forked from OSchip/llvm-project
666 lines
19 KiB
Go
666 lines
19 KiB
Go
//===- cabi.go - C ABI abstraction layer ----------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements an abstraction layer for the platform's C ABI (currently
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// supports only Linux/x86_64).
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//
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//===----------------------------------------------------------------------===//
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package irgen
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import (
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"llvm.org/llgo/third_party/gotools/go/types"
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"llvm.org/llvm/bindings/go/llvm"
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)
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type abiArgInfo int
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const (
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AIK_Direct = abiArgInfo(iota)
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AIK_Indirect
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)
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type backendType interface {
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ToLLVM(llvm.Context) llvm.Type
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}
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type ptrBType struct {
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}
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func (t ptrBType) ToLLVM(c llvm.Context) llvm.Type {
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return llvm.PointerType(c.Int8Type(), 0)
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}
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type intBType struct {
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width int
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signed bool
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}
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func (t intBType) ToLLVM(c llvm.Context) llvm.Type {
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return c.IntType(t.width * 8)
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}
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type floatBType struct {
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isDouble bool
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}
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func (t floatBType) ToLLVM(c llvm.Context) llvm.Type {
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if t.isDouble {
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return c.DoubleType()
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} else {
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return c.FloatType()
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}
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}
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type structBType struct {
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fields []backendType
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}
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func (t structBType) ToLLVM(c llvm.Context) llvm.Type {
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var lfields []llvm.Type
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for _, f := range t.fields {
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lfields = append(lfields, f.ToLLVM(c))
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}
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return c.StructType(lfields, false)
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}
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type arrayBType struct {
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length uint64
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elem backendType
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}
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func (t arrayBType) ToLLVM(c llvm.Context) llvm.Type {
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return llvm.ArrayType(t.elem.ToLLVM(c), int(t.length))
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}
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// align returns the smallest y >= x such that y % a == 0.
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func align(x, a int64) int64 {
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y := x + a - 1
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return y - y%a
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}
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func (tm *llvmTypeMap) sizeofStruct(fields ...types.Type) int64 {
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var o int64
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for _, f := range fields {
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a := tm.Alignof(f)
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o = align(o, a)
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o += tm.Sizeof(f)
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}
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return o
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}
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// This decides whether the x86_64 classification algorithm produces MEMORY for
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// the given type. Given the subset of types that Go supports, this is exactly
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// equivalent to testing the type's size. See in particular the first step of
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// the algorithm and its footnote.
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func (tm *llvmTypeMap) classify(t ...types.Type) abiArgInfo {
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if tm.sizeofStruct(t...) > 16 {
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return AIK_Indirect
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}
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return AIK_Direct
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}
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func (tm *llvmTypeMap) sliceBackendType() backendType {
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i8ptr := &ptrBType{}
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uintptr := &intBType{tm.target.PointerSize(), false}
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return &structBType{[]backendType{i8ptr, uintptr, uintptr}}
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}
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func (tm *llvmTypeMap) getBackendType(t types.Type) backendType {
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switch t := t.(type) {
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case *types.Named:
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return tm.getBackendType(t.Underlying())
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case *types.Basic:
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switch t.Kind() {
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case types.Bool, types.Uint8:
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return &intBType{1, false}
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case types.Int8:
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return &intBType{1, true}
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case types.Uint16:
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return &intBType{2, false}
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case types.Int16:
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return &intBType{2, true}
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case types.Uint32:
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return &intBType{4, false}
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case types.Int32:
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return &intBType{4, true}
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case types.Uint64:
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return &intBType{8, false}
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case types.Int64:
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return &intBType{8, true}
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case types.Uint, types.Uintptr:
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return &intBType{tm.target.PointerSize(), false}
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case types.Int:
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return &intBType{tm.target.PointerSize(), true}
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case types.Float32:
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return &floatBType{false}
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case types.Float64:
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return &floatBType{true}
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case types.UnsafePointer:
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return &ptrBType{}
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case types.Complex64:
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f32 := &floatBType{false}
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return &structBType{[]backendType{f32, f32}}
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case types.Complex128:
