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digitalmars.D.bugs - char[] ~= causes segfault on Linux (DMD v0.101) - sc_diff.txt

reply Dave <Dave_member pathlink.com> writes:
DMD v0.101 for Linux

_After_ rebuilding libphobos.a on Linux, this code will cause a segfault:

void main()
{
char[] str;
str ~= "test"; // segfault
//str = str ~ "test"; // Ok
}

Tracing it into internal/gc/gc.d, it will cause the segfault at this line of
code (dereferencing px.data is the culprit):

extern (C)
Array _d_arrayappend(Array *px, byte[] y, uint size)
{
uint cap = _gc.capacity(px.data); // segfault here

Used ar to extract and obj2asm to dump the assembler from both the newly
recompiled gc.o and the as-shipped gc.o. The diff file showed differences in the
generated code for the _d_arrayappend function.

as-shipped:
_d_arrayappend:
push    EBP
mov EBP,ESP
sub ESP,0Ch
push    EBX
mov EBX,8[EBP]  ; <-----------
mov EAX,_D3std2gc3_gcPS3gcx2GC
push    ESI
push    EDI
mov EDI,014h[EBP]
push    dword ptr 4[EBX]
call    near ptr _D3gcx2GC8capacityFPvZk

as-compiled:
_d_arrayappend:
push    EBP
mov EBP,ESP
sub ESP,010h
push    EBX
mov EBX,0Ch[EBP] ; <----------
mov EAX,_D3std2gc3_gcPS3gcx2GC
push    ESI
push    EDI
mov EDI,018h[EBP]
push    dword ptr 4[EBX]
call    near ptr _D3gcx2GC8capacityFPvZk

The obj2asm for the program (-O -inline -release):
_Dmain:
push    EBP
mov     EBP,ESP
sub     ESP,8
push    1
lea     EAX,-8[EBP]
mov     dword ptr -8[EBP],0
mov     dword ptr -4[EBP],0
push    dword ptr _TMP0[01Fh]
push    dword ptr _TMP0[021h]
push    EAX
call    near ptr _d_arrayappend
add     ESP,010h
mov     ESP,EBP
pop     EBP
ret

The relavant assembler for the non-release build is the same, and also causes
the segfault.

The diff file is attached.

- Dave
Sep 02 2004
parent reply Dave <Dave_member pathlink.com> writes:
Anything else I could provide regarding this?

Thanks,

- Dave

In article <ch8ukr$172i$1 digitaldaemon.com>, Dave says...
DMD v0.101 for Linux

_After_ rebuilding libphobos.a on Linux, this code will cause a segfault:

void main()
{
char[] str;
str ~= "test"; // segfault
//str = str ~ "test"; // Ok
}

Tracing it into internal/gc/gc.d, it will cause the segfault at this line of
code (dereferencing px.data is the culprit):

extern (C)
Array _d_arrayappend(Array *px, byte[] y, uint size)
{
uint cap = _gc.capacity(px.data); // segfault here

Used ar to extract and obj2asm to dump the assembler from both the newly
recompiled gc.o and the as-shipped gc.o. The diff file showed differences in the
generated code for the _d_arrayappend function.

as-shipped:
_d_arrayappend:
push    EBP
mov EBP,ESP
sub ESP,0Ch
push    EBX
mov EBX,8[EBP]  ; <-----------
mov EAX,_D3std2gc3_gcPS3gcx2GC
push    ESI
push    EDI
mov EDI,014h[EBP]
push    dword ptr 4[EBX]
call    near ptr _D3gcx2GC8capacityFPvZk

as-compiled:
_d_arrayappend:
push    EBP
mov EBP,ESP
sub ESP,010h
push    EBX
mov EBX,0Ch[EBP] ; <----------
mov EAX,_D3std2gc3_gcPS3gcx2GC
push    ESI
push    EDI
mov EDI,018h[EBP]
push    dword ptr 4[EBX]
call    near ptr _D3gcx2GC8capacityFPvZk

The obj2asm for the program (-O -inline -release):
_Dmain:
push    EBP
mov     EBP,ESP
sub     ESP,8
push    1
lea     EAX,-8[EBP]
mov     dword ptr -8[EBP],0
mov     dword ptr -4[EBP],0
push    dword ptr _TMP0[01Fh]
push    dword ptr _TMP0[021h]
push    EAX
call    near ptr _d_arrayappend
add     ESP,010h
mov     ESP,EBP
pop     EBP
ret

The relavant assembler for the non-release build is the same, and also causes
the segfault.

