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llvm.go
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llvm.go
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package compiler
import (
"github.com/tinygo-org/tinygo/compiler/llvmutil"
"tinygo.org/x/go-llvm"
)
// This file contains helper functions for LLVM that are not exposed in the Go
// bindings.
// 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
}
// createTemporaryAlloca creates a new alloca in the entry block and adds
// lifetime start infromation in the IR signalling that the alloca won't be used
// before this point.
//
// This is useful for creating temporary allocas for intrinsics. Don't forget to
// end the lifetime using emitLifetimeEnd after you're done with it.
func (c *Compiler) createTemporaryAlloca(t llvm.Type, name string) (alloca, bitcast, size llvm.Value) {
return llvmutil.CreateTemporaryAlloca(c.builder, c.mod, t, name)
}
// emitLifetimeEnd signals the end of an (alloca) lifetime by calling the
// llvm.lifetime.end intrinsic. It is commonly used together with
// createTemporaryAlloca.
func (c *Compiler) emitLifetimeEnd(ptr, size llvm.Value) {
llvmutil.EmitLifetimeEnd(c.builder, c.mod, ptr, size)
}
// emitPointerPack packs the list of values into a single pointer value using
// bitcasts, or else allocates a value on the heap if it cannot be packed in the
// pointer value directly. It returns the pointer with the packed data.
func (c *Compiler) emitPointerPack(values []llvm.Value) llvm.Value {
return llvmutil.EmitPointerPack(c.builder, c.mod, c.Config, values)
}
// emitPointerUnpack extracts a list of values packed using emitPointerPack.
func (c *Compiler) emitPointerUnpack(ptr llvm.Value, valueTypes []llvm.Type) []llvm.Value {
return llvmutil.EmitPointerUnpack(c.builder, c.mod, ptr, valueTypes)
}
// splitBasicBlock splits a LLVM basic block into two parts. All instructions
// after afterInst are moved into a new basic block (created right after the
// current one) with the given name.
func (c *Compiler) splitBasicBlock(afterInst llvm.Value, insertAfter llvm.BasicBlock, name string) llvm.BasicBlock {
oldBlock := afterInst.InstructionParent()
newBlock := c.ctx.InsertBasicBlock(insertAfter, name)
var nextInstructions []llvm.Value // values to move
// Collect to-be-moved instructions.
inst := afterInst
for {
inst = llvm.NextInstruction(inst)
if inst.IsNil() {
break
}
nextInstructions = append(nextInstructions, inst)
}
// Move instructions.
c.builder.SetInsertPointAtEnd(newBlock)
for _, inst := range nextInstructions {
inst.RemoveFromParentAsInstruction()
c.builder.Insert(inst)
}
// Find PHI nodes to update.
var phiNodes []llvm.Value // PHI nodes to update
for bb := insertAfter.Parent().FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
if inst.IsAPHINode().IsNil() {
continue
}
needsUpdate := false
incomingCount := inst.IncomingCount()
for i := 0; i < incomingCount; i++ {
if inst.IncomingBlock(i) == oldBlock {
needsUpdate = true
break
}
}
if !needsUpdate {
// PHI node has no incoming edge from the old block.
continue
}
phiNodes = append(phiNodes, inst)
}
}
// Update PHI nodes.
for _, phi := range phiNodes {
c.builder.SetInsertPointBefore(phi)
newPhi := c.builder.CreatePHI(phi.Type(), "")
incomingCount := phi.IncomingCount()
incomingVals := make([]llvm.Value, incomingCount)
incomingBlocks := make([]llvm.BasicBlock, incomingCount)
for i := 0; i < incomingCount; i++ {
value := phi.IncomingValue(i)
block := phi.IncomingBlock(i)
if block == oldBlock {
block = newBlock
}
incomingVals[i] = value
incomingBlocks[i] = block
}
newPhi.AddIncoming(incomingVals, incomingBlocks)
phi.ReplaceAllUsesWith(newPhi)
phi.EraseFromParentAsInstruction()
}
return newBlock
}
// makeGlobalArray creates a new LLVM global with the given name and integers as
// contents, and returns the global.
// Note that it is left with the default linkage etc., you should set
// linkage/constant/etc properties yourself.
func (c *Compiler) makeGlobalArray(buf []byte, name string, elementType llvm.Type) llvm.Value {
globalType := llvm.ArrayType(elementType, len(buf))
global := llvm.AddGlobal(c.mod, globalType, name)
value := llvm.Undef(globalType)
for i := 0; i < len(buf); i++ {
ch := uint64(buf[i])
value = llvm.ConstInsertValue(value, llvm.ConstInt(elementType, ch, false), []uint32{uint32(i)})
}
global.SetInitializer(value)
return global
}