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cpu: Fixed PC shifting on LTAGE branch predictor

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The PC needs to be shifted according to the instShiftAmt parameter

Change-Id: I272619c093695b56cf7f8ff7163e3b5d23205d16
Signed-off-by: Pau Cabre <pau.cabre@metempsy.com>
Reviewed-on: https://gem5-review.googlesource.com/c/14035
Reviewed-by: Sudhanshu Jha <sudhanshu.jha@arm.com>
Reviewed-by: Ilias Vougioukas <ilias.vougioukas@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
This commit is contained in:
Pau Cabre
2018-11-07 23:32:55 +01:00
parent 2f52a9b65e
commit f3016e6846
1 changed files with 10 additions and 7 deletions
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17
src/cpu/pred/ltage.cc
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@@ -138,13 +138,14 @@ LTAGE::LTAGE(const LTAGEParams *params)
int
LTAGE::bindex(Addr pc_in) const
{
return ((pc_in) & ((ULL(1) << (logSizeBiMP)) - 1));
return ((pc_in >> instShiftAmt) & ((ULL(1) << (logSizeBiMP)) - 1));
}
int
LTAGE::lindex(Addr pc_in) const
{
return (((pc_in) & ((ULL(1) << (logSizeLoopPred - 2)) - 1)) << 2);
return (((pc_in >> instShiftAmt) &
((ULL(1) << (logSizeLoopPred - 2)) - 1)) << 2);
}
int
@@ -171,7 +172,8 @@ LTAGE::gindex(ThreadID tid, Addr pc, int bank) const
int index;
int hlen = (histLengths[bank] > 16) ? 16 : histLengths[bank];
index =
(pc) ^ ((pc) >> ((int) abs(tagTableSizes[bank] - bank) + 1)) ^
(pc >> instShiftAmt) ^
((pc >> instShiftAmt) >> ((int) abs(tagTableSizes[bank] - bank) + 1)) ^
threadHistory[tid].computeIndices[bank].comp ^
F(threadHistory[tid].pathHist, hlen, bank);
@@ -183,8 +185,9 @@ LTAGE::gindex(ThreadID tid, Addr pc, int bank) const
uint16_t
LTAGE::gtag(ThreadID tid, Addr pc, int bank) const
{
int tag = (pc) ^ threadHistory[tid].computeTags[0][bank].comp
^ (threadHistory[tid].computeTags[1][bank].comp << 1);
int tag = (pc >> instShiftAmt) ^
threadHistory[tid].computeTags[0][bank].comp ^
(threadHistory[tid].computeTags[1][bank].comp << 1);
return (tag & ((ULL(1) << tagWidths[bank]) - 1));
}
@@ -239,7 +242,7 @@ LTAGE::getLoop(Addr pc, BranchInfo* bi) const
bi->loopHit = -1;
bi->loopPredValid = false;
bi->loopIndex = lindex(pc);
bi->loopTag = ((pc) >> (logSizeLoopPred - 2));
bi->loopTag = ((pc) >> (instShiftAmt + logSizeLoopPred - 2));
for (int i = 0; i < 4; i++) {
if (ltable[bi->loopIndex + i].tag == bi->loopTag) {
@@ -630,7 +633,7 @@ LTAGE::updateHistories(ThreadID tid, Addr branch_pc, bool taken, void* b)
BranchInfo* bi = (BranchInfo*)(b);
ThreadHistory& tHist = threadHistory[tid];
// UPDATE HISTORIES
bool pathbit = ((branch_pc) & 1);
bool pathbit = ((branch_pc >> instShiftAmt) & 1);
//on a squash, return pointers to this and recompute indices.
//update user history
updateGHist(tHist.gHist, taken, tHist.globalHistory, tHist.ptGhist);