On Sat, Feb 19, 2022 at 1:15 AM Andrew Pinski <pins...@gmail.com> wrote: > > On Fri, Feb 18, 2022 at 11:04 AM Shubham Narlawar via Gcc > <gcc@gcc.gnu.org> wrote: > > > > Hello, > > > > I want to know whether it is correct to add left shift instruction to > > a constant expression statement like "_3 + 4"? > > > > I am trying to add a left shift instruction in between below GIMPLE > > instructions - > > > > <bb 2> : > > instrn_buffer.0_1 = instrn_buffer; > > _2 = tree.cnt; > > _3 = (int) _2; > > _4 = _3 + 4; > > _5 = (unsigned int) _4; // I want to add left shift here > > D.2993 = __builtin_riscv_sfploadi (instrn_buffer.0_1, 0, _5); > > //this is "stmt" > > > > I am using this snippet in custom gcc plugin - > > > > tree lshift_tmp = make_temp_ssa_name (integer_type_node, > > NULL, "slli"); > > A couple of things. > I Noticed you use integer_type_node here. Why not the type of what is > being replaced? > That is the main thing I see right now.
I want to apply left shift to a constant expression with 8 which is an integer. Since I am not replacing a statement, I am creating new GIMPLE statement - tree shift_amt = build_int_cst (integer_type_node, 8); Here, I am not replacing any GIMPLE statement. Is this the correct way to do this? My goal is to left shift constant expression and update its usage as below - _19 = (unsigned int) _18; D.2996 = __builtin_riscv_sfploadi (lexer.5_16, 12, _19); into _19 = (unsigned int) _18; temp = _19 << 8 D.2996 = __builtin_riscv_sfploadi (lexer.5_16, 12, temp); I am storing the left shift result to the new ssa variable name "temp" and updating sfploadi parameters as expected. On doing the above, dom_walker_eliminate is prohibiting me to do the above gimple transformation. Is the above transformation complete and correct? > > Also you shouldn't need to do: > update_ssa (TODO_update_ssa); > > As make_temp_ssa_name is a new SSA name already and such. Understood. Thanks and Regards, Shubham > > Thanks, > Andrew Pinski > > > gimple *lshift = gimple_build_assign (lshift_tmp, LSHIFT_EXPR, > > parm, > > build_int_cst > > (integer_type_node, 8)); > > gsi_insert_before(&gsi, lshift, GSI_NEW_STMT); > > //Update function call > > gimple_call_set_arg (stmt, idx, lshift_tmp); > > update_stmt (stmt); > > update_ssa (TODO_update_ssa); > > > > from which above GIMPLE IR is modified to - > > > > <bb 2> : > > instrn_buffer.0_1 = instrn_buffer; > > _2 = tree.cnt; > > _3 = (int) _2; > > _4 = _3 + 4; > > _5 = (unsigned int) _4; > > slli_24 = _5 << 8; > > D.2993 = __builtin_riscv_sfploadi (instrn_buffer.0_1, 0, slli_24); > > > > > > 1. When I run above code, either dominator tree validation or tree cfg > > fixup is failing which suggests to me it is either incorrect to apply > > such left shift or some more work is missing? > > > > 2. I followed how a left shift gimple assignment is generated but > > still feels there is something wrong with the above generation. Can > > someone please point me out? > > > > Thanks in advance! As always, the GCC community and its members are > > very supportive, responsive and helpful! > > > > Regards, > > Shubham
