1681ed02d3
Constant globals can't have been modified, even if a pointer is passed externally. Therefore, don't treat it as such in hasExternalStore. In addition, it doesn't make sense to update values of constant globals after the interp pass is finished. So don't do this. TODO: track whether objects are actually modified and only update the globals if this is the case.
303 строки
10 КиБ
Go
303 строки
10 КиБ
Go
// Package interp is a partial evaluator of code run at package init time. See
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// the README in this package for details.
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package interp
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import (
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"fmt"
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"os"
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"strings"
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"time"
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"tinygo.org/x/go-llvm"
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)
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// Version of the interp package. It must be incremented whenever the interp
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// package is changed in a way that affects the output so that cached package
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// builds will be invalidated.
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// This version is independent of the TinyGo version number.
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const Version = 2 // last change: fix GEP on untyped pointers
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// Enable extra checks, which should be disabled by default.
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// This may help track down bugs by adding a few more sanity checks.
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const checks = true
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// runner contains all state related to one interp run.
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type runner struct {
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mod llvm.Module
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targetData llvm.TargetData
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builder llvm.Builder
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pointerSize uint32 // cached pointer size from the TargetData
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i8ptrType llvm.Type // often used type so created in advance
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maxAlign int // maximum alignment of an object, alignment of runtime.alloc() result
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debug bool // log debug messages
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pkgName string // package name of the currently executing package
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functionCache map[llvm.Value]*function // cache of compiled functions
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objects []object // slice of objects in memory
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globals map[llvm.Value]int // map from global to index in objects slice
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start time.Time
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callsExecuted uint64
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}
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func newRunner(mod llvm.Module, debug bool) *runner {
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r := runner{
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mod: mod,
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targetData: llvm.NewTargetData(mod.DataLayout()),
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debug: debug,
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functionCache: make(map[llvm.Value]*function),
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objects: []object{{}},
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globals: make(map[llvm.Value]int),
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start: time.Now(),
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}
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r.pointerSize = uint32(r.targetData.PointerSize())
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r.i8ptrType = llvm.PointerType(mod.Context().Int8Type(), 0)
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r.maxAlign = r.targetData.PrefTypeAlignment(r.i8ptrType) // assume pointers are maximally aligned (this is not always the case)
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return &r
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}
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// Run evaluates runtime.initAll function as much as possible at compile time.
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// Set debug to true if it should print output while running.
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func Run(mod llvm.Module, debug bool) error {
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r := newRunner(mod, debug)
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initAll := mod.NamedFunction("runtime.initAll")
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bb := initAll.EntryBasicBlock()
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// Create a builder, to insert instructions that could not be evaluated at
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// compile time.
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r.builder = mod.Context().NewBuilder()
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defer r.builder.Dispose()
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// Create a dummy alloca in the entry block that we can set the insert point
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// to. This is necessary because otherwise we might be removing the
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// instruction (init call) that we are removing after successful
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// interpretation.
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r.builder.SetInsertPointBefore(bb.FirstInstruction())
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dummy := r.builder.CreateAlloca(r.mod.Context().Int8Type(), "dummy")
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r.builder.SetInsertPointBefore(dummy)
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defer dummy.EraseFromParentAsInstruction()
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// Get a list if init calls. A runtime.initAll might look something like this:
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// func initAll() {
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// unsafe.init()
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// machine.init()
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// runtime.init()
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// }
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// This function gets a list of these call instructions.
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var initCalls []llvm.Value
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for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
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if inst == dummy {
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continue
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}
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if !inst.IsAReturnInst().IsNil() {
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break // ret void
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}
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if inst.IsACallInst().IsNil() || inst.CalledValue().IsAFunction().IsNil() {
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return errorAt(inst, "interp: expected all instructions in "+initAll.Name()+" to be direct calls")
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}
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initCalls = append(initCalls, inst)
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}
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// Run initializers for each package. Once the package initializer is
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// finished, the call to the package initializer can be removed.
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for _, call := range initCalls {
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initName := call.CalledValue().Name()
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if !strings.HasSuffix(initName, ".init") {
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return errorAt(call, "interp: expected all instructions in "+initAll.Name()+" to be *.init() calls")
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}
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r.pkgName = initName[:len(initName)-len(".init")]
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fn := call.CalledValue()
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if r.debug {
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fmt.Fprintln(os.Stderr, "call:", fn.Name())
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}
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_, mem, callErr := r.run(r.getFunction(fn), nil, nil, " ")
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call.EraseFromParentAsInstruction()
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if callErr != nil {
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if isRecoverableError(callErr.Err) {
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if r.debug {
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fmt.Fprintln(os.Stderr, "not interpreting", r.pkgName, "because of error:", callErr.Error())
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}
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// Remove instructions that were created as part of interpreting
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// the package.
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mem.revert()
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// Create a call to the package initializer (which was
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// previously deleted).
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i8undef := llvm.Undef(r.i8ptrType)
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r.builder.CreateCall(fn, []llvm.Value{i8undef, i8undef}, "")
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// Make sure that any globals touched by the package
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// initializer, won't be accessed by later package initializers.
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r.markExternalLoad(fn)
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continue
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}
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return callErr
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}
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for index, obj := range mem.objects {
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r.objects[index] = obj
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}
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}
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r.pkgName = ""
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// Update all global variables in the LLVM module.
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mem := memoryView{r: r}
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for i, obj := range r.objects {
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if obj.llvmGlobal.IsNil() {
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continue
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}
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if obj.buffer == nil {
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continue
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}
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if obj.constant {
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continue // constant buffers can't have been modified
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}
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initializer, err := obj.buffer.toLLVMValue(obj.llvmGlobal.Type().ElementType(), &mem)
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if err == errInvalidPtrToIntSize {
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// This can happen when a previous interp run did not have the
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// correct LLVM type for a global and made something up. In that
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// case, some fields could be written out as a series of (null)
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// bytes even though they actually contain a pointer value.
