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-rw-r--r--src/cmd/compile/internal/ssa/expand_calls.go975
1 files changed, 975 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/expand_calls.go b/src/cmd/compile/internal/ssa/expand_calls.go
new file mode 100644
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--- /dev/null
+++ b/src/cmd/compile/internal/ssa/expand_calls.go
@@ -0,0 +1,975 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+import (
+ "cmd/compile/internal/types"
+ "cmd/internal/src"
+ "fmt"
+ "sort"
+)
+
+type selKey struct {
+ from *Value
+ offset int64
+ size int64
+ typ *types.Type
+}
+
+type offsetKey struct {
+ from *Value
+ offset int64
+ pt *types.Type
+}
+
+// expandCalls converts LE (Late Expansion) calls that act like they receive value args into a lower-level form
+// that is more oriented to a platform's ABI. The SelectN operations that extract results are rewritten into
+// more appropriate forms, and any StructMake or ArrayMake inputs are decomposed until non-struct values are
+// reached. On the callee side, OpArg nodes are not decomposed until this phase is run.
+// TODO results should not be lowered until this phase.
+func expandCalls(f *Func) {
+ // Calls that need lowering have some number of inputs, including a memory input,
+ // and produce a tuple of (value1, value2, ..., mem) where valueK may or may not be SSA-able.
+
+ // With the current ABI those inputs need to be converted into stores to memory,
+ // rethreading the call's memory input to the first, and the new call now receiving the last.
+
+ // With the current ABI, the outputs need to be converted to loads, which will all use the call's
+ // memory output as their input.
+ if !LateCallExpansionEnabledWithin(f) {
+ return
+ }
+ debug := f.pass.debug > 0
+
+ if debug {
+ fmt.Printf("\nexpandsCalls(%s)\n", f.Name)
+ }
+
+ canSSAType := f.fe.CanSSA
+ regSize := f.Config.RegSize
+ sp, _ := f.spSb()
+ typ := &f.Config.Types
+ ptrSize := f.Config.PtrSize
+
+ // For 32-bit, need to deal with decomposition of 64-bit integers, which depends on endianness.
+ var hiOffset, lowOffset int64
+ if f.Config.BigEndian {
+ lowOffset = 4
+ } else {
+ hiOffset = 4
+ }
+
+ namedSelects := make(map[*Value][]namedVal)
+
+ sdom := f.Sdom()
+
+ common := make(map[selKey]*Value)
+
+ // intPairTypes returns the pair of 32-bit int types needed to encode a 64-bit integer type on a target
+ // that has no 64-bit integer registers.
+ intPairTypes := func(et types.EType) (tHi, tLo *types.Type) {
+ tHi = typ.UInt32
+ if et == types.TINT64 {
+ tHi = typ.Int32
+ }
+ tLo = typ.UInt32
+ return
+ }
+
+ // isAlreadyExpandedAggregateType returns whether a type is an SSA-able "aggregate" (multiple register) type
+ // that was expanded in an earlier phase (currently, expand_calls is intended to run after decomposeBuiltin,
+ // so this is all aggregate types -- small struct and array, complex, interface, string, slice, and 64-bit
+ // integer on 32-bit).
+ isAlreadyExpandedAggregateType := func(t *types.Type) bool {
+ if !canSSAType(t) {
+ return false
+ }
+ return t.IsStruct() || t.IsArray() || t.IsComplex() || t.IsInterface() || t.IsString() || t.IsSlice() ||
+ t.Size() > regSize && t.IsInteger()
+ }
+
+ offsets := make(map[offsetKey]*Value)
+
+ // offsetFrom creates an offset from a pointer, simplifying chained offsets and offsets from SP
+ // TODO should also optimize offsets from SB?
