do not record Return Kind in GCInfo

Author: VSadov

src/coreclr/gcinfo/gcinfoencoder.cpp

@@ -494,8 +494,6 @@ GcInfoEncoder::GcInfoEncoder(
     // If the compiler doesn't set the GCInfo, report RT_Unset.
     // This is used for compatibility with JITs that aren't updated to use the new API.
     m_ReturnKind = RT_Unset;
-#else
-    m_ReturnKind = RT_Illegal;
 #endif // TARGET_X86
     m_CodeLength = 0;
 #ifdef FIXED_STACK_PARAMETER_SCRATCH_AREA
@@ -776,12 +774,14 @@ void GcInfoEncoder::SetReversePInvokeFrameSlot(INT32 spOffset)
     m_ReversePInvokeFrameSlot = spOffset;
 }
 
+#ifndef TARGET_X86
 void GcInfoEncoder::SetReturnKind(ReturnKind returnKind)
 {
     _ASSERTE(IsValidReturnKind(returnKind));
 
     m_ReturnKind = returnKind;
 }
+#endif
 
 struct GcSlotDescAndId
 {
@@ -1045,16 +1045,15 @@ void GcInfoEncoder::Build()
     BOOL slimHeader = (!m_IsVarArg && !hasGSCookie && (m_PSPSymStackSlot == NO_PSP_SYM) &&
         !hasContextParamType && (m_InterruptibleRanges.Count() == 0) && !hasReversePInvokeFrame &&
         ((m_StackBaseRegister == NO_STACK_BASE_REGISTER) || (NORMALIZE_STACK_BASE_REGISTER(m_StackBaseRegister) == 0))) &&
-        (m_SizeOfEditAndContinuePreservedArea == NO_SIZE_OF_EDIT_AND_CONTINUE_PRESERVED_AREA) &&
 #ifdef TARGET_AMD64
         !m_WantsReportOnlyLeaf &&
 #elif defined(TARGET_ARM) || defined(TARGET_ARM64) || defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
         !m_HasTailCalls &&
 #endif // TARGET_AMD64
-        !IsStructReturnKind(m_ReturnKind);
+        (m_SizeOfEditAndContinuePreservedArea == NO_SIZE_OF_EDIT_AND_CONTINUE_PRESERVED_AREA);
 
     // All new code is generated for the latest GCINFO_VERSION.
-    // So, always encode RetunrKind and encode ReversePInvokeFrameSlot where applicable.
+    // So, always encode ReversePInvokeFrameSlot where applicable.
     if (slimHeader)
     {
         // Slim encoding means nothing special, partially interruptible, maybe a default frame register
@@ -1065,8 +1064,6 @@ void GcInfoEncoder::Build()
         assert(m_StackBaseRegister == 8 || 2 == m_StackBaseRegister);
 #endif
         GCINFO_WRITE(m_Info1, (m_StackBaseRegister == NO_STACK_BASE_REGISTER) ? 0 : 1, 1, FlagsSize);
-
-        GCINFO_WRITE(m_Info1, m_ReturnKind, SIZE_OF_RETURN_KIND_IN_SLIM_HEADER, RetKindSize);
     }
     else
     {
@@ -1089,8 +1086,6 @@ void GcInfoEncoder::Build()
 #endif // TARGET_AMD64
         GCINFO_WRITE(m_Info1, ((m_SizeOfEditAndContinuePreservedArea != NO_SIZE_OF_EDIT_AND_CONTINUE_PRESERVED_AREA) ? 1 : 0), 1, FlagsSize);
         GCINFO_WRITE(m_Info1, (hasReversePInvokeFrame ? 1 : 0), 1, FlagsSize);
-
-        GCINFO_WRITE(m_Info1, m_ReturnKind, SIZE_OF_RETURN_KIND_IN_FAT_HEADER, RetKindSize);
     }
 
     _ASSERTE( m_CodeLength > 0 );

src/coreclr/inc/gcinfoencoder.h

@@ -409,12 +409,13 @@ class GcInfoEncoder
                                     GcSlotState slotState
                                     );
 
