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author | Rekai Gonzalez-Alberquilla <rekai.gonzalezalberquilla@arm.com> | 2017-02-06 11:10:06 +0000 |
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committer | Giacomo Gabrielli <giacomo.gabrielli@arm.com> | 2018-11-16 10:39:03 +0000 |
commit | 0c50a0b4fe3956f9d2e08e75d47c9cbd79bf0268 (patch) | |
tree | 7679abe2343e0504c93eb73d09635d546a211455 /src/cpu/o3/commit_impl.hh | |
parent | 338a173e822298bd22741342a7b24352450afdd1 (diff) | |
download | gem5-0c50a0b4fe3956f9d2e08e75d47c9cbd79bf0268.tar.xz |
cpu: Fix the usage of const DynInstPtr
Summary: Usage of const DynInstPtr& when possible and introduction of
move operators to RefCountingPtr.
In many places, scoped references to dynamic instructions do a copy of
the DynInstPtr when a reference would do. This is detrimental to
performance. On top of that, in case there is a need for reference
tracking for debugging, the redundant copies make the process much more
painful than it already is.
Also, from the theoretical point of view, a function/method that
defines a convenience name to access an instruction should not be
considered an owner of the data, i.e., doing a copy and not a reference
is not justified.
On a related topic, C++11 introduces move semantics, and those are
useful when, for example, there is a class modelling a HW structure that
contains a list, and has a getHeadOfList function, to prevent doing a
copy to an internal variable -> update pointer, remove from the list ->
update pointer, return value making a copy to the assined variable ->
update pointer, destroy the returned value -> update pointer.
Change-Id: I3bb46c20ef23b6873b469fd22befb251ac44d2f6
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/13105
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Diffstat (limited to 'src/cpu/o3/commit_impl.hh')
-rw-r--r-- | src/cpu/o3/commit_impl.hh | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/src/cpu/o3/commit_impl.hh b/src/cpu/o3/commit_impl.hh index d32493cbc..8fd142c08 100644 --- a/src/cpu/o3/commit_impl.hh +++ b/src/cpu/o3/commit_impl.hh @@ -636,7 +636,7 @@ DefaultCommit<Impl>::squashFromSquashAfter(ThreadID tid) template <class Impl> void -DefaultCommit<Impl>::squashAfter(ThreadID tid, DynInstPtr &head_inst) +DefaultCommit<Impl>::squashAfter(ThreadID tid, const DynInstPtr &head_inst) { DPRINTF(Commit, "Executing squash after for [tid:%i] inst [sn:%lli]\n", tid, head_inst->seqNum); @@ -696,14 +696,14 @@ DefaultCommit<Impl>::tick() // will be active. _nextStatus = Active; - DynInstPtr inst = rob->readHeadInst(tid); + const DynInstPtr &inst M5_VAR_USED = rob->readHeadInst(tid); DPRINTF(Commit,"[tid:%i]: Instruction [sn:%lli] PC %s is head of" " ROB and ready to commit\n", tid, inst->seqNum, inst->pcState()); } else if (!rob->isEmpty(tid)) { - DynInstPtr inst = rob->readHeadInst(tid); + const DynInstPtr &inst = rob->readHeadInst(tid); ppCommitStall->notify(inst); @@ -1136,7 +1136,7 @@ DefaultCommit<Impl>::commitInsts() template <class Impl> bool -DefaultCommit<Impl>::commitHead(DynInstPtr &head_inst, unsigned inst_num) +DefaultCommit<Impl>::commitHead(const DynInstPtr &head_inst, unsigned inst_num) { assert(head_inst); @@ -1317,9 +1317,7 @@ DefaultCommit<Impl>::getInsts() int insts_to_process = std::min((int)renameWidth, fromRename->size); for (int inst_num = 0; inst_num < insts_to_process; ++inst_num) { - DynInstPtr inst; - - inst = fromRename->insts[inst_num]; + const DynInstPtr &inst = fromRename->insts[inst_num]; ThreadID tid = inst->threadNumber; if (!inst->isSquashed() && @@ -1366,7 +1364,7 @@ DefaultCommit<Impl>::markCompletedInsts() template <class Impl> void -DefaultCommit<Impl>::updateComInstStats(DynInstPtr &inst) +DefaultCommit<Impl>::updateComInstStats(const DynInstPtr &inst) { ThreadID tid = inst->threadNumber; @@ -1507,7 +1505,7 @@ DefaultCommit<Impl>::oldestReady() if (rob->isHeadReady(tid)) { - DynInstPtr head_inst = rob->readHeadInst(tid); + const DynInstPtr &head_inst = rob->readHeadInst(tid); if (first) { oldest = tid; |