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. 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. 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
