[Wasm RyuJIT] Wire up GC info encoding/decoding for Wasm (#126932)

* Wire up basic gc info encoding in the wasm jit
* Build gcinfo_universal_wasm and link it into the wasm version of the jit
* Move gcdecode/gcencode into JIT_SOURCES
* Remove the TARGET_WASM exclusion for the gc info encoder and decoder
* Define a Wasm32 GcInfoEncoding
* Allow building with EMIT_GENERATE_GCINFO on targets without a fixed register set like Wasm, and set EMIT_GENERATE_GCINFO on Wasm
* Never generate tracked gc slots on Wasm
* Update wasm regalloc to never enregister gc refs
* Consume temporary regs for the operand of GT_NULLCHECK nodes to handle the case where a dead block store leaves behind an orphaned indirection that turns into a null check

Author: kg

src/coreclr/gcinfo/CMakeLists.txt

@@ -66,6 +66,7 @@ endif()
 if (CLR_CMAKE_TARGET_ARCH_ARM64 OR CLR_CMAKE_TARGET_ARCH_AMD64)
   create_gcinfo_lib(TARGET gcinfo_universal_arm64 OS universal ARCH arm64)
   create_gcinfo_lib(TARGET gcinfo_unix_x64 OS unix ARCH x64)
+  create_gcinfo_lib(TARGET gcinfo_universal_wasm OS universal ARCH wasm)
   if (CLR_CMAKE_BUILD_COMMUNITY_ALTJITS EQUAL 1)
     create_gcinfo_lib(TARGET gcinfo_unix_loongarch64 OS unix ARCH loongarch64)
     create_gcinfo_lib(TARGET gcinfo_unix_riscv64 OS unix ARCH riscv64)

src/coreclr/gcinfo/gcinfoencoder.cpp

@@ -2634,10 +2634,8 @@ int BitStreamWriter::EncodeVarLengthSigned( SSIZE_T n, UINT32 base )
     }
 }
 
-#ifndef TARGET_WASM
 // Instantiate the encoder so other files can use it
 template class TGcInfoEncoder<TargetGcInfoEncoding>;
-#endif // !TARGET_WASM
 
 #ifdef FEATURE_INTERPRETER
 template class TGcInfoEncoder<InterpreterGcInfoEncoding>;

src/coreclr/inc/gcinfotypes.h

@@ -909,13 +909,62 @@ struct X86GcInfoEncoding {
     static const bool HAS_FIXED_STACK_PARAMETER_SCRATCH_AREA = true;
 };
 
-#elif defined(TARGET_WASM)
+#elif defined(TARGET_WASM) && !defined(TARGET_64BIT)
 
 #ifndef TARGET_POINTER_SIZE
 #define TARGET_POINTER_SIZE 4   // equal to sizeof(void*) and the managed pointer size in bytes for this target
 #endif
 
