blob: 6f9b9eedcb27596cd30602f0d931ad460b419af9 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
|
#ifndef __CPU_BETA_CPU_2BIT_LOCAL_PRED_HH__
#define __CPU_BETA_CPU_2BIT_LOCAL_PRED_HH__
// For Addr type.
#include "arch/alpha/isa_traits.hh"
#include "cpu/beta_cpu/sat_counter.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:
/** Returns the taken/not taken prediction given the value of the
* counter.
*/
inline bool getPrediction(uint8_t &count);
/** Calculates the local index based on the PC. */
inline unsigned getLocalIndex(Addr &PC);
/** 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 // __CPU_BETA_CPU_2BIT_LOCAL_PRED_HH__
|