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f64 := &floatBType{true}
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return &structBType{[]backendType{f64, f64}}
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case types.String:
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return &structBType{[]backendType{&ptrBType{}, &intBType{tm.target.PointerSize(), false}}}
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}
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case *types.Struct:
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var fields []backendType
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for i := 0; i != t.NumFields(); i++ {
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f := t.Field(i)
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fields = append(fields, tm.getBackendType(f.Type()))
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}
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return &structBType{fields}
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case *types.Pointer, *types.Signature, *types.Map, *types.Chan:
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return &ptrBType{}
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case *types.Interface:
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i8ptr := &ptrBType{}
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return &structBType{[]backendType{i8ptr, i8ptr}}
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case *types.Slice:
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return tm.sliceBackendType()
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case *types.Array:
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return &arrayBType{uint64(t.Len()), tm.getBackendType(t.Elem())}
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}
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panic("unhandled type: " + t.String())
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}
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type offsetedType struct {
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typ backendType
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offset uint64
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}
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func (tm *llvmTypeMap) getBackendOffsets(bt backendType) (offsets []offsetedType) {
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switch bt := bt.(type) {
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case *structBType:
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t := bt.ToLLVM(tm.ctx)
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for i, f := range bt.fields {
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offset := tm.target.ElementOffset(t, i)
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fieldOffsets := tm.getBackendOffsets(f)
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for _, fo := range fieldOffsets {
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offsets = append(offsets, offsetedType{fo.typ, offset + fo.offset})
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}
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}
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case *arrayBType:
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size := tm.target.TypeAllocSize(bt.elem.ToLLVM(tm.ctx))
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fieldOffsets := tm.getBackendOffsets(bt.elem)
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for i := uint64(0); i != bt.length; i++ {
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for _, fo := range fieldOffsets {
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offsets = append(offsets, offsetedType{fo.typ, i*size + fo.offset})
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}
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}
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default:
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offsets = []offsetedType{offsetedType{bt, 0}}
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}
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return
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}
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func (tm *llvmTypeMap) classifyEightbyte(offsets []offsetedType, numInt, numSSE *int) llvm.Type {
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if len(offsets) == 1 {
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if _, ok := offsets[0].typ.(*floatBType); ok {
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*numSSE++
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} else {
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*numInt++
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}
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return offsets[0].typ.ToLLVM(tm.ctx)
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}
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// This implements classification for the basic types and step 4 of the
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// classification algorithm. At this point, the only two possible
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// classifications are SSE (floats) and INTEGER (everything else).
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sse := true
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for _, ot := range offsets {
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if _, ok := ot.typ.(*floatBType); !ok {
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sse = false
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break
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}
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}
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if sse {
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// This can only be (float, float), which uses an SSE vector.
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*numSSE++
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return llvm.VectorType(tm.ctx.FloatType(), 2)
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} else {
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*numInt++
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width := offsets[len(offsets)-1].offset + tm.target.TypeAllocSize(offsets[len(offsets)-1].typ.ToLLVM(tm.ctx)) - offsets[0].offset
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return tm.ctx.IntType(int(width) * 8)
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}
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}
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func (tm *llvmTypeMap) expandType(argTypes []llvm.Type, argAttrs []llvm.Attribute, bt backendType) ([]llvm.Type, []llvm.Attribute, int, int) {
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var numInt, numSSE int
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var argAttr llvm.Attribute
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switch bt := bt.(type) {
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case *structBType, *arrayBType:
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bo := tm.getBackendOffsets(bt)
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sp := 0
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for sp != len(bo) && bo[sp].offset < 8 {
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sp++
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}
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eb1 := bo[0:sp]
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eb2 := bo[sp:]
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if len(eb2) > 0 {
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argTypes = append(argTypes, tm.classifyEightbyte(eb1, &numInt, &numSSE), tm.classifyEightbyte(eb2, &numInt, &numSSE))
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argAttrs = append(argAttrs, 0, 0)
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} else {
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argTypes = append(argTypes, tm.classifyEightbyte(eb1, &numInt, &numSSE))
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argAttrs = append(argAttrs, 0)
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}
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return argTypes, argAttrs, numInt, numSSE
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case *intBType:
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if bt.width < 4 {
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if bt.signed {
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argAttr = llvm.SExtAttribute
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} else {
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argAttr = llvm.ZExtAttribute
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}
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}
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}
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argTypes = append(argTypes, tm.classifyEightbyte([]offsetedType{{bt, 0}}, &numInt, &numSSE))
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argAttrs = append(argAttrs, argAttr)
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return argTypes, argAttrs, numInt, numSSE
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}
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type argInfo interface {
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// Emit instructions to builder to ABI encode val and store result to args.
