<div class="gmail_quote">On Thu, Sep 15, 2011 at 6:51 AM, Peng Wang <span dir="ltr"><<a href="mailto:paulart.wang@gmail.com">paulart.wang@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div>Hi all,</div>
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<div>I am writing a llvm backend for a small stream processor. Because of its special application field, the processor does not support function. When I built the llvm backend for the new target, I leave the calling convention and frame lowering part blank. It compilered correctly, but I encountered execution errors, like </div>
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<div><em>[xxx@localhost ex]$ llc test.ll -march=SSP -o test.s<br>0 llc 0x08f7ee49<br>1 llc 0x08f7f41a<br>2 0x003b1420 __kernel_sigreturn + 0<br>3 llc 0x08de0d52 llvm::TargetData::getAlignment(llvm::Type const*, bool) const + 44<br>
4 llc 0x08de108a llvm::TargetData::getABITypeAlignment(llvm::Type const*) const + 44<br>5 llc 0x0863e289 llvm::TargetData::getTypeAllocSize(llvm::Type const*) const + 37<br>6 llc 0x08a707ed llvm::GetReturnInfo(llvm::Type const*, unsigned int, llvm::SmallVectorImpl<llvm::ISD::OutputArg>&, llvm::TargetLowering const&, llvm::SmallVectorImpl<unsigned long long>*) + 573<br>
7 llc 0x089b59be llvm::FunctionLoweringInfo::set(llvm::Function const&, llvm::MachineFunction&) + 156<br>8 llc 0x08a4ec8a llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) + 280<br>
9 llc 0x08b7c191 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) + 89<br>10 llc 0x08eb92f1 llvm::FPPassManager::runOnFunction(llvm::Function&) + 315<br>11 llc 0x08eb94bb llvm::FPPassManager::runOnModule(llvm::Module&) + 121<br>
12 llc 0x08eb8fbf llvm::MPPassManager::runOnModule(llvm::Module&) + 413<br>13 llc 0x08eba3b0 llvm::PassManagerImpl::run(llvm::Module&) + 124<br>14 llc 0x08eba415 llvm::PassManager::run(llvm::Module&) + 39<br>
15 llc 0x0859a610 main + 2470<br>16 libc.so.6 0x0097de9c __libc_start_main + 220<br>17 llc 0x08598b61<br>Stack dump:<br>0. Program arguments: llc test.ll -march=SSP -o test.s <br>1. Running pass 'Function Pass Manager' on module 'test.ll'.<br>
2. Running pass 'SSP DAG->DAG Pattern Instruction Selection' on function '@add'<br>Segmentation fault<br></em></div></blockquote><div><br></div><div>This error seems to suggest there is something wrong with how you implement your TargetData field in your TargetMachine subclass.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div><em></em></div>
<div>I think the error comes from the lacking support of function call. Should I write some fake codes to walk around, or I have some ways to tell LLVM that I do not want function call?</div></blockquote><div><br></div><div>
You do not need to handle call instructions, but you do need to handle parameter passing. A function is the basic unit of compilation in LLVM, and a function can have zero or more parameters, and an output parameter. You need to specify how to lower these parameters. If you always have a function that takes no arguments, and returns nothing, then you can just omit the implementation.</div>
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<div>Actually, I tried to write LLVM IR without the function form of define @main(..., but with function body directly. Unfortunately, everything seems must work with a function call, otherwise llc will not work.</div></blockquote>
<div><br></div><div>Yes, LLVM requires all instructions to be within a block within a function.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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<div>Best wishes!</div>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><br><div>Thanks,</div><div><br></div><div>Justin Holewinski</div><br>