-
+#ifndef TARGET_X86
     //------------------------------------------------------------------------
     // ReturnKind
     //------------------------------------------------------------------------
 
     void SetReturnKind(ReturnKind returnKind);
+#endif
 
     //------------------------------------------------------------------------
     // Miscellaneous method information
@@ -509,7 +510,9 @@ class GcInfoEncoder
     INT32  m_PSPSymStackSlot;
     INT32  m_GenericsInstContextStackSlot;
     GENERIC_CONTEXTPARAM_TYPE m_contextParamType;
+#ifndef TARGET_X86
     ReturnKind m_ReturnKind;
+#endif
     UINT32 m_CodeLength;
     UINT32 m_StackBaseRegister;
     UINT32 m_SizeOfEditAndContinuePreservedArea;

src/coreclr/inc/gcinfotypes.h

@@ -637,8 +637,6 @@ void FASTCALL decodeCallPattern(int         pattern,
 #define SECURITY_OBJECT_STACK_SLOT_ENCBASE 6
 #define GS_COOKIE_STACK_SLOT_ENCBASE 6
 #define CODE_LENGTH_ENCBASE 8
-#define SIZE_OF_RETURN_KIND_IN_SLIM_HEADER 2
-#define SIZE_OF_RETURN_KIND_IN_FAT_HEADER  4
 #define STACK_BASE_REGISTER_ENCBASE 3
 #define SIZE_OF_STACK_AREA_ENCBASE 3
 #define SIZE_OF_EDIT_AND_CONTINUE_PRESERVED_AREA_ENCBASE 4
@@ -695,8 +693,6 @@ void FASTCALL decodeCallPattern(int         pattern,
 #define SECURITY_OBJECT_STACK_SLOT_ENCBASE 5
 #define GS_COOKIE_STACK_SLOT_ENCBASE 5
 #define CODE_LENGTH_ENCBASE 7
-#define SIZE_OF_RETURN_KIND_IN_SLIM_HEADER 2
-#define SIZE_OF_RETURN_KIND_IN_FAT_HEADER  2
 #define STACK_BASE_REGISTER_ENCBASE 1
 #define SIZE_OF_STACK_AREA_ENCBASE 3
 #define SIZE_OF_EDIT_AND_CONTINUE_PRESERVED_AREA_ENCBASE 3
@@ -750,8 +746,6 @@ void FASTCALL decodeCallPattern(int         pattern,
 #define SECURITY_OBJECT_STACK_SLOT_ENCBASE 6
 #define GS_COOKIE_STACK_SLOT_ENCBASE 6
 #define CODE_LENGTH_ENCBASE 8
-#define SIZE_OF_RETURN_KIND_IN_SLIM_HEADER 2
-#define SIZE_OF_RETURN_KIND_IN_FAT_HEADER  4
 #define STACK_BASE_REGISTER_ENCBASE 2 // FP encoded as 0, SP as 2.
 #define SIZE_OF_STACK_AREA_ENCBASE 3
 #define SIZE_OF_EDIT_AND_CONTINUE_PRESERVED_AREA_ENCBASE 4
@@ -805,8 +799,6 @@ void FASTCALL decodeCallPattern(int         pattern,
 #define SECURITY_OBJECT_STACK_SLOT_ENCBASE 6
 #define GS_COOKIE_STACK_SLOT_ENCBASE 6
 #define CODE_LENGTH_ENCBASE 8
-#define SIZE_OF_RETURN_KIND_IN_SLIM_HEADER 2
-#define SIZE_OF_RETURN_KIND_IN_FAT_HEADER  4
 // FP/SP encoded as 0 or 1.
 #define STACK_BASE_REGISTER_ENCBASE 2
 #define SIZE_OF_STACK_AREA_ENCBASE 3
@@ -860,8 +852,6 @@ void FASTCALL decodeCallPattern(int         pattern,
 #define SECURITY_OBJECT_STACK_SLOT_ENCBASE 6
 #define GS_COOKIE_STACK_SLOT_ENCBASE 6
 #define CODE_LENGTH_ENCBASE 8
-#define SIZE_OF_RETURN_KIND_IN_SLIM_HEADER 2
-#define SIZE_OF_RETURN_KIND_IN_FAT_HEADER  4
 #define STACK_BASE_REGISTER_ENCBASE 2
 // FP encoded as 0, SP as 1
 #define SIZE_OF_STACK_AREA_ENCBASE 3
@@ -924,8 +914,6 @@ PORTABILITY_WARNING("Please specialize these definitions for your platform!")
 #define SECURITY_OBJECT_STACK_SLOT_ENCBASE 6
 #define GS_COOKIE_STACK_SLOT_ENCBASE 6
 #define CODE_LENGTH_ENCBASE 6
-#define SIZE_OF_RETURN_KIND_IN_SLIM_HEADER 2
-#define SIZE_OF_RETURN_KIND_IN_FAT_HEADER  2
 #define STACK_BASE_REGISTER_ENCBASE 3
 #define SIZE_OF_STACK_AREA_ENCBASE 6
 #define SIZE_OF_EDIT_AND_CONTINUE_PRESERVED_AREA_ENCBASE 3