The diff file is attached.

- Dave


begin 0644 sc_diff.txt
M,3 T83$X-0T*/B`)"7AO< E%0U L14-8#0HQ.#5A,3 W+#$Y,0T*/B`)"6UO
M= E;14%872Q%0U -"CX "0EM;W8)-%M%05A=+$5#6`T*/B`)"6UO= DX6T5!
M6%TL14-8#0H^(`D);6]V"3!#:%M%05A=+$5#6`T*/B`)"6UO= DP,3!H6T5!
M6%TL14-8#0HW-C-C-S8Y#0H\(`D)<W5B"4534"PP0V -"BTM+0T*/B`)"7-U
M8 E%4U`L,#$P:`T*-S8U8S<W,0T*/"`)"6UO= E%0E L.%M%0E!=#0HM+2T-
M"CX "0EM;W8)14)8+#!#:%M%0E!=#0HW-CEC-S<U#0H\(`D);6]V"45$22PP
M,31H6T5"4%T-"BTM+0T*/B`)"6UO= E%1$DL,#$X:%M%0E!=#0HW-S5C-S Q
M#0H\(`D)861D"45#6"PP0VA;14)070T*+2TM#0H^(`D)861D"45#6"PP,3!H
M6T5"4%T-"C<Y-&,X,#`-"CP 3#4Y. D);6]V"3`Q-&A;14)072Q%1$D-"BTM
M+0T*/B!,-3DZ"0EM;W8),#$X:%M%0E!=+$5$20T*-SDV8S P, T*/"`)"6UO
M= E%1% L,#$P:%M%0E!=#0HM+2T-"CX "0EM;W8)1418+#`Q-&A;14)070T*
M-SDX8S P-`T*/"`)"6UO= E%05 L,$-H6T5"4%T-"BTM+0T*/B`)"6UO= E%
M05 L,#$P:%M%0E!=#0HX,#%C.#`W#0H\(`D):6UU;`E%1$DL,#$T:%M%0E!=
M#0HM+2T-"CX "0EI;75L"45$22PP,3AH6T5"4%T-"C P,V,X,#D-"CP "0EI
M;75L"45#6"PP,31H6T5"4%T-"BTM+0T*/B`)"6EM=6P)14-8+#`Q.&A;14)0
M70T*.#$Q83 Q.`T*/B`)"6UO= E%4TDL.%M%0E!=#0HX,3-A.#(Q+# R,PT*
M/B`)"6UO= E;15-)72Q%05 -"CX "0EM;W8)14%8+$5320T*/B`)"6UO= DT
J6T5325TL1418#0HX,C$L.#(R9# S,`T*/"`)"6YO<`T*/"`)"6YO<`T*
`
end

Sep 08 2004
parent reply "Walter" <newshound digitalmars.com> writes:
"Dave" <Dave_member pathlink.com> wrote in message
news:chnlj1$14uf$1 digitaldaemon.com...
 Anything else I could provide regarding this?

No, I know what's wrong. The calling conventions on linux are slightly different, and that tripped me up. It's now fixed.
Sep 11 2004
parent Dave <Dave_member pathlink.com> writes:
In article <chvn4n$3tt$1 digitaldaemon.com>, Walter says...
"Dave" <Dave_member pathlink.com> wrote in message
news:chnlj1$14uf$1 digitaldaemon.com...
 Anything else I could provide regarding this?

No, I know what's wrong. The calling conventions on linux are slightly different, and that tripped me up. It's now fixed.

Thanks! - Dave
Sep 12 2004