Golang llvm.ConstNull函数代码示例

func (fr *frame) memsetZero(ptr llvm.Value, size llvm.Value) {
	memset := fr.runtime.memset
	ptr = fr.builder.CreateBitCast(ptr, llvm.PointerType(llvm.Int8Type(), 0), "")
	fill := llvm.ConstNull(llvm.Int8Type())
	size = fr.createZExtOrTrunc(size, fr.target.IntPtrType(), "")
	align := llvm.ConstInt(llvm.Int32Type(), 1, false)
	isvolatile := llvm.ConstNull(llvm.Int1Type())
	fr.builder.CreateCall(memset, []llvm.Value{ptr, fill, size, align, isvolatile}, "")
}

func (fr *frame) registerGcRoots() {
	if len(fr.gcRoots) != 0 {
		rootty := fr.gcRoots[0].Type()
		roots := append(fr.gcRoots, llvm.ConstNull(rootty))
		rootsarr := llvm.ConstArray(rootty, roots)
		rootsstruct := llvm.ConstStruct([]llvm.Value{llvm.ConstNull(llvm.PointerType(llvm.Int8Type(), 0)), rootsarr}, false)

		rootsglobal := llvm.AddGlobal(fr.module.Module, rootsstruct.Type(), "")
		rootsglobal.SetInitializer(rootsstruct)
		rootsglobal.SetLinkage(llvm.InternalLinkage)
		fr.runtime.registerGcRoots.callOnly(fr, llvm.ConstBitCast(rootsglobal, llvm.PointerType(llvm.Int8Type(), 0)))
	}
}

func (gi *globalInit) build(typ llvm.Type) llvm.Value {
	if gi.val.C != nil {
		return gi.val
	}
	if len(gi.elems) == 0 {
		return llvm.ConstNull(typ)
	}

	switch typ.TypeKind() {
	case llvm.StructTypeKind:
		eltypes := typ.StructElementTypes()
		elems := make([]llvm.Value, len(eltypes))
		for i, eltyp := range eltypes {
			elems[i] = gi.elems[i].build(eltyp)
		}
		return llvm.ConstStruct(elems, false)
	case llvm.ArrayTypeKind:
		eltyp := typ.ElementType()
		elems := make([]llvm.Value, len(gi.elems))
		for i := range gi.elems {
			elems[i] = gi.elems[i].build(eltyp)
		}
		return llvm.ConstArray(eltyp, elems)
	default:
		panic("unexpected type")
	}
}

func (fr *frame) compareStrings(lhs, rhs *govalue, op token.Token) *govalue {
	if op == token.EQL {
		if lhs.value.IsNull() {
			return fr.compareStringEmpty(rhs.value)
		}
		if rhs.value.IsNull() {
			return fr.compareStringEmpty(lhs.value)
		}
	}

	result := fr.runtime.strcmp.call(fr, lhs.value, rhs.value)[0]
	zero := llvm.ConstNull(fr.types.inttype)
	var pred llvm.IntPredicate
	switch op {
	case token.EQL:
		pred = llvm.IntEQ
	case token.LSS:
		pred = llvm.IntSLT
	case token.GTR:
		pred = llvm.IntSGT
	case token.LEQ:
		pred = llvm.IntSLE
	case token.GEQ:
		pred = llvm.IntSGE
	case token.NEQ:
		panic("NEQ is handled in govalue.BinaryOp")
	default:
		panic("unreachable")
	}
	result = fr.builder.CreateICmp(pred, result, zero, "")
	result = fr.builder.CreateZExt(result, llvm.Int8Type(), "")
	return newValue(result, types.Typ[types.Bool])
}

