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[LLVM] Support CodeGenBlob for large >2GB models #10882

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Merged
FrozenGene merged 1 commit into from
Apr 5, 2022
Merged

[LLVM] Support CodeGenBlob for large >2GB models #10882

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12 changes: 12 additions & 0 deletions src/target/llvm/codegen_blob.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,18 @@ std::pair<std::unique_ptr<llvm::Module>, std::shared_ptr<llvm::LLVMContext>> Cod
*module, blob_value->getType(), true, llvm::GlobalValue::ExternalLinkage, blob_value,
runtime::symbol::tvm_dev_mblob, nullptr, llvm::GlobalVariable::NotThreadLocal, 0);

// If large const data (>2GB) is saved to default .rodata section
// then linking it to shared library will fail - relocation truncated to fit: R_X86_64_PC32.
// The issue exists on Linux x86_64 platform.
// GCC handles this situation by using -mcmodel=medium parameter but LLVM ignores it.
// The workaround is to explicitly put large const data to .lrodata section.
// Lets put const data which is larger than 1GB to .lrodata section
const size_t large_data_threshold = 1 << 30;
if (data.size() > large_data_threshold && triple.getArch() == llvm::Triple::x86_64 &&
triple.isOSBinFormatELF()) {
tvm_dev_mblob->setSection(".lrodata");
}

#if TVM_LLVM_VERSION >= 100
tvm_dev_mblob->setAlignment(llvm::Align(1));
#else
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