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[mlir][spirv] Truncate Literal String size at max number words #142916

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Merged
merged 4 commits into from
Jun 11, 2025
Merged

[mlir][spirv] Truncate Literal String size at max number words #142916

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54172aa
[mlir][spirv] Truncate Literal String size at max number words
davidegrohmann Jan 29, 2025
89989ba
Fix review comments
davidegrohmann Jun 6, 2025
fefa194
Add missing full stop marks
davidegrohmann Jun 10, 2025
9402ece
resolve clang-format problem
davidegrohmann Jun 11, 2025
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6 changes: 6 additions & 0 deletions mlir/include/mlir/Target/SPIRV/SPIRVBinaryUtils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,12 @@ constexpr uint32_t kMagicNumber = 0x07230203;
/// The serializer tool ID registered to the Khronos Group
constexpr uint32_t kGeneratorNumber = 22;

// Max number of words
constexpr uint32_t kMaxWordCount = 65535;

// Max number of words for literal
constexpr uint32_t kMaxLiteralWordCount = kMaxWordCount - 3;

/// Appends a SPRI-V module header to `header` with the given `version` and
/// `idBound`.
void appendModuleHeader(SmallVectorImpl<uint32_t> &header,
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16 changes: 15 additions & 1 deletion mlir/lib/Target/SPIRV/SPIRVBinaryUtils.cpp
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Expand Up @@ -13,6 +13,9 @@
#include "mlir/Target/SPIRV/SPIRVBinaryUtils.h"
#include "mlir/Dialect/SPIRV/IR/SPIRVTypes.h"
#include "llvm/Config/llvm-config.h" // for LLVM_VERSION_MAJOR
#include "llvm/Support/Debug.h"

#define DEBUG_TYPE "spirv-binary-utils"

using namespace mlir;

Expand Down Expand Up @@ -68,7 +71,18 @@ void spirv::encodeStringLiteralInto(SmallVectorImpl<uint32_t> &binary,
StringRef literal) {
// We need to encode the literal and the null termination.
auto encodingSize = literal.size() / 4 + 1;
auto sizeOfDataToCopy = literal.size();
if (encodingSize >= kMaxLiteralWordCount) {
// reserve one word for the null termination
encodingSize = kMaxLiteralWordCount - 1;
// do not override the last word (null termination) when copying
sizeOfDataToCopy = (encodingSize - 1) * 4;
LLVM_DEBUG(llvm::dbgs() << "Truncating string literal to max size ("
<< std::to_string(kMaxLiteralWordCount - 1)
<< "): " << literal << "\n");
}
auto bufferStartSize = binary.size();
binary.resize(bufferStartSize + encodingSize, 0);
std::memcpy(binary.data() + bufferStartSize, literal.data(), literal.size());
std::memcpy(binary.data() + bufferStartSize, literal.data(),
sizeOfDataToCopy);
}