+ offsetFrom := func(from *Value, offset int64, pt *types.Type) *Value {
+ if offset == 0 && from.Type == pt { // this is not actually likely
+ return from
+ }
+ // Simplify, canonicalize
+ for from.Op == OpOffPtr {
+ offset += from.AuxInt
+ from = from.Args[0]
+ }
+ if from == sp {
+ return f.ConstOffPtrSP(pt, offset, sp)
+ }
+ key := offsetKey{from, offset, pt}
+ v := offsets[key]
+ if v != nil {
+ return v
+ }
+ v = from.Block.NewValue1I(from.Pos.WithNotStmt(), OpOffPtr, pt, offset, from)
+ offsets[key] = v
+ return v
+ }
+
+ // splitSlots splits one "field" (specified by sfx, offset, and ty) out of the LocalSlots in ls and returns the new LocalSlots this generates.
+ splitSlots := func(ls []LocalSlot, sfx string, offset int64, ty *types.Type) []LocalSlot {
+ var locs []LocalSlot
+ for i := range ls {
+ locs = append(locs, f.fe.SplitSlot(&ls[i], sfx, offset, ty))
+ }
+ return locs
+ }
+
+ // removeTrivialWrapperTypes unwraps layers of
+ // struct { singleField SomeType } and [1]SomeType
+ // until a non-wrapper type is reached. This is useful
+ // for working with assignments to/from interface data
+ // fields (either second operand to OpIMake or OpIData)
+ // where the wrapping or type conversion can be elided
+ // because of type conversions/assertions in source code
+ // that do not appear in SSA.
+ removeTrivialWrapperTypes := func(t *types.Type) *types.Type {
+ for {
+ if t.IsStruct() && t.NumFields() == 1 {
+ t = t.Field(0).Type
+ continue
+ }
+ if t.IsArray() && t.NumElem() == 1 {
+ t = t.Elem()
+ continue
+ }
+ break
+ }
+ return t
+ }
+
+ // Calls that need lowering have some number of inputs, including a memory input,
+ // and produce a tuple of (value1, value2, ..., mem) where valueK may or may not be SSA-able.
+
+ // With the current ABI those inputs need to be converted into stores to memory,
+ // rethreading the call's memory input to the first, and the new call now receiving the last.
+
+ // With the current ABI, the outputs need to be converted to loads, which will all use the call's
+ // memory output as their input.
+
+ // rewriteSelect recursively walks from leaf selector to a root (OpSelectN, OpLoad, OpArg)
+ // through a chain of Struct/Array/builtin Select operations. If the chain of selectors does not
+ // end in an expected root, it does nothing (this can happen depending on compiler phase ordering).
+ // The "leaf" provides the type, the root supplies the container, and the leaf-to-root path
+ // accumulates the offset.
+ // It emits the code necessary to implement the leaf select operation that leads to the root.
+ //
+ // TODO when registers really arrive, must also decompose anything split across two registers or registers and memory.
+ var rewriteSelect func(leaf *Value, selector *Value, offset int64) []LocalSlot
+ rewriteSelect = func(leaf *Value, selector *Value, offset int64) []LocalSlot {
+ if debug {
+ fmt.Printf("rewriteSelect(%s, %s, %d)\n", leaf.LongString(), selector.LongString(), offset)
+ }
+ var locs []LocalSlot
+ leafType := leaf.Type
+ if len(selector.Args) > 0 {
+ w := selector.Args[0]
+ if w.Op == OpCopy {
+ for w.Op == OpCopy {
+ w = w.Args[0]
+ }
+ selector.SetArg(0, w)
+ }
+ }
+ switch selector.Op {
+ case OpArg:
+ if !isAlreadyExpandedAggregateType(selector.Type) {
+ if leafType == selector.Type { // OpIData leads us here, sometimes.
+ leaf.copyOf(selector)
+ } else {
+ f.Fatalf("Unexpected OpArg type, selector=%s, leaf=%s\n", selector.LongString(), leaf.LongString())
+ }
+ if debug {
+ fmt.Printf("\tOpArg, break\n")
+ }
+ break
+ }
+ switch leaf.Op {
+ case OpIData, OpStructSelect, OpArraySelect:
+ leafType = removeTrivialWrapperTypes(leaf.Type)
+ }
+ aux := selector.Aux
+ auxInt := selector.AuxInt + offset
+ if leaf.Block == selector.Block {
+ leaf.reset(OpArg)
+ leaf.Aux = aux
+ leaf.AuxInt = auxInt
+ leaf.Type = leafType
+ } else {
+ w := selector.Block.NewValue0IA(leaf.Pos, OpArg, leafType, auxInt, aux)
+ leaf.copyOf(w)
+ if debug {
+ fmt.Printf("\tnew %s\n", w.LongString())
+ }
+ }
+ for _, s := range namedSelects[selector] {
+ locs = append(locs, f.Names[s.locIndex])
+ }
+
+ case OpLoad: // We end up here because of IData of immediate structures.
