On Tue, Feb 22, 2022 at 8:38 AM Shubham Narlawar <gsocshub...@gmail.com> wrote: > > On Mon, Feb 21, 2022 at 1:02 PM Richard Biener > <richard.guent...@gmail.com> wrote: > > > > On Sun, Feb 20, 2022 at 11:44 PM Andrew Pinski via Gcc <gcc@gcc.gnu.org> > > wrote: > > > > > > On Sun, Feb 20, 2022 at 10:45 AM Shubham Narlawar <gsocshub...@gmail.com> > > > wrote: > > > > > > > > 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? > > > > > > I think you misunderstood me. I was saying for a left shift gimple, > > > the result type and the first operand type must be compatible (signed > > > and unsigned types are not compatible). In the above case, you have: > > > integer_type_node = unsigned_int << integer_type_name . > > > > > > Does that make sense now? > > > > Btw, the error you see is still odd - please make sure to build GCC with > > checking enabled or run your tests with -fchecking. For further help > > Sure. > > > it might be useful to post the patch you are testing to show where exactly > > you are hooking into to add this statement. > > My goal is to transform below IR - > > _5 = (unsigned int) _4; > D.2993 = __builtin_riscv_* (instrn_buffer.0_1, 0, _5); > > to target IR - > > _5 = (unsigned int) _4; > lshiftamt_27 = _5 << 8; > D.2996 = __builtin_riscv_* (instrn_buffer.0_1, 0, lshiftamt_27); > > I have followed this approach to build a new GIMPLE left shift > instruction - > https://github.com/gcc-mirror/gcc/blob/0435b978f95971e139882549f5a1765c50682216/gcc/ubsan.cc#L1257 > > Here is the patch which I am using - > > ------------------------------------------Patch------------------------------------------------------- > unsigned int > pass_custom_lowering::execute (function *fun) > { > /* Code for iterating over all statements of function to find > function call of form - __builtin* > > where one of parameter is constant expression of type "7 + > expression" i.e. 7 + _8 > > <bb 2> : > instrn_buffer.0_1 = instrn_buffer; > _2 = tree.cnt; > _3 = (int) _2; > _4 = _3 + 4; > _5 = (unsigned int) _4; // I want to apply left shift to _5 > D.2993 = __builtin_riscv_* (instrn_buffer.0_1, 0, _5); > > */ > gcall *stmt = dyn_cast<gcall *> (g); //here g is > __builtin_riscv_* where one of parameter is "_3 + 4" > tree parm = gimple_call_arg (stmt, 2); > > unsigned int shift = 8; > tree shift_amt = build_int_cst (unsigned_type_node, shift); > tree lshift_tmp_name = make_temp_ssa_name > (unsigned_type_node, NULL, "slli"); > gimple *lshift_stmt = gimple_build_assign (lshift_tmp_name, > LSHIFT_EXPR, parm, > shift_amt); > gsi_insert_before(&gsi, lshift_stmt, GSI_NEW_STMT); > gimple_call_set_arg (stmt, 2, lshift_tmp_name); > //update_stmt (stmt);
This update_stmt is required > //update_ssa (TODO_update_ssa); > > return 0; > } > --------------------------------------------------------------------------------------------------------- > > Is the above code correct? Yes, the code is incomplete of course, it misses how you get to 'g' but I assume it's just FOR_EACH_BB_FN and iteration over each BBs stmts. > I was hoping to do the below transformation using above code but feel > there is some missing operation that needs to be added to above code. > The goal is simple to generate a left shift to the 3rd parameter of > function which is constant expression. > > _5 = (unsigned int) _4; > D.2993 = __builtin_riscv_* (instrn_buffer.0_1, 0, _5); > > to > > _5 = (unsigned int) _4; > lshiftamt_27 = _5 << 8; > D.2996 = __builtin_riscv_* (instrn_buffer.0_1, 0, lshiftamt_27); > > Thanks and Regards, > Shubham > > > > > > Richard. > > > > > Thanks, > > > Andrew > > > > > > > > > > > > > > > > > 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
