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author | Nilay Vaish <nilay@cs.wisc.edu> | 2015-04-29 22:35:22 -0500 |
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committer | Nilay Vaish <nilay@cs.wisc.edu> | 2015-04-29 22:35:22 -0500 |
commit | 0dbd696aaef47205c1430b53841423c7d25455ed (patch) | |
tree | eada915ea9c506520042b57a1d011ec3fe18a149 /src/cpu/o3/FuncUnitConfig.py | |
parent | ee06fed656d404c19c68c838df1dc8dbba37ec80 (diff) | |
download | gem5-0dbd696aaef47205c1430b53841423c7d25455ed.tar.xz |
cpu: o3: single cycle default div microop latency on x86
This patch sets the default latency of the division microop to a single cycle
on x86. This is because the division instructions DIV and IDIV have been
implemented as loops of div microops, where each microop computes a single bit
of the quotient.
Diffstat (limited to 'src/cpu/o3/FuncUnitConfig.py')
-rw-r--r-- | src/cpu/o3/FuncUnitConfig.py | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/src/cpu/o3/FuncUnitConfig.py b/src/cpu/o3/FuncUnitConfig.py index 34c56163d..0f5efb776 100644 --- a/src/cpu/o3/FuncUnitConfig.py +++ b/src/cpu/o3/FuncUnitConfig.py @@ -39,6 +39,7 @@ # Authors: Kevin Lim from m5.SimObject import SimObject +from m5.defines import buildEnv from m5.params import * from FuncUnit import * @@ -49,6 +50,15 @@ class IntALU(FUDesc): class IntMultDiv(FUDesc): opList = [ OpDesc(opClass='IntMult', opLat=3), OpDesc(opClass='IntDiv', opLat=20, issueLat=19) ] + + # DIV and IDIV instructions in x86 are implemented using a loop which + # issues division microops. The latency of these microops should really be + # one (or a small number) cycle each since each of these computes one bit + # of the quotient. + if buildEnv['TARGET_ISA'] in ('x86'): + opList[1].opLat=1 + opList[1].issueLat=1 + count=2 class FP_ALU(FUDesc): |