Golang llvm.AddBasicBlock函數代碼示例

func (c *compiler) VisitIfStmt(stmt *ast.IfStmt) {
	currBlock := c.builder.GetInsertBlock()
	resumeBlock := llvm.AddBasicBlock(currBlock.Parent(), "endif")
	resumeBlock.MoveAfter(currBlock)
	defer c.builder.SetInsertPointAtEnd(resumeBlock)

	var ifBlock, elseBlock llvm.BasicBlock
	if stmt.Else != nil {
		elseBlock = llvm.InsertBasicBlock(resumeBlock, "else")
		ifBlock = llvm.InsertBasicBlock(elseBlock, "if")
	} else {
		ifBlock = llvm.InsertBasicBlock(resumeBlock, "if")
	}
	if stmt.Else == nil {
		elseBlock = resumeBlock
	}

	if stmt.Init != nil {
		c.VisitStmt(stmt.Init)
	}

	cond_val := c.VisitExpr(stmt.Cond)
	c.builder.CreateCondBr(cond_val.LLVMValue(), ifBlock, elseBlock)
	c.builder.SetInsertPointAtEnd(ifBlock)
	c.VisitBlockStmt(stmt.Body, false)
	c.maybeImplicitBranch(resumeBlock)

	if stmt.Else != nil {
		c.builder.SetInsertPointAtEnd(elseBlock)
		c.VisitStmt(stmt.Else)
		c.maybeImplicitBranch(resumeBlock)
	}
}

// Binary logical operators are handled specially, outside of the Value
// type, because of the need to perform lazy evaluation.
//
// Binary logical operators are implemented using a Phi node, which takes
// on the appropriate value depending on which basic blocks branch to it.
func (c *compiler) compileLogicalOp(op token.Token, lhs Value, rhsFunc func() Value) Value {
	lhsBlock := c.builder.GetInsertBlock()
	resultBlock := llvm.AddBasicBlock(lhsBlock.Parent(), "")
	resultBlock.MoveAfter(lhsBlock)
	rhsBlock := llvm.InsertBasicBlock(resultBlock, "")
	falseBlock := llvm.InsertBasicBlock(resultBlock, "")

	if op == token.LOR {
		c.builder.CreateCondBr(lhs.LLVMValue(), resultBlock, rhsBlock)
	} else {
		c.builder.CreateCondBr(lhs.LLVMValue(), rhsBlock, falseBlock)
	}
	c.builder.SetInsertPointAtEnd(rhsBlock)
	rhs := rhsFunc()
	rhsBlock = c.builder.GetInsertBlock() // rhsFunc may create blocks
	c.builder.CreateCondBr(rhs.LLVMValue(), resultBlock, falseBlock)
	c.builder.SetInsertPointAtEnd(falseBlock)
	c.builder.CreateBr(resultBlock)
	c.builder.SetInsertPointAtEnd(resultBlock)

	result := c.builder.CreatePHI(llvm.Int1Type(), "")
	trueValue := llvm.ConstAllOnes(llvm.Int1Type())
	falseValue := llvm.ConstNull(llvm.Int1Type())
	var values []llvm.Value
	var blocks []llvm.BasicBlock
	if op == token.LOR {
		values = []llvm.Value{trueValue, trueValue, falseValue}
		blocks = []llvm.BasicBlock{lhsBlock, rhsBlock, falseBlock}
	} else {
		values = []llvm.Value{trueValue, falseValue}
		blocks = []llvm.BasicBlock{rhsBlock, falseBlock}
	}
	result.AddIncoming(values, blocks)
	return c.NewLLVMValue(result, types.Bool)
}

