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Anders Alexandersson

2004-May-11 04:12 UTC

[LLVMdev] Problems accessing structs

Hello!

I get some odd behaviour using my structs:

"myKernelMap" = type {int (sbyte*)*, int ()*}
"Kernel" = type {"myKernelMap"*}

The second member (  int()*  ) is a pointer to the %getchar() function.

I want to call getchar using this function:

int "callmyKernelgetchar_kernel"("Kernel"*
"myKernel")
{
        "PTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
"MAP" = load "myKernelMap"** "PTRMAP"
"getchar_kernelPTR" = getelementptr "myKernelMap"*
"MAP", long 0, ubyte 1
%tmp = load int ()** "getchar_kernelPTR"
"tmp_result" = call int ()* %tmp()
ret int "tmp_result"
}

I call it from main():

int %main() {
;Malloc's a Kernel and returns a pointer to it
"myKernel" = call "Kernel"* "createKernel"()

call int "callmyKernelgetchar_kernel"("Kernel"*
"myKernel")
ret int 0
}


I get this output error message:

Hello Kernel
lli[0x844dd24]
lli[0x844df30]
/lib/tls/libc.so.6[0x420275c8]
lli(llvm::ExecutionEngine::runFunctionAsMain(llvm::Function*,
std::vector<std::basic_string<char, std::char_traits<char>,
std::allocator<char> >, std::allocator<std::basic_string<char,
std::char_traits<char>, std::allocator<char> > > >
const&, char const* const*)+0x25b)[0x8305ca5]
lli(main+0x23c)[0x82aa058]
/lib/tls/libc.so.6(__libc_start_main+0xe4)[0x42015574]
lli(dlopen+0x41)[0x82a9d8d]
Segmentation fault

I have tried to have different function pointers, but ONLY pointers in position
0 in the map-struct works. If I try to access any other posistion, e.g. long 0,
ubyte 1, this error comes.

What is wrong? Getelementptr again? :)

The detailed complete source code is below.

Regards
Anders

-----

"Hello KernelConst" = internal constant  [14 x sbyte ] c"Hello
Kernel\0A\00"

"myKernelMap" = type {int (sbyte*)*, int ()*}
"Kernel" = type {"myKernelMap"*}

declare int %printf(sbyte*, ...)
declare int %getchar(...)

int %puts_kernel(sbyte* %string)
{
%tmp0 = call int (sbyte*, ...)* %printf(sbyte* %string)
ret int 0
}

int %getchar_kernel()
{
%tmp0 = call int (...)* %getchar()
ret int 0
}

"Kernel"* "createKernel"()
{
"myKernelMapInstance" = malloc "myKernelMap"
"myKernel" = malloc "Kernel"
"myKernelMapPTR" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
store "myKernelMap"* "myKernelMapInstance",
"myKernelMap"** "myKernelMapPTR"
"puts_kernelPTRPTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
"puts_kernelPTRMAP" = load "myKernelMap"**
"puts_kernelPTRPTRMAP"
"puts_kernelPTR" = getelementptr "myKernelMap"*
"puts_kernelPTRMAP", long 0, ubyte 0
store int (sbyte*)* %puts_kernel, int (sbyte*)** "puts_kernelPTR"
ret "Kernel"* "myKernel"
"getchar_kernelPTRPTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
"getchar_kernelPTRMAP" = load "myKernelMap"**
"getchar_kernelPTRPTRMAP"
"getchar_kernelPTR" = getelementptr "myKernelMap"*
"getchar_kernelPTRMAP", long 0, ubyte 1
store int ()* %getchar_kernel, int ()** "getchar_kernelPTR"
ret "Kernel"* "myKernel"
}

