invisispec-1.0 source

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+/*
+ * Copyright (c) 2011, 2014 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Copyright (c) 2004-2006 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Kevin Lim
+ *          Timothy M. Jones
+ */
+
+#ifndef __CPU_PRED_STATIC_PRED_HH__
+#define __CPU_PRED_STATIC_PRED_HH__
+
+#include <vector>
+
+#include "base/types.hh"
+#include "cpu/pred/bpred_unit.hh"
+#include "params/StaticBP.hh"
+
+/**
+ * Implements a local predictor that uses the PC to index into a table of
+ * counters.  Note that any time a pointer to the bp_history is given, it
+ * should be NULL using this predictor because it does not have any branch
+ * predictor state that needs to be recorded or updated; the update can be
+ * determined solely by the branch being taken or not taken.
+ */
+class StaticBP : public BPredUnit
+{
+  public:
+    /**
+     * Default branch predictor constructor.
+     */
+    StaticBP(const StaticBPParams *params);
+
+    virtual void uncondBranch(ThreadID tid, Addr pc, void * &bp_history);
+
+    /**
+     * 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.
+     * @param bp_history Pointer to any bp history state.
+     * @return Whether or not the branch is taken.
+     */
+    bool lookup(ThreadID tid, Addr branch_addr, void * &bp_history);
+
+    /**
+     * Updates the branch predictor to Not Taken if a BTB entry is
+     * invalid or not found.
+     * @param branch_addr The address of the branch to look up.
+     * @param bp_history Pointer to any bp history state.
+     * @return Whether or not the branch is taken.
+     */
+    void btbUpdate(ThreadID tid, Addr branch_addr, void * &bp_history);
+
+    /**
+     * 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(ThreadID tid, Addr branch_addr, bool taken, void *bp_history,
+                bool squashed)
+    { assert(bp_history == NULL); }
+
+    void squash(ThreadID tid, void *bp_history)
+    { assert(bp_history == NULL); }
+
+  private:
+    /** Static prediction. */
+    bool staticPrediction;
+};
+
+#endif // __CPU_PRED_STATIC_PRED_HH__