// contextFunction creates a wrapper function that
// has the same signature as the specified function,
// but has an additional first parameter that accepts
// and ignores the function context value.
//
// contextFunction must be called with a global function
// pointer.
func contextFunction(c *compiler, f *LLVMValue) *LLVMValue {
	defer c.builder.SetInsertPointAtEnd(c.builder.GetInsertBlock())
	resultType := c.llvmtypes.ToLLVM(f.Type())
	fnptr := f.LLVMValue()
	contextType := resultType.StructElementTypes()[1]
	llfntyp := fnptr.Type().ElementType()
	llfntyp = llvm.FunctionType(
		llfntyp.ReturnType(),
		append([]llvm.Type{contextType}, llfntyp.ParamTypes()...),
		llfntyp.IsFunctionVarArg(),
	)
	wrapper := llvm.AddFunction(c.module.Module, fnptr.Name()+".ctx", llfntyp)
	wrapper.SetLinkage(llvm.PrivateLinkage)
	entry := llvm.AddBasicBlock(wrapper, "entry")
	c.builder.SetInsertPointAtEnd(entry)
	args := make([]llvm.Value, len(llfntyp.ParamTypes())-1)
	for i := range args {
		args[i] = wrapper.Param(i + 1)
	}
	result := c.builder.CreateCall(fnptr, args, "")
	switch nresults := f.Type().(*types.Signature).Results().Len(); nresults {
	case 0:
		c.builder.CreateRetVoid()
	case 1:
		c.builder.CreateRet(result)
	default:
		results := make([]llvm.Value, nresults)
		for i := range results {
			results[i] = c.builder.CreateExtractValue(result, i, "")
		}
		c.builder.CreateAggregateRet(results)
	}
	return c.NewValue(wrapper, f.Type())
}

func (c *compiler) defineMemcpyFunction(fn llvm.Value) {
	entry := llvm.AddBasicBlock(fn, "entry")
	c.builder.SetInsertPointAtEnd(entry)
	dst, src, size := fn.Param(0), fn.Param(1), fn.Param(2)

	pint8 := llvm.PointerType(llvm.Int8Type(), 0)
	dst = c.builder.CreateIntToPtr(dst, pint8, "")
	src = c.builder.CreateIntToPtr(src, pint8, "")

	sizeType := size.Type()
	sizeBits := sizeType.IntTypeWidth()
	memcpyName := "llvm.memcpy.p0i8.p0i8.i" + strconv.Itoa(sizeBits)
	memcpy := c.module.NamedFunction(memcpyName)
	if memcpy.IsNil() {
		paramtypes := []llvm.Type{
			pint8, pint8, size.Type(), llvm.Int32Type(), llvm.Int1Type()}
		memcpyType := llvm.FunctionType(llvm.VoidType(), paramtypes, false)
		memcpy = llvm.AddFunction(c.module.Module, memcpyName, memcpyType)
	}

	args := []llvm.Value{
		dst, src, size,
		llvm.ConstInt(llvm.Int32Type(), 1, false), // single byte alignment
		llvm.ConstInt(llvm.Int1Type(), 0, false),  // not volatile
	}
	c.builder.CreateCall(memcpy, args, "")
	c.builder.CreateRetVoid()
}

func (c *compiler) defineFreeFunction(fn llvm.Value) {
	entry := llvm.AddBasicBlock(fn, "entry")
	c.builder.SetInsertPointAtEnd(entry)
	ptr := fn.FirstParam()
	ptrtyp := llvm.PointerType(llvm.Int8Type(), 0)
	c.builder.CreateFree(c.builder.CreateIntToPtr(ptr, ptrtyp, ""))
	c.builder.CreateRetVoid()
}

// promoteMethod promotes a named type's method to another type
// which has embedded the named type.
func (c *compiler) promoteMethod(m *types.Func, recv types.Type, indices []int) types.Object {
	var pkg *types.Package
	if recv, ok := recv.(*types.Named); ok {
		pkg = c.objectdata[recv.Obj()].Package
	}
	recvvar := types.NewVar(pkg, "", recv)
	sig := m.Type().(*types.Signature)
	sig = types.NewSignature(recvvar, sig.Params(), sig.Results(), sig.IsVariadic())
	f := &synthFunc{pkg: pkg, name: m.Name(), typ: sig}
	ident := ast.NewIdent(f.Name())

	var isptr bool
	if ptr, ok := recv.(*types.Pointer); ok {
		isptr = true
		recv = ptr.Elem()
	}

	c.objects[ident] = f
	c.objectdata[f] = &ObjectData{Ident: ident, Package: pkg}

	if pkg == nil || pkg == c.pkg {
		if currblock := c.builder.GetInsertBlock(); !currblock.IsNil() {
			defer c.builder.SetInsertPointAtEnd(currblock)
		}
		llvmfn := c.Resolve(ident).LLVMValue()
		llvmfn = c.builder.CreateExtractValue(llvmfn, 0, "")
		llvmfn.SetLinkage(llvm.LinkOnceODRLinkage)
		entry := llvm.AddBasicBlock(llvmfn, "entry")
		c.builder.SetInsertPointAtEnd(entry)