-#define TargetGcInfoEncoding InterpreterGcInfoEncoding
+#define TargetGcInfoEncoding Wasm32GcInfoEncoding
+
+// TODO-WASM: Investigate normalizing stack slots to save space based on wasm stack alignment
+
+struct Wasm32GcInfoEncoding {
+    static const uint32_t NUM_NORM_CODE_OFFSETS_PER_CHUNK = (64);
+    static const uint32_t NUM_NORM_CODE_OFFSETS_PER_CHUNK_LOG2 = (6);
+    static inline constexpr int32_t NORMALIZE_STACK_SLOT (int32_t x) { return (x); }
+    static inline constexpr int32_t DENORMALIZE_STACK_SLOT (int32_t x) { return (x); }
+    static inline constexpr uint32_t NORMALIZE_CODE_LENGTH (uint32_t x) { return (x); }
+    static inline constexpr uint32_t DENORMALIZE_CODE_LENGTH (uint32_t x) { return (x); }
+    static inline constexpr uint32_t NORMALIZE_STACK_BASE_REGISTER (uint32_t x) { return (x); }
+    static inline constexpr uint32_t DENORMALIZE_STACK_BASE_REGISTER (uint32_t x) { return (x); }
+    static inline constexpr uint32_t NORMALIZE_SIZE_OF_STACK_AREA (uint32_t x) { return (x); }
+    static inline constexpr uint32_t DENORMALIZE_SIZE_OF_STACK_AREA (uint32_t x) { return (x); }
+    static const bool CODE_OFFSETS_NEED_NORMALIZATION = false;
+    static inline constexpr uint32_t NORMALIZE_CODE_OFFSET (uint32_t x) { return (x); }
+    static inline constexpr uint32_t DENORMALIZE_CODE_OFFSET (uint32_t x) { return (x); }
+
+    static const int PSP_SYM_STACK_SLOT_ENCBASE = 6;
+    static const int GENERICS_INST_CONTEXT_STACK_SLOT_ENCBASE = 6;
+    static const int SECURITY_OBJECT_STACK_SLOT_ENCBASE = 6;
+    static const int GS_COOKIE_STACK_SLOT_ENCBASE = 6;
+    static const int CODE_LENGTH_ENCBASE = 6;
+    static const int SIZE_OF_RETURN_KIND_IN_SLIM_HEADER = 2;
+    static const int SIZE_OF_RETURN_KIND_IN_FAT_HEADER = 2;
+    static const int STACK_BASE_REGISTER_ENCBASE = 3;
+    static const int SIZE_OF_STACK_AREA_ENCBASE = 6;
+    static const int SIZE_OF_EDIT_AND_CONTINUE_PRESERVED_AREA_ENCBASE = 3;
+    static const int REVERSE_PINVOKE_FRAME_ENCBASE = 6;
+    static const int NUM_REGISTERS_ENCBASE = 3;
+    static const int NUM_STACK_SLOTS_ENCBASE = 5;
+    static const int NUM_UNTRACKED_SLOTS_ENCBASE = 5;
+    static const int NORM_PROLOG_SIZE_ENCBASE = 4;
+    static const int NORM_EPILOG_SIZE_ENCBASE = 3;
+    static const int NORM_CODE_OFFSET_DELTA_ENCBASE = 3;
+    static const int INTERRUPTIBLE_RANGE_DELTA1_ENCBASE = 5;
+    static const int INTERRUPTIBLE_RANGE_DELTA2_ENCBASE = 5;
+    static const int REGISTER_ENCBASE = 3;
+    static const int REGISTER_DELTA_ENCBASE = REGISTER_ENCBASE;
+    static const int STACK_SLOT_ENCBASE = 6;
+    static const int STACK_SLOT_DELTA_ENCBASE = 4;
+    static const int NUM_SAFE_POINTS_ENCBASE = 4;
+    static const int NUM_INTERRUPTIBLE_RANGES_ENCBASE = 1;
+    static const int NUM_EH_CLAUSES_ENCBASE = 2;
+    static const int POINTER_SIZE_ENCBASE = 3;
+    static const int LIVESTATE_RLE_RUN_ENCBASE = 2;
+    static const int LIVESTATE_RLE_SKIP_ENCBASE = 4;
+    static const bool HAS_FIXED_STACK_PARAMETER_SCRATCH_AREA = false;
+};
 
 #else // No target defined
 

src/coreclr/jit/CMakeLists.txt

@@ -23,7 +23,7 @@ function(create_standalone_jit)
 
   if(TARGETDETAILS_OS STREQUAL "unix_osx" OR TARGETDETAILS_OS STREQUAL "unix_anyos")
     set(JIT_ARCH_LINK_LIBRARIES gcinfo_unix_${TARGETDETAILS_ARCH})
-  elseif(NOT ${TARGETDETAILS_ARCH} MATCHES "wasm")
+  else()
     set(JIT_ARCH_LINK_LIBRARIES gcinfo_${TARGETDETAILS_OS}_${TARGETDETAILS_ARCH})
   endif()
 
