forked from go-llvm/llgo
/
channels.go
269 lines (248 loc) · 9.2 KB
/
channels.go
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// Copyright 2012 The llgo Authors.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
package llgo
import (
"code.google.com/p/go.tools/go/types"
"fmt"
"github.com/axw/gollvm/llvm"
"go/ast"
"go/token"
)
func (c *compiler) VisitSendStmt(stmt *ast.SendStmt) {
channel := c.VisitExpr(stmt.Chan).(*LLVMValue)
value := c.VisitExpr(stmt.Value)
channel.chanSend(value)
}
func (c *compiler) visitClose(expr *ast.CallExpr) {
channel := c.VisitExpr(expr.Args[0]).(*LLVMValue)
channel.chanClose()
}
func (v *LLVMValue) chanClose() {
f := v.compiler.NamedFunction("runtime.chanclose", "func(c uintptr)")
v.compiler.builder.CreateCall(f, []llvm.Value{v.LLVMValue()}, "")
}
func (v *LLVMValue) chanSend(value Value) {
var ptr llvm.Value
if value, ok := value.(*LLVMValue); ok && value.pointer != nil {
ptr = value.pointer.LLVMValue()
}
elttyp := v.typ.Underlying().(*types.Chan).Elem()
c := v.compiler
if ptr.IsNil() {
ptr = c.builder.CreateAlloca(c.types.ToLLVM(elttyp), "")
value := value.Convert(elttyp).LLVMValue()
c.builder.CreateStore(value, ptr)
}
uintptr_ := c.builder.CreatePtrToInt(ptr, c.target.IntPtrType(), "")
nb := boolLLVMValue(false)
f := c.NamedFunction("runtime.chansend", "func(t *chanType, c, ptr uintptr, nb bool) bool")
chantyp := c.types.ToRuntime(v.typ.Underlying())
chantyp = c.builder.CreateBitCast(chantyp, f.Type().ElementType().ParamTypes()[0], "")
c.builder.CreateCall(f, []llvm.Value{chantyp, v.LLVMValue(), uintptr_, nb}, "")
// Ignore result; only used in runtime.
}
func (v *LLVMValue) chanRecv(commaok bool) (value, received *LLVMValue) {
c := v.compiler
elttyp := v.typ.Underlying().(*types.Chan).Elem()
ptr := c.builder.CreateAlloca(c.types.ToLLVM(elttyp), "")
uintptr_ := c.builder.CreatePtrToInt(ptr, c.target.IntPtrType(), "")
nb := boolLLVMValue(false)
f := c.NamedFunction("runtime.chanrecv", "func(t *chanType, c, ptr uintptr, nb bool) (received bool)")
chantyp := c.types.ToRuntime(v.typ.Underlying())
chantyp = c.builder.CreateBitCast(chantyp, f.Type().ElementType().ParamTypes()[0], "")
callresult := c.builder.CreateCall(f, []llvm.Value{chantyp, v.LLVMValue(), uintptr_, nb}, "")
llvmvalue := c.builder.CreateLoad(ptr, "")
if commaok {
received = c.NewValue(callresult, types.Typ[types.Bool])
}
return c.NewValue(llvmvalue, elttyp), received
}
func (c *compiler) VisitSelectStmt(stmt *ast.SelectStmt) {
// TODO optimisations:
// 1. No clauses: runtime.block.
// 2. Single recv, and default clause: runtime.selectnbrecv
// 2. Single send, and default clause: runtime.selectnbsend
startBlock := c.builder.GetInsertBlock()
function := startBlock.Parent()
endBlock := llvm.AddBasicBlock(function, "end")
endBlock.MoveAfter(startBlock)
defer c.builder.SetInsertPointAtEnd(endBlock)
// Cache runtime functions
var selectrecv, selectsend llvm.Value
getselectsend := func() llvm.Value {
if selectsend.IsNil() {
selectsend = c.NamedFunction("runtime.selectsend", "func(selectp, blockaddr, ch, elem unsafe.Pointer)")
}
return selectsend
}
getselectrecv := func() llvm.Value {
if selectrecv.IsNil() {
selectrecv = c.NamedFunction("runtime.selectrecv", "func(selectp, blockaddr, ch, elem unsafe.Pointer, received *bool)")
}
return selectrecv
}
// We create a pointer-pointer for each newly defined var on the
// lhs of receive expressions, which will be assigned to when the
// expressions are (conditionally) evaluated.