		realfn := c.Resolve(c.objectdata[m].Ident).LLVMValue()
		realfn = c.builder.CreateExtractValue(realfn, 0, "")

		args := llvmfn.Params()
		recvarg := args[0]
		if !isptr {
			ptr := c.builder.CreateAlloca(recvarg.Type(), "")
			c.builder.CreateStore(recvarg, ptr)
			recvarg = ptr
		}
		for _, i := range indices {
			if i == -1 {
				recvarg = c.builder.CreateLoad(recvarg, "")
			} else {
				recvarg = c.builder.CreateStructGEP(recvarg, i, "")
			}
		}

		args[0] = recvarg
		result := c.builder.CreateCall(realfn, args, "")
		if sig.Results().Len() == 0 {
			c.builder.CreateRetVoid()
		} else {
			c.builder.CreateRet(result)
		}
	}
	return f
}

func (c *compiler) VisitForStmt(stmt *ast.ForStmt) {
	currBlock := c.builder.GetInsertBlock()
	doneBlock := llvm.AddBasicBlock(currBlock.Parent(), "done")
	doneBlock.MoveAfter(currBlock)
	loopBlock := llvm.InsertBasicBlock(doneBlock, "loop")
	defer c.builder.SetInsertPointAtEnd(doneBlock)

	condBlock := loopBlock
	if stmt.Cond != nil {
		condBlock = llvm.InsertBasicBlock(loopBlock, "cond")
	}

	postBlock := condBlock
	if stmt.Post != nil {
		postBlock = llvm.InsertBasicBlock(doneBlock, "post")
	}

	if c.lastlabel != nil {
		labelData := c.labelData(c.lastlabel)
		labelData.Break = doneBlock
		labelData.Continue = postBlock
		c.lastlabel = nil
	}

	c.breakblocks = append(c.breakblocks, doneBlock)
	c.continueblocks = append(c.continueblocks, postBlock)
	defer func() {
		c.breakblocks = c.breakblocks[:len(c.breakblocks)-1]
		c.continueblocks = c.continueblocks[:len(c.continueblocks)-1]
	}()

	// Is there an initializer? Create a new scope and visit the statement.
	if stmt.Init != nil {
		c.VisitStmt(stmt.Init)
	}

	// Start the loop.
	if stmt.Cond != nil {
		c.builder.CreateBr(condBlock)
		c.builder.SetInsertPointAtEnd(condBlock)
		condVal := c.VisitExpr(stmt.Cond)
		c.builder.CreateCondBr(condVal.LLVMValue(), loopBlock, doneBlock)
	} else {
		c.builder.CreateBr(loopBlock)
	}

	// Post.
	if stmt.Post != nil {
		c.builder.SetInsertPointAtEnd(postBlock)
		c.VisitStmt(stmt.Post)
		c.builder.CreateBr(condBlock)
	}

	// Loop body.
	c.builder.SetInsertPointAtEnd(loopBlock)
	c.VisitBlockStmt(stmt.Body, false)
	c.maybeImplicitBranch(postBlock)
}

func (c *compiler) createMainFunction() error {
	// In a PNaCl program (plugin), there should not be a "main.main";
	// instead, we expect a "main.CreateModule" function.
	// See pkg/nacl/ppapi/ppapi.go for more details.
	mainMain := c.module.NamedFunction("main.main")
	if c.pnacl {
		// PNaCl's libppapi_stub.a implements "main", which simply
		// calls through to PpapiPluginMain. We define our own "main"
		// so that we can capture argc/argv.
		if !mainMain.IsNil() {
			return fmt.Errorf("Found main.main")
		}
		pluginMain := c.NamedFunction("PpapiPluginMain", "func() int32")

