Revert "Read and store gnu build id from loaded core file" (#92181)

Reverts llvm/llvm-project#92078

1 files changed, 59 insertions, 2 deletions

diff --git a/lldb/source/Commands/CommandObjectMemory.cpp b/lldb/source/Commands/CommandObjectMemory.cpp
index 1c13484..b78a049 100644
--- a/lldb/source/Commands/CommandObjectMemory.cpp
+++ b/lldb/source/Commands/CommandObjectMemory.cpp
@@ -977,6 +977,35 @@ public:
   Options *GetOptions() override { return &m_option_group; }
 
 protected:
+  class ProcessMemoryIterator {
+  public:
+    ProcessMemoryIterator(ProcessSP process_sp, lldb::addr_t base)
+        : m_process_sp(process_sp), m_base_addr(base) {
+      lldbassert(process_sp.get() != nullptr);
+    }
+
+    bool IsValid() { return m_is_valid; }
+
+    uint8_t operator[](lldb::addr_t offset) {
+      if (!IsValid())
+        return 0;
+
+      uint8_t retval = 0;
+      Status error;
+      if (0 ==
+          m_process_sp->ReadMemory(m_base_addr + offset, &retval, 1, error)) {
+        m_is_valid = false;
+        return 0;
+      }
+
+      return retval;
+    }
+
+  private:
+    ProcessSP m_process_sp;
+    lldb::addr_t m_base_addr;
+    bool m_is_valid = true;
+  };
   void DoExecute(Args &command, CommandReturnObject &result) override {
     // No need to check "process" for validity as eCommandRequiresProcess
     // ensures it is valid
@@ -1077,8 +1106,8 @@ protected:
     found_location = low_addr;
     bool ever_found = false;
     while (count) {
-      found_location = process->FindInMemory(
-          found_location, high_addr, buffer.GetBytes(), buffer.GetByteSize());
+      found_location = FastSearch(found_location, high_addr, buffer.GetBytes(),
+                                  buffer.GetByteSize());
       if (found_location == LLDB_INVALID_ADDRESS) {
         if (!ever_found) {
           result.AppendMessage("data not found within the range.\n");
@@ -1115,6 +1144,34 @@ protected:
     result.SetStatus(lldb::eReturnStatusSuccessFinishResult);
   }
 
+  lldb::addr_t FastSearch(lldb::addr_t low, lldb::addr_t high, uint8_t *buffer,
+                          size_t buffer_size) {
+    const size_t region_size = high - low;
+
+    if (region_size < buffer_size)
+      return LLDB_INVALID_ADDRESS;
+
+    std::vector<size_t> bad_char_heuristic(256, buffer_size);
+    ProcessSP process_sp = m_exe_ctx.GetProcessSP();
+    ProcessMemoryIterator iterator(process_sp, low);
+
+    for (size_t idx = 0; idx < buffer_size - 1; idx++) {
+      decltype(bad_char_heuristic)::size_type bcu_idx = buffer[idx];
+      bad_char_heuristic[bcu_idx] = buffer_size - idx - 1;
+    }
+    for (size_t s = 0; s <= (region_size - buffer_size);) {
+      int64_t j = buffer_size - 1;
+      while (j >= 0 && buffer[j] == iterator[s + j])
+        j--;
+      if (j < 0)
+        return low + s;
+      else
+        s += bad_char_heuristic[iterator[s + buffer_size - 1]];
+    }
+
+    return LLDB_INVALID_ADDRESS;
+  }
+
   OptionGroupOptions m_option_group;
   OptionGroupFindMemory m_memory_options;
   OptionGroupMemoryTag m_memory_tag_options;