+ // Failure case:
+ // (note the failure case is very rare; w/o this case, make.bash and run.bash both pass, as well as
+ // the hard cases of building {syscall,math,math/cmplx,math/bits,go/constant} on ppc64le and mips-softfloat).
+ //
+ // GOSSAFUNC='(*dumper).dump' go build -gcflags=-l -tags=math_big_pure_go cmd/compile/internal/gc
+ // cmd/compile/internal/gc/dump.go:136:14: internal compiler error: '(*dumper).dump': not lowered: v827, StructSelect PTR PTR
+ // b2: ← b1
+ // v20 (+142) = StaticLECall <interface {},mem> {AuxCall{reflect.Value.Interface([reflect.Value,0])[interface {},24]}} [40] v8 v1
+ // v21 (142) = SelectN <mem> [1] v20
+ // v22 (142) = SelectN <interface {}> [0] v20
+ // b15: ← b8
+ // v71 (+143) = IData <Nodes> v22 (v[Nodes])
+ // v73 (+146) = StaticLECall <[]*Node,mem> {AuxCall{"".Nodes.Slice([Nodes,0])[[]*Node,8]}} [32] v71 v21
+ //
+ // translates (w/o the "case OpLoad:" above) to:
+ //
+ // b2: ← b1
+ // v20 (+142) = StaticCall <mem> {AuxCall{reflect.Value.Interface([reflect.Value,0])[interface {},24]}} [40] v715
+ // v23 (142) = Load <*uintptr> v19 v20
+ // v823 (142) = IsNonNil <bool> v23
+ // v67 (+143) = Load <*[]*Node> v880 v20
+ // b15: ← b8
+ // v827 (146) = StructSelect <*[]*Node> [0] v67
+ // v846 (146) = Store <mem> {*[]*Node} v769 v827 v20
+ // v73 (+146) = StaticCall <mem> {AuxCall{"".Nodes.Slice([Nodes,0])[[]*Node,8]}} [32] v846
+ // i.e., the struct select is generated and remains in because it is not applied to an actual structure.
+ // The OpLoad was created to load the single field of the IData
+ // This case removes that StructSelect.
+ if leafType != selector.Type {
+ f.Fatalf("Unexpected Load as selector, leaf=%s, selector=%s\n", leaf.LongString(), selector.LongString())
+ }
+ leaf.copyOf(selector)
+ for _, s := range namedSelects[selector] {
+ locs = append(locs, f.Names[s.locIndex])
+ }
+
+ case OpSelectN:
+ // TODO these may be duplicated. Should memoize. Intermediate selectors will go dead, no worries there.
+ call := selector.Args[0]
+ aux := call.Aux.(*AuxCall)
+ which := selector.AuxInt
+ if which == aux.NResults() { // mem is after the results.
+ // rewrite v as a Copy of call -- the replacement call will produce a mem.
+ leaf.copyOf(call)
+ } else {
+ leafType := removeTrivialWrapperTypes(leaf.Type)
+ if canSSAType(leafType) {
+ pt := types.NewPtr(leafType)
+ off := offsetFrom(sp, offset+aux.OffsetOfResult(which), pt)
+ // Any selection right out of the arg area/registers has to be same Block as call, use call as mem input.
