From 30143baf7e35a73acaff1d02cf71278248a86515 Mon Sep 17 00:00:00 2001 From: Ali Saidi Date: Thu, 17 Mar 2011 19:20:19 -0500 Subject: [PATCH] O3: Cleanup the commitInfo comm struct. Get rid of unused members and use base types rather than derrived values where possible to limit amount of state. --- src/cpu/o3/comm.hh | 57 ++++++++++++++++++++++++++++----------- src/cpu/o3/commit.hh | 3 ++- src/cpu/o3/commit_impl.hh | 28 +++++++++++-------- src/cpu/o3/fetch_impl.hh | 7 ++--- src/cpu/o3/iew_impl.hh | 6 ++--- 5 files changed, 64 insertions(+), 37 deletions(-) diff --git a/src/cpu/o3/comm.hh b/src/cpu/o3/comm.hh index 897807fdb..840dde9ea 100644 --- a/src/cpu/o3/comm.hh +++ b/src/cpu/o3/comm.hh @@ -1,4 +1,16 @@ /* + * Copyright (c) 2011 ARM Limited + * All rights reserved + * + * The license below extends only to copyright in the software and shall + * not be construed as granting a license to any other intellectual + * property including but not limited to intellectual property relating + * to a hardware implementation of the functionality of the software + * licensed hereunder. You may use the software subject to the license + * terms below provided that you ensure that this notice is replicated + * unmodified and in its entirety in all distributions of the software, + * modified or unmodified, in source code or in binary form. + * * Copyright (c) 2004-2006 The Regents of The University of Michigan * All rights reserved. * @@ -123,7 +135,6 @@ struct TimeBufStruct { bool branchTaken; Addr mispredPC; TheISA::PCState nextPC; - unsigned branchCount; }; @@ -151,29 +162,45 @@ struct TimeBufStruct { iewComm iewInfo[Impl::MaxThreads]; struct commitComm { - bool usedROB; - unsigned freeROBEntries; - bool emptyROB; + /////////////// For Decode, IEW, Rename, Fetch /////////// bool squash; bool robSquashing; - bool branchMispredict; - DynInstPtr mispredictInst; - bool branchTaken; - Addr mispredPC; - TheISA::PCState pc; - + ////////// For Fetch & IEW ///////////// // Represents the instruction that has either been retired or // squashed. Similar to having a single bus that broadcasts the // retired or squashed sequence number. InstSeqNum doneSeqNum; - //Just in case we want to do a commit/squash on a cycle - //(necessary for multiple ROBs?) - bool commitInsts; - InstSeqNum squashSeqNum; + ////////////// For Rename ///////////////// + // Rename should re-read number of free rob entries + bool usedROB; + // Notify Rename that the ROB is empty + bool emptyROB; + // Tell Rename how many free entries it has in the ROB + unsigned freeROBEntries; + + + ///////////// For Fetch ////////////////// + // Provide fetch the instruction that mispredicted, if this + // pointer is not-null a misprediction occured + DynInstPtr mispredictInst; + // Was the branch taken or not + bool branchTaken; + // The pc of the next instruction to execute. This is the next + // instruction for a branch mispredict, but the same instruction for + // order violation and the like + TheISA::PCState pc; + + // Instruction that caused the a non-mispredict squash + DynInstPtr squashInst; + // If an interrupt is pending and fetch should stall + bool interruptPending; + // If the interrupt ended up being cleared before being handled + bool clearInterrupt; + //////////// For IEW ////////////////// // Communication specifically to the IQ to tell the IQ that it can // schedule a non-speculative instruction. InstSeqNum nonSpecSeqNum; @@ -182,8 +209,6 @@ struct TimeBufStruct { bool uncached; DynInstPtr uncachedLoad; - bool interruptPending; - bool clearInterrupt; }; commitComm commitInfo[Impl::MaxThreads]; diff --git a/src/cpu/o3/commit.hh b/src/cpu/o3/commit.hh index 047e29f5d..ff7b53440 100644 --- a/src/cpu/o3/commit.hh +++ b/src/cpu/o3/commit.hh @@ -262,7 +262,8 @@ class DefaultCommit * instructions instead of the current instruction and doesn't * clean up various status bits about traps/tc writes pending. */ - void squashAfter(ThreadID tid, uint64_t squash_after_seq_num); + void squashAfter(ThreadID tid, DynInstPtr &head_inst, + uint64_t squash_after_seq_num); #if FULL_SYSTEM /** Handles processing an interrupt. */ diff --git a/src/cpu/o3/commit_impl.hh b/src/cpu/o3/commit_impl.hh index 104e7fb58..8c651e203 100644 --- a/src/cpu/o3/commit_impl.hh +++ b/src/cpu/o3/commit_impl.hh @@ -541,8 +541,8 @@ DefaultCommit::squashAll(ThreadID tid) // the ROB is in the process of squashing. toIEW->commitInfo[tid].robSquashing = true; - toIEW->commitInfo[tid].branchMispredict = false; toIEW->commitInfo[tid].mispredictInst = NULL; + toIEW->commitInfo[tid].squashInst = NULL; toIEW->commitInfo[tid].pc = pc[tid]; } @@ -584,7 +584,8 @@ DefaultCommit::squashFromTC(ThreadID