// emitInitPrologue emits the init-specific function prologue (guard check and
// initialization of dependent packages under the llgo native ABI), and returns
// the basic block into which the GC registration call should be emitted.
func (fr *frame) emitInitPrologue() llvm.BasicBlock {
	if fr.GccgoABI {
		return fr.builder.GetInsertBlock()
	}

	initGuard := llvm.AddGlobal(fr.module.Module, llvm.Int1Type(), "init$guard")
	initGuard.SetLinkage(llvm.InternalLinkage)
	initGuard.SetInitializer(llvm.ConstNull(llvm.Int1Type()))

	returnBlock := llvm.AddBasicBlock(fr.function, "")
	initBlock := llvm.AddBasicBlock(fr.function, "")

	initGuardVal := fr.builder.CreateLoad(initGuard, "")
	fr.builder.CreateCondBr(initGuardVal, returnBlock, initBlock)

	fr.builder.SetInsertPointAtEnd(returnBlock)
	fr.builder.CreateRetVoid()

	fr.builder.SetInsertPointAtEnd(initBlock)
	fr.builder.CreateStore(llvm.ConstInt(llvm.Int1Type(), 1, false), initGuard)
	int8ptr := llvm.PointerType(fr.types.ctx.Int8Type(), 0)
	ftyp := llvm.FunctionType(llvm.VoidType(), []llvm.Type{int8ptr}, false)
	for _, pkg := range fr.pkg.Object.Imports() {
		initname := ManglePackagePath(pkg.Path()) + "..import"
		initfn := fr.module.Module.NamedFunction(initname)
		if initfn.IsNil() {
			initfn = llvm.AddFunction(fr.module.Module, initname, ftyp)
		}
		args := []llvm.Value{llvm.Undef(int8ptr)}
		fr.builder.CreateCall(initfn, args, "")
	}

	return initBlock
}

func (fr *frame) callRecover(isDeferredRecover bool) *govalue {
	startbb := fr.builder.GetInsertBlock()
	recoverbb := llvm.AddBasicBlock(fr.function, "")
	contbb := llvm.AddBasicBlock(fr.function, "")
	canRecover := fr.builder.CreateTrunc(fr.canRecover, llvm.Int1Type(), "")
	fr.builder.CreateCondBr(canRecover, recoverbb, contbb)

	fr.builder.SetInsertPointAtEnd(recoverbb)
	var recovered llvm.Value
	if isDeferredRecover {
		recovered = fr.runtime.deferredRecover.call(fr)[0]
	} else {
		recovered = fr.runtime.recover.call(fr)[0]
	}
	recoverbb = fr.builder.GetInsertBlock()
	fr.builder.CreateBr(contbb)

	fr.builder.SetInsertPointAtEnd(contbb)
	eface := types.NewInterface(nil, nil)
	llv := fr.builder.CreatePHI(fr.types.ToLLVM(eface), "")
	llv.AddIncoming(
		[]llvm.Value{llvm.ConstNull(llv.Type()), recovered},
		[]llvm.BasicBlock{startbb, recoverbb},
	)
	return newValue(llv, eface)
}

func directDecode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, valType llvm.Type, args []llvm.Value) llvm.Value {
	var alloca llvm.Value

	switch len(args) {
	case 0:
		return llvm.ConstNull(ctx.StructType(nil, false))

	case 1:
		if args[0].Type().C == valType.C {
			return args[0]
		}
		alloca = allocaBuilder.CreateAlloca(valType, "")
		bitcast := builder.CreateBitCast(alloca, llvm.PointerType(args[0].Type(), 0), "")
		builder.CreateStore(args[0], bitcast)

	case 2:
		alloca = allocaBuilder.CreateAlloca(valType, "")
		var argTypes []llvm.Type
		for _, a := range args {
			argTypes = append(argTypes, a.Type())
		}
		encodeType := ctx.StructType(argTypes, false)
		bitcast := builder.CreateBitCast(alloca, llvm.PointerType(encodeType, 0), "")
		builder.CreateStore(args[0], builder.CreateStructGEP(bitcast, 0, ""))
		builder.CreateStore(args[1], builder.CreateStructGEP(bitcast, 1, ""))

	default:
		panic("unexpected argTypes size")
	}

	return builder.CreateLoad(alloca, "")
}

func (fr *frame) chanSelect(sel *ssa.Select) (index, recvOk *govalue, recvElems []*govalue) {
	n := uint64(len(sel.States))
	if !sel.Blocking {
		// non-blocking means there's a default case
		n++
	}
	size := llvm.ConstInt(llvm.Int32Type(), n, false)
	selectp := fr.runtime.newSelect.call(fr, size)[0]