+ if leaf.Block == call.Block {
+ leaf.reset(OpLoad)
+ leaf.SetArgs2(off, call)
+ leaf.Type = leafType
+ } else {
+ w := call.Block.NewValue2(leaf.Pos, OpLoad, leafType, off, call)
+ leaf.copyOf(w)
+ if debug {
+ fmt.Printf("\tnew %s\n", w.LongString())
+ }
+ }
+ for _, s := range namedSelects[selector] {
+ locs = append(locs, f.Names[s.locIndex])
+ }
+ } else {
+ f.Fatalf("Should not have non-SSA-able OpSelectN, selector=%s", selector.LongString())
+ }
+ }
+
+ case OpStructSelect:
+ w := selector.Args[0]
+ var ls []LocalSlot
+ if w.Type.Etype != types.TSTRUCT { // IData artifact
+ ls = rewriteSelect(leaf, w, offset)
+ } else {
+ ls = rewriteSelect(leaf, w, offset+w.Type.FieldOff(int(selector.AuxInt)))
+ if w.Op != OpIData {
+ for _, l := range ls {
+ locs = append(locs, f.fe.SplitStruct(l, int(selector.AuxInt)))
+ }
+ }
+ }
+
+ case OpArraySelect:
+ w := selector.Args[0]
+ rewriteSelect(leaf, w, offset+selector.Type.Size()*selector.AuxInt)
+
+ case OpInt64Hi:
+ w := selector.Args[0]
+ ls := rewriteSelect(leaf, w, offset+hiOffset)
+ locs = splitSlots(ls, ".hi", hiOffset, leafType)
+
+ case OpInt64Lo:
+ w := selector.Args[0]
+ ls := rewriteSelect(leaf, w, offset+lowOffset)
+ locs = splitSlots(ls, ".lo", lowOffset, leafType)
+
+ case OpStringPtr:
+ ls := rewriteSelect(leaf, selector.Args[0], offset)
+ locs = splitSlots(ls, ".ptr", 0, typ.BytePtr)
+
+ case OpSlicePtr:
+ w := selector.Args[0]
+ ls := rewriteSelect(leaf, w, offset)
+ locs = splitSlots(ls, ".ptr", 0, types.NewPtr(w.Type.Elem()))
+
+ case OpITab:
+ w := selector.Args[0]
+ ls := rewriteSelect(leaf, w, offset)
+ sfx := ".itab"
+ if w.Type.IsEmptyInterface() {
+ sfx = ".type"
+ }
+ locs = splitSlots(ls, sfx, 0, typ.Uintptr)
+
+ case OpComplexReal:
+ ls := rewriteSelect(leaf, selector.Args[0], offset)
+ locs = splitSlots(ls, ".real", 0, leafType)
+
+ case OpComplexImag:
+ ls := rewriteSelect(leaf, selector.Args[0], offset+leafType.Width) // result is FloatNN, width of result is offset of imaginary part.
+ locs = splitSlots(ls, ".imag", leafType.Width, leafType)
+
+ case OpStringLen, OpSliceLen:
+ ls := rewriteSelect(leaf, selector.Args[0], offset+ptrSize)
+ locs = splitSlots(ls, ".len", ptrSize, leafType)
+
+ case OpIData:
+ ls := rewriteSelect(leaf, selector.Args[0], offset+ptrSize)
+ locs = splitSlots(ls, ".data", ptrSize, leafType)
+
+ case OpSliceCap:
+ ls := rewriteSelect(leaf, selector.Args[0], offset+2*ptrSize)
+ locs = splitSlots(ls, ".cap", 2*ptrSize, leafType)
+
+ case OpCopy: // If it's an intermediate result, recurse
+ locs = rewriteSelect(leaf, selector.Args[0], offset)
+ for _, s := range namedSelects[selector] {
+ // this copy may have had its own name, preserve that, too.
+ locs = append(locs, f.Names[s.locIndex])
+ }
+
+ default:
+ // Ignore dead ends. These can occur if this phase is run before decompose builtin (which is not intended, but allowed).
+ }
+
+ return locs
+ }
+
+ // storeArgOrLoad converts stores of SSA-able aggregate arguments (passed to a call) into a series of primitive-typed
+ // stores of non-aggregate types. It recursively walks up a chain of selectors until it reaches a Load or an Arg.