		// Synthesise a main which has no return value. We could cast
		// PpapiPluginMain, but this is potentially unsafe as its
		// calling convention is unspecified.
		ftyp := llvm.FunctionType(llvm.VoidType(), nil, false)
		mainMain = llvm.AddFunction(c.module.Module, "main.main", ftyp)
		entry := llvm.AddBasicBlock(mainMain, "entry")
		c.builder.SetInsertPointAtEnd(entry)
		c.builder.CreateCall(pluginMain, nil, "")
		c.builder.CreateRetVoid()
	} else {
		mainMain = c.module.NamedFunction("main.main")
	}

	if mainMain.IsNil() {
		return fmt.Errorf("Could not find main.main")
	}

	// runtime.main is called by main, with argc, argv, argp,
	// and a pointer to main.main, which must be a niladic
	// function with no result.
	runtimeMain := c.NamedFunction("runtime.main", "func(int32, **byte, **byte, *int8) int32")
	main := c.NamedFunction("main", "func(int32, **byte, **byte) int32")
	c.builder.SetCurrentDebugLocation(c.debug_info.MDNode(nil))
	entry := llvm.AddBasicBlock(main, "entry")
	c.builder.SetInsertPointAtEnd(entry)
	mainMain = c.builder.CreateBitCast(mainMain, runtimeMain.Type().ElementType().ParamTypes()[3], "")
	args := []llvm.Value{main.Param(0), main.Param(1), main.Param(2), mainMain}
	result := c.builder.CreateCall(runtimeMain, args, "")
	c.builder.CreateRet(result)
	return nil
}

func (c *compiler) defineMallocFunction(fn llvm.Value) {
	entry := llvm.AddBasicBlock(fn, "entry")
	c.builder.SetInsertPointAtEnd(entry)
	size := fn.FirstParam()
	ptr := c.builder.CreateArrayMalloc(llvm.Int8Type(), size, "")
	// XXX memset to zero, or leave that to Go runtime code?
	fn_type := fn.Type().ElementType()
	result := c.builder.CreatePtrToInt(ptr, fn_type.ReturnType(), "")
	c.builder.CreateRet(result)
}

func (c *compiler) labelData(label *ast.Ident) *LabelData {
	data, ok := label.Obj.Data.(*LabelData)
	if !ok {
		bb := c.builder.GetInsertBlock()
		data = &LabelData{}
		data.Goto = llvm.AddBasicBlock(bb.Parent(), label.Name)
		label.Obj.Data = data
	}
	return data
}

func (c *compiler) VisitLabeledStmt(stmt *ast.LabeledStmt) {
	currBlock := c.builder.GetInsertBlock()
	labeledBlock, _ := stmt.Label.Obj.Data.(llvm.BasicBlock)
	if labeledBlock.IsNil() {
		labeledBlock = llvm.AddBasicBlock(currBlock.Parent(), stmt.Label.Name)
		stmt.Label.Obj.Data = labeledBlock
	}
	labeledBlock.MoveAfter(currBlock)
	c.builder.CreateBr(labeledBlock)
	c.builder.SetInsertPointAtEnd(labeledBlock)
	c.VisitStmt(stmt.Stmt)
}

func (c *compiler) VisitForStmt(stmt *ast.ForStmt) {
	curr_block := c.builder.GetInsertBlock()
	var cond_block, loop_block, done_block llvm.BasicBlock
	if stmt.Cond != nil {
		cond_block = llvm.AddBasicBlock(curr_block.Parent(), "cond")
	}
	loop_block = llvm.AddBasicBlock(curr_block.Parent(), "loop")
	done_block = llvm.AddBasicBlock(curr_block.Parent(), "done")

	// Is there an initializer? Create a new scope and visit the statement.
	if stmt.Init != nil {
		c.PushScope()
		c.VisitStmt(stmt.Init)
		defer c.PopScope()
	}

	// Start the loop.
	if stmt.Cond != nil {
		c.builder.CreateBr(cond_block)
		c.builder.SetInsertPointAtEnd(cond_block)
		cond_val := c.VisitExpr(stmt.Cond)
		c.builder.CreateCondBr(
			cond_val.LLVMValue(), loop_block, done_block)
	} else {
		c.builder.CreateBr(loop_block)
	}

