Hi Richard, a_2 is used in g1 already, I don't know how this data structure is managed and afraid that it'll be freed twice if you also use it in the newly inserted stmt. Do you think it'll be safe here?
Feng On Wed, May 18, 2011 at 6:10 PM, Richard Guenther <richard.guent...@gmail.com> wrote: > 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 >> >
