- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄373017 > BENCHMARKING Benchmarking the Am186EM: Using the Dhrystone V2.1 As An Example Application Note? 1.66MB (PDF) PDF資料下載
參數(shù)資料
| 型號： | BENCHMARKING |
| 英文描述： | Benchmarking the Am186EM: Using the Dhrystone V2.1 As An Example Application Note? 1.66MB (PDF) |
| 中文描述： | 基準Am186EM：作為示例應(yīng)用注意Dhrystone的V2.1版本？ 1.66MB（PDF格式） |
| 文件頁數(shù)： | 54/88頁 |
| 文件大?。?/td> | 1701K |
| 代理商： | BENCHMARKING |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁第33頁第34頁第35頁第36頁第37頁第38頁第39頁第40頁第41頁第42頁第43頁第44頁第45頁第46頁第47頁第48頁第49頁第50頁第51頁第52頁第53頁當(dāng)前第54頁第55頁第56頁第57頁第58頁第59頁第60頁第61頁第62頁第63頁第64頁第65頁第66頁第67頁第68頁第69頁第70頁第71頁第72頁第73頁第74頁第75頁第76頁第77頁第78頁第79頁第80頁第81頁第82頁第83頁第84頁第85頁第86頁第87頁第88頁
54
Optimization
As you benchmark your programs keep in mind that optimization can greatly
improve the performance of the program as well as inflate code size, cause
erratic behavior and even cause the program to run slower! Take careful note of
the compiler selections you use (-O1, -G, -O2 etc.) as they determine the
optimizations the compiler will perform on your code.
Below are some simple explanations of each major optimization.
Be sure you know the effect of each before you
attempt to call any timing optimal.
Conventional wisdom says there are three components to generating
good code on the 80x86 processors; register allocation, register
allocation and register allocation.
Global register
allocation
Because memory references are so expensive on these processors, it is
extremely important to minimize those references through the intelligent
use of registers. Global register allocation both increases the speed and
decreases the size of your application. You should always use global
register allocation when compiling your application with optimizations on.
Dead-code
elimination
Although you may never intentionally write code to do things which are
unnecessary, the optimizer may reveal possibilities to eliminate stores
into variables that are not needed.
Common
subexpression
elimination
Common subexpression elimination is the process of finding duplicate
expressions within the target scope and storing the calculated value of
those expressions once so as to avoid recalculating the expression.
Although in theory this optimization could reduce code-size, in practice,
it is a speed optimization and will only rarely result in size reductions.
You should also use global common subexpression analysis if you like to
reuse expressions rather than create explicit stack locations for them.
Loop invariant
code motion
Moving invariant code out of loops is a speed optimization. The
optimizer uses the information about all the expressions in the function
gathered during common subexpression elimination to find expressions
whose values do not change inside a loop. To prevent the calculation
from being done many times inside the loop, the optimizer moves the
code outside the loop so that it is calculated only once. The optimizer
then reuses the calculated value inside the loop.
You should use loop invariant code motion whenever you are compiling
for speed and you have used global common subexpressions, since
moving code out of loops can result in enormous speed gains.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| BF-21 | High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications |
| BF-22 | Current Limited Load Switch |
| BF1102R | Dual N-channel dual gate MOS-FETs |
| BF173 | ECONOLINE: RJZ & RGZ - 2W Single and Dual Outputs in DIP 14 - 3kVDC and 4kVDC Isolation - Optional Continuous Short Circuit Protected - Custom Solutions Available - UL94V-0 Package Material - Efficiency up to 85% |
| BF200B | TRANSISTOR | BJT | NPN | 20V V(BR)CEO | 20MA I(C) | TO-92 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| BENCR5P3016B | 功能描述:控制開關(guān) ENCLOS DISCON SWITC RoHS:否 制造商:Omron Industrial 控制類型:Emergency Stop 觸點額定值:5 A at 125 VAC 觸點形式:1 Form B (SPST-NC) 電壓額定值: 電流額定值: 執(zhí)行器:Pushbutton 照明:N 安裝風(fēng)格: |
| BENCR5P3040B | 功能描述:控制開關(guān) ENCLOS DISCON SWITC RoHS:否 制造商:Omron Industrial 控制類型:Emergency Stop 觸點額定值:5 A at 125 VAC 觸點形式:1 Form B (SPST-NC) 電壓額定值: 電流額定值: 執(zhí)行器:Pushbutton 照明:N 安裝風(fēng)格: |
| BEND-M162GT | 制造商:PMA 功能描述:M16 STR CONDUIT FITTING |
| BENELI-81-ALL-ELECTR | 制造商:TE Connectivity 功能描述:CS4901-000 |
| BENFREIGHTPROMET!A | 制造商:Amphenol Corporation 功能描述: |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。