Cov lus teb thiab cov lus teb: Hauv kev tshawb xav compiler, kev tshem tawm cov lus tshaj tawm ntau (CSE) yog kev ua kom zoo tshaj plaws uas tshawb nrhiav cov piv txwv ntawm cov kab lus zoo ib yam (piv txwv li, lawv txhua tus ntsuas rau tib tus nqi), thiab tshuaj xyuas seb nws puas tsim nyog hloov pauv. lawv nrog ib qho sib txawv uas tuav tus nqi suav.
Dab tsi yog qhov kev nthuav qhia ntau thiab koj yuav tshem tawm nws li cas?
Kev Tshaj Tawm Tshaj Tawm Tshaj Tawm yog kev ua kom zoo dua uas tshawb nrhiav cov piv txwv ntawm cov kab lus zoo tib yam, thiab hloov lawv nrog ib qho sib txawv uas tuav tus nqi suav.
Yuav ua li cas txheeb xyuas cov lus tshaj tawm hauv cov lus qhia?
Ib qho tshwm sim ntawm ib qho kev qhia hauv ib qhov kev pab cuam yog ib qho kev nthuav qhia yog tias muaj lwm qhov tshwm sim ntawm qhov kev qhia uas nws qhov kev ntsuam xyuas ib txwm ua ntej qhov no hauv kev txiav txim siab thiab yog tias qhov kev ua haujlwm ntawm cov lus tseem tsis hloov pauv nruab nrab ntawm ob qhov kev ntsuam xyuas.
Dab tsi yog qhov kev tshem tawm cov lus tshaj tawm Mcq?
Common subexpression elimination (CSE) yog hais txog rau compiler optimization hloov cov kab lus zoo tib yam (piv txwv li, lawv txhua tus ntsuas rau tib tus nqi) nrog ib qho sib txawv tuav tus nqi suav thaum nws yog tsim nyog ua li ntawd.
Dab tsi yog kev tshem tawm ib nrab ntawm kev tshem tawm hauv kev tsim qauv?
Nyob rau hauv txoj kev xav compiler, ib nrab redundancy tshem tawm (PRE) yog kev ua kom zoo tshaj plawsuas tshem tawm cov kab lus uas tsis txaus ntseeg ntawm qee qhov tab sis tsis tas txhua txoj hauv kev los ntawm txoj haujlwm. … qhov kev qhia x + 4 muab rau z yog ib nrab redundant vim nws suav ob zaug yog tias qee qhov xwm txheej muaj tseeb.