+ // If it does not reach a Load or an Arg, nothing happens; this allows a little freedom in phase ordering.
+ var storeArgOrLoad func(pos src.XPos, b *Block, base, source, mem *Value, t *types.Type, offset int64) *Value
+
+ // decomposeArgOrLoad is a helper for storeArgOrLoad.
+ // It decomposes a Load or an Arg into smaller parts, parameterized by the decomposeOne and decomposeTwo functions
+ // passed to it, and returns the new mem. If the type does not match one of the expected aggregate types, it returns nil instead.
+ decomposeArgOrLoad := func(pos src.XPos, b *Block, base, source, mem *Value, t *types.Type, offset int64,
+ decomposeOne func(pos src.XPos, b *Block, base, source, mem *Value, t1 *types.Type, offArg, offStore int64) *Value,
+ decomposeTwo func(pos src.XPos, b *Block, base, source, mem *Value, t1, t2 *types.Type, offArg, offStore int64) *Value) *Value {
+ u := source.Type
+ switch u.Etype {
+ case types.TARRAY:
+ elem := u.Elem()
+ for i := int64(0); i < u.NumElem(); i++ {
+ elemOff := i * elem.Size()
+ mem = decomposeOne(pos, b, base, source, mem, elem, source.AuxInt+elemOff, offset+elemOff)
+ pos = pos.WithNotStmt()
+ }
+ return mem
+ case types.TSTRUCT:
+ for i := 0; i < u.NumFields(); i++ {
+ fld := u.Field(i)
+ mem = decomposeOne(pos, b, base, source, mem, fld.Type, source.AuxInt+fld.Offset, offset+fld.Offset)
+ pos = pos.WithNotStmt()
+ }
+ return mem
+ case types.TINT64, types.TUINT64:
+ if t.Width == regSize {
+ break
+ }
+ tHi, tLo := intPairTypes(t.Etype)
+ mem = decomposeOne(pos, b, base, source, mem, tHi, source.AuxInt+hiOffset, offset+hiOffset)
+ pos = pos.WithNotStmt()
+ return decomposeOne(pos, b, base, source, mem, tLo, source.AuxInt+lowOffset, offset+lowOffset)
+ case types.TINTER:
+ return decomposeTwo(pos, b, base, source, mem, typ.Uintptr, typ.BytePtr, source.AuxInt, offset)
+ case types.TSTRING:
+ return decomposeTwo(pos, b, base, source, mem, typ.BytePtr, typ.Int, source.AuxInt, offset)
+ case types.TCOMPLEX64:
+ return decomposeTwo(pos, b, base, source, mem, typ.Float32, typ.Float32, source.AuxInt, offset)
+ case types.TCOMPLEX128:
+ return decomposeTwo(pos, b, base, source, mem, typ.Float64, typ.Float64, source.AuxInt, offset)
+ case types.TSLICE:
+ mem = decomposeTwo(pos, b, base, source, mem, typ.BytePtr, typ.Int, source.AuxInt, offset)
+ return decomposeOne(pos, b, base, source, mem, typ.Int, source.AuxInt+2*ptrSize, offset+2*ptrSize)
+ }
+ return nil
+ }
+
+ // storeOneArg creates a decomposed (one step) arg that is then stored.
+ // pos and b locate the store instruction, base is the base of the store target, source is the "base" of the value input,
+ // mem is the input mem, t is the type in question, and offArg and offStore are the offsets from the respective bases.
+ storeOneArg := func(pos src.XPos, b *Block, base, source, mem *Value, t *types.Type, offArg, offStore int64) *Value {
+ w := common[selKey{source, offArg, t.Width, t}]
+ if w == nil {
+ w = source.Block.NewValue0IA(source.Pos, OpArg, t, offArg, source.Aux)
+ common[selKey{source, offArg, t.Width, t}] = w
+ }
+ return storeArgOrLoad(pos, b, base, w, mem, t, offStore)
+ }
+
+ // storeOneLoad creates a decomposed (one step) load that is then stored.
