[Mesa-dev] powerpc / gallium/drivers/llvmpipe segfaults running lp_test_* tests

[Will Schmidt]

On Wed, 2012-07-04 at 05:33 -0700, Jose Fonseca wrote:
> ----- Original Message -----
> > On Tue, 2012-07-03 at 16:07 -0500, Will Schmidt wrote:
> > > (gdb) info reg r3
> > > r3             0xfffb7f60010	17590977429520
> > > (gdb) info reg r10
> > > r10            0x7c0802a6f8010010	8937396376665391120
> > 
> > BenH points out to me that r10 value looks like code.
> >  ppcdis 0x7c0802a6
> > mflr    r0
> > 
> >  ppcdis 0xf8010010
> > std     r0,16(r1)
> > 
> > So we are getting a pointer to the actual code, rather than a OPD
> > (function descriptor).
> > 
> > I'll dig into this more...
> > 
> > Thanks,
> > -Will
> 
> I'm not familair with PowerPc architecture.
> 
> Does llvm/examples/HowToUseJIT/HowToUseJIT.cpp work well there?
> 
> If so then you can take a look at lib/ExecutionEngine/JIT/JIT.cpp 's JIT::runFunction method, and compare what's happening differently.
> 

Thanks for the pointer.  It took me a bit to get the example built, but
in the end, the behavior appears to be the same.  Single-stepping in GDB
shows the steps leading up to the SIGSEGV are the same.  The value moved
into the CTR that we branch to is code rather than OPD.


> g++ `llvm-config --ldflags` -o HowToUseJIT HowToUseJIT.o  `llvm-config --libs`

[willschm at fuzzy Release]$ ./HowToUseJIT 
We just constructed this LLVM module:

; ModuleID = 'test'
<snip...>
Running foo: Segmentation fault

[willschm at fuzzy Release]$ gdb ./HowToUseJIT 
<snip...>
Breakpoint 2, 0x00000000100313c0 in ._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE ()
=> 0x00000000100313c0 <._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE+4032>:	e9 3e 00 00	ld      r9,0(r30)
(gdb) stepi
0x00000000100313c4 in ._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE ()
=> 0x00000000100313c4 <._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE+4036>:	f8 41 00 28	std     r2,40(r1)
(gdb) 
0x00000000100313c8 in ._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE ()
=> 0x00000000100313c8 <._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE+4040>:	7d 29 03 a6	mtctr   r9
(gdb) 
0x00000000100313cc in ._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE ()
=> 0x00000000100313cc <._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE+4044>:	e9 7e 00 10	ld      r11,16(r30)
(gdb) 
0x00000000100313d0 in ._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE ()
=> 0x00000000100313d0 <._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE+4048>:	e8 5e 00 08	ld      r2,8(r30)
(gdb) 
0x00000000100313d4 in ._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE ()
=> 0x00000000100313d4 <._ZN4llvm3JIT11runFunctionEPNS_8FunctionERKSt6vectorINS_12GenericValueESaIS4_EE+4052>:	4e 80 04 21	bctrl
(gdb) 
0x7c0802a6f8010010 in ?? ()
=> 0x7c0802a6f8010010:	Cannot access memory at address 0x7c0802a6f8010010


Thanks, 
-Will