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encode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, args []llvm.Value, val llvm.Value)
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// Emit instructions to builder to ABI decode and return the resulting Value.
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decode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder) llvm.Value
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}
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type retInfo interface {
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// Prepare args to receive a value. allocaBuilder refers to a builder in the entry block.
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prepare(ctx llvm.Context, allocaBuilder llvm.Builder, args []llvm.Value)
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// Emit instructions to builder to ABI decode the return value(s), if any. call is the
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// call instruction. Must be called after prepare().
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decode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, call llvm.Value) []llvm.Value
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// Emit instructions to builder to ABI encode the return value(s), if any, and return.
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encode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, vals []llvm.Value)
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}
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type directArgInfo struct {
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argOffset int
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argTypes []llvm.Type
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valType llvm.Type
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}
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func directEncode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, argTypes []llvm.Type, args []llvm.Value, val llvm.Value) {
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valType := val.Type()
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switch len(argTypes) {
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case 0:
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// do nothing
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case 1:
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if argTypes[0].C == valType.C {
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args[0] = val
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return
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}
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alloca := allocaBuilder.CreateAlloca(valType, "")
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bitcast := builder.CreateBitCast(alloca, llvm.PointerType(argTypes[0], 0), "")
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builder.CreateStore(val, alloca)
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args[0] = builder.CreateLoad(bitcast, "")
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case 2:
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encodeType := llvm.StructType(argTypes, false)
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alloca := allocaBuilder.CreateAlloca(valType, "")
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bitcast := builder.CreateBitCast(alloca, llvm.PointerType(encodeType, 0), "")
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builder.CreateStore(val, alloca)
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args[0] = builder.CreateLoad(builder.CreateStructGEP(bitcast, 0, ""), "")
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args[1] = builder.CreateLoad(builder.CreateStructGEP(bitcast, 1, ""), "")
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default:
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panic("unexpected argTypes size")
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}
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}
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func (ai *directArgInfo) encode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, args []llvm.Value, val llvm.Value) {
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directEncode(ctx, allocaBuilder, builder, ai.argTypes, args[ai.argOffset:ai.argOffset+len(ai.argTypes)], val)
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}
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func directDecode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, valType llvm.Type, args []llvm.Value) llvm.Value {
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var alloca llvm.Value
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switch len(args) {
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case 0:
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return llvm.ConstNull(ctx.StructType(nil, false))
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case 1:
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if args[0].Type().C == valType.C {
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return args[0]
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}
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alloca = allocaBuilder.CreateAlloca(valType, "")
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bitcast := builder.CreateBitCast(alloca, llvm.PointerType(args[0].Type(), 0), "")
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builder.CreateStore(args[0], bitcast)
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case 2:
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alloca = allocaBuilder.CreateAlloca(valType, "")
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var argTypes []llvm.Type
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for _, a := range args {
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argTypes = append(argTypes, a.Type())
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}
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encodeType := ctx.StructType(argTypes, false)
