diff options
| -rw-r--r-- | third_party/llvm-project/DWARFVisitor.cpp | 40 |
1 files changed, 32 insertions, 8 deletions
diff --git a/third_party/llvm-project/DWARFVisitor.cpp b/third_party/llvm-project/DWARFVisitor.cpp index 1f4403563..4b6ed5ada 100644 --- a/third_party/llvm-project/DWARFVisitor.cpp +++ b/third_party/llvm-project/DWARFVisitor.cpp @@ -8,6 +8,8 @@ // //===----------------------------------------------------------------------===// +#include <unordered_map> + #include "DWARFVisitor.h" #include "llvm/ObjectYAML/DWARFYAML.h" @@ -49,19 +51,41 @@ template <typename T> void DWARFYAML::VisitorImpl<T>::traverseDebugInfo() { // TODO: This code appears to assume that abbreviation codes increment by 1 // so that lookups are linear. In LLVM output that is true, but it might not // be in general. + // Create a map of [byte offset into the abbreviation section] => [index in + // DebugInfo.AbbrevDecls]. This avoids linear search for each CU. + std::unordered_map<size_t, size_t> abbrByteOffsetToDeclsIndex; + for (size_t i = 0; i < DebugInfo.AbbrevDecls.size(); i++) { + auto offset = DebugInfo.AbbrevDecls[i].ListOffset; + // The offset is the same for all entries for the same CU, so only note the + // first as that is where the list for the CU (that LLVM DeclSet) begins. + // That is, DebugInfo.AbbrevDecls looks like this: + // + // i CU Abbrev ListOffset + // ============================ + // 0 X X1 150 + // 1 X X2 150 + // 2 X X3 150 + // .. + // 6 Y Y1 260 + // 7 Y Y2 260 + // + // Note how multiple rows i have the same CU. All those abbrevs have the + // same ListOffset, which is the byte offset into the abbreviation section + // for that set of abbreviations. + if (abbrByteOffsetToDeclsIndex.count(offset)) { + continue; + } + abbrByteOffsetToDeclsIndex[offset] = i; + } for (auto &Unit : DebugInfo.CompileUnits) { // AbbrOffset is the byte offset into the abbreviation section, which we // need to find among the Abbrev's ListOffsets (which are the byte offsets // of where that abbreviation list begins). // TODO: Optimize this to not be O(#CUs * #abbrevs). - size_t AbbrevStart = -1; - for (size_t i = 0; i < DebugInfo.AbbrevDecls.size(); i++) { - if (DebugInfo.AbbrevDecls[i].ListOffset == Unit.AbbrOffset) { - AbbrevStart = i; - break; - } - } - assert(AbbrevStart != -1); // must find the list + auto offset = Unit.AbbrOffset; + assert(abbrByteOffsetToDeclsIndex.count(offset)); + size_t AbbrevStart = abbrByteOffsetToDeclsIndex[offset]; + assert(DebugInfo.AbbrevDecls[AbbrevStart].ListOffset == offset); // Find the last entry in this abbreviation list. size_t AbbrevEnd = AbbrevStart; while (AbbrevEnd < DebugInfo.AbbrevDecls.size() && |