@@ -120,6 +120,8 @@ set( JIT_SOURCES
   fgstmt.cpp
   flowgraph.cpp
   forwardsub.cpp
+  gcdecode.cpp
+  gcencode.cpp
   gcinfo.cpp
   gentree.cpp
   gschecks.cpp
@@ -186,8 +188,6 @@ set ( JIT_NATIVE_TARGET_SOURCES
   lsra.cpp
   lsrabuild.cpp
   regMaskTPOps.cpp
-  gcdecode.cpp
-  gcencode.cpp
   unwind.cpp
 )
 

src/coreclr/jit/codegencommon.cpp

@@ -854,7 +854,9 @@ bool CodeGen::genIsSameLocalVar(GenTree* op1, GenTree* op2)
 // inline
 void CodeGenInterface::genUpdateRegLife(const LclVarDsc* varDsc, bool isBorn, bool isDying DEBUGARG(GenTree* tree))
 {
-#if EMIT_GENERATE_GCINFO // The regset being updated here is only needed for codegen-level GCness tracking
+    // Targets like Wasm do not have a fixed set of registers so the regset logic in this method is unnecessary.
+#if EMIT_GENERATE_GCINFO && HAS_FIXED_REGISTER_SET
+    // The regset being updated here is only needed for codegen-level GCness tracking.
     regMaskTP regMask = genGetRegMask(varDsc);
 
 #ifdef DEBUG
@@ -884,7 +886,7 @@ void CodeGenInterface::genUpdateRegLife(const LclVarDsc* varDsc, bool isBorn, bo
         assert(varDsc->IsAlwaysAliveInMemory() || ((regSet.GetMaskVars() & regMask) == 0));
         regSet.AddMaskVars(regMask);
     }
-#endif // EMIT_GENERATE_GCINFO
+#endif // EMIT_GENERATE_GCINFO && HAS_FIXED_REGISTER_SET
 }
 
 #ifndef TARGET_WASM
@@ -1032,6 +1034,7 @@ void Compiler::compChangeLife(VARSET_VALARG_TP newLife)
         bool isByRef    = varDsc->TypeIs(TYP_BYREF);
         bool isInReg    = varDsc->lvIsInReg();
         bool isInMemory = !isInReg || varDsc->IsAlwaysAliveInMemory();
+#ifndef TARGET_WASM
         if (isInReg)
         {
             // TODO-Cleanup: Move the code from compUpdateLifeVar to genUpdateRegLife that updates the
@@ -1047,7 +1050,8 @@ void Compiler::compChangeLife(VARSET_VALARG_TP newLife)
             }
             codeGen->genUpdateRegLife(varDsc, false /*isBorn*/, true /*isDying*/ DEBUGARG(nullptr));
         }
-        // Update the gcVarPtrSetCur if it is in memory.
+#endif // !TARGET_WASM
+       // Update the gcVarPtrSetCur if it is in memory.
         if (isInMemory && (isGCRef || isByRef))
         {
             VarSetOps::RemoveElemD(this, codeGen->gcInfo.gcVarPtrSetCur, deadVarIndex);
@@ -1070,6 +1074,7 @@ void Compiler::compChangeLife(VARSET_VALARG_TP newLife)
         bool isByRef = varDsc->TypeIs(TYP_BYREF);
         if (varDsc->lvIsInReg())
         {
+#ifndef TARGET_WASM
             // If this variable is going live in a register, it is no longer live on the stack,
             // unless it is an EH/"spill at single-def" var, which always remains live on the stack.
             if (!varDsc->IsAlwaysAliveInMemory())
@@ -1092,6 +1097,7 @@ void Compiler::compChangeLife(VARSET_VALARG_TP newLife)
             {
                 codeGen->gcInfo.gcRegByrefSetCur |= regMask;
             }
+#endif // !TARGET_WASM
         }
         else if (lvaIsGCTracked(varDsc))
         {
@@ -1769,7 +1775,7 @@ void CodeGen::genExitCode(BasicBlock* block)
 
     genIPmappingAdd(IPmappingDscKind::Epilog, DebugInfo(), true);
 
-#if EMIT_GENERATE_GCINFO && defined(DEBUG)
+#if EMIT_GENERATE_GCINFO && defined(DEBUG) && !defined(TARGET_WASM)
     // For returnining epilogs do some validation that the GC info looks right.
     if (!block->HasFlag(BBF_HAS_JMP))
     {
@@ -1791,7 +1797,7 @@ void CodeGen::genExitCode(BasicBlock* block)
             }
         }
     }
-#endif // EMIT_GENERATE_GCINFO && defined(DEBUG)
+#endif // EMIT_GENERATE_GCINFO && defined(DEBUG) && !defined(TARGET_WASM)
 
     if (m_compiler->getNeedsGSSecurityCookie())
     {
@@ -7202,12 +7208,12 @@ void CodeGen::genReturn(GenTree* treeNode)
         }
     }
 