	// Loop body.
	c.builder.SetInsertPointAtEnd(loop_block)
	c.VisitBlockStmt(stmt.Body)
	if stmt.Post != nil {
		c.VisitStmt(stmt.Post)
	}
	if stmt.Cond != nil {
		c.builder.CreateBr(cond_block)
	} else {
		c.builder.CreateBr(loop_block)
	}
	c.builder.SetInsertPointAtEnd(done_block)
}

func (c *compiler) VisitForStmt(stmt *ast.ForStmt) {
	currBlock := c.builder.GetInsertBlock()
	doneBlock := llvm.AddBasicBlock(currBlock.Parent(), "done")
	doneBlock.MoveAfter(currBlock)
	loopBlock := llvm.InsertBasicBlock(doneBlock, "loop")
	defer c.builder.SetInsertPointAtEnd(doneBlock)

	condBlock := loopBlock
	if stmt.Cond != nil {
		condBlock = llvm.InsertBasicBlock(loopBlock, "cond")
	}

	postBlock := condBlock
	if stmt.Post != nil {
		postBlock = llvm.InsertBasicBlock(doneBlock, "post")
	}

	// Is there an initializer? Create a new scope and visit the statement.
	if stmt.Init != nil {
		c.PushScope()
		c.VisitStmt(stmt.Init)
		defer c.PopScope()
	}

	// Start the loop.
	if stmt.Cond != nil {
		c.builder.CreateBr(condBlock)
		c.builder.SetInsertPointAtEnd(condBlock)
		condVal := c.VisitExpr(stmt.Cond)
		c.builder.CreateCondBr(condVal.LLVMValue(), loopBlock, doneBlock)
	} else {
		c.builder.CreateBr(loopBlock)
	}

	// Post.
	if stmt.Post != nil {
		c.builder.SetInsertPointAtEnd(postBlock)
		c.VisitStmt(stmt.Post)
		c.builder.CreateBr(condBlock)
	}

	// Loop body.
	c.builder.SetInsertPointAtEnd(loopBlock)
	c.VisitBlockStmt(stmt.Body)
	c.maybeImplicitBranch(postBlock)
}

func (c *compiler) buildPtrRecvFunction(fn llvm.Value) llvm.Value {
	defer c.builder.SetInsertPointAtEnd(c.builder.GetInsertBlock())
	ifname := "*" + fn.Name()
	ifn := c.module.Module.NamedFunction(ifname)
	fntyp := fn.Type().ElementType()
	entry := llvm.AddBasicBlock(ifn, "entry")
	c.builder.SetInsertPointAtEnd(entry)
	args := ifn.Params()
	args[0] = c.builder.CreateLoad(args[0], "recv")
	result := c.builder.CreateCall(fn, args, "")
	if fntyp.ReturnType().TypeKind() == llvm.VoidTypeKind {
		c.builder.CreateRetVoid()
	} else {
		c.builder.CreateRet(result)
	}
	return ifn
}

func (c *compiler) VisitIfStmt(stmt *ast.IfStmt) {
	curr_block := c.builder.GetInsertBlock()
	resume_block := llvm.AddBasicBlock(curr_block.Parent(), "endif")
	resume_block.MoveAfter(curr_block)

	var if_block, else_block llvm.BasicBlock
	if stmt.Else != nil {
		else_block = llvm.InsertBasicBlock(resume_block, "else")
		if_block = llvm.InsertBasicBlock(else_block, "if")
	} else {
		if_block = llvm.InsertBasicBlock(resume_block, "if")
	}
	if stmt.Else == nil {
		else_block = resume_block
	}

	if stmt.Init != nil {
		c.PushScope()
		c.VisitStmt(stmt.Init)
		defer c.PopScope()
	}

	cond_val := c.VisitExpr(stmt.Cond)
	c.builder.CreateCondBr(cond_val.LLVMValue(), if_block, else_block)
	c.builder.SetInsertPointAtEnd(if_block)
	c.VisitBlockStmt(stmt.Body)
	if in := if_block.LastInstruction(); in.IsNil() || in.IsATerminatorInst().IsNil() {
		c.builder.CreateBr(resume_block)
	}

	if stmt.Else != nil {
		c.builder.SetInsertPointAtEnd(else_block)
		c.VisitStmt(stmt.Else)
		if in := else_block.LastInstruction(); in.IsNil() || in.IsATerminatorInst().IsNil() {
			c.builder.CreateBr(resume_block)
		}
	}

	// If there's a block after the "resume" block (i.e. a nested control
	// statement), then create a branch to it as the last instruction.
	c.builder.SetInsertPointAtEnd(resume_block)
	if last := resume_block.Parent().LastBasicBlock(); last != resume_block {
		c.builder.CreateBr(last)
		c.builder.SetInsertPointBefore(resume_block.FirstInstruction())
	}
}