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bitcast := builder.CreateBitCast(alloca, llvm.PointerType(encodeType, 0), "")
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builder.CreateStore(args[0], builder.CreateStructGEP(bitcast, 0, ""))
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builder.CreateStore(args[1], builder.CreateStructGEP(bitcast, 1, ""))
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default:
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panic("unexpected argTypes size")
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}
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return builder.CreateLoad(alloca, "")
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}
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func (ai *directArgInfo) decode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder) llvm.Value {
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var args []llvm.Value
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fn := builder.GetInsertBlock().Parent()
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for i, _ := range ai.argTypes {
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args = append(args, fn.Param(ai.argOffset+i))
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}
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return directDecode(ctx, allocaBuilder, builder, ai.valType, args)
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}
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type indirectArgInfo struct {
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argOffset int
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}
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func (ai *indirectArgInfo) encode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, args []llvm.Value, val llvm.Value) {
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alloca := allocaBuilder.CreateAlloca(val.Type(), "")
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builder.CreateStore(val, alloca)
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args[ai.argOffset] = alloca
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}
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func (ai *indirectArgInfo) decode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder) llvm.Value {
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fn := builder.GetInsertBlock().Parent()
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return builder.CreateLoad(fn.Param(ai.argOffset), "")
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}
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type directRetInfo struct {
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numResults int
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retTypes []llvm.Type
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resultsType llvm.Type
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}
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func (ri *directRetInfo) prepare(ctx llvm.Context, allocaBuilder llvm.Builder, args []llvm.Value) {
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}
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func (ri *directRetInfo) decode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, call llvm.Value) []llvm.Value {
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var args []llvm.Value
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switch len(ri.retTypes) {
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case 0:
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return nil
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case 1:
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args = []llvm.Value{call}
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default:
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args = make([]llvm.Value, len(ri.retTypes))
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for i := 0; i != len(ri.retTypes); i++ {
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args[i] = builder.CreateExtractValue(call, i, "")
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}
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}
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d := directDecode(ctx, allocaBuilder, builder, ri.resultsType, args)
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if ri.numResults == 1 {
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return []llvm.Value{d}
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} else {
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results := make([]llvm.Value, ri.numResults)
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for i := 0; i != ri.numResults; i++ {
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results[i] = builder.CreateExtractValue(d, i, "")
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}
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return results
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}
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}
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func (ri *directRetInfo) encode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, vals []llvm.Value) {
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if len(ri.retTypes) == 0 {
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builder.CreateRetVoid()
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return
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}
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var val llvm.Value
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switch ri.numResults {
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case 1:
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val = vals[0]
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default:
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val = llvm.Undef(ri.resultsType)
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for i, v := range vals {
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val = builder.CreateInsertValue(val, v, i, "")
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}
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}
