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* [Bug rtl-optimization/107047] New: load introduced of struct fields after assigning it to a local variable @ 2022-09-27 7:25 absoler at smail dot nju.edu.cn 2022-09-27 9:10 ` [Bug middle-end/107047] " rguenth at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: absoler at smail dot nju.edu.cn @ 2022-09-27 7:25 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107047 Bug ID: 107047 Summary: load introduced of struct fields after assigning it to a local variable Product: gcc Version: 12.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization Assignee: unassigned at gcc dot gnu.org Reporter: absoler at smail dot nju.edu.cn Target Milestone: --- for gcc-12.1.0, with this code: struct S6 { short f0; char f1; int f2; }; struct S6 g_36 = {2UL,4L,0x32B3D10AL}; int g_48 = (-1L); void func_30() { struct S6 f[4][7]; f[1][6] = g_36; if (f[1][6].f0 || f[1][6].f1) g_48 = f[1][6].f1; } when compiled with -O1 option, generated binaries will be like: 0000000000401186 <func_30>: 401186: 48 83 ec 70 sub $0x70,%rsp 40118a: f7 05 d4 2e 00 00 ff testl $0xffffff,0x2ed4(%rip) # 404068 <g_36> 401191: ff ff 00 401194: 74 0d je 4011a3 <func_30+0x1d> 401196: 0f be 05 cd 2e 00 00 movsbl 0x2ecd(%rip),%eax # 40406a <g_36+0x2> 40119d: 89 05 bd 2e 00 00 mov %eax,0x2ebd(%rip) # 404060 <g_48> 4011a3: 48 83 c4 70 add $0x70,%rsp 4011a7: c3 retq we can see the use of f[1][6] is replaced by g_36 in the if-condition and "g_48 = f[1][6].f1", and the f is not optimized away. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/107047] load introduced of struct fields after assigning it to a local variable 2022-09-27 7:25 [Bug rtl-optimization/107047] New: load introduced of struct fields after assigning it to a local variable absoler at smail dot nju.edu.cn @ 2022-09-27 9:10 ` rguenth at gcc dot gnu.org 2022-10-05 20:02 ` pinskia at gcc dot gnu.org 2022-10-26 8:31 ` [Bug middle-end/107047] load introduced of struct/union " absoler at smail dot nju.edu.cn 2 siblings, 0 replies; 4+ messages in thread From: rguenth at gcc dot gnu.org @ 2022-09-27 9:10 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107047 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2022-09-27 Keywords| |missed-optimization Known to fail| |12.2.1, 13.0 Ever confirmed|0 |1 Component|rtl-optimization |middle-end --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- Confirmed, we see <bb 2> [local count: 1073741824]: f[1][6] = g_36; _1 = BIT_FIELD_REF <f[1][6], 32, 0>; _8 = _1 & 16777215; if (_8 != 0) VN probably sees the def but it doesn't consider replacing the use with a BIT_FIELD_REF of g_36, it just translates the ref but doesn't find any definition to CSE from. SRA says Candidate (1991): f Too big to totally scalarize: f (UID: 1991) Created a replacement for f offset: 848, size: 8: f$1$6$f1D.1996 Access trees for f (UID: 1991): access { base = (1991)'f', offset = 832, size = 64, expr = f[1][6], type = struct S6, reverse = 0, grp_read = 1, grp_write = 1, grp_assignment_read = 1, grp_assignment_write = 1, grp_scalar_read = 0, grp_scalar_write = 0, grp_total_scalarization = 0, grp_hint = 0, grp_covered = 0, grp_unscalarizable_region = 0, grp_unscalarized_data = 1, grp_same_access_path = 1, grp_partial_lhs = 0, grp_to_be_replaced = 0, grp_to_be_debug_replaced = 0} * access { base = (1991)'f', offset = 848, size = 8, expr = f[1][6].f1, type = char, reverse = 0, grp_read = 1, grp_write = 1, grp_assignment_read = 1, grp_assignment_write = 1, grp_scalar_read = 1, grp_scalar_write = 0, grp_total_scalarization = 0, grp_hint = 0, grp_covered = 1, grp_unscalarizable_region = 0, grp_unscalarized_data = 0, grp_same_access_path = 1, grp_partial_lhs = 0, grp_to_be_replaced = 1, grp_to_be_debug_replaced = 0} but somehow it does not create an access for _1 = BIT_FIELD_REF <f[1][6], 32, 0>; _2 = (unsigned int) _1; note the real offender here is (again) optimize_bit_field_compare ... ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/107047] load introduced of struct fields after assigning it to a local variable 2022-09-27 7:25 [Bug rtl-optimization/107047] New: load introduced of struct fields after assigning it to a local variable absoler at smail dot nju.edu.cn 2022-09-27 9:10 ` [Bug middle-end/107047] " rguenth at gcc dot gnu.org @ 2022-10-05 20:02 ` pinskia at gcc dot gnu.org 2022-10-26 8:31 ` [Bug middle-end/107047] load introduced of struct/union " absoler at smail dot nju.edu.cn 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2022-10-05 20:02 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107047 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot gnu.org Status|NEW |ASSIGNED --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Mine but for GCC 14. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/107047] load introduced of struct/union fields after assigning it to a local variable 2022-09-27 7:25 [Bug rtl-optimization/107047] New: load introduced of struct fields after assigning it to a local variable absoler at smail dot nju.edu.cn 2022-09-27 9:10 ` [Bug middle-end/107047] " rguenth at gcc dot gnu.org 2022-10-05 20:02 ` pinskia at gcc dot gnu.org @ 2022-10-26 8:31 ` absoler at smail dot nju.edu.cn 2 siblings, 0 replies; 4+ messages in thread From: absoler at smail dot nju.edu.cn @ 2022-10-26 8:31 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107047 --- Comment #3 from absoler at smail dot nju.edu.cn --- and for union there's similar behavior: union U2 { long long f0; unsigned short f2; int f4; }; void func_17(union U2 p_20); void func_1() { func_17(g_39[0]); } void func_17(union U2 e) { int *f = &g_30; if (e.f0 || e.f2) *f = e.f2; } are compiled with gcc-12.1 -O1 to: 0000000000402020 <func_1>: func_17(): /home/csmith-2.3.0/test/output2.c:87 402020: 48 83 3d 68 3e 00 00 cmpq $0x0,0x3e68(%rip) # 405e90 <g_39> 402027: 00 402028: 74 0d je 402037 <func_1+0x17> /home/csmith-2.3.0/test/output2.c:88 40202a: 0f b7 05 5f 3e 00 00 movzwl 0x3e5f(%rip),%eax # 405e90 <g_39> 402031: 89 05 71 3e 00 00 mov %eax,0x3e71(%rip) # 405ea8 <g_30> uses of e.f0 and e.f2 are replaced by g_39[0] ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-10-26 8:31 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-09-27 7:25 [Bug rtl-optimization/107047] New: load introduced of struct fields after assigning it to a local variable absoler at smail dot nju.edu.cn 2022-09-27 9:10 ` [Bug middle-end/107047] " rguenth at gcc dot gnu.org 2022-10-05 20:02 ` pinskia at gcc dot gnu.org 2022-10-26 8:31 ` [Bug middle-end/107047] load introduced of struct/union " absoler at smail dot nju.edu.cn
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