	// Allocate stack for the values to send and receive.
	ptrs := make([]llvm.Value, len(sel.States))
	for i, state := range sel.States {
		chantyp := state.Chan.Type().Underlying().(*types.Chan)
		elemtyp := fr.types.ToLLVM(chantyp.Elem())
		if state.Dir == types.SendOnly {
			ptrs[i] = fr.allocaBuilder.CreateAlloca(elemtyp, "")
			fr.builder.CreateStore(fr.llvmvalue(state.Send), ptrs[i])
		} else {
			// Only allocate stack space if the received value is used.
			used := chanSelectStateUsed(sel, len(recvElems))
			if used {
				ptrs[i] = fr.allocaBuilder.CreateAlloca(elemtyp, "")
			} else {
				ptrs[i] = llvm.ConstNull(llvm.PointerType(llvm.Int8Type(), 0))
			}
			recvElems = append(recvElems, newValue(ptrs[i], chantyp.Elem()))
		}
	}

	// Create select{send,recv2} calls.
	var receivedp llvm.Value
	if len(recvElems) > 0 {
		receivedp = fr.allocaBuilder.CreateAlloca(fr.types.ToLLVM(types.Typ[types.Bool]), "")
	}
	if !sel.Blocking {
		// If the default case is chosen, the index must be -1.
		fr.runtime.selectdefault.call(fr, selectp, llvm.ConstAllOnes(llvm.Int32Type()))
	}
	for i, state := range sel.States {
		ch := fr.llvmvalue(state.Chan)
		index := llvm.ConstInt(llvm.Int32Type(), uint64(i), false)
		if state.Dir == types.SendOnly {
			fr.runtime.selectsend.call(fr, selectp, ch, ptrs[i], index)
		} else {
			fr.runtime.selectrecv2.call(fr, selectp, ch, ptrs[i], receivedp, index)
		}
	}

	// Fire off the select.
	index = newValue(fr.runtime.selectgo.call(fr, selectp)[0], types.Typ[types.Int])
	if len(recvElems) > 0 {
		recvOk = newValue(fr.builder.CreateLoad(receivedp, ""), types.Typ[types.Bool])
		for _, recvElem := range recvElems {
			recvElem.value = fr.builder.CreateLoad(recvElem.value, "")
		}
	}
	return index, recvOk, recvElems
}

func (fr *frame) memcpy(dest llvm.Value, src llvm.Value, size llvm.Value) {
	memcpy := fr.runtime.memcpy
	dest = fr.builder.CreateBitCast(dest, llvm.PointerType(llvm.Int8Type(), 0), "")
	src = fr.builder.CreateBitCast(src, llvm.PointerType(llvm.Int8Type(), 0), "")
	size = fr.createZExtOrTrunc(size, fr.target.IntPtrType(), "")
	align := llvm.ConstInt(llvm.Int32Type(), 1, false)
	isvolatile := llvm.ConstNull(llvm.Int1Type())
	fr.builder.CreateCall(memcpy, []llvm.Value{dest, src, size, align, isvolatile}, "")
}

func (fr *frame) createLandingPad(cleanup bool) llvm.Value {
	lp := fr.builder.CreateLandingPad(fr.runtime.gccgoExceptionType, fr.runtime.gccgoPersonality, 0, "")
	if cleanup {
		lp.SetCleanup(true)
	} else {
		lp.AddClause(llvm.ConstNull(llvm.PointerType(llvm.Int8Type(), 0)))
	}
	return lp
}

