From a1c04b25428b2c800f281ad2a4b7241199612bac Mon Sep 17 00:00:00 2001
From: Amy Yu <amycmyu@gmail.com>
Date: Thu, 14 Jun 2018 17:34:47 -0700
Subject: [PATCH] Fixed some bugs with gc transitions

---
 src/tools/r2rdump/GCInfo.cs       | 15 ++++++++++++---
 src/tools/r2rdump/GCSlotTable.cs  |  4 ++--
 src/tools/r2rdump/NativeReader.cs |  2 +-
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/tools/r2rdump/GCInfo.cs b/src/tools/r2rdump/GCInfo.cs
index 2b8c1f1..a39a85a 100644
--- a/src/tools/r2rdump/GCInfo.cs
+++ b/src/tools/r2rdump/GCInfo.cs
@@ -385,12 +385,21 @@ namespace R2RDump
             {
                 chunkPointers[i] = NativeReader.ReadBits(image, numBitsPerPointer, ref bitOffset);
             }
-            bitOffset = (int)Math.Ceiling(bitOffset / 8.0) * 8;
+            int info2Offset = (int)Math.Ceiling(bitOffset / 8.0) * 8;
 
             List<GcTransition> transitions = new List<GcTransition>();
             bool[] liveAtEnd = new bool[slots.Count];
             for (int currentChunk = 0; currentChunk < numChunks; currentChunk++)
             {
+                if (chunkPointers[currentChunk] == 0)
+                {
+                    continue;
+                }
+                else
+                {
+                    bitOffset = info2Offset + chunkPointers[currentChunk] - 1;
+                }
+
                 int couldBeLiveOffset = bitOffset;
                 int slotId = 0;
                 bool fSimple = (NativeReader.ReadBits(image, 1, ref couldBeLiveOffset) == 0);
@@ -410,7 +419,7 @@ namespace R2RDump
                 int normChunkBaseCodeOffset = currentChunk * gcInfoTypes.NUM_NORM_CODE_OFFSETS_PER_CHUNK;
                 for (int i = 0; i < numCouldBeLiveSlots; i++)
                 {
-                    slotId = GetSlotId(image, gcInfoTypes, fSimple, fSkipFirst, slotId, ref couldBeLiveCnt, ref couldBeLiveOffset);
+                    slotId = GetNextSlotId(image, gcInfoTypes, fSimple, fSkipFirst, slotId, ref couldBeLiveCnt, ref couldBeLiveOffset);
 
                     bool isLive = !liveAtEnd[slotId];
                     liveAtEnd[slotId] = (NativeReader.ReadBits(image, 1, ref finalStateOffset) != 0);
@@ -469,7 +478,7 @@ namespace R2RDump
             return numCouldBeLiveSlots;
         }
 
-        private int GetSlotId(byte[] image, GcInfoTypes gcInfoTypes, bool fSimple, bool fSkipFirst, int slotId, ref int couldBeLiveCnt, ref int couldBeLiveOffset)
+        private int GetNextSlotId(byte[] image, GcInfoTypes gcInfoTypes, bool fSimple, bool fSkipFirst, int slotId, ref int couldBeLiveCnt, ref int couldBeLiveOffset)
         {
             if (fSimple)
             {
diff --git a/src/tools/r2rdump/GCSlotTable.cs b/src/tools/r2rdump/GCSlotTable.cs
index 5828b95..750c65d 100644
--- a/src/tools/r2rdump/GCSlotTable.cs
+++ b/src/tools/r2rdump/GCSlotTable.cs
@@ -103,7 +103,7 @@ namespace R2RDump
             GcSlotFlags flags = (GcSlotFlags)NativeReader.ReadBits(image, 2, ref bitOffset);
             GcSlots.Add(new GcSlot((int)regNum, null, flags));
 
-            for (int i = 1; i < NumRegisters && i < gcInfoTypes.MAX_PREDECODED_SLOTS; i++)
+            for (int i = 1; i < NumRegisters; i++)
             {
                 if ((uint)flags != 0)
                 {
@@ -128,7 +128,7 @@ namespace R2RDump
             GcSlotFlags flags = (GcSlotFlags)NativeReader.ReadBits(image, 2, ref bitOffset);
             GcSlots.Add(new GcSlot(-1, new GcStackSlot(spOffset, spBase), flags));
 
-            for (int i = 1; i < nSlots && GcSlots.Count < gcInfoTypes.MAX_PREDECODED_SLOTS; i++)
+            for (int i = 1; i < nSlots; i++)
             {
                 spBase = (GcStackSlotBase)NativeReader.ReadBits(image, 2, ref bitOffset);
                 if ((uint)flags != 0)
diff --git a/src/tools/r2rdump/NativeReader.cs b/src/tools/r2rdump/NativeReader.cs
index cfc9a68..9871c2e 100644
--- a/src/tools/r2rdump/NativeReader.cs
+++ b/src/tools/r2rdump/NativeReader.cs
@@ -107,7 +107,7 @@ namespace R2RDump
             int bits = bitOffset % BITS_PER_BYTE;
             int val = image[start] >> bits;
             bits += numBits;
-            if (bits > BITS_PER_BYTE)
+            while (bits > BITS_PER_BYTE)
             {
                 start++;
                 bits -= BITS_PER_BYTE;
-- 
2.7.4