On Wed, May 18, 2011 at 5:01 PM, Feng LI <nemoking...@gmail.com> wrote: > Hi, > > I have the code like: > a_2 = 5; g1 > b_3 = 6; g2 > d_4 = a_2 + b_3; g3 > > And I'd like to insert "tmp.globe = a_2" just after the definition of > a_2 (after g1), so that the code will be: > > a_2 = 5; g1 > tmp.globe = a_2; inserted code > b_3 = 6; g2 > d_4 = a_2 + b_3; g3 > > This pass is with SSA form, and I write code like: > > tree use = make_ssa_name (var, NULL); //create a_11 > /* Set the DEF_P (referred to a_2) to be the DEF of the newly created USE. */ > SET_DEF (def_p, use); > > But this will invalidate the original USE-DEF chain, where the a_11 defined > in g1 will never match the use in g3 of a_2, and the code will look like: > > a_11 = 5; g1 > tmp.globe = a_11; inserted code > b_3 = 6; g2 > d_4 = a_2 + b_3; g3 > > It seems that I have to update all the use of the original a_2 again and set > the use to a_11. Is there some solutions that I don't have to update the > def-use chains manually?
Why do you allocate a new a_11 instead of using a_2? Richard. > Thanks, > Feng >