src/coreclr/inc/readytorun.h

@@ -38,7 +38,7 @@
 //                 uses GCInfo v3, which makes safe points in partially interruptible code interruptible.
 // R2R Version 10.0 adds support for the statics being allocated on a per type basis instead of on a per module basis, disable support for LogMethodEnter helper
 // R2R Version 10.1 adds Unbox_TypeTest helper
-// R2R Version 11 uses GCInfo v4, which encodes safe points without -1 offset
+// R2R Version 11 uses GCInfo v4, which encodes safe points without -1 offset and does not track return kinds in GCInfo
 
 struct READYTORUN_CORE_HEADER
 {

src/coreclr/jit/gcencode.cpp

@@ -3709,6 +3709,7 @@ class GcInfoEncoderWithLogging
         }
     }
 
+#ifndef TARGET_X86
     void SetReturnKind(ReturnKind returnKind)
     {
         m_gcInfoEncoder->SetReturnKind(returnKind);
@@ -3717,6 +3718,7 @@ class GcInfoEncoderWithLogging
             printf("Set ReturnKind to %s.\n", ReturnKindToString(returnKind));
         }
     }
+#endif
 
     void SetStackBaseRegister(UINT32 registerNumber)
     {
@@ -3832,7 +3834,9 @@ void GCInfo::gcInfoBlockHdrSave(GcInfoEncoder* gcInfoEncoder, unsigned methodSiz
 
     gcInfoEncoderWithLog->SetCodeLength(methodSize);
 
+#ifndef TARGET_X86
     gcInfoEncoderWithLog->SetReturnKind(getReturnKind());
+#endif
 
     if (compiler->isFramePointerUsed())
     {

src/coreclr/tools/aot/ILCompiler.Reflection.ReadyToRun/Amd64/GcInfo.cs

@@ -47,6 +47,7 @@ public SafePointOffset(int index, uint value)
         }
 
         private const int MIN_GCINFO_VERSION_WITH_RETURN_KIND = 2;
+        private const int MAX_GCINFO_VERSION_WITH_RETURN_KIND = 3;
         private const int MIN_GCINFO_VERSION_WITH_REV_PINVOKE_FRAME = 2;
         private const int MIN_GCINFO_VERSION_WITH_NORMALIZED_CODE_OFFSETS = 3;
 
@@ -107,7 +108,7 @@ public GcInfo(byte[] image, int offset, Machine machine, ushort majorVersion, us
 
             ParseHeaderFlags(image, ref bitOffset);
 
-            if (Version >= MIN_GCINFO_VERSION_WITH_RETURN_KIND) // IsReturnKindAvailable
+            if (Version >= MIN_GCINFO_VERSION_WITH_RETURN_KIND && Version <= MAX_GCINFO_VERSION_WITH_RETURN_KIND) // IsReturnKindAvailable
             {
                 int returnKindBits = (_slimHeader) ? _gcInfoTypes.SIZE_OF_RETURN_KIND_SLIM : _gcInfoTypes.SIZE_OF_RETURN_KIND_FAT;
                 ReturnKind = (ReturnKinds)NativeReader.ReadBits(image, returnKindBits, ref bitOffset);
@@ -405,7 +406,7 @@ private int ReadyToRunVersionToGcInfoVersion(int readyToRunMajorVersion, int rea
 
             // R2R 11.0+ uses GCInfo v4
             if (readyToRunMajorVersion < 11)
-            return 3;
+                return 3;
 
             return 4;
         }

src/coreclr/vm/gcinfodecoder.cpp

@@ -91,9 +91,6 @@ bool GcInfoDecoder::PredecodeFatHeader(int remainingFlags)
     int numFlagBits = (m_Version == 1) ? GC_INFO_FLAGS_BIT_SIZE_VERSION_1 : GC_INFO_FLAGS_BIT_SIZE;
     m_headerFlags = (GcInfoHeaderFlags)m_Reader.Read(numFlagBits);
 
-    // skip over the unused return kind.
-    m_Reader.Read(SIZE_OF_RETURN_KIND_IN_FAT_HEADER);
-
     remainingFlags &= ~DECODE_VARARG;
 #if defined(TARGET_ARM) || defined(TARGET_ARM64) || defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
     remainingFlags &= ~DECODE_HAS_TAILCALLS;
@@ -299,9 +296,6 @@ GcInfoDecoder::GcInfoDecoder(
             m_StackBaseRegister = NO_STACK_BASE_REGISTER;
         }
 
-        // skip over the unused return kind.
-        m_Reader.Read(SIZE_OF_RETURN_KIND_IN_SLIM_HEADER);
-
         remainingFlags &= ~DECODE_VARARG;
 #if defined(TARGET_ARM) || defined(TARGET_ARM64) || defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
         remainingFlags &= ~DECODE_HAS_TAILCALLS;