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package transform
import (
"reflect"
"tinygo.org/x/go-llvm"
)
// Return a list of values (actually, instructions) where this value is used as
// an operand.
func getUses(value llvm.Value) []llvm.Value {
if value.IsNil() {
return nil
}
var uses []llvm.Value
use := value.FirstUse()
for !use.IsNil() {
uses = append(uses, use.User())
use = use.NextUse()
}
return uses
}
// hasUses returns whether the given value has any uses. It is equivalent to
// getUses(value) != nil but faster.
func hasUses(value llvm.Value) bool {
if value.IsNil() {
return false
}
return !value.FirstUse().IsNil()
}
// makeGlobalArray creates a new LLVM global with the given name and integers as
// contents, and returns the global and initializer type.
// Note that it is left with the default linkage etc., you should set
// linkage/constant/etc properties yourself.
func makeGlobalArray(mod llvm.Module, bufItf interface{}, name string, elementType llvm.Type) (llvm.Type, llvm.Value) {
buf := reflect.ValueOf(bufItf)
var values []llvm.Value
for i := 0; i < buf.Len(); i++ {
ch := buf.Index(i).Uint()
values = append(values, llvm.ConstInt(elementType, ch, false))
}
value := llvm.ConstArray(elementType, values)
global := llvm.AddGlobal(mod, value.Type(), name)
global.SetInitializer(value)
return value.Type(), global
}
// getGlobalBytes returns the slice contained in the array of the provided
// global. It can recover the bytes originally created using makeGlobalArray, if
// makeGlobalArray was given a byte slice.
//
// The builder parameter is only used for constant operations.
func getGlobalBytes(global llvm.Value, builder llvm.Builder) []byte {
value := global.Initializer()
buf := make([]byte, value.Type().ArrayLength())
for i := range buf {
buf[i] = byte(builder.CreateExtractValue(value, i, "").ZExtValue())
}
return buf
}
// replaceGlobalByteWithArray replaces a global integer type in the module with
// an integer array, using a GEP to make the types match. It is a convenience
// function used for creating reflection sidetables, for example.
func replaceGlobalIntWithArray(mod llvm.Module, name string, buf interface{}) llvm.Value {
oldGlobal := mod.NamedGlobal(name)
globalType, global := makeGlobalArray(mod, buf, name+".tmp", oldGlobal.GlobalValueType())
gep := llvm.ConstGEP(globalType, global, []llvm.Value{
llvm.ConstInt(mod.Context().Int32Type(), 0, false),
llvm.ConstInt(mod.Context().Int32Type(), 0, false),
})
oldGlobal.ReplaceAllUsesWith(gep)
oldGlobal.EraseFromParentAsGlobal()
global.SetName(name)
return global
}
// stripPointerCasts strips instruction pointer casts (getelementptr and
// bitcast) and returns the original value without the casts.
func stripPointerCasts(value llvm.Value) llvm.Value {
if !value.IsAConstantExpr().IsNil() {
switch value.Opcode() {
case llvm.GetElementPtr, llvm.BitCast:
return stripPointerCasts(value.Operand(0))
}
}
if !value.IsAInstruction().IsNil() {
switch value.InstructionOpcode() {
case llvm.GetElementPtr, llvm.BitCast:
return stripPointerCasts(value.Operand(0))
}
}
return value
}
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