| Message ID | CAAgBjMnin_uqmwnku+UW48DTCTEZ=5CTDxXXffYGCyW_0n6Jiw@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On 16 July 2015 at 12:39, Richard Biener <rguenther@suse.de> wrote: > On Wed, 15 Jul 2015, Prathamesh Kulkarni wrote: > >> Hi, >> We allow c_expr to be empty which accepts cases like the following: >> >> (simplify >> match-operand >> (if () >> result-operand)) >> >> (simplify >> match-operand >> {}) > > Yes we do. We also do not reject various other "bad" forms like > > { ( blah! } > > so I am not sure treating empty ones specially makes sense. After > all a c-expr is just a list of preprocessing tokens we re-inject > into the generated C code. Well the empty () causes genmatch to segfault. (simplify (plus @x @y) (if () @x))) segfaults here at genmatch.c:2583 output_line_directive (f, ife->cond->code[0].src_loc); IIUC, since we bail out early from parse_c_expr on "()", code remains vNULL and accessing code[0] leads to segfault. backtrace with gdb: #0 operator[] (ix=0, this=0x6bb628) at ../../src/gcc/vec.h:1180 #1 dt_simplify::gen_1 (this=this@entry=0x6bac30, f=f@entry=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=indent@entry=10, gimple=gimple@entry=true, result=0x6bb5e0) at ../../src/gcc/genmatch.c:2583 #2 0x0000000000413430 in dt_simplify::gen (this=0x6bac30, f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=10, gimple=<optimized out>) at ../../src/gcc/genmatch.c:2873 #3 0x000000000040de6f in dt_node::gen_kids_1 (this=this@entry=0x6babc0, f=f@entry=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=indent@entry=8, gimple=gimple@entry=true, gimple_exprs=gimple_exprs@entry=..., generic_exprs=generic_exprs@entry=..., fns=fns@entry=..., generic_fns=generic_fns@entry=..., preds=preds@entry=..., others=others@entry=...) at ../../src/gcc/genmatch.c:2510 #4 0x000000000040ecf3 in dt_node::gen_kids (this=0x6babc0, f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=8, gimple=true) at ../../src/gcc/genmatch.c:2312 #5 0x000000000040f491 in dt_operand::gen (this=0x6babc0, f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=8, gimple=<optimized out>) at ../../src/gcc/genmatch.c:2548 #6 0x000000000040e3a2 in dt_node::gen_kids (this=0x6bab80, f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=8, gimple=true) at ../../src/gcc/genmatch.c:2298 #7 0x000000000040f491 in dt_operand::gen (this=0x6bab80, f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=8, gimple=<optimized out>) at ../../src/gcc/genmatch.c:2548 #8 0x000000000040e3a2 in dt_node::gen_kids (this=0x6bab40, f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=8, gimple=true) at ../../src/gcc/genmatch.c:2298 #9 0x000000000040f667 in decision_tree::gen_gimple (this=0x7fffffffde00, f=0x7ffff7dd4400 <_IO_2_1_stdout_>) at ../../src/gcc/genmatch.c:2913 #10 0x000000000040835e in main (argc=7056432, argv=0x0) at ../../src/gcc/genmatch.c:4135 Thanks, Prathamesh > >> The attached patch rejects empty c_expr. >> Ok for trunk after bootstrap + test ? >> >> Thank you, >> Prathamesh >> > > -- > Richard Biener <rguenther@suse.de> > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Dilip Upmanyu, Graham Norton, HRB 21284 (AG Nuernberg)
Index: genmatch.c =================================================================== --- genmatch.c (revision 225834) +++ genmatch.c (working copy) @@ -3375,6 +3375,7 @@ unsigned opencnt; vec<cpp_token> code = vNULL; unsigned nr_stmts = 0; + bool empty = true; eat_token (start); if (start == CPP_OPEN_PAREN) end = CPP_CLOSE_PAREN; @@ -3394,6 +3395,7 @@ && --opencnt == 0) break; + empty = false; /* This is a lame way of counting the number of statements. */ if (token->type == CPP_SEMICOLON) nr_stmts++; @@ -3412,6 +3414,10 @@ code.safe_push (*token); } while (1); + + if (empty) + fatal_at (token, "c_expr cannot be empty"); + return new c_expr (r, code, nr_stmts, vNULL, capture_ids); }
Hi, We allow c_expr to be empty which accepts cases like the following: (simplify match-operand (if () result-operand)) (simplify match-operand {}) The attached patch rejects empty c_expr. Ok for trunk after bootstrap + test ? Thank you, Prathamesh 2015-07-15 Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org> * genmatch.c (parse_c_expr): Reject empty c_expr.