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// As a fallback, use asRawValue to get something of the correct
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// memory layout.
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initializer, err := obj.buffer.asRawValue(r).rawLLVMValue(&mem)
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if err != nil {
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return err
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}
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initializerType := initializer.Type()
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newGlobal := llvm.AddGlobal(mod, initializerType, obj.llvmGlobal.Name()+".tmp")
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newGlobal.SetInitializer(initializer)
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newGlobal.SetLinkage(obj.llvmGlobal.Linkage())
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newGlobal.SetAlignment(obj.llvmGlobal.Alignment())
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// TODO: copy debug info, unnamed_addr, ...
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bitcast := llvm.ConstBitCast(newGlobal, obj.llvmGlobal.Type())
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obj.llvmGlobal.ReplaceAllUsesWith(bitcast)
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name := obj.llvmGlobal.Name()
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obj.llvmGlobal.EraseFromParentAsGlobal()
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newGlobal.SetName(name)
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// Update interp-internal references.
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delete(r.globals, obj.llvmGlobal)
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obj.llvmGlobal = newGlobal
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r.globals[newGlobal] = i
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r.objects[i] = obj
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continue
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}
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if err != nil {
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return err
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}
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if checks && initializer.Type() != obj.llvmGlobal.Type().ElementType() {
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panic("initializer type mismatch")
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}
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obj.llvmGlobal.SetInitializer(initializer)
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}
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return nil
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}
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// RunFunc evaluates a single package initializer at compile time.
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// Set debug to true if it should print output while running.
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func RunFunc(fn llvm.Value, debug bool) error {
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// Create and initialize *runner object.
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mod := fn.GlobalParent()
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r := newRunner(mod, debug)
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initName := fn.Name()
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if !strings.HasSuffix(initName, ".init") {
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return errorAt(fn, "interp: unexpected function name (expected *.init)")
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}
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r.pkgName = initName[:len(initName)-len(".init")]
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// Create new function with the interp result.
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newFn := llvm.AddFunction(mod, fn.Name()+".tmp", fn.Type().ElementType())
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newFn.SetLinkage(fn.Linkage())
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newFn.SetVisibility(fn.Visibility())
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entry := mod.Context().AddBasicBlock(newFn, "entry")
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// Create a builder, to insert instructions that could not be evaluated at
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// compile time.
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r.builder = mod.Context().NewBuilder()
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defer r.builder.Dispose()
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r.builder.SetInsertPointAtEnd(entry)
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// Copy debug information.
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subprogram := fn.Subprogram()
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if !subprogram.IsNil() {
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newFn.SetSubprogram(subprogram)
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r.builder.SetCurrentDebugLocation(subprogram.SubprogramLine(), 0, subprogram, llvm.Metadata{})
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}
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// Run the initializer, filling the .init.tmp function.
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if r.debug {
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fmt.Fprintln(os.Stderr, "interp:", fn.Name())
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}
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_, pkgMem, callErr := r.run(r.getFunction(fn), nil, nil, " ")
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if callErr != nil {
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if isRecoverableError(callErr.Err) {
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// Could not finish, but could recover from it.
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if r.debug {
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fmt.Fprintln(os.Stderr, "not interpreting", r.pkgName, "because of error:", callErr.Error())
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}
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newFn.EraseFromParentAsFunction()
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return nil
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}
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return callErr
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}
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for index, obj := range pkgMem.objects {
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r.objects[index] = obj
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}
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// Update globals with values determined while running the initializer above.
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mem := memoryView{r: r}
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for _, obj := range r.objects {
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if obj.llvmGlobal.IsNil() {
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continue
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}
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if obj.buffer == nil {
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continue
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}
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if obj.constant {
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continue // constant, so can't have been modified
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}
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initializer, err := obj.buffer.toLLVMValue(obj.llvmGlobal.Type().ElementType(), &mem)
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if err != nil {
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return err
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}
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if checks && initializer.Type() != obj.llvmGlobal.Type().ElementType() {
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panic("initializer type mismatch")
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}
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obj.llvmGlobal.SetInitializer(initializer)
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}
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// Finalize: remove the old init function and replace it with the new
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// (.init.tmp) function.
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r.builder.CreateRetVoid()
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fnName := fn.Name()
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fn.ReplaceAllUsesWith(newFn)
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fn.EraseFromParentAsFunction()
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newFn.SetName(fnName)
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return nil
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}
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// getFunction returns the compiled version of the given LLVM function. It
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// compiles the function if necessary and caches the result.
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func (r *runner) getFunction(llvmFn llvm.Value) *function {
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if fn, ok := r.functionCache[llvmFn]; ok {
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return fn
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}
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fn := r.compileFunction(llvmFn)
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r.functionCache[llvmFn] = fn
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return fn
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}
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// markExternalLoad marks the given llvmValue as being loaded externally. This
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// is primarily used to mark package initializers that could not be run at
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// compile time. As an example, a package initialize might store to a global
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// variable. Another package initializer might read from the same global
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// variable. By marking this function as being run at runtime, that load
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// instruction will need to be run at runtime instead of at compile time.
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func (r *runner) markExternalLoad(llvmValue llvm.Value) {
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mem := memoryView{r: r}
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mem.markExternalLoad(llvmValue)
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for index, obj := range mem.objects {
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if obj.marked > r.objects[index].marked {
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r.objects[index].marked = obj.marked
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}
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}
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}
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