changeset c9b1a0ed2311 in /z/repo/m5
details: http://repo.m5sim.org/m5?cmd=changeset;node=c9b1a0ed2311
description:
inorder: timing for inst forwarding
when insts execute, they mark the time they finish to be used for
subsequent isnts
they may need forwarding of data. However, the regdepmap was using the
wrong
value to index into the destination operands of the instruction to be
forwarded.
Thus, in some cases, we are checking to see if the 3rd destination
register
for an instruction is executed at a certain time, when there is only 1
dest. register
valid. Thus, we get a bad, uninitialized time value that will stall
forwarding
causing performance loss but still the correct execution.
diffstat:
4 files changed, 30 insertions(+), 10 deletions(-)
src/cpu/inorder/inorder_dyn_inst.cc | 15 +++++++++++++--
src/cpu/inorder/reg_dep_map.cc | 20 +++++++++++++++-----
src/cpu/inorder/reg_dep_map.hh | 2 +-
src/cpu/inorder/resources/use_def.cc | 3 +--
diffs (112 lines):
diff -r ad784e759a74 -r c9b1a0ed2311 src/cpu/inorder/inorder_dyn_inst.cc
--- a/src/cpu/inorder/inorder_dyn_inst.cc Fri Apr 02 15:28:22 2010 -0700
+++ b/src/cpu/inorder/inorder_dyn_inst.cc Sat Apr 10 23:31:36 2010 -0400
@@ -534,6 +534,10 @@
instResult[idx].type = Integer;
instResult[idx].val.integer = val;
instResult[idx].tick = curTick;
+
+ DPRINTF(InOrderDynInst, "[tid:%i]: [sn:%i] Setting Result Int Reg. %i "
+ "being set to %#x (result-tick:%i).\n",
+ threadNumber, seqNum, idx, val, instResult[idx].tick);
}
/** Sets a FP register. */
@@ -542,8 +546,11 @@
{
instResult[idx].val.dbl = val;
instResult[idx].type = Float;
+ instResult[idx].tick = curTick;
- instResult[idx].tick = curTick;
+ DPRINTF(InOrderDynInst, "[tid:%i]: [sn:%i] Setting Result Float Reg. %i "
+ "being set to %#x (result-tick:%i).\n",
+ threadNumber, seqNum, idx, val, instResult[idx].tick);
}
/** Sets a FP register as a integer. */
@@ -554,6 +561,10 @@
instResult[idx].type = Integer;
instResult[idx].val.integer = val;
instResult[idx].tick = curTick;
+
+ DPRINTF(InOrderDynInst, "[tid:%i]: [sn:%i] Setting Result Float Reg. %i "
+ "being set to %#x (result-tick:%i).\n",
+ threadNumber, seqNum, idx, val, instResult[idx].tick);
}
/** Sets a misc. register. */
@@ -655,7 +666,7 @@
storeData = data;
DPRINTF(InOrderDynInst, "[tid:%i]: [sn:%i] Setting store data to %#x.\n",
- threadNumber, seqNum, memData);
+ threadNumber, seqNum, storeData);
return cpu->write(this, data, addr, flags, res);
}
diff -r ad784e759a74 -r c9b1a0ed2311 src/cpu/inorder/reg_dep_map.cc
--- a/src/cpu/inorder/reg_dep_map.cc Fri Apr 02 15:28:22 2010 -0700
+++ b/src/cpu/inorder/reg_dep_map.cc Sat Apr 10 23:31:36 2010 -0400
@@ -161,7 +161,7 @@
}
ThePipeline::DynInstPtr
-RegDepMap::canForward(unsigned reg_idx, unsigned src_idx, DynInstPtr inst)
+RegDepMap::canForward(unsigned reg_idx, DynInstPtr inst)
{
std::list<DynInstPtr>::iterator list_it = regMap[reg_idx].begin();
std::list<DynInstPtr>::iterator list_end = regMap[reg_idx].end();
@@ -176,13 +176,23 @@
}
if (forward_inst) {
+ int dest_reg_idx = forward_inst->getDestIdxNum(reg_idx);
+ assert(dest_reg_idx != -1);
+
if (forward_inst->isExecuted() &&
- forward_inst->readResultTime(src_idx) < curTick) {
+ forward_inst->readResultTime(dest_reg_idx) < curTick) {
return forward_inst;
} else {
- DPRINTF(RegDepMap, "[sn:%i] Can't get value through forwarding, "
- " [sn:%i] has not been executed yet.\n",
- inst->seqNum, forward_inst->seqNum);
+ if (!forward_inst->isExecuted()) {
+ DPRINTF(RegDepMap, "[sn:%i] Can't get value through
forwarding, "
+ " [sn:%i] has not been executed yet.\n",
+ inst->seqNum, forward_inst->seqNum);
+ } else if (forward_inst->readResultTime(dest_reg_idx) >= curTick) {
+ DPRINTF(RegDepMap, "[sn:%i] Can't get value through
forwarding, "
+ " [sn:%i] executed on tick:%i.\n",
+ inst->seqNum, forward_inst->seqNum,
forward_inst->readResultTime(dest_reg_idx));
+ }
+
return NULL;
}
} else {
diff -r ad784e759a74 -r c9b1a0ed2311 src/cpu/inorder/reg_dep_map.hh
--- a/src/cpu/inorder/reg_dep_map.hh Fri Apr 02 15:28:22 2010 -0700
+++ b/src/cpu/inorder/reg_dep_map.hh Sat Apr 10 23:31:36 2010 -0400
@@ -77,7 +77,7 @@
/** Is the current instruction able to get a forwarded value from another
instruction
* for this destination register? */
- DynInstPtr canForward(unsigned reg_idx, unsigned src_idx, DynInstPtr inst);
+ DynInstPtr canForward(unsigned reg_idx, DynInstPtr inst);
/** find an instruction to forward/bypass a value from */
DynInstPtr findBypassInst(unsigned idx);
diff -r ad784e759a74 -r c9b1a0ed2311 src/cpu/inorder/resources/use_def.cc
--- a/src/cpu/inorder/resources/use_def.cc Fri Apr 02 15:28:22 2010 -0700
+++ b/src/cpu/inorder/resources/use_def.cc Sat Apr 10 23:31:36 2010 -0400
@@ -196,8 +196,7 @@
} else {
// Look for forwarding opportunities
- DynInstPtr forward_inst = regDepMap[tid]->canForward(reg_idx,
- ud_idx,
+ DynInstPtr forward_inst = regDepMap[tid]->canForward(reg_idx,
inst);
if (forward_inst) {
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