int "callmyKernelputs_kernel"("Kernel"*
"myKernel")
{
        "PTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
"MAP" = load "myKernelMap"** "PTRMAP"
"puts_kernelPTR" = getelementptr "myKernelMap"*
"MAP", long 0, ubyte 0
%tmp = load int (sbyte*)** "puts_kernelPTR"
"Hello Kernel" = getelementptr [14 x sbyte]* "Hello
KernelConst", long 0, long 0
"tmp_result" = call int (sbyte*)* %tmp(sbyte* "Hello
Kernel")
ret int "tmp_result"
}

int "callmyKernelgetchar_kernel"("Kernel"*
"myKernel")
{
        "PTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
"MAP" = load "myKernelMap"** "PTRMAP"
"getchar_kernelPTR" = getelementptr "myKernelMap"*
"MAP", long 0, ubyte 1
%tmp = load int ()** "getchar_kernelPTR"
"tmp_result" = call int ()* %tmp()
ret int "tmp_result"
}

int %main() {
"myKernel" = call "Kernel"* "createKernel"()
call int "callmyKernelputs_kernel"("Kernel"*
"myKernel")
call int "callmyKernelgetchar_kernel"("Kernel"*
"myKernel")
"myKernel_MapPTRPTR" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
"myKernel_MapPTR" = load "myKernelMap"**
"myKernel_MapPTRPTR"
free "myKernelMap"* "myKernel_MapPTR"
free "Kernel"* "myKernel"
ret int 0
}


----------------------------------------------------------------
Anders Alexandersson
Masters student at the special year of Software Engineering, HTU Trollhättan
E-mail: anders.alexandersson at student.htu.se

John Criswell

2004-May-11 09:58 UTC

head link

[LLVMdev] Problems accessing structs

Anders Alexandersson wrote:> Hello!
> 
> I get some odd behaviour using my structs:
> 
> "myKernelMap" = type {int (sbyte*)*, int ()*}
> "Kernel" = type {"myKernelMap"*}
> 
> The second member (  int()*  ) is a pointer to the %getchar() function.
> 
> I want to call getchar using this function:
> 
> int "callmyKernelgetchar_kernel"("Kernel"*
"myKernel")
> {
>         "PTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
> "MAP" = load "myKernelMap"** "PTRMAP"
> "getchar_kernelPTR" = getelementptr "myKernelMap"*
"MAP", long 0, ubyte 1
> %tmp = load int ()** "getchar_kernelPTR"
> "tmp_result" = call int ()* %tmp()
> ret int "tmp_result"
> }
> 
> I call it from main():
> 
> int %main() {
> ;Malloc's a Kernel and returns a pointer to it
> "myKernel" = call "Kernel"* "createKernel"()
> 
> call int "callmyKernelgetchar_kernel"("Kernel"*
"myKernel")
> ret int 0
> }
> 
> 
> I get this output error message:
> 
> Hello Kernel
> lli[0x844dd24]
> lli[0x844df30]
> /lib/tls/libc.so.6[0x420275c8]
> lli(llvm::ExecutionEngine::runFunctionAsMain(llvm::Function*,
std::vector<std::basic_string<char, std::char_traits<char>,
std::allocator<char> >, std::allocator<std::basic_string<char,
std::char_traits<char>, std::allocator<char> > > >
const&, char const* const*)+0x25b)[0x8305ca5]
> lli(main+0x23c)[0x82aa058]
> /lib/tls/libc.so.6(__libc_start_main+0xe4)[0x42015574]
> lli(dlopen+0x41)[0x82a9d8d]
> Segmentation fault
> 
> I have tried to have different function pointers, but ONLY pointers in
position 0 in the map-struct works. If I try to access any other posistion, e.g.
long 0, ubyte 1, this error comes.
> 
> What is wrong? Getelementptr again? :)
> 
> The detailed complete source code is below.
> 
> Regards
> Anders
> 
> -----
> 
> "Hello KernelConst" = internal constant  [14 x sbyte ]
c"Hello Kernel\0A\00"
> 
> "myKernelMap" = type {int (sbyte*)*, int ()*}
> "Kernel" = type {"myKernelMap"*}
> 
> declare int %printf(sbyte*, ...)
> declare int %getchar(...)
> 
> int %puts_kernel(sbyte* %string)
> {
> %tmp0 = call int (sbyte*, ...)* %printf(sbyte* %string)
> ret int 0
> }
> 
> int %getchar_kernel()
> {
> %tmp0 = call int (...)* %getchar()
> ret int 0
> }
> 
> "Kernel"* "createKernel"()
> {
> "myKernelMapInstance" = malloc "myKernelMap"
> "myKernel" = malloc "Kernel"
> "myKernelMapPTR" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
> store "myKernelMap"* "myKernelMapInstance",
"myKernelMap"** "myKernelMapPTR"
> "puts_kernelPTRPTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
> "puts_kernelPTRMAP" = load "myKernelMap"**
"puts_kernelPTRPTRMAP"
> "puts_kernelPTR" = getelementptr "myKernelMap"*
"puts_kernelPTRMAP", long 0, ubyte 0
> store int (sbyte*)* %puts_kernel, int (sbyte*)** "puts_kernelPTR"
> ret "Kernel"* "myKernel"    ^---------------
    + I'm guessing this line might be the problem.
    :)


