cpu: Fixes on the loop predictor part of LTAGE

Fixed the following fields of the loop predictor entries as described on
the LTAGE paper:
 - Age counter (it was 3 bits and it should be 8 bits)
 - Tag (it was 16 bits and it should be 14 bits). Also some times it used
   int variables and some times uint16_t, leading to wrong behaviour
 - Confidence counter (it was 2 bits ins some parts of the code and 3 bits
   in some other parts. It should be 2 bits)
 - Iteration counters (they were 16 bits and they should be 14 bits)
All the new sizes are now configurable

Change-Id: I8884c7454c1e510b65160eb4d5749d3259d34096
Signed-off-by: Pau Cabre <pau.cabre@metempsy.com>
Reviewed-on: https://gem5-review.googlesource.com/c/14216
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/cpu/pred/BranchPredictor.py b/src/cpu/pred/BranchPredictor.py
index 1eeecde95..a42819419 100644
--- a/src/cpu/pred/BranchPredictor.py
+++ b/src/cpu/pred/BranchPredictor.py
@@ -106,3 +106,9 @@ class LTAGE(BranchPredictor):
     maxHist = Param.Unsigned(640, "Maximum history size of LTAGE")
     minTagWidth = Param.Unsigned(7, "Minimum tag size in tag tables")
 
+    loopTableAgeBits = Param.Unsigned(8, "Number of age bits per loop entry")
+    loopTableConfidenceBits = Param.Unsigned(2,
+            "Number of confidence bits per loop entry")
+    loopTableTagBits = Param.Unsigned(14, "Number of tag bits per loop entry")
+    loopTableIterBits = Param.Unsigned(14, "Nuber of iteration bits per loop")
+