lhsptrs := make([][]llvm.Value, len(stmt.Body.List))
for i, stmt := range stmt.Body.List {
clause := stmt.(*ast.CommClause)
if stmt, ok := clause.Comm.(*ast.AssignStmt); ok && stmt.Tok == token.DEFINE {
lhs := make([]llvm.Value, len(stmt.Lhs))
for i, expr := range stmt.Lhs {
ident := expr.(*ast.Ident)
if !isBlank(ident.Name) {
typ := c.target.IntPtrType()
lhs[i] = c.builder.CreateAlloca(typ, "")
c.builder.CreateStore(llvm.ConstNull(typ), lhs[i])
}
}
lhsptrs[i] = lhs
}
}
// Create clause basic blocks.
blocks := make([]llvm.BasicBlock, len(stmt.Body.List))
var basesize uint64
for i, stmt := range stmt.Body.List {
clause := stmt.(*ast.CommClause)
if clause.Comm == nil {
basesize++
}
currBlock := c.builder.GetInsertBlock()
block := llvm.InsertBasicBlock(endBlock, "")
c.builder.SetInsertPointAtEnd(block)
blocks[i] = block
lhs := lhsptrs[i]
if stmt, ok := clause.Comm.(*ast.AssignStmt); ok {
for i, expr := range stmt.Lhs {
ident := expr.(*ast.Ident)
if !isBlank(ident.Name) {
ptr := c.builder.CreateLoad(lhs[i], "")
obj := c.typeinfo.Objects[ident]
ptrtyp := types.NewPointer(obj.Type())
ptr = c.builder.CreateIntToPtr(ptr, c.types.ToLLVM(ptrtyp), "")
value := c.NewValue(ptr, ptrtyp).makePointee()
c.objectdata[obj].Value = value
}
}
}
for _, stmt := range clause.Body {
c.VisitStmt(stmt)
}
c.maybeImplicitBranch(endBlock)
c.builder.SetInsertPointAtEnd(currBlock)
}
// We need to make an initial pass through the cases,
// discarding those where the channel is nil.
size := llvm.ConstInt(llvm.Int32Type(), basesize, false)
channels := make([]Value, len(stmt.Body.List))
rhs := make([]*LLVMValue, len(stmt.Body.List))
for i, stmt := range stmt.Body.List {
clause := stmt.(*ast.CommClause)
switch comm := clause.Comm.(type) {
case nil:
case *ast.SendStmt:
channels[i] = c.VisitExpr(comm.Chan)
rhs[i] = c.VisitExpr(comm.Value).(*LLVMValue)
case *ast.ExprStmt:
channels[i] = c.VisitExpr(comm.X.(*ast.UnaryExpr).X)
case *ast.AssignStmt:
channels[i] = c.VisitExpr(comm.Rhs[0].(*ast.UnaryExpr).X)
default:
panic(fmt.Errorf("unhandled: %T", comm))
}
if channels[i] != nil {
nonnil := c.builder.CreateIsNotNull(channels[i].LLVMValue(), "")
zero := llvm.ConstInt(llvm.Int32Type(), 0, false)
one := llvm.ConstInt(llvm.Int32Type(), 1, false)
addend := c.builder.CreateSelect(nonnil, one, zero, "")
size = c.builder.CreateAdd(size, addend, "")
}
}
f := c.NamedFunction("runtime.selectsize", "func(size int32) uintptr")
selectsize := c.builder.CreateCall(f, []llvm.Value{size}, "")
selectp := c.builder.CreateArrayAlloca(llvm.Int8Type(), selectsize, "selectp")
c.memsetZero(selectp, selectsize)
selectp = c.builder.CreatePtrToInt(selectp, c.target.IntPtrType(), "")
f = c.NamedFunction("runtime.initselect", "func(size int32, ptr unsafe.Pointer)")
