blob: 50074294857271dfecd2702de87db6c0d01a19a9 [file] [log] [blame]
//===- indirect.go - IR generation for thunks -----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements IR generation for thunks required by the "defer" and
// "go" builtins.
//
//===----------------------------------------------------------------------===//
package irgen
import (
"llvm.org/llgo/third_party/gotools/go/ssa"
"llvm.org/llgo/third_party/gotools/go/types"
"llvm.org/llvm/bindings/go/llvm"
)
// createThunk creates a thunk from a
// given function and arguments, suitable for use with
// "defer" and "go".
func (fr *frame) createThunk(call ssa.CallInstruction) (thunk llvm.Value, arg llvm.Value) {
seenarg := make(map[ssa.Value]bool)
var args []ssa.Value
var argtypes []*types.Var
packArg := func(arg ssa.Value) {
switch arg.(type) {
case *ssa.Builtin, *ssa.Function, *ssa.Const, *ssa.Global:
// Do nothing: we can generate these in the thunk
default:
if !seenarg[arg] {
seenarg[arg] = true
args = append(args, arg)
field := types.NewField(0, nil, "_", arg.Type(), true)
argtypes = append(argtypes, field)
}
}
}
packArg(call.Common().Value)
for _, arg := range call.Common().Args {
packArg(arg)
}
var isRecoverCall bool
i8ptr := llvm.PointerType(llvm.Int8Type(), 0)
var structllptr llvm.Type
if len(args) == 0 {
if builtin, ok := call.Common().Value.(*ssa.Builtin); ok {
isRecoverCall = builtin.Name() == "recover"
}
if isRecoverCall {
// When creating a thunk for recover(), we must pass fr.canRecover.
arg = fr.builder.CreateZExt(fr.canRecover, fr.target.IntPtrType(), "")
arg = fr.builder.CreateIntToPtr(arg, i8ptr, "")
} else {
arg = llvm.ConstPointerNull(i8ptr)
}
} else {
structtype := types.NewStruct(argtypes, nil)
arg = fr.createTypeMalloc(structtype)
structllptr = arg.Type()
for i, ssaarg := range args {
argptr := fr.builder.CreateStructGEP(arg, i, "")
fr.builder.CreateStore(fr.llvmvalue(ssaarg), argptr)
}
arg = fr.builder.CreateBitCast(arg, i8ptr, "")
}
thunkfntype := llvm.FunctionType(llvm.VoidType(), []llvm.Type{i8ptr}, false)
thunkfn := llvm.AddFunction(fr.module.Module, "", thunkfntype)
thunkfn.SetLinkage(llvm.InternalLinkage)
fr.addCommonFunctionAttrs(thunkfn)
thunkfr := newFrame(fr.unit, thunkfn)
defer thunkfr.dispose()
prologuebb := llvm.AddBasicBlock(thunkfn, "prologue")
thunkfr.builder.SetInsertPointAtEnd(prologuebb)
if isRecoverCall {
thunkarg := thunkfn.Param(0)
thunkarg = thunkfr.builder.CreatePtrToInt(thunkarg, fr.target.IntPtrType(), "")
thunkfr.canRecover = thunkfr.builder.CreateTrunc(thunkarg, llvm.Int1Type(), "")
} else if len(args) > 0 {
thunkarg := thunkfn.Param(0)
thunkarg = thunkfr.builder.CreateBitCast(thunkarg, structllptr, "")
for i, ssaarg := range args {
thunkargptr := thunkfr.builder.CreateStructGEP(thunkarg, i, "")
thunkarg := thunkfr.builder.CreateLoad(thunkargptr, "")
thunkfr.env[ssaarg] = newValue(thunkarg, ssaarg.Type())
}
}
_, isDefer := call.(*ssa.Defer)
entrybb := llvm.AddBasicBlock(thunkfn, "entry")
br := thunkfr.builder.CreateBr(entrybb)
thunkfr.allocaBuilder.SetInsertPointBefore(br)
thunkfr.builder.SetInsertPointAtEnd(entrybb)
var exitbb llvm.BasicBlock
if isDefer {
exitbb = llvm.AddBasicBlock(thunkfn, "exit")
thunkfr.runtime.setDeferRetaddr.call(thunkfr, llvm.BlockAddress(thunkfn, exitbb))
}
if isDefer && isRecoverCall {
thunkfr.callRecover(true)
} else {
thunkfr.callInstruction(call)
}
if isDefer {
thunkfr.builder.CreateBr(exitbb)
thunkfr.builder.SetInsertPointAtEnd(exitbb)
}
thunkfr.builder.CreateRetVoid()
thunk = fr.builder.CreateBitCast(thunkfn, i8ptr, "")
return
}