[LLVMdev] Always unfold memory operand

[Eli Friedman]

On Tue, Jun 8, 2010 at 4:20 PM, David Meyer <pdox at google.com> wrote:
> Hi Eli,
> I have tried this, but the resulting tool-chain was broken.
> There are only two references to "CALL64m": the definition in
> X86Instr64bit.td, and an entry in X86InstrInfo.cpp.
> After commenting both out, compilation of a large application fails with:
> llc: ScheduleDAG.cpp:462: void
> llvm::ScheduleDAGTopologicalSort::InitDAGTopologicalSorting(): Assertion
> `Node2Index[SU->NodeNum] > Node2Index[I->getSUnit()->NodeNum] && "Wrong
> topological sorting"' failed.
> bugpoint produced this minimal example which triggers the problem:
> define ccc void @ArgsFree() nounwind {
> entry:
>   %0 = load void (i8*)** undef, align 4
>   call ccc void %0(i8* undef) nounwind
>   unreachable
> }
> Any ideas?
> - David

I'm not really sure... possibly something is expecting to be able to
fold the load into the call inst, and fails.

-Eli

>
> On Tue, Jun 8, 2010 at 4:04 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
>>
>> On Tue, Jun 8, 2010 at 2:05 PM, David Meyer <pdox at google.com> wrote:
>> > Hi,
>> > I am attempting to modify LLVM to generate code for an architecture
>> > which is
>> > nearly identical to X86-64, but with a few minor differences.
>> > In particular, "call" must always have a register operand, and cannot
>> > have a
>> > memory operand. Any ideas on how I can express this rule?
>>
>> Just get rid of the pattern for matching the CALL64m instruction, or
>> make it require a target feature your target doesn't have.
>>
>> -Eli
>
>