From f9a4fbff8693a11aea4af9ac5bb07d9e3fe34be3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Rylek?= <trylek@microsoft.com>
Date: Sun, 6 Dec 2020 20:10:56 +0100
Subject: [PATCH] Add support for diffing GC ref map info to R2RDump; small
 bugfix (#45619)

---
 src/coreclr/src/tools/r2rdump/Extensions.cs |  2 +-
 src/coreclr/src/tools/r2rdump/R2RDiff.cs    | 46 +++++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/src/coreclr/src/tools/r2rdump/Extensions.cs b/src/coreclr/src/tools/r2rdump/Extensions.cs
index 3d297963a85b8..5240a70fc586a 100644
--- a/src/coreclr/src/tools/r2rdump/Extensions.cs
+++ b/src/coreclr/src/tools/r2rdump/Extensions.cs
@@ -250,7 +250,7 @@ public static void WriteTo(this GCRefMap theThis, TextWriter writer)
         {
             if (theThis.StackPop != GCRefMap.InvalidStackPop)
             {
-                writer.Write(@"POP(0x{StackPop:X}) ");
+                writer.Write($@"POP(0x{theThis.StackPop:X}) ");
             }
             for (int entryIndex = 0; entryIndex < theThis.Entries.Length; entryIndex++)
             {
diff --git a/src/coreclr/src/tools/r2rdump/R2RDiff.cs b/src/coreclr/src/tools/r2rdump/R2RDiff.cs
index 1e0c639139957..91962d3ee929a 100644
--- a/src/coreclr/src/tools/r2rdump/R2RDiff.cs
+++ b/src/coreclr/src/tools/r2rdump/R2RDiff.cs
@@ -57,6 +57,7 @@ public void Run()
             DiffTitle();
             DiffPESections();
             DiffR2RSections();
+            DiffImportSections();
             DiffR2RMethods();
 
             DiffMethodsForModule(AllModules, AllModules);
@@ -144,6 +145,37 @@ private void DiffR2RSections()
             ShowDiff(GetR2RSectionMap(_leftDumper.Reader), GetR2RSectionMap(_rightDumper.Reader), "R2R sections");
         }
 
+        private void DiffImportSections()
+        {
+            Dictionary<string, ReadyToRunImportSection.ImportSectionEntry> leftImports = GetImports(_leftDumper.Reader);
+            Dictionary<string, ReadyToRunImportSection.ImportSectionEntry> rightImports = GetImports(_rightDumper.Reader);
+            HashSet<string> commonKeys = new HashSet<string>(leftImports.Keys);
+            commonKeys.IntersectWith(rightImports.Keys);
+
+            _writer.WriteLine("Import entries");
+            _writer.WriteLine("--------------");
+
+            foreach (string key in commonKeys.OrderBy(k => k))
+            {
+                ReadyToRunImportSection.ImportSectionEntry leftEntry = leftImports[key];
+                ReadyToRunImportSection.ImportSectionEntry rightEntry = rightImports[key];
+                StringWriter leftInfo = new StringWriter();
+                StringWriter rightInfo = new StringWriter();
+                leftEntry.GCRefMap?.WriteTo(leftInfo);
+                rightEntry.GCRefMap?.WriteTo(rightInfo);
+                string leftGCRefMap = leftInfo.ToString();
+                string rightGCRefMap = rightInfo.ToString();
+                if (leftGCRefMap != rightGCRefMap)
+                {
+                    _writer.WriteLine($@"Method:           {key}");
+                    _writer.WriteLine($@"Left GC ref map:  {leftGCRefMap}");
+                    _writer.WriteLine($@"Right GC ref map: {rightGCRefMap}");
+                }
+            }
+
+            _writer.WriteLine();
+        }
+
         /// <summary>
         /// Diff the R2R method maps.
         /// </summary>
@@ -349,6 +381,20 @@ private void DumpCommonMethods(Dumper dumper, int moduleIndex, Dictionary<string
             }
         }
 
+        private static Dictionary<string, ReadyToRunImportSection.ImportSectionEntry> GetImports(ReadyToRunReader reader)
+        {
+            var result = new Dictionary<string, ReadyToRunImportSection.ImportSectionEntry>();
+            var signatureOptions = new SignatureFormattingOptions() { Naked = true };
+            foreach (ReadyToRunImportSection section in reader.ImportSections)
+            {
+                foreach (ReadyToRunImportSection.ImportSectionEntry entry in section.Entries)
+                {
+                    result[entry.Signature.ToString(signatureOptions)] = entry;
+                }
+            }
+            return result;
+        }
+
         /// <summary>
         /// Filter out methods that have identical left / right disassembly.
         /// </summary>