+ storeOneLoad := func(pos src.XPos, b *Block, base, source, mem *Value, t *types.Type, offArg, offStore int64) *Value {
+ from := offsetFrom(source.Args[0], offArg, types.NewPtr(t))
+ w := source.Block.NewValue2(source.Pos, OpLoad, t, from, mem)
+ return storeArgOrLoad(pos, b, base, w, mem, t, offStore)
+ }
+
+ storeTwoArg := func(pos src.XPos, b *Block, base, source, mem *Value, t1, t2 *types.Type, offArg, offStore int64) *Value {
+ mem = storeOneArg(pos, b, base, source, mem, t1, offArg, offStore)
+ pos = pos.WithNotStmt()
+ t1Size := t1.Size()
+ return storeOneArg(pos, b, base, source, mem, t2, offArg+t1Size, offStore+t1Size)
+ }
+
+ storeTwoLoad := func(pos src.XPos, b *Block, base, source, mem *Value, t1, t2 *types.Type, offArg, offStore int64) *Value {
+ mem = storeOneLoad(pos, b, base, source, mem, t1, offArg, offStore)
+ pos = pos.WithNotStmt()
+ t1Size := t1.Size()
+ return storeOneLoad(pos, b, base, source, mem, t2, offArg+t1Size, offStore+t1Size)
+ }
+
+ storeArgOrLoad = func(pos src.XPos, b *Block, base, source, mem *Value, t *types.Type, offset int64) *Value {
+ if debug {
+ fmt.Printf("\tstoreArgOrLoad(%s; %s; %s; %s; %d)\n", base.LongString(), source.LongString(), mem.String(), t.String(), offset)
+ }
+
+ switch source.Op {
+ case OpCopy:
+ return storeArgOrLoad(pos, b, base, source.Args[0], mem, t, offset)
+
+ case OpLoad:
+ ret := decomposeArgOrLoad(pos, b, base, source, mem, t, offset, storeOneLoad, storeTwoLoad)
+ if ret != nil {
+ return ret
+ }
+
+ case OpArg:
+ ret := decomposeArgOrLoad(pos, b, base, source, mem, t, offset, storeOneArg, storeTwoArg)
+ if ret != nil {
+ return ret
+ }
+
+ case OpArrayMake0, OpStructMake0:
+ return mem
+
+ case OpStructMake1, OpStructMake2, OpStructMake3, OpStructMake4:
+ for i := 0; i < t.NumFields(); i++ {
+ fld := t.Field(i)
+ mem = storeArgOrLoad(pos, b, base, source.Args[i], mem, fld.Type, offset+fld.Offset)
+ pos = pos.WithNotStmt()
+ }
+ return mem
+
+ case OpArrayMake1:
+ return storeArgOrLoad(pos, b, base, source.Args[0], mem, t.Elem(), offset)
+
+ case OpInt64Make:
+ tHi, tLo := intPairTypes(t.Etype)
+ mem = storeArgOrLoad(pos, b, base, source.Args[0], mem, tHi, offset+hiOffset)
+ pos = pos.WithNotStmt()
+ return storeArgOrLoad(pos, b, base, source.Args[1], mem, tLo, offset+lowOffset)
+
+ case OpComplexMake:
+ tPart := typ.Float32
+ wPart := t.Width / 2
+ if wPart == 8 {
+ tPart = typ.Float64
+ }
+ mem = storeArgOrLoad(pos, b, base, source.Args[0], mem, tPart, offset)
+ pos = pos.WithNotStmt()
+ return storeArgOrLoad(pos, b, base, source.Args[1], mem, tPart, offset+wPart)
+
+ case OpIMake:
+ mem = storeArgOrLoad(pos, b, base, source.Args[0], mem, typ.Uintptr, offset)
+ pos = pos.WithNotStmt()
+ return storeArgOrLoad(pos, b, base, source.Args[1], mem, typ.BytePtr, offset+ptrSize)
+
+ case OpStringMake:
+ mem = storeArgOrLoad(pos, b, base, source.Args[0], mem, typ.BytePtr, offset)
+ pos = pos.WithNotStmt()
+ return storeArgOrLoad(pos, b, base, source.Args