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args := make([]llvm.Value, len(ri.retTypes))
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directEncode(ctx, allocaBuilder, builder, ri.retTypes, args, val)
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var retval llvm.Value
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switch len(ri.retTypes) {
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case 1:
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retval = args[0]
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default:
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retval = llvm.Undef(ctx.StructType(ri.retTypes, false))
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for i, a := range args {
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retval = builder.CreateInsertValue(retval, a, i, "")
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}
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}
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builder.CreateRet(retval)
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}
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type indirectRetInfo struct {
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numResults int
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sretSlot llvm.Value
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resultsType llvm.Type
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}
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func (ri *indirectRetInfo) prepare(ctx llvm.Context, allocaBuilder llvm.Builder, args []llvm.Value) {
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ri.sretSlot = allocaBuilder.CreateAlloca(ri.resultsType, "")
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args[0] = ri.sretSlot
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}
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func (ri *indirectRetInfo) decode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, call llvm.Value) []llvm.Value {
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if ri.numResults == 1 {
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return []llvm.Value{builder.CreateLoad(ri.sretSlot, "")}
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} else {
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vals := make([]llvm.Value, ri.numResults)
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for i, _ := range vals {
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vals[i] = builder.CreateLoad(builder.CreateStructGEP(ri.sretSlot, i, ""), "")
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}
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return vals
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}
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}
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func (ri *indirectRetInfo) encode(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, vals []llvm.Value) {
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fn := builder.GetInsertBlock().Parent()
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sretSlot := fn.Param(0)
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if ri.numResults == 1 {
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builder.CreateStore(vals[0], sretSlot)
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} else {
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for i, v := range vals {
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builder.CreateStore(v, builder.CreateStructGEP(sretSlot, i, ""))
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}
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}
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builder.CreateRetVoid()
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}
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type functionTypeInfo struct {
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functionType llvm.Type
|
|
argAttrs []llvm.Attribute
|
|
retAttr llvm.Attribute
|
|
argInfos []argInfo
|
|
retInf retInfo
|
|
}
|
|
|
|
func (fi *functionTypeInfo) declare(m llvm.Module, name string) llvm.Value {
|
|
fn := llvm.AddFunction(m, name, fi.functionType)
|
|
fn.AddFunctionAttr(fi.retAttr)
|
|
for i, a := range fi.argAttrs {
|
|
if a != 0 {
|
|
fn.Param(i).AddAttribute(a)
|
|
}
|
|
}
|
|
return fn
|
|
}
|
|
|
|
func (fi *functionTypeInfo) call(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, callee llvm.Value, args []llvm.Value) []llvm.Value {
|
|
callArgs := make([]llvm.Value, len(fi.argAttrs))
|
|
for i, a := range args {
|
|
fi.argInfos[i].encode(ctx, allocaBuilder, builder, callArgs, a)
|
|
}
|
|
fi.retInf.prepare(ctx, allocaBuilder, callArgs)
|
|
typedCallee := builder.CreateBitCast(callee, llvm.PointerType(fi.functionType, 0), "")
|
|
call := builder.CreateCall(typedCallee, callArgs, "")
|
|
call.AddInstrAttribute(0, fi.retAttr)
|
|
for i, a := range fi.argAttrs {
|
|
call.AddInstrAttribute(i+1, a)
|
|
}
|
|
return fi.retInf.decode(ctx, allocaBuilder, builder, call)
|
|
}
|
|
|
|
func (fi *functionTypeInfo) invoke(ctx llvm.Context, allocaBuilder llvm.Builder, builder llvm.Builder, callee llvm.Value, args []llvm.Value, cont, lpad llvm.BasicBlock) []llvm.Value {
|
|
callArgs := make([]llvm.Value, len(fi.argAttrs))
|
|
for i, a := range args {
|
|
fi.argInfos[i].encode(ctx, allocaBuilder, builder, callArgs, a)
|
|
}
|
|
fi.retInf.prepare(ctx, allocaBuilder, callArgs)
|
|
typedCallee := builder.CreateBitCast(callee, llvm.PointerType(fi.functionType, 0), "")
|
|
call := builder.CreateInvoke(typedCallee, callArgs, cont, lpad, "")
|
|
call.AddInstrAttribute(0, fi.retAttr)
|
|
for i, a := range fi.argAttrs {
|
|
call.AddInstrAttribute(i+1, a)
|
|
}
|
|
builder.SetInsertPointAtEnd(cont)
|
|
return fi.retInf.decode(ctx, allocaBuilder, builder, call)
|
|
}
|
|
|
|
func (tm *llvmTypeMap) getFunctionTypeInfo(args []types.Type, results []types.Type) (fi functionTypeInfo) {
|
|
var returnType llvm.Type
|
|
var argTypes []llvm.Type
|
|
if len(results) == 0 {
|
|
returnType = llvm.VoidType()
|
|
fi.retInf = &directRetInfo{}
|
|
} else {
|
|
aik := tm.classify(results...)
