1/*
2 * Copyright (c) 2014 The University of Wisconsin
3 *
4 * Copyright (c) 2006 INRIA (Institut National de Recherche en
5 * Informatique et en Automatique / French National Research Institute
6 * for Computer Science and Applied Mathematics)
7 *
8 * All rights reserved.

--- 52 unchanged lines hidden (view full) ---

61
62class LTAGE: public TAGE
63{
64 public:
65 LTAGE(const LTAGEParams *params);
66
67 // Base class methods.
68 void squash(ThreadID tid, void *bp_history) override;
69 void update(ThreadID tid, Addr branch_addr, bool taken, void *bp_history,
70 bool squashed, const StaticInstPtr & inst,
71 Addr corrTarget) override;
72
73 void regStats() override;
74
75 private:
76 // Prediction Structures
77 // Loop Predictor Entry
78 struct LoopEntry
79 {

--- 6 unchanged lines hidden (view full) ---

86 bool dir; // only for useDirectionBit
87
88 LoopEntry() : numIter(0), currentIter(0), currentIterSpec(0),
89 confidence(0), tag(0), age(0), dir(0) { }
90 };
91
92 // more provider types
93 enum {
94 LOOP = TAGEBase::LAST_TAGE_PROVIDER_TYPE + 1
95 };
96
97 // Primary branch history entry
98 struct LTageBranchInfo : public TageBranchInfo
99 {
100 uint16_t loopTag;
101 uint16_t currentIter;
102
103 bool loopPred;
104 bool loopPredValid;
105 int loopIndex;
106 int loopLowPcBits; // only for useHashing
107 int loopHit;
108
109 LTageBranchInfo(TAGEBase &tage)
110 : TageBranchInfo(tage),
111 loopTag(0), currentIter(0),
112 loopPred(false),
113 loopPredValid(false), loopIndex(0), loopLowPcBits(0), loopHit(0)
114 {}
115
116 virtual ~LTageBranchInfo()
117 {}
118 };
119
120 /**
121 * Computes the index used to access the
122 * loop predictor.
123 * @param pc_in The unshifted branch PC.
124 */
125 int lindex(Addr pc_in) const;

--- 32 unchanged lines hidden (view full) ---

158 * iteration count (only for useSpeculation).
159 * @param taken The predicted branch outcome.
160 * @param bi Pointer to information on the prediction
161 * recorded at prediction time.
162 */
163 void specLoopUpdate(bool taken, LTageBranchInfo* bi);
164
165 /**
166 * Get a branch prediction from LTAGE. *NOT* an override of
167 * BpredUnit::predict().
168 * @param tid The thread ID to select the global
169 * histories to use.
170 * @param branch_pc The unshifted branch PC.
171 * @param cond_branch True if the branch is conditional.
172 * @param b Reference to wrapping pointer to allow storing
173 * derived class prediction information in the base class.
174 */
175 bool predict(
176 ThreadID tid, Addr branch_pc, bool cond_branch, void* &b) override;
177
178 /**
179 * Restores speculatively updated path and direction histories.
180 * Also recomputes compressed (folded) histories based on the
181 * correct branch outcome.
182 * @param bi Branch information.
183 */
184 void squashLoop(LTageBranchInfo * bi);
185
186 const unsigned logSizeLoopPred;
187 const unsigned loopTableAgeBits;
188 const unsigned loopTableConfidenceBits;
189 const unsigned loopTableTagBits;
190 const unsigned loopTableIterBits;
191 const unsigned logLoopTableAssoc;
192 const uint8_t confidenceThreshold;
193 const uint16_t loopTagMask;

--- 18 unchanged lines hidden ---