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[DWARF] Speedup .gdb_index dumping #151806

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[DWARF] Speedup .gdb_index dumping #151806

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25 changes: 20 additions & 5 deletions llvm/lib/DebugInfo/DWARF/DWARFGdbIndex.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include <cinttypes>
#include <cstdint>
#include <set>
#include <unordered_map>
#include <utility>

using namespace llvm;
Expand Down Expand Up @@ -60,6 +61,24 @@ void DWARFGdbIndex::dumpSymbolTable(raw_ostream &OS) const {
", filled slots:",
SymbolTableOffset, (uint64_t)SymbolTable.size())
<< '\n';

std::unordered_map<uint32_t, decltype(ConstantPoolVectors)::const_iterator>
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Probably use a DenseMap? ( https://llvm.org/docs/ProgrammersManual.html#picking-the-right-data-structure-for-a-task )

CuVectorMap{};
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Probably drop these {} as they're redundant.

CuVectorMap.reserve(ConstantPoolVectors.size());
const auto FindCuVector =
[&CuVectorMap, notFound = ConstantPoolVectors.end()](uint32_t vecOffset) {
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I probably wouldn't bother separately capturing things like this in a locally scoped non-erased functor. Probably just use [&] and return ConstantPoolVectors.end(); in the fail-case.

const auto it = CuVectorMap.find(vecOffset);
if (it != CuVectorMap.end()) {
return it->second;
}
Comment on lines +70 to +73
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LLVM's coding style skips {} on single-line blocks, and reduces scope where possible, so probably something like:

if (auto it = CuVectorMap.find(vecOffset); it != CuVectorMap.end())
  return it->second;


return notFound;
};
for (auto it = ConstantPoolVectors.begin(); it != ConstantPoolVectors.end();
++it) {
CuVectorMap.emplace(it->first, it);
}
Comment on lines +78 to +80
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Could drop the {} here.

Could use a range-based for loop, and instead of putting iterators as values in the map, use pointers (then you can get a pointer to the value in the range based for loop where there aren't any visible/name-able iterators)


uint32_t I = -1;
for (const SymTableEntry &E : SymbolTable) {
++I;
Expand All @@ -72,11 +91,7 @@ void DWARFGdbIndex::dumpSymbolTable(raw_ostream &OS) const {
StringRef Name = ConstantPoolStrings.substr(
ConstantPoolOffset - StringPoolOffset + E.NameOffset);

auto CuVector = llvm::find_if(
ConstantPoolVectors,
[&](const std::pair<uint32_t, SmallVector<uint32_t, 0>> &V) {
return V.first == E.VecOffset;
});
auto CuVector = FindCuVector(E.VecOffset);
assert(CuVector != ConstantPoolVectors.end() && "Invalid symbol table");
uint32_t CuVectorId = CuVector - ConstantPoolVectors.begin();
OS << format(" String name: %s, CU vector index: %d\n", Name.data(),
Expand Down
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