https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801
Bug ID: 61801
Summary: sched2 miscompiles syscall sequence with -g
Product: gcc
Version: 4.8.3
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target: i?86-*-*
Created attachment 33118
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33118&action=edit
testcase from glibc trunk
gcc-4.8 -S bug-887141_pthread_create.i -m32 -std=gnu99 -fgnu89-inline -O2
-fmerge-all-constants -frounding-math -fPIC -mpreferred-stack-boundary=4
-fverbose-asm -da -fdump-tree-all -g
sched2 moves the load from 20(%esp) up across the spill.
__nptl_setxid:
...
.LBB347:
.loc 1 1174 0
movl 80(%esp), %eax # cmdp, tmp189
movl 20(%esp), %esi # %sfp, result <---- bogus location
.LVL184:
movl (%eax), %eax # cmdp_33(D)->syscall_no,
cmdp_33(D)->syscall_no
movl %eax, 20(%esp) # cmdp_33(D)->syscall_no, %sfp
.LVL185:
movl 80(%esp), %eax # cmdp, tmp191
movl 4(%eax), %edi # cmdp_33(D)->id, cmdp_33(D)->id
movl 8(%eax), %ecx # cmdp_33(D)->id, cmdp_33(D)->id
movl 12(%eax), %edx # cmdp_33(D)->id, cmdp_33(D)->id
<---- moved from here
movl %esi, %eax # result, result
#APP
# 1174 "allocatestack.c" 1
xchgl %ebx, %edi
int $0x80
xchgl %edi, %ebx
before sched2 everything looks ok (apart from odd
debug-insn with asm):
(code_label 308 344 309 40 194 "" [1 uses])
(note 309 308 531 40 [bb 40] NOTE_INSN_BASIC_BLOCK)
(insn 531 309 310 40 (set (reg:SI 0 ax [189])
(mem/f/c:SI (plus:SI (reg/f:SI 7 sp)
(const_int 80 [0x50])) [4 cmdp+0 S4 A32])) allocatestack.c:1174
89 {*movsi_internal}
(nil))
(insn 310 531 532 40 (set (reg:SI 0 ax [orig:137 cmdp_33(D)->syscall_no ]
[137])
(mem:SI (reg:SI 0 ax [189]) [2 cmdp_33(D)->syscall_no+0 S4 A32]))
allocatestack.c:1174 89 {*movsi_internal}
(nil))
(insn 532 310 533 40 (set (mem/c:SI (plus:SI (reg/f:SI 7 sp)
(const_int 20 [0x14])) [54 %sfp+-12 S4 A32])
(reg:SI 0 ax [orig:137 cmdp_33(D)->syscall_no ] [137]))
allocatestack.c:1174 89 {*movsi_internal}
(expr_list:REG_DEAD (reg:SI 0 ax [orig:137 cmdp_33(D)->syscall_no ] [137])
(nil)))
(insn 533 532 311 40 (set (reg:SI 0 ax [191])
(mem/f/c:SI (plus:SI (reg/f:SI 7 sp)
(const_int 80 [0x50])) [4 cmdp+0 S4 A32])) allocatestack.c:1174
89 {*movsi_internal}
(nil))
(insn 311 533 312 40 (set (reg:SI 5 di [orig:138 cmdp_33(D)->id ] [138])
(mem:SI (plus:SI (reg:SI 0 ax [191])
(const_int 4 [0x4])) [5 cmdp_33(D)->id+0 S4 A32]))
allocatestack.c:1174 89 {*movsi_internal}
(nil))
(insn 312 311 313 40 (set (reg:SI 2 cx [orig:139 cmdp_33(D)->id+4 ] [139])
(mem:SI (plus:SI (reg:SI 0 ax [192])
(const_int 8 [0x8])) [5 cmdp_33(D)->id+4 S4 A32]))
allocatestack.c:1174 89 {*movsi_internal}
(nil))
(insn 313 312 314 40 (set (reg:SI 1 dx [orig:140 cmdp_33(D)->id+8 ] [140])
(mem:SI (plus:SI (reg:SI 0 ax [193])
(const_int 12 [0xc])) [5 cmdp_33(D)->id+8 S4 A32]))
allocatestack.c:1174 89 {*movsi_internal}
(expr_list:REG_DEAD (reg:SI 0 ax [193])
(nil)))
(note 314 313 316 40 NOTE_INSN_DELETED)
(debug_insn 316 314 477 40 (var_location:SI resultvar (asm_operands/v:SI
("xchgl %%ebx, %%edi
int $0x80
xchgl %%edi, %%ebx
") ("=a") 0 [
(mem/c:SI (plus:SI (reg/f:SI 7 sp)
(const_int 20 [0x14])) [54 %sfp+-12 S4 A32])
(reg:SI 5 di [orig:138 cmdp_33(D)->id ] [138])
(reg:SI 2 cx [orig:139 cmdp_33(D)->id+4 ] [139])
(reg:SI 1 dx [orig:140 cmdp_33(D)->id+8 ] [140])
]
[
(asm_input:SI ("0") (null):0)
(asm_input:SI ("D") (null):0)
(asm_input:SI ("c") (null):0)
(asm_input:SI ("d") (null):0)
]
[] allocatestack.c:1174)) allocatestack.c:1174 -1
(nil))
(insn 477 316 536 40 (set (reg/v:SI 4 si [orig:60 result ] [60])
(mem/c:SI (plus:SI (reg/f:SI 7 sp)
(const_int 20 [0x14])) [54 %sfp+-12 S4 A32]))
allocatestack.c:1174 89 {*movsi_internal}
(nil))
(insn 536 477 317 40 (set (reg/v:SI 0 ax [orig:60 result ] [60])
(reg/v:SI 4 si [orig:60 result ] [60])) allocatestack.c:1174 89
{*movsi_internal}
(expr_list:REG_DEAD (reg/v:SI 4 si [orig:60 result ] [60])
(nil)))
(insn 317 536 537 40 (parallel [
(set (reg/v:SI 0 ax [orig:60 result ] [60])
(asm_operands/v:SI ("xchgl %%ebx, %%edi
int $0x80
xchgl %%edi, %%ebx
