Implement GcInfo v2 for X86

This commit includes the following changes:
1) Thread GcInfo version through X86 specific APIs
2) Add ReturnKind and ReversePinvokeOffset fields to InfoHdr structure
   GcInfo v1 and v2 use the same InfoHdr structures, because:
   InfoHdrSmall: ReturnKind is encoded within previously unused bits.
   InfoHdr: revPInvokeOffset will never be written to the image,
            since ReversePinvokeOffset==INVALID_REV_PINVOKE_OFFSET for V1.
3) Update the Pre-computed header table to include bits for the above
   [The default setting of ReturnKind=RT_Scalar is used for all entries in the table.
    Optimizing this table based in most frequent usage scenarios is to be done separately]
4) Change the GC encoder/decoder to handle the above two fields
5) Use the ReturnKind in the GCInfo from thread-suspension code.

GcInfo version is changed for CoreCLR X86 only, not for Desktop JIT
Fixes #4379

2 files changed, 20 insertions, 6 deletions

diff --git a/src/gcdump/gcdumpnonx86.cpp b/src/gcdump/gcdumpnonx86.cpp
index 7343ac9771..c2f41c933a 100644
--- a/src/gcdump/gcdumpnonx86.cpp
+++ b/src/gcdump/gcdumpnonx86.cpp
@@ -505,7 +505,7 @@ size_t      GCDump::DumpGCTable(PTR_CBYTE      gcInfoBlock,
 
 /*****************************************************************************/
 
-void    GCDump::DumpPtrsInFrame(PTR_CBYTE   infoBlock,
+void    GCDump::DumpPtrsInFrame(PTR_CBYTE   gcInfoBlock,
                                 PTR_CBYTE   codeBlock,
                                 unsigned    offs,
                                 bool        verifyGCTables)
diff --git a/src/gcdump/i386/gcdumpx86.cpp b/src/gcdump/i386/gcdumpx86.cpp
index 70334dee65..0c903970e1 100644
--- a/src/gcdump/i386/gcdumpx86.cpp
+++ b/src/gcdump/i386/gcdumpx86.cpp
@@ -60,12 +60,13 @@ const char *        CalleeSavedRegName(unsigned reg)
 
 /*****************************************************************************/
 
-unsigned            GCDump::DumpInfoHdr (PTR_CBYTE      table,
+unsigned            GCDump::DumpInfoHdr (PTR_CBYTE      gcInfoBlock,
                                          InfoHdr*       header,
                                          unsigned *     methodSize,
                                          bool           verifyGCTables)
 {
     unsigned        count;
+    PTR_CBYTE       table       = gcInfoBlock;
     PTR_CBYTE       tableStart  = table;
     PTR_CBYTE       bp          = table;
 
@@ -76,7 +77,7 @@ unsigned            GCDump::DumpInfoHdr (PTR_CBYTE      table,
 
     table += decodeUnsigned(table, methodSize);
 
-    table = decodeHeader(table, header);
+    table = decodeHeader(table, gcInfoVersion, header);
 
     BOOL hasArgTabOffset = FALSE;
     if (header->untrackedCnt == HAS_UNTRACKED)
@@ -107,6 +108,12 @@ unsigned            GCDump::DumpInfoHdr (PTR_CBYTE      table,
         header->syncEndOffset = count;
     }
 
+    if (header->revPInvokeOffset == HAS_REV_PINVOKE_FRAME_OFFSET)
+    {
+        table += decodeUnsigned(table, &count);
+        header->revPInvokeOffset = count;
+    }
+
     //
     // First print out all the basic information
     //
@@ -931,12 +938,12 @@ DONE_REGTAB:
 
 /*****************************************************************************/
 
-void                GCDump::DumpPtrsInFrame(PTR_CBYTE   infoBlock,
+void                GCDump::DumpPtrsInFrame(PTR_CBYTE   gcInfoBlock,
                                             PTR_CBYTE   codeBlock,
                                             unsigned    offs,
                                             bool        verifyGCTables)
 {
-    PTR_CBYTE       table = infoBlock;
+    PTR_CBYTE       table = gcInfoBlock;
 
     size_t          methodSize;
     size_t          stackSize;
@@ -963,7 +970,7 @@ void                GCDump::DumpPtrsInFrame(PTR_CBYTE   infoBlock,
     // Typically only uses one-byte to store everything.
     //
     InfoHdr header;
-    table = decodeHeader(table, &header);
+    table = decodeHeader(table, gcInfoVersion, &header);
     
     if (header.untrackedCnt == HAS_UNTRACKED)
     {
@@ -994,6 +1001,13 @@ void                GCDump::DumpPtrsInFrame(PTR_CBYTE   infoBlock,
         header.syncEndOffset = offset;
         _ASSERTE(offset != INVALID_SYNC_OFFSET);
     }
+    if (header.revPInvokeOffset == HAS_REV_PINVOKE_FRAME_OFFSET)
+    {
+        unsigned offset;
+        table += decodeUnsigned(table, &offset);
+        header.revPInvokeOffset = offset;
+        _ASSERTE(offset != INVALID_REV_PINVOKE_OFFSET);
+    }
 
     prologSize = header.prologSize;
     epilogSize = header.epilogSize;