Repository: dotnet/runtime
File: src/coreclr/jit/emitwasm.cpp (C++)

Code before:
        record an updated set of live GC variables.
     */
    instrDesc* id = nullptr;

    assert(params.argSize % REGSIZE_BYTES == 0);
    int argCnt = (int)(params.argSize / (int)REGSIZE_BYTES);

    // All Wasm calls we generate are indirect, it's just a question of *how* much indirection
    instruction ins;

    // TODO-WASM: Currently while we're loading SP onto the stack we're not loading PEP, so generate one here.
    emitIns_I(INS_i32_const, EA_4BYTE, 0);

    switch (params.callType)
    {
        case EC_FUNC_TOKEN:
            ins = params.isJump ? INS_return_call : INS_call;
            id  = emitNewInstrSC(EA_8BYTE, (cnsval_ssize_t)(ssize_t)params.addr /* function index */);
            id->idIns(ins);
            id->idInsFmt(IF_ULEB128);
            break;
        case EC_INDIR_R:
            // Indirect load of actual ftn ptr from indirection cell (on the stack)
            emitIns_I(INS_i32_load, EA_8BYTE, 0);
            ins = params.isJump ? INS_return_call_indirect : INS_call_indirect;
            id  = emitNewInstrSC(EA_8BYTE, 0 /* FIXME-WASM: type index */);
            id->idIns(ins);
            id->idInsFmt(IF_CALL_INDIRECT);
            break;
        default:
            unreached();
    }

    // for the purpose of GC safepointing tail-calls are not real calls
    id->idSetIsNoGC(params.isJump || params.noSafePoint || emitNoGChelper(params.methHnd));

#ifdef DEBUG
    if (EMIT_GC_VERBOSE)
    {
        if (id->idIsLargeCall())
        {
            printf("[%02u] Rec call GC vars = %s\n", id->idDebugOnlyInfo()->idNum,
                   VarSetOps::ToString(emitComp, ((instrDescCGCA*)id)->idcGCvars));
        }
    }
#endif

    if (m_debugInfoSize > 0)
    {
        INDEBUG(id->idDebugOnlyInfo()->idCallSig = params.sigInfo);
        id->idDebugOnlyInfo()->idMemCookie = (size_t)params.methHnd; // method token

Review comment (bug):
The emitAttr EA_8BYTE is incorrect for WASM32, where pointers are 4 bytes. Use EA_PTRSIZE or EA_4BYTE instead to ensure correct behavior on WASM32.

Code after:
            id->idIns(ins);
            id->idInsFmt(IF_ULEB128);
            break;
        case EC_INDIR_R:
            // Indirect load of actual ftn ptr from indirection cell (on the stack)
            // TODO-WASM: temporary, move this into higher layers (lowering).
            emitIns_I(INS_i32_load, EA_PTRSIZE, 0);
            ins = params.isJump ? INS_return_call_indirect : INS_call_indirect;
            id  = emitNewInstrSC(EA_8BYTE, 0 /* FIXME-WASM: type index reloc */);
            id->idIns(ins);
            id->idInsFmt(IF_CALL_INDIRECT);
            break;
        default:
            unreached();
    }

    if (m_debugInfoSize > 0)
    {
        INDEBUG(id->idDebugOnlyInfo()->idCallSig = params.sigInfo);
        id->idDebugOnlyInfo()->idMemCookie = (size_t)params.methHnd; // method token
    }

    dispIns(id);
    appendToCurIG(id);
    // emitLastMemBarrier = nullptr; // Cannot optimize away future memory barriers
}

//-----------------------------------------------------------------------------
// emitNewInstrLclVarDecl: Construct an instrDesc corresponding to a wasm local
// declaration.
//
// Arguments:
//   attr        - emit attributes
//   localCount  - the count of locals in this declaration
//   type        - the type of local in the declaration
//   lclOffset   - used to provide the starting index of this local
//
// Notes:
//   `lclOffset` is stored as debug info attached to the instruction,
//    so the offset will only be used if m_debugInfoSize > 0
emitter::instrDesc* emitter::emitNewInstrLclVarDecl(emitAttr      attr,
                                                    unsigned int  localCount,
                                                    WasmValueType type,
                                                    int           lclOffset)
{
    instrDescLclVarDecl* id = static_cast<instrDescLclVarDecl*>(emitAllocAnyInstr(sizeof(instrDescLclVarDecl), attr));
    id->idLclCnt(localCount);
    id->idLclType(type);

    if (m_debugInfoSize > 0)
    {