The initialization code below is never getting reached, so the getchar() 
function pointer is never initialized.
> "getchar_kernelPTRPTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
> "getchar_kernelPTRMAP" = load "myKernelMap"**
"getchar_kernelPTRPTRMAP"
> "getchar_kernelPTR" = getelementptr "myKernelMap"*
"getchar_kernelPTRMAP", long 0, ubyte 1
> store int ()* %getchar_kernel, int ()** "getchar_kernelPTR"
> ret "Kernel"* "myKernel"
> }
> 
> int "callmyKernelputs_kernel"("Kernel"*
"myKernel")
> {
>         "PTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
> "MAP" = load "myKernelMap"** "PTRMAP"
> "puts_kernelPTR" = getelementptr "myKernelMap"*
"MAP", long 0, ubyte 0
> %tmp = load int (sbyte*)** "puts_kernelPTR"
> "Hello Kernel" = getelementptr [14 x sbyte]* "Hello
KernelConst", long 0, long 0
> "tmp_result" = call int (sbyte*)* %tmp(sbyte* "Hello
Kernel")
> ret int "tmp_result"
> }
> 
> int "callmyKernelgetchar_kernel"("Kernel"*
"myKernel")
> {
>         "PTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
> "MAP" = load "myKernelMap"** "PTRMAP"
> "getchar_kernelPTR" = getelementptr "myKernelMap"*
"MAP", long 0, ubyte 1
> %tmp = load int ()** "getchar_kernelPTR"
> "tmp_result" = call int ()* %tmp()
> ret int "tmp_result"
> }
> 
> int %main() {
> "myKernel" = call "Kernel"* "createKernel"()
> call int "callmyKernelputs_kernel"("Kernel"*
"myKernel")
> call int "callmyKernelgetchar_kernel"("Kernel"*
"myKernel")
> "myKernel_MapPTRPTR" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
> "myKernel_MapPTR" = load "myKernelMap"**
"myKernel_MapPTRPTR"
> free "myKernelMap"* "myKernel_MapPTR"
> free "Kernel"* "myKernel"
> ret int 0
> }
> 
> 
> ----------------------------------------------------------------
> Anders Alexandersson
> Masters student at the special year of Software Engineering, HTU
Trollhättan
> E-mail: anders.alexandersson at student.htu.se
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev

-- John T.

