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authorRekai Gonzalez-Alberquilla <rekai.gonzalezalberquilla@arm.com>2017-02-06 11:10:06 +0000
committerGiacomo Gabrielli <giacomo.gabrielli@arm.com>2018-11-16 10:39:03 +0000
commit0c50a0b4fe3956f9d2e08e75d47c9cbd79bf0268 (patch)
tree7679abe2343e0504c93eb73d09635d546a211455 /src/cpu/o3/commit.hh
parent338a173e822298bd22741342a7b24352450afdd1 (diff)
downloadgem5-0c50a0b4fe3956f9d2e08e75d47c9cbd79bf0268.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.hh')
-rw-r--r--src/cpu/o3/commit.hh6
1 files changed, 3 insertions, 3 deletions
diff --git a/src/cpu/o3/commit.hh b/src/cpu/o3/commit.hh
index f508a372e..b74917da3 100644
--- a/src/cpu/o3/commit.hh
+++ b/src/cpu/o3/commit.hh
@@ -282,7 +282,7 @@ class DefaultCommit
* @param tid ID of the thread to squash.
* @param head_inst Instruction that requested the squash.
*/
- void squashAfter(ThreadID tid, DynInstPtr &head_inst);
+ void squashAfter(ThreadID tid, const DynInstPtr &head_inst);
/** Handles processing an interrupt. */
void handleInterrupt();
@@ -296,7 +296,7 @@ class DefaultCommit
/** Tries to commit the head ROB instruction passed in.
* @param head_inst The instruction to be committed.
*/
- bool commitHead(DynInstPtr &head_inst, unsigned inst_num);
+ bool commitHead(const DynInstPtr &head_inst, unsigned inst_num);
/** Gets instructions from rename and inserts them into the ROB. */
void getInsts();
@@ -477,7 +477,7 @@ class DefaultCommit
bool avoidQuiesceLiveLock;
/** Updates commit stats based on this instruction. */
- void updateComInstStats(DynInstPtr &inst);
+ void updateComInstStats(const DynInstPtr &inst);
/** Stat for the total number of squashed instructions discarded by commit.
*/