[Zucchini] Simplify Abs32GapFinder and Rel32Finder.

Previously, using Abs32GapFinder / Rel32Finder to visit gaps / rel32
references involves calling a getter that returns an optional<> value
whose emptiness indicates end of iteration. The code to use this looks
like:

  for (auto value = finder.GetNext(); value; value = finder.GetNext()) {
    ...
  }

This CL abandons optional<> usage and caches the results in Finders,
thereby removing repetition in iteration code:

  while (finder.FindNext() {
    auto value = finder.GetValue();
    ...
  }

Additional changes:
* Incorporate AddressTranslator into Rel32Finder to offload translation
  work from callers.
* Add tests to integrate Abs32GapFinder with Rel32Finder.
  * Stylize test data to better show overlap between abs32 references
    with disassembled test data.

Bug: 918867
Change-Id: Id044b67550f81c3f46ab383c5b6200906f56ca4e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2918113
Reviewed-by: Etienne Pierre-Doray <etiennep@chromium.org>
Commit-Queue: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#888049}
NOKEYCHECK=True
GitOrigin-RevId: 89023e1c511e599e6aeaf0b8d80e3efa2e730b5b

1 files changed, 11 insertions, 18 deletions

diff --git a/disassembler_win32.cc b/disassembler_win32.cc
index da830bf..a23201b 100644
--- a/disassembler_win32.cc
+++ b/disassembler_win32.cc
@@ -363,7 +363,6 @@ bool DisassemblerWin32<Traits>::ParseAndStoreRel32() {
 
   ParseAndStoreAbs32();
 
-  AddressTranslator::OffsetToRvaCache location_offset_to_rva(translator_);
   AddressTranslator::RvaToOffsetCache target_rva_checker(translator_);
 
   for (const pe::ImageSectionHeader& section : sections_) {
@@ -382,24 +381,18 @@ bool DisassemblerWin32<Traits>::ParseAndStoreRel32() {
         image_[{section.file_offset_of_raw_data, size_to_use}];
     Abs32GapFinder gap_finder(image_, region, abs32_locations_,
                               Traits::kVAWidth);
-    typename Traits::RelFinder finder;
+    typename Traits::RelFinder rel_finder(image_, translator_);
     // Iterate over gaps between abs32 references, to avoid collision.
-    for (auto gap = gap_finder.GetNext(); gap.has_value();
-         gap = gap_finder.GetNext()) {
-      finder.SetRegion(gap.value());
-      // Iterate over heuristically detected rel32 references, validate, and add
-      // to |rel32_locations_|.
-      for (auto rel32 = finder.GetNext(); rel32.has_value();
-           rel32 = finder.GetNext()) {
-        offset_t rel32_offset = offset_t(rel32->location - image_.begin());
-        rva_t rel32_rva = location_offset_to_rva.Convert(rel32_offset);
-        DCHECK_NE(rel32_rva, kInvalidRva);
-        rva_t target_rva = rel32_rva + 4 + image_.read<uint32_t>(rel32_offset);
-        if (target_rva_checker.IsValid(target_rva) &&
-            (rel32->can_point_outside_section ||
-             (start_rva <= target_rva && target_rva < end_rva))) {
-          finder.Accept();
-          rel32_locations_.push_back(rel32_offset);
+    while (gap_finder.FindNext()) {
+      rel_finder.SetRegion(gap_finder.GetGap());
+      // Heuristically detect rel32 references, store if valid.
+      while (rel_finder.FindNext()) {
+        auto rel32 = rel_finder.GetRel32();
+        if (target_rva_checker.IsValid(rel32.target_rva) &&
+            (rel32.can_point_outside_section ||
+             (start_rva <= rel32.target_rva && rel32.target_rva < end_rva))) {
+          rel_finder.Accept();
+          rel32_locations_.push_back(rel32.location);
         }
       }
     }