[LLVMdev] LLC Bug x86 with thread local storage

Eric Christopher echristo at apple.com
Thu Jul 8 00:37:51 PDT 2010

On Jul 7, 2010, at 11:20 AM, Eric Christopher wrote:

> On Jul 7, 2010, at 4:52 AM, Patrick Marlier wrote:
>> Which one is correct ?
>> - movl    $tm_nest_level at TPOFF, %ecx
>> or
>> - movq    $tm_nest_level at TPOFF, %rcx
>> or
>> - movl    tm_nest_level at TPOFF, %ecx
> I believe this is initial exec and so from:
> http://people.redhat.com/drepper/tls.pdf
> it would be movl tm_nest_level at TPOFF, %ecx

As a correction, I don't know that any of these is correct. 
I need to look into this a bit more.  I think that it requires the
relocation to be off of a register, i.e.

	movabs  $foo at tpoff, %rax
	add     $foo at tpoff, %rax
        mov     foo at tpoff(%rbx), %eax

are all legal, while:

	mov     foo at tpoff(%ebx), %eax
    	call    foo at tpoff
     	mov     $foo at tpoff, %eax
     	mov     $foo at tpoff, %ax
     	mov     $foo at tpoff, %al

are all illegal.

So we appear to be lowering something, and trying to make
an illegal move out of it.

Unfortunately we're really short on testcases here. :)  I've made
an attempt that works for the current test and passes our set of tests

Sending        lib/Target/X86/X86Instr64bit.td
Sending        test/CodeGen/X86/x86-64-tls-1.ll
Transmitting file data ..
Committed revision 107860.

Going to need some more testcases soon though if you run into
any more problems :)


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