bb35d842d7c3f63
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diff --git a/cpu/beta_cpu/2bit_local_pred.hh b/cpu/beta_cpu/2bit_local_pred.hh
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+#ifndef __2BIT_LOCAL_PRED_HH__
+#define __2BIT_LOCAL_PRED_HH__
+
+// For Addr type.
+#include "arch/alpha/isa_traits.hh"
+
+class DefaultBP
+{
+ public:
+ /**
+ * Default branch predictor constructor.
+ */
+ DefaultBP(unsigned localPredictorSize, unsigned localCtrBits,
+ unsigned instShiftAmt);
+
+ /**
+ * Looks up the given address in the branch predictor and returns
+ * a true/false value as to whether it is taken.
+ * @param branch_addr The address of the branch to look up.
+ * @return Whether or not the branch is taken.
+ */
+ bool lookup(Addr &branch_addr);
+
+ /**
+ * Updates the branch predictor with the actual result of a branch.
+ * @param branch_addr The address of the branch to update.
+ * @param taken Whether or not the branch was taken.
+ */
+ void update(Addr &branch_addr, bool taken);
+
+ private:
+
+ inline bool getPrediction(uint8_t &count);
+
+ inline unsigned getLocalIndex(Addr &PC);
+
+ /**
+ * Private counter class for the internal saturating counters.
+ * Implements an n bit saturating counter and provides methods to
+ * increment, decrement, and read it.
+ * @todo Consider making this something that more closely mimics a
+ * built in class so you can use ++ or --.
+ */
+ class SatCounter
+ {
+ public:
+ /**
+ * Constructor for the counter.
+ * @param bits How many bits the counter will have.
+ */
+ SatCounter(unsigned bits);
+
+ /**
+ * Constructor for the counter.
+ * @param bits How many bits the counter will have.
+ * @param initial_val Starting value for each counter.
+ */
+ SatCounter(unsigned bits, unsigned initial_val);
+
+ /**
+ * Increments the counter's current value.
+ */
+ void increment();
+
+ /**
+ * Decrements the counter's current value.
+ */
+ void decrement();
+
+ /**
+ * Read the counter's value.
+ */
+ uint8_t read()
+ {
+ return counter;
+ }
+
+ private:
+ uint8_t maxVal;
+ uint8_t counter;
+ };
+
+ /** Array of counters that make up the local predictor. */
+ SatCounter *localCtrs;
+
+ /** Size of the local predictor. */
+ unsigned localPredictorSize;
+
+ /** Number of bits of the local predictor's counters. */
+ unsigned localCtrBits;
+
+ /** Number of bits to shift the PC when calculating index. */
+ unsigned instShiftAmt;
+
+ /** Mask to get index bits. */
+ unsigned indexMask;
+};
+
+#endif // __2BIT_LOCAL_PRED_HH__