c.builder.CreateCall(f, []llvm.Value{size, selectp}, "")
for i, stmt := range stmt.Body.List {
clause := stmt.(*ast.CommClause)
blockaddr := llvm.BlockAddress(function, blocks[i])
blockaddr = c.builder.CreatePtrToInt(blockaddr, c.target.IntPtrType(), "")
if clause.Comm == nil {
// default clause
f := c.NamedFunction("runtime.selectdefault", "func(selectp, blockaddr unsafe.Pointer)")
c.builder.CreateCall(f, []llvm.Value{selectp, blockaddr}, "")
continue
}
currBlock := c.builder.GetInsertBlock()
nextBlock := llvm.InsertBasicBlock(currBlock, "")
nextBlock.MoveAfter(currBlock)
block := llvm.InsertBasicBlock(endBlock, "")
chanval := channels[i].LLVMValue()
nonnilchan := c.builder.CreateIsNotNull(chanval, "")
c.builder.CreateCondBr(nonnilchan, block, nextBlock)
c.builder.SetInsertPointAtEnd(block)
switch comm := clause.Comm.(type) {
case *ast.SendStmt:
// c <- val
elem := rhs[i]
var elemptr llvm.Value
if elem.pointer == nil {
value := elem.LLVMValue()
elemptr = c.builder.CreateAlloca(value.Type(), "")
c.builder.CreateStore(value, elemptr)
} else {
elemptr = elem.pointer.LLVMValue()
}
elemptr = c.builder.CreatePtrToInt(elemptr, c.target.IntPtrType(), "")
f := getselectsend()
c.builder.CreateCall(f, []llvm.Value{selectp, blockaddr, chanval, elemptr}, "")
case *ast.ExprStmt:
// <-c
f := getselectrecv()
paramtypes := f.Type().ElementType().ParamTypes()
elem := llvm.ConstNull(paramtypes[3])
received := llvm.ConstNull(paramtypes[4])
c.builder.CreateCall(f, []llvm.Value{selectp, blockaddr, chanval, elem, received}, "")
case *ast.AssignStmt:
// val := <-c
// val, ok = <-c
f := getselectrecv()
lhs := c.assignees(comm)
paramtypes := f.Type().ElementType().ParamTypes()
var elem llvm.Value
if lhs[0] != nil {
elem = lhs[0].pointer.LLVMValue()
elem = c.builder.CreatePtrToInt(elem, paramtypes[3], "")
if !lhsptrs[i][0].IsNil() {
c.builder.CreateStore(elem, lhsptrs[i][0])
}
} else {
elem = llvm.ConstNull(paramtypes[3])
}
var received llvm.Value
if len(lhs) == 2 && lhs[1] != nil {
received = lhs[1].pointer.LLVMValue()
received = c.builder.CreatePtrToInt(received, paramtypes[4], "")
if !lhsptrs[i][1].IsNil() {
c.builder.CreateStore(received, lhsptrs[i][1])
}
} else {
received = llvm.ConstNull(paramtypes[4])
}
c.builder.CreateCall(f, []llvm.Value{selectp, blockaddr, chanval, elem, received}, "")
}
c.builder.CreateBr(nextBlock)
c.builder.SetInsertPointAtEnd(nextBlock)
}
f = c.NamedFunction("runtime.selectgo", "func(selectp unsafe.Pointer) unsafe.Pointer")
blockaddr := c.builder.CreateCall(f, []llvm.Value{selectp}, "")
blockaddr = c.builder.CreateIntToPtr(blockaddr, llvm.PointerType(llvm.Int8Type(), 0), "")
ibr := c.builder.CreateIndirectBr(blockaddr, len(stmt.Body.List))
for _, block := range blocks {
ibr.AddDest(block)
}
}