36d1198115
This code is required by transformation passes which are being moved into a separate package, but is too complicated to simply copy. Therefore, I decided to move them into a new package.
96 строки
4,1 КиБ
Go
96 строки
4,1 КиБ
Go
// Package llvmutil contains utility functions used across multiple compiler
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// packages. For example, they may be used by both the compiler pacakge and
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// transformation packages.
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//
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// Normally, utility packages are avoided. However, in this case, the utility
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// functions are non-trivial and hard to get right. Copying them to multiple
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// places would be a big risk if only one of them is updated.
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package llvmutil
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import "tinygo.org/x/go-llvm"
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// CreateEntryBlockAlloca creates a new alloca in the entry block, even though
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// the IR builder is located elsewhere. It assumes that the insert point is
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// at the end of the current block.
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func CreateEntryBlockAlloca(builder llvm.Builder, t llvm.Type, name string) llvm.Value {
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currentBlock := builder.GetInsertBlock()
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entryBlock := currentBlock.Parent().EntryBasicBlock()
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if entryBlock.FirstInstruction().IsNil() {
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builder.SetInsertPointAtEnd(entryBlock)
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} else {
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builder.SetInsertPointBefore(entryBlock.FirstInstruction())
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}
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alloca := builder.CreateAlloca(t, name)
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builder.SetInsertPointAtEnd(currentBlock)
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return alloca
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}
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// CreateTemporaryAlloca creates a new alloca in the entry block and adds
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// lifetime start infromation in the IR signalling that the alloca won't be used
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// before this point.
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//
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// This is useful for creating temporary allocas for intrinsics. Don't forget to
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// end the lifetime using emitLifetimeEnd after you're done with it.
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func CreateTemporaryAlloca(builder llvm.Builder, mod llvm.Module, t llvm.Type, name string) (alloca, bitcast, size llvm.Value) {
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ctx := t.Context()
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targetData := llvm.NewTargetData(mod.DataLayout())
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i8ptrType := llvm.PointerType(ctx.Int8Type(), 0)
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alloca = CreateEntryBlockAlloca(builder, t, name)
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bitcast = builder.CreateBitCast(alloca, i8ptrType, name+".bitcast")
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size = llvm.ConstInt(ctx.Int64Type(), targetData.TypeAllocSize(t), false)
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builder.CreateCall(getLifetimeStartFunc(mod), []llvm.Value{size, bitcast}, "")
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return
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}
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// CreateInstructionAlloca creates an alloca in the entry block, and places lifetime control intrinsics around the instruction
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func CreateInstructionAlloca(builder llvm.Builder, mod llvm.Module, t llvm.Type, inst llvm.Value, name string) llvm.Value {
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ctx := mod.Context()
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targetData := llvm.NewTargetData(mod.DataLayout())
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i8ptrType := llvm.PointerType(ctx.Int8Type(), 0)
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alloca := CreateEntryBlockAlloca(builder, t, name)
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builder.SetInsertPointBefore(inst)
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bitcast := builder.CreateBitCast(alloca, i8ptrType, name+".bitcast")
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size := llvm.ConstInt(ctx.Int64Type(), targetData.TypeAllocSize(t), false)
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builder.CreateCall(getLifetimeStartFunc(mod), []llvm.Value{size, bitcast}, "")
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if next := llvm.NextInstruction(inst); !next.IsNil() {
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builder.SetInsertPointBefore(next)
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} else {
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builder.SetInsertPointAtEnd(inst.InstructionParent())
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}
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builder.CreateCall(getLifetimeEndFunc(mod), []llvm.Value{size, bitcast}, "")
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return alloca
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}
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// EmitLifetimeEnd signals the end of an (alloca) lifetime by calling the
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// llvm.lifetime.end intrinsic. It is commonly used together with
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// createTemporaryAlloca.
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func EmitLifetimeEnd(builder llvm.Builder, mod llvm.Module, ptr, size llvm.Value) {
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builder.CreateCall(getLifetimeEndFunc(mod), []llvm.Value{size, ptr}, "")
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}
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// getLifetimeStartFunc returns the llvm.lifetime.start intrinsic and creates it
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// first if it doesn't exist yet.
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func getLifetimeStartFunc(mod llvm.Module) llvm.Value {
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fn := mod.NamedFunction("llvm.lifetime.start.p0i8")
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ctx := mod.Context()
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i8ptrType := llvm.PointerType(ctx.Int8Type(), 0)
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if fn.IsNil() {
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fnType := llvm.FunctionType(ctx.VoidType(), []llvm.Type{ctx.Int64Type(), i8ptrType}, false)
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fn = llvm.AddFunction(mod, "llvm.lifetime.start.p0i8", fnType)
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}
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return fn
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}
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// getLifetimeEndFunc returns the llvm.lifetime.end intrinsic and creates it
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// first if it doesn't exist yet.
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func getLifetimeEndFunc(mod llvm.Module) llvm.Value {
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fn := mod.NamedFunction("llvm.lifetime.end.p0i8")
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ctx := mod.Context()
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i8ptrType := llvm.PointerType(ctx.Int8Type(), 0)
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if fn.IsNil() {
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fnType := llvm.FunctionType(ctx.VoidType(), []llvm.Type{ctx.Int64Type(), i8ptrType}, false)
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fn = llvm.AddFunction(mod, "llvm.lifetime.end.p0i8", fnType)
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}
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return fn
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}
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