From c7f1cf1d58cf50118c18b1afc4c938eafba81492 Mon Sep 17 00:00:00 2001
From: Gabe Black <gblack@eecs.umich.edu>
Date: Fri, 13 Apr 2007 13:59:31 +0000
Subject: Remove most of the special handling for delay slots since they have
 to be squashed anyway on a mispredict. This is because the NNPC value they
 saw when executing was incorrect.

--HG--
extra : convert_revision : b42c4eb28b4fbba66c65cbd0a5033bf886c1532d
---
 src/cpu/o3/decode_impl.hh | 65 +----------------------------------------------
 1 file changed, 1 insertion(+), 64 deletions(-)

(limited to 'src/cpu/o3/decode_impl.hh')

diff --git a/src/cpu/o3/decode_impl.hh b/src/cpu/o3/decode_impl.hh
index 314864f94..c9d0a1885 100644
--- a/src/cpu/o3/decode_impl.hh
+++ b/src/cpu/o3/decode_impl.hh
@@ -49,8 +49,6 @@ DefaultDecode<Impl>::DefaultDecode(O3CPU *_cpu, Params *params)
         stalls[i].rename = false;
         stalls[i].iew = false;
         stalls[i].commit = false;
-
-        squashAfterDelaySlot[i] = false;
     }
 
     // @todo: Make into a parameter
@@ -278,17 +276,12 @@ DefaultDecode<Impl>::squash(DynInstPtr &inst, unsigned tid)
 #if ISA_HAS_DELAY_SLOT
     toFetch->decodeInfo[tid].branchTaken = inst->readNextNPC() !=
         (inst->readNextPC() + sizeof(TheISA::MachInst));
-
-    toFetch->decodeInfo[tid].bdelayDoneSeqNum = bdelayDoneSeqNum[tid];
-    squashAfterDelaySlot[tid] = false;
-
-    InstSeqNum squash_seq_num = bdelayDoneSeqNum[tid];
 #else
     toFetch->decodeInfo[tid].branchTaken =
         inst->readNextPC() != (inst->readPC() + sizeof(TheISA::MachInst));
+#endif
 
     InstSeqNum squash_seq_num = inst->seqNum;
-#endif
 
     // Might have to tell fetch to unblock.
     if (decodeStatus[tid] == Blocked ||
@@ -309,30 +302,10 @@ DefaultDecode<Impl>::squash(DynInstPtr &inst, unsigned tid)
     // Clear the instruction list and skid buffer in case they have any
     // insts in them.
     while (!insts[tid].empty()) {
-
-#if ISA_HAS_DELAY_SLOT
-        if (insts[tid].front()->seqNum <= squash_seq_num) {
-            DPRINTF(Decode, "[tid:%i]: Cannot remove incoming decode "
-                    "instructions before delay slot [sn:%i]. %i insts"
-                    "left in decode.\n", tid, squash_seq_num,
-                    insts[tid].size());
-            break;
-        }
-#endif
         insts[tid].pop();
     }
 
     while (!skidBuffer[tid].empty()) {
-
-#if ISA_HAS_DELAY_SLOT
-        if (skidBuffer[tid].front()->seqNum <= squash_seq_num) {
-            DPRINTF(Decode, "[tid:%i]: Cannot remove skidBuffer "
-                    "instructions before delay slot [sn:%i]. %i insts"
-                    "left in decode.\n", tid, squash_seq_num,
-                    insts[tid].size());
-            break;
-        }
-#endif
         skidBuffer[tid].pop();
     }
 
@@ -760,48 +733,12 @@ DefaultDecode<Impl>::decodeInsts(unsigned tid)
 
                 // Might want to set some sort of boolean and just do
                 // a check at the end
-#if !ISA_HAS_DELAY_SLOT
                 squash(inst, inst->threadNumber);
                 Addr target = inst->branchTarget();
                 inst->setPredTarg(target, target + sizeof(TheISA::MachInst));
                 break;
-#else
-                // If mispredicted as taken, then ignore delay slot
-                // instruction... else keep delay slot and squash
-                // after it is sent to rename
-                if (inst->readPredTaken() && inst->isCondDelaySlot()) {
-                    DPRINTF(Decode, "[tid:%i]: Conditional delay slot inst."
-                            "[sn:%i] PC %#x mispredicted as taken.\n", tid,
-                            inst->seqNum, inst->PC);
-                    bdelayDoneSeqNum[tid] = inst->seqNum;
-                    squash(inst, inst->threadNumber);
-                    Addr target = inst->branchTarget();
-                    inst->setPredTarg(target,
-                            target + sizeof(TheISA::MachInst));
-                    break;
-                } else {
-                    DPRINTF(Decode, "[tid:%i]: Misprediction detected at "
-                            "[sn:%i] PC %#x, will squash after delay slot "
-                            "inst. is sent to Rename\n",
-                            tid, inst->seqNum, inst->PC);
-                    bdelayDoneSeqNum[tid] = inst->seqNum + 1;
-                    squashAfterDelaySlot[tid] = true;
-                    squashInst[tid] = inst;
-                    continue;
-                }
-#endif
             }
         }
-
-        if (squashAfterDelaySlot[tid]) {
-            assert(!inst->isSquashed());
-            squash(squashInst[tid], squashInst[tid]->threadNumber);
-            Addr target = squashInst[tid]->branchTarget();
-            squashInst[tid]->setPredTarg(target,
-                    target + sizeof(TheISA::MachInst));
-            assert(!inst->isSquashed());
-            break;
-        }
     }
 
     // If we didn't process all instructions, then we will need to block
-- 
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