// If cond is true, reads the value from the given interface type, otherwise
// returns a nil value.
func (fr *frame) getInterfaceValueOrNull(cond llvm.Value, v *govalue, ty types.Type) *govalue {
	val := fr.builder.CreateExtractValue(v.value, 1, "")
	if _, ok := ty.Underlying().(*types.Pointer); ok {
		val = fr.builder.CreateSelect(cond, val, llvm.ConstNull(val.Type()), "")
	} else {
		val = fr.loadOrNull(cond, val, ty).value
	}
	return newValue(val, ty)
}

func (v *Codegen) genSizeofExpr(n *parser.SizeofExpr) llvm.Value {
	if n.Expr != nil {
		gep := v.builder.CreateGEP(llvm.ConstNull(llvm.PointerType(v.typeToLLVMType(n.Expr.GetType()), 0)), []llvm.Value{llvm.ConstInt(llvm.Int32Type(), 1, false)}, "")
		return v.builder.CreatePtrToInt(gep, v.typeToLLVMType(n.GetType()), "sizeof")
	} else {
		// we have a type
		panic("can't do this yet")
	}
}

// mapIterInit creates a map iterator
func (fr *frame) mapIterInit(m *govalue) []*govalue {
	// We represent an iterator as a tuple (map, *bool). The second element
	// controls whether the code we generate for "next" (below) calls the
	// runtime function for the first or the next element. We let the
	// optimizer reorganize this into something more sensible.
	isinit := fr.allocaBuilder.CreateAlloca(llvm.Int1Type(), "")
	fr.builder.CreateStore(llvm.ConstNull(llvm.Int1Type()), isinit)

	return []*govalue{m, newValue(isinit, types.NewPointer(types.Typ[types.Bool]))}
}

func (n *ForExpr) Gen(cg *CG) llvm.Value {
	startVal := n.Start.Gen(cg)
	if startVal.IsNil() {
		return errv("Code generation failed for start expression")
	}

	fun := cg.GetInsertBlock().Parent()
	alloca := createEntryBlockAlloca(fun, n.Var)
	cg.CreateStore(startVal, alloca)

	loopBB := llvm.AddBasicBlock(fun, "loop")
	cg.CreateBr(loopBB)
	cg.SetInsertPointAtEnd(loopBB)

	oldVal := cg.NamedValues[n.Var]
	cg.NamedValues[n.Var] = alloca

	if n.Body.Gen(cg).IsNil() {
		return llvm.Value{}
	}

	var stepVal llvm.Value
	if n.Step != nil {
		stepVal = n.Step.Gen(cg)
		if stepVal.IsNil() {
			return llvm.ConstNull(llvm.DoubleType())
		}
	} else {
		stepVal = llvm.ConstFloat(llvm.DoubleType(), 1)
	}

	endVal := n.End.Gen(cg)
	if endVal.IsNil() {
		return llvm.Value{}
	}

	curVar := cg.CreateLoad(alloca, n.Var)
	nextVar := cg.CreateFAdd(curVar, stepVal, "nextvar")
	cg.CreateStore(nextVar, alloca)

	endVal = cg.CreateFCmp(llvm.FloatONE, endVal, llvm.ConstFloat(llvm.DoubleType(), 0), "loopcond")
	afterBB := cg.AddBasicBlock(fun, "afterloop")

	cg.CreateCondBr(endVal, loopBB, afterBB)

	cg.SetInsertPointAtEnd(afterBB)

	if !oldVal.IsNil() {
		cg.NamedValues[n.Var] = oldVal
	} else {
		delete(cg.NamedValues, n.Var)
	}

	return llvm.ConstFloat(llvm.DoubleType(), 0)
}

// makeMap implements make(maptype[, initial space])
func (fr *frame) makeMap(typ types.Type, cap_ *govalue) *govalue {
	// TODO(pcc): call __go_new_map_big here if needed
	dyntyp := fr.types.getMapDescriptorPointer(typ)
	dyntyp = fr.builder.CreateBitCast(dyntyp, llvm.PointerType(llvm.Int8Type(), 0), "")
	var cap llvm.Value
	if cap_ != nil {
		cap = fr.convert(cap_, types.Typ[types.Uintptr]).value
	} else {
		cap = llvm.ConstNull(fr.types.inttype)
	}
	m := fr.runtime.newMap.call(fr, dyntyp, cap)
	return newValue(m[0], typ)
}