digitalmars.D.bugs - [Issue 10462] New: interface thunk doesn't preserve EBX
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http://d.puremagic.com/issues/show_bug.cgi?id=10462
Summary: interface thunk doesn't preserve EBX
Product: D
Version: D2
Platform: x86
OS/Version: All
Status: NEW
Severity: normal
Priority: P2
Component: DMD
AssignedTo: nobody puremagic.com
ReportedBy: code dawg.eu
This is a followup of Bug 9729.
The generated interface thunk now look like this.
_TMP3 LABEL NEAR
sub eax, 8 ; 0050 _ 83. E8, 08
call ?_007 ; 0053 _ E8, 00000000
?_007 LABEL NEAR
pop ebx ; 0058 _ 5B
add ebx, offset _GLOBAL_OFFSET_TABLE_-$+1H ; 0059 _ 81. C3,
00000003(GOT r)
jmp _D3bug4Lock4lockMFZv ; 005F _ E9,
FFFFFFFC(PLT r)
The problem here is that the EBX is not restored after the direct jump which
leads to bug when it was used in the calling function.
Not sure what the best solution to this is. Replacing the jump with a call is
not a good solution because of it alters the stack, i.e. parameters and return
values don't fit.
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Jun 24 2013
d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=10462
Martin Nowak <code dawg.eu> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |critical
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Jun 24 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bugzilla digitalmars.com
12:31:44 PDT ---
The code that generates this in cod3_thunk().
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Jun 29 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462 We could probably assume, that any interface call kills EBX so that the caller would have to save it. But a solution in accordance with the ABI would be better. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 29 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462 14:25:28 PDT --- https://github.com/D-Programming-Language/dmd/pull/2278 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 29 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462 Commits pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/c331f2021404ecc75e8e62bd4d46b92de573008c fix Issue 10462 - interface thunk doesn't preserve EBX https://github.com/D-Programming-Language/dmd/commit/51efce6654e35a3ccb737fd7146acfda7dbf1210 fix Issue 10462 - interface thunk doesn't preserve EBX -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jul 01 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462 Commit pushed to dmd-1.x at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/ed1174fb43c6abc3baa94c80c711227fc7ab6830 fix Issue 10462 - interface thunk doesn't preserve EBX -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jul 01 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462
The fix seems to work but I found another corner case.
Calling an interface thunk through a delegate still crashes.
----
cat > bug.d << CODE
void call(int delegate() dg)
{
assert(dg() == 7);
}
interface I { int opCall(); }
class C : I { int opCall() { return 7; } }
void test()
{
I i = new C;
call(&i.opCall);
}
CODE
cat > main.d << CODE
import bug;
void main() { bug.test(); }
CODE
${DMD} -g -m32 -fPIC -shared bug.d -oflibbug.so
${DMD} -g -m32 main.d -L-L. -L-lbug -L-rpath=.
./main
----
The code generated to call the delegate trashes EBX.
<_D3bug4callFDFZiZv>:
...
mov 0x8(%ebp),%eax // loads context ptr
mov -0x4(%ebp),%ebx // correctly loads GOT into EBX
mov 0xc(%ebp),%edx // loads function ptr
mov 0x8(%ebp),%ebx // overwrites EBX with context ptr ???
call *%edx
The interface thunk call through call *%edx needs a correct EBX.
<_TMP3>:
sub $0x8,%eax
jmp d3e0 <_D3bug1C6opCallMFZi plt>
So the problematic instruction is the additional load into EBX.
This works correctly with optimized builds btw.
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Jul 19 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462 https://github.com/D-Programming-Language/dmd/pull/2367 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jul 19 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462 Commits pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/e3510d1b801808934ba074b357546960b0bc180e fix Issue 10462 - call through function pointer might trash EBX add EBX to the keepmsk after GOT was loaded https://github.com/D-Programming-Language/dmd/commit/d4d0c61c510ed60b2601945a4252f6f6239594ca fix Issue 10462 - call through function pointer might trash EBX -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jul 19 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462 Commit pushed to dmd-1.x at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/109c41f5ff2f814982d02ce0932c95249934618d fix Issue 10462 - call through function pointer might trash EBX -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jul 19 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Version|D2 |D1 & D2
Resolution| |FIXED
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Jul 19 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10462
Martin Nowak <code dawg.eu> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |siegelords_abode yahoo.com
*** Issue 10515 has been marked as a duplicate of this issue. ***
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Aug 13 2013