-#if EMIT_GENERATE_GCINFO
+#if EMIT_GENERATE_GCINFO && HAS_FIXED_REGISTER_SET
     if (treeNode->OperIs(GT_RETURN, GT_SWIFT_ERROR_RET))
     {
         genMarkReturnGCInfo();
     }
-#endif // EMIT_GENERATE_GCINFO
+#endif // EMIT_GENERATE_GCINFO && HAS_FIXED_REGISTER_SET
 
 #ifdef PROFILING_SUPPORTED
 

src/coreclr/jit/codegenlinear.cpp

@@ -259,7 +259,7 @@ void CodeGen::genCodeForBlock(BasicBlock* block)
     // and before first of the current block is emitted
     genUpdateLife(block->bbLiveIn);
 
-#if EMIT_GENERATE_GCINFO
+#if EMIT_GENERATE_GCINFO && HAS_FIXED_REGISTER_SET
     // Even if liveness didn't change, we need to update the registers containing GC references.
     // genUpdateLife will update the registers live due to liveness changes. But what about registers that didn't
     // change? We cleared them out above. Maybe we should just not clear them out, but update the ones that change
@@ -353,7 +353,7 @@ void CodeGen::genCodeForBlock(BasicBlock* block)
             }
         }
     }
-#endif // EMIT_GENERATE_GCINFO
+#endif // EMIT_GENERATE_GCINFO && HAS_FIXED_REGISTER_SET
 
     /* Start a new code output block */
 
@@ -569,7 +569,7 @@ void CodeGen::genCodeForBlock(BasicBlock* block)
 
     regSet.rsSpillChk();
 
-#if EMIT_GENERATE_GCINFO
+#if EMIT_GENERATE_GCINFO && HAS_FIXED_REGISTER_SET
     // Make sure we didn't bungle pointer register tracking
     regMaskTP ptrRegs       = gcInfo.gcRegGCrefSetCur | gcInfo.gcRegByrefSetCur;
     regMaskTP nonVarPtrRegs = ptrRegs & ~regSet.GetMaskVars();
@@ -618,7 +618,7 @@ void CodeGen::genCodeForBlock(BasicBlock* block)
     }
 
     noway_assert(nonVarPtrRegs == RBM_NONE);
-#endif // EMIT_GENERATE_GCINFO
+#endif // EMIT_GENERATE_GCINFO && HAS_FIXED_REGISTER_SET
 #endif // DEBUG
 
 #if defined(DEBUG)
@@ -1601,7 +1601,7 @@ regNumber CodeGen::genConsumeReg(GenTree* tree)
     // genUpdateLife() will also spill local var if marked as GTF_SPILL by calling CodeGen::genSpillVar
     genUpdateLife(tree);
 
-#if EMIT_GENERATE_GCINFO
+#if EMIT_GENERATE_GCINFO && HAS_FIXED_REGISTER_SET
     // there are three cases where consuming a reg means clearing the bit in the live mask
     // 1. it was not produced by a local
     // 2. it was produced by a local that is going dead
@@ -1659,7 +1659,7 @@ regNumber CodeGen::genConsumeReg(GenTree* tree)
     {
         gcInfo.gcMarkRegSetNpt(tree->gtGetRegMask());
     }
-#endif // EMIT_GENERATE_GCINFO
+#endif // EMIT_GENERATE_GCINFO && HAS_FIXED_REGISTER_SET
 
     genCheckConsumeNode(tree);
     return tree->GetRegNum();

src/coreclr/jit/codegenwasm.cpp

@@ -9,6 +9,8 @@
 #include "codegen.h"
 #include "regallocwasm.h"
 #include "fgwasm.h"
+#include "gcinfo.h"
+#include "gcinfoencoder.h"
 
 static const int LINEAR_MEMORY_INDEX = 0;
 
