From 0c50a0b4fe3956f9d2e08e75d47c9cbd79bf0268 Mon Sep 17 00:00:00 2001 From: Rekai Gonzalez-Alberquilla Date: Mon, 6 Feb 2017 11:10:06 +0000 Subject: 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 Reviewed-on: https://gem5-review.googlesource.com/c/13105 Reviewed-by: Andreas Sandberg Reviewed-by: Jason Lowe-Power Maintainer: Andreas Sandberg Maintainer: Jason Lowe-Power --- src/cpu/o3/commit.hh | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'src/cpu/o3/commit.hh') 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. */ -- cgit v1.2.3