|
|
|
|
var resultsType llvm.Type
|
|
if len(results) == 1 {
|
|
resultsType = tm.ToLLVM(results[0])
|
|
} else {
|
|
elements := make([]llvm.Type, len(results))
|
|
for i := range elements {
|
|
elements[i] = tm.ToLLVM(results[i])
|
|
}
|
|
resultsType = tm.ctx.StructType(elements, false)
|
|
}
|
|
|
|
switch aik {
|
|
case AIK_Direct:
|
|
var retFields []backendType
|
|
for _, t := range results {
|
|
retFields = append(retFields, tm.getBackendType(t))
|
|
}
|
|
bt := &structBType{retFields}
|
|
|
|
retTypes, retAttrs, _, _ := tm.expandType(nil, nil, bt)
|
|
switch len(retTypes) {
|
|
case 0: // e.g., empty struct
|
|
returnType = llvm.VoidType()
|
|
case 1:
|
|
returnType = retTypes[0]
|
|
fi.retAttr = retAttrs[0]
|
|
case 2:
|
|
returnType = llvm.StructType(retTypes, false)
|
|
default:
|
|
panic("unexpected expandType result")
|
|
}
|
|
fi.retInf = &directRetInfo{numResults: len(results), retTypes: retTypes, resultsType: resultsType}
|
|
|
|
case AIK_Indirect:
|
|
returnType = llvm.VoidType()
|
|
argTypes = []llvm.Type{llvm.PointerType(resultsType, 0)}
|
|
fi.argAttrs = []llvm.Attribute{llvm.StructRetAttribute}
|
|
fi.retInf = &indirectRetInfo{numResults: len(results), resultsType: resultsType}
|
|
}
|
|
}
|
|
|
|
// Keep track of the number of INTEGER/SSE class registers remaining.
|
|
remainingInt := 6
|
|
remainingSSE := 8
|
|
|
|
for _, arg := range args {
|
|
aik := tm.classify(arg)
|
|
|
|
isDirect := aik == AIK_Direct
|
|
if isDirect {
|
|
bt := tm.getBackendType(arg)
|
|
directArgTypes, directArgAttrs, numInt, numSSE := tm.expandType(argTypes, fi.argAttrs, bt)
|
|
|
|
// Check if the argument can fit into the remaining registers, or if
|
|
// it would just occupy one register (which pushes the whole argument
|
|
// onto the stack anyway).
|
|
if numInt <= remainingInt && numSSE <= remainingSSE || numInt+numSSE == 1 {
|
|
remainingInt -= numInt
|
|
remainingSSE -= numSSE
|
|
argInfo := &directArgInfo{argOffset: len(argTypes), valType: bt.ToLLVM(tm.ctx)}
|
|
fi.argInfos = append(fi.argInfos, argInfo)
|
|
argTypes = directArgTypes
|
|
fi.argAttrs = directArgAttrs
|
|
argInfo.argTypes = argTypes[argInfo.argOffset:len(argTypes)]
|
|
} else {
|
|
// No remaining registers; pass on the stack.
|
|
isDirect = false
|
|
}
|
|
}
|
|
|
|
if !isDirect {
|
|
fi.argInfos = append(fi.argInfos, &indirectArgInfo{len(argTypes)})
|
|
argTypes = append(argTypes, llvm.PointerType(tm.ToLLVM(arg), 0))
|
|
fi.argAttrs = append(fi.argAttrs, llvm.ByValAttribute)
|
|
}
|
|
}
|
|
|
|
fi.functionType = llvm.FunctionType(returnType, argTypes, false)
|
|
return
|
|
}
|
|
|
|
func (tm *llvmTypeMap) getSignatureInfo(sig *types.Signature) functionTypeInfo {
|
|
var args, results []types.Type
|
|
if sig.Recv() != nil {
|
|
recvtype := sig.Recv().Type()
|
|
if _, ok := recvtype.Underlying().(*types.Pointer); !ok && recvtype != types.Typ[types.UnsafePointer] {
|
|
recvtype = types.NewPointer(recvtype)
|
|
}
|
|
args = []types.Type{recvtype}
|
|
}
|
|
|
|
for i := 0; i != sig.Params().Len(); i++ {
|
|
args = append(args, sig.Params().At(i).Type())
|
|
}
|
|
for i := 0; i != sig.Results().Len(); i++ {
|
|
results = append(results, sig.Results().At(i).Type())
|
|
}
|
|
return tm.getFunctionTypeInfo(args, results)
|
|
}
|