@@ -3351,7 +3353,40 @@ void CodeGen::inst_JMP(emitJumpKind jmp, BasicBlock* tgtBlock)
 
 void CodeGen::genCreateAndStoreGCInfo(unsigned codeSize, unsigned prologSize, unsigned epilogSize DEBUGARG(void* code))
 {
-    // GCInfo not captured/created by codegen.
+    IAllocator*    allowZeroAlloc = new (m_compiler, CMK_GC) CompIAllocator(m_compiler->getAllocatorGC());
+    GcInfoEncoder* gcInfoEncoder  = new (m_compiler, CMK_GC)
+        GcInfoEncoder(m_compiler->info.compCompHnd, m_compiler->info.compMethodInfo, allowZeroAlloc, NOMEM);
+    assert(gcInfoEncoder != nullptr);
+
+    // Follow the code pattern of the x86 gc info encoder (genCreateAndStoreGCInfoJIT32).
+    gcInfo.gcInfoBlockHdrSave(gcInfoEncoder, codeSize, prologSize);
+
+    // We keep the call count for the second call to gcMakeRegPtrTable() below.
+    unsigned callCnt = 0;
+
+    // First we figure out the encoder ID's for the stack slots and registers.
+    gcInfo.gcMakeRegPtrTable(gcInfoEncoder, codeSize, prologSize, GCInfo::MAKE_REG_PTR_MODE_ASSIGN_SLOTS, &callCnt);
+
+    // Now we've requested all the slots we'll need; "finalize" these (make more compact data structures for them).
+    gcInfoEncoder->FinalizeSlotIds();
+
+    // Now we can actually use those slot ID's to declare live ranges.
+    gcInfo.gcMakeRegPtrTable(gcInfoEncoder, codeSize, prologSize, GCInfo::MAKE_REG_PTR_MODE_DO_WORK, &callCnt);
+
+    if (m_compiler->opts.IsReversePInvoke())
+    {
+        unsigned reversePInvokeFrameVarNumber = m_compiler->lvaReversePInvokeFrameVar;
+        assert(reversePInvokeFrameVarNumber != BAD_VAR_NUM);
+        const LclVarDsc* reversePInvokeFrameVar = m_compiler->lvaGetDesc(reversePInvokeFrameVarNumber);
+        gcInfoEncoder->SetReversePInvokeFrameSlot(reversePInvokeFrameVar->GetStackOffset());
+    }
+
+    gcInfoEncoder->Build();
+
+    // GC Encoder automatically puts the GC info in the right spot using ICorJitInfo::allocGCInfo(size_t)
+    // let's save the values anyway for debugging purposes
+    m_compiler->compInfoBlkAddr = gcInfoEncoder->Emit();
+    m_compiler->compInfoBlkSize = gcInfoEncoder->GetEncodedGCInfoSize();
 }
 
 //---------------------------------------------------------------------

src/coreclr/jit/compiler.cpp

@@ -10738,6 +10738,10 @@ void Compiler::EnregisterStats::RecordLocal(const LclVarDsc* varDsc)
                 m_simdUserForcesDep++;
                 break;
 
+            case DoNotEnregisterReason::WasmGCVisibility:
+                m_wasmGcVisibility++;
+                break;
+
             default:
                 unreached();
                 break;
@@ -10866,6 +10870,7 @@ void Compiler::EnregisterStats::Dump(FILE* fout) const
     PRINT_STATS(m_swizzleArg, notEnreg);
     PRINT_STATS(m_blockOpRet, notEnreg);
     PRINT_STATS(m_returnSpCheck, notEnreg);
+    PRINT_STATS(m_wasmGcVisibility, notEnreg);
     PRINT_STATS(m_callSpCheck, notEnreg);
     PRINT_STATS(m_simdUserForcesDep, notEnreg);
 

src/coreclr/jit/compiler.h

@@ -488,6 +488,7 @@ enum class DoNotEnregisterReason
     CallSpCheck,           // the local is used to do SP check on every call
     SimdUserForcesDep,     // a promoted struct was used by a SIMD/HWI node; it must be dependently promoted
     HiddenBufferStructArg, // the argument is a hidden return buffer passed to a method.
+    WasmGCVisibility,
 };
 
 enum class AddressExposedReason
@@ -11761,6 +11762,7 @@ class Compiler
         unsigned m_liveInOutHndlr;
         unsigned m_depField;
         unsigned m_noRegVars;
+        unsigned m_wasmGcVisibility;
 #ifdef JIT32_GCENCODER
         unsigned m_PinningRef;
 #endif // JIT32_GCENCODER