Remove sequential search from DwarfEhFrameWithHdr.
Since there has never been a time that a sequential search has been
necessary, simply remove the sequential code and allow the DwarfEhFrame
object to be used in that case. If this does come up regularly, I'm not
sure that it wouldn't be more performant to use the DwarfEhFrame object
regardless.
Bug: 129550015
Test: libunwindstack unit tests, libbacktrace unit tests.
Change-Id: I738e81accb9bc1e182168cddc9c0c22823e3369b
diff --git a/libunwindstack/DwarfEhFrameWithHdr.cpp b/libunwindstack/DwarfEhFrameWithHdr.cpp
index 668527a..802beca 100644
--- a/libunwindstack/DwarfEhFrameWithHdr.cpp
+++ b/libunwindstack/DwarfEhFrameWithHdr.cpp
@@ -61,6 +61,14 @@
table_encoding_ = data[3];
table_entry_size_ = memory_.template GetEncodedSize<AddressType>(table_encoding_);
+ // If we can't perform a binary search on the entries, it's not worth
+ // using this object. The calling code will fall back to the DwarfEhFrame
+ // object in this case.
+ if (table_entry_size_ == 0) {
+ last_error_.code = DWARF_ERROR_ILLEGAL_VALUE;
+ return false;
+ }
+
memory_.set_pc_offset(memory_.cur_offset());
if (!memory_.template ReadEncodedValue<AddressType>(ptr_encoding_, &ptr_offset_)) {
last_error_.code = DWARF_ERROR_MEMORY_INVALID;
@@ -137,13 +145,13 @@
}
template <typename AddressType>
-bool DwarfEhFrameWithHdr<AddressType>::GetFdeOffsetBinary(uint64_t pc, uint64_t* fde_offset,
- uint64_t total_entries) {
- CHECK(fde_count_ > 0);
- CHECK(total_entries <= fde_count_);
+bool DwarfEhFrameWithHdr<AddressType>::GetFdeOffsetFromPc(uint64_t pc, uint64_t* fde_offset) {
+ if (fde_count_ == 0) {
+ return false;
+ }
size_t first = 0;
- size_t last = total_entries;
+ size_t last = fde_count_;
while (first < last) {
size_t current = (first + last) / 2;
const FdeInfo* info = GetFdeInfoFromIndex(current);
@@ -172,87 +180,6 @@
}
template <typename AddressType>
-bool DwarfEhFrameWithHdr<AddressType>::GetFdeOffsetSequential(uint64_t pc, uint64_t* fde_offset) {
- CHECK(fde_count_ != 0);
- last_error_.code = DWARF_ERROR_NONE;
- last_error_.address = 0;
-
- // We can do a binary search if the pc is in the range of the elements
- // that have already been cached.
- if (!fde_info_.empty()) {
- const FdeInfo* info = &fde_info_[fde_info_.size() - 1];
- if (pc >= info->pc) {
- *fde_offset = info->offset;
- return true;
- }
- if (pc < info->pc) {
- return GetFdeOffsetBinary(pc, fde_offset, fde_info_.size());
- }
- }
-
- if (cur_entries_offset_ == 0) {
- // All entries read, or error encountered.
- return false;
- }
-
- memory_.set_data_offset(entries_data_offset_);
- memory_.set_cur_offset(cur_entries_offset_);
- memory_.set_pc_offset(0);
- cur_entries_offset_ = 0;
-
- FdeInfo* prev_info = nullptr;
- for (size_t current = fde_info_.size();
- current < fde_count_ && memory_.cur_offset() < entries_end_; current++) {
- FdeInfo* info = &fde_info_[current];
- uint64_t value;
- if (!memory_.template ReadEncodedValue<AddressType>(table_encoding_, &value) ||
- !memory_.template ReadEncodedValue<AddressType>(table_encoding_, &info->offset)) {
- fde_info_.erase(current);
- last_error_.code = DWARF_ERROR_MEMORY_INVALID;
- last_error_.address = memory_.cur_offset();
- return false;
- }
-
- // Relative encodings require adding in the load bias.
- if (IsEncodingRelative(table_encoding_)) {
- value += load_bias_;
- }
- info->pc = value;
-
- if (pc < info->pc) {
- if (prev_info == nullptr) {
- return false;
- }
- cur_entries_offset_ = memory_.cur_offset();
- *fde_offset = prev_info->offset;
- return true;
- }
- prev_info = info;
- }
-
- if (fde_count_ == fde_info_.size() && pc >= prev_info->pc) {
- *fde_offset = prev_info->offset;
- return true;
- }
- return false;
-}
-
-template <typename AddressType>
-bool DwarfEhFrameWithHdr<AddressType>::GetFdeOffsetFromPc(uint64_t pc, uint64_t* fde_offset) {
- if (fde_count_ == 0) {
- return false;
- }
-
- if (table_entry_size_ > 0) {
- // Do a binary search since the size of each table entry is fixed.
- return GetFdeOffsetBinary(pc, fde_offset, fde_count_);
- } else {
- // Do a sequential search since each table entry size is variable.
- return GetFdeOffsetSequential(pc, fde_offset);
- }
-}
-
-template <typename AddressType>
void DwarfEhFrameWithHdr<AddressType>::GetFdes(std::vector<const DwarfFde*>* fdes) {
for (size_t i = 0; i < fde_count_; i++) {
const FdeInfo* info = GetFdeInfoFromIndex(i);