Available Expressions Analysis The aim of the Available Expressions Analysis is to determine For each program point,which expressions must have already been computed,and not later modified,on all paths to the pro- gram point. Example: point of interest 业 [x:-a+b]1;[y:=a*b]2;while[y>a+b]3do([a:=a+1]4;[x:=-a+b]5) The analysis enables a transformation into [x:=a+b]1;[y:=a*b]2;while[y>x]3do([a:=a+1]4;[x:=a+b]5) PPA Section 2.1 F.Nielson H.Riis Nielson C.Hankin (May 2005) 10Available Expressions Analysis The aim of the Available Expressions Analysis is to determine For each program point, which expressions must have already been computed, and not later modified, on all paths to the pro￾gram point. Example: point of interest ⇓ [x:= a+b ] 1 ; [y:=a*b] 2 ; while [y> a+b ] 3 do ([a:=a+1] 4 ; [x:= a+b ] 5 ) The analysis enables a transformation into [x:= a+b] 1 ; [y:=a*b] 2 ; while [y> x ] 3 do ([a:=a+1] 4 ; [x:= a+b] 5 ) PPA Section 2.1 c F.Nielson & H.Riis Nielson & C.Hankin (May 2005) 10