-- 
*********************************************************************
* John T. Criswell                         Email: criswell at uiuc.edu *
* Research Programmer                                               *
* University of Illinois at Urbana-Champaign                        *
*                                                                   *
* "It's today!" said Piglet. "My favorite day," said
Pooh.          *
*********************************************************************

Chris Lattner

2004-May-11 10:03 UTC

head link

[LLVMdev] Problems accessing structs

On Tue, 11 May 2004, John Criswell wrote:> > "Kernel"* "createKernel"()
> > {
> > "myKernelMapInstance" = malloc "myKernelMap"
> > "myKernel" = malloc "Kernel"
> > "myKernelMapPTR" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
> > store "myKernelMap"* "myKernelMapInstance",
"myKernelMap"** "myKernelMapPTR"
> > "puts_kernelPTRPTRMAP" = getelementptr "Kernel"*
"myKernel", long 0, ubyte 0
> > "puts_kernelPTRMAP" = load "myKernelMap"**
"puts_kernelPTRPTRMAP"
> > "puts_kernelPTR" = getelementptr "myKernelMap"*
"puts_kernelPTRMAP", long 0, ubyte 0
> > store int (sbyte*)* %puts_kernel, int (sbyte*)**
"puts_kernelPTR"
> > ret "Kernel"* "myKernel"
>     ^---------------
>     + I'm guessing this line might be the problem.
>     :)
>
>
> The initialization code below is never getting reached, so the getchar()
> function pointer is never initialized.
I agree with John.  If you run your code through the optimizers:

$ llvm-as < t.ll | opt -inline -load-vn -gcse -simplifycfg | llvm-dis

You get the following function:

int %main() {
createKernel.entry:
        %myKernelMapInstance.i = malloc %myKernelMap            ;
<%myKernelMap*> [#uses=2]
        %myKernel.i = malloc %Kernel            ; <%Kernel*> [#uses=3]
        %myKernelMapPTR.i = getelementptr %Kernel* %myKernel.i, long 0, uint 0  
; <%myKernelMap**> [#uses=1]
        store %myKernelMap* %myKernelMapInstance.i, %myKernelMap**
%myKernelMapPTR.i
        %puts_kernelPTR.i = getelementptr %myKernelMap* %myKernelMapInstance.i,
long 0, uint 0          ; <int (sbyte*)**> [#uses=1]
        store int (sbyte*)* %puts_kernel, int (sbyte*)** %puts_kernelPTR.i
        %PTRMAP.i = getelementptr %Kernel* %myKernel.i, long 0, uint 0         
; <%myKernelMap**> [#uses=3]
        %MAP.i = load %myKernelMap** %PTRMAP.i          ; <%myKernelMap*>
[#uses=1]
        %puts_kernelPTR.i2 = getelementptr %myKernelMap* %MAP.i, long 0, uint 0 
; <int (sbyte*)**> [#uses=1]
        %tmp.i = load int (sbyte*)** %puts_kernelPTR.i2         ; <int
(sbyte*)*> [#uses=1]
        "Hello Kernel.i" = getelementptr [14 x sbyte]* "Hello
KernelConst", long 0, long 0              ; <sbyte*> [#uses=1]
        %tmp_result.i = call int %tmp.i( sbyte* "Hello Kernel.i" )    
; <int> [#uses=0]
        %MAP.i4 = load %myKernelMap** %PTRMAP.i         ; <%myKernelMap*>
[#uses=1]
        %getchar_kernelPTR.i5 = getelementptr %myKernelMap* %MAP.i4, long 0,
uint 1             ; <int ()**> [#uses=1]
        %tmp.i = load int ()** %getchar_kernelPTR.i5            ; <int
()*> [#uses=1]
        %tmp_result.i6 = call int %tmp.i( )             ; <int> [#uses=0]
        %myKernel_MapPTR = load %myKernelMap** %PTRMAP.i                ;
<%myKernelMap*> [#uses=1]
        free %myKernelMap* %myKernel_MapPTR
        free %Kernel* %myKernel.i
        ret int 0
}


-Chris

-- 
http://llvm.cs.uiuc.edu/
http://www.nondot.org/~sabre/Projects/

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