tid) template void -DefaultCommit::squashAfter(ThreadID tid, uint64_t squash_after_seq_num) +DefaultCommit::squashAfter(ThreadID tid, DynInstPtr &head_inst, + uint64_t squash_after_seq_num) { youngestSeqNum[tid] = squash_after_seq_num; @@ -594,6 +595,7 @@ DefaultCommit::squashAfter(ThreadID tid, uint64_t squash_after_seq_num) // Send back the sequence number of the squashed instruction. toIEW->commitInfo[tid].doneSeqNum = squash_after_seq_num; + toIEW->commitInfo[tid].squashInst = head_inst; // Send back the squash signal to tell stages that they should squash. toIEW->commitInfo[tid].squash = true; @@ -601,7 +603,7 @@ DefaultCommit::squashAfter(ThreadID tid, uint64_t squash_after_seq_num) // the ROB is in the process of squashing. toIEW->commitInfo[tid].robSquashing = true; - toIEW->commitInfo[tid].branchMispredict = false; + toIEW->commitInfo[tid].mispredictInst = NULL; toIEW->commitInfo[tid].pc = pc[tid]; DPRINTF(Commit, "Executing squash after for [tid:%i] inst [sn:%lli]\n", @@ -801,10 +803,17 @@ DefaultCommit::commit() commitStatus[tid] != TrapPending && fromIEW->squashedSeqNum[tid] <= youngestSeqNum[tid]) { - DPRINTF(Commit, "[tid:%i]: Squashing due to PC %#x [sn:%i]\n", + if (fromIEW->mispredictInst[tid]) { + DPRINTF(Commit, + "[tid:%i]: Squashing due to branch mispred PC:%#x [sn:%i]\n", tid, - fromIEW->mispredPC[tid], + fromIEW->mispredictInst[tid]->instAddr(), fromIEW->squashedSeqNum[tid]); + } else { + DPRINTF(Commit, + "[tid:%i]: Squashing due to order violation [sn:%i]\n", + tid, fromIEW->squashedSeqNum[tid]); + } DPRINTF(Commit, "[tid:%i]: Redirecting to PC %#x\n", tid, @@ -835,18 +844,15 @@ DefaultCommit::commit() // the ROB is in the process of squashing. toIEW->commitInfo[tid].robSquashing = true; - toIEW->commitInfo[tid].branchMispredict = - fromIEW->branchMispredict[tid]; toIEW->commitInfo[tid].mispredictInst = fromIEW->mispredictInst[tid]; toIEW->commitInfo[tid].branchTaken = fromIEW->branchTaken[tid]; + toIEW->commitInfo[tid].squashInst = NULL; toIEW->commitInfo[tid].pc = fromIEW->pc[tid]; - toIEW->commitInfo[tid].mispredPC = fromIEW->mispredPC[tid]; - - if (toIEW->commitInfo[tid].branchMispredict) { + if (toIEW->commitInfo[tid].mispredictInst) { ++branchMispredicts; } } @@ -988,7 +994,7 @@ DefaultCommit::commitInsts() // If this is an instruction that doesn't play nicely with // others squash everything and restart fetch if (head_inst->isSquashAfter()) - squashAfter(tid, head_inst->seqNum); + squashAfter(tid, head_inst, head_inst->seqNum); int count = 0; Addr oldpc; diff --git a/src/cpu/o3/fetch_impl.hh b/src/cpu/o3/fetch_impl.hh index 3092bd937..5f9be039f 100644 --- a/src/cpu/o3/fetch_impl.hh +++ b/src/cpu/o3/fetch_impl.hh @@ -934,15 +934,12 @@ DefaultFetch::checkSignalsAndUpdate(ThreadID tid) // In any case, squash. squash(fromCommit->commitInfo[tid].pc, fromCommit->commitInfo[tid].doneSeqNum, - tid); + fromCommit->commitInfo[tid].squashInst, tid); // If it was a branch mispredict on a control instruction, update the // branch predictor with that instruction, otherwise just kill the // invalid state we generated in after sequence number - assert(!fromCommit->commitInfo[tid].branchMispredict || - fromCommit->commitInfo[tid].mispredictInst); - - if (fromCommit->commitInfo[tid].branchMispredict && + if (fromCommit->commitInfo[tid].mispredictInst && fromCommit->commitInfo[tid].mispredictInst->isControl()) { branchPred.squash(fromCommit->commitInfo[tid].doneSeqNum, fromCommit->commitInfo[tid].pc, diff --git a/src/cpu/o3/iew_impl.hh b/src/cpu/o3/iew_impl.hh index dff287ff5..8bf3c56f4 100644 --- a/src/cpu/o3/iew_impl.hh +++ b/src/cpu/o3/iew_impl.hh @@ -456,8 +456,6 @@ DefaultIEW::squashDueToBranch(DynInstPtr &inst, ThreadID tid) inst->seqNum < toCommit->squashedSeqNum[tid]) { toCommit->squash[tid] = true; toCommit->squashedSeqNum[tid] = inst->seqNum; - toCommit->mispredPC[tid] = inst->instAddr(); - toCommit->branchMispredict[tid] = true; toCommit->branchTaken[tid] = inst->pcState().branching(); TheISA::PCState pc = inst->pcState(); @@ -486,7 +484,7 @@ DefaultIEW::squashDueToMemOrder(DynInstPtr &inst, ThreadID tid) TheISA::PCState pc = inst->pcState(); TheISA::advancePC(pc, inst->staticInst); toCommit->pc[tid] = pc; - toCommit->branchMispredict[tid] = false; + toCommit->mispredictInst[tid] = NULL; toCommit->includeSquashInst[tid] = false; @@ -506,7 +504,7 @@ DefaultIEW::squashDueToMemBlocked(DynInstPtr &inst, ThreadID tid) toCommit->squashedSeqNum[tid] = inst->seqNum; toCommit->pc[tid] = inst->pcState(); - toCommit->branchMispredict[tid] = false; + toCommit->mispredictInst[tid] = NULL; // Must include the broadcasted SN in the squash. toCommit->includeSquashInst[tid] = true; -- 2.30.2