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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/dep_graph.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/dep_graph.hh')
-rw-r--r-- | src/cpu/o3/dep_graph.hh | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/src/cpu/o3/dep_graph.hh b/src/cpu/o3/dep_graph.hh index 41ab6e94f..212130e2b 100644 --- a/src/cpu/o3/dep_graph.hh +++ b/src/cpu/o3/dep_graph.hh @@ -89,10 +89,10 @@ class DependencyGraph void reset(); /** Inserts an instruction to be dependent on the given index. */ - void insert(PhysRegIndex idx, DynInstPtr &new_inst); + void insert(PhysRegIndex idx, const DynInstPtr &new_inst); /** Sets the producing instruction of a given register. */ - void setInst(PhysRegIndex idx, DynInstPtr &new_inst) + void setInst(PhysRegIndex idx, const DynInstPtr &new_inst) { dependGraph[idx].inst = new_inst; } /** Clears the producing instruction. */ @@ -100,7 +100,7 @@ class DependencyGraph { dependGraph[idx].inst = NULL; } /** Removes an instruction from a single linked list. */ - void remove(PhysRegIndex idx, DynInstPtr &inst_to_remove); + void remove(PhysRegIndex idx, const DynInstPtr &inst_to_remove); /** Removes and returns the newest dependent of a specific register. */ DynInstPtr pop(PhysRegIndex idx); @@ -182,7 +182,8 @@ DependencyGraph<DynInstPtr>::reset() template <class DynInstPtr> void -DependencyGraph<DynInstPtr>::insert(PhysRegIndex idx, DynInstPtr &new_inst) +DependencyGraph<DynInstPtr>::insert(PhysRegIndex idx, + const DynInstPtr &new_inst) { //Add this new, dependent instruction at the head of the dependency //chain. @@ -203,7 +204,7 @@ DependencyGraph<DynInstPtr>::insert(PhysRegIndex idx, DynInstPtr &new_inst) template <class DynInstPtr> void DependencyGraph<DynInstPtr>::remove(PhysRegIndex idx, - DynInstPtr &inst_to_remove) + const DynInstPtr &inst_to_remove) { DepEntry *prev = &dependGraph[idx]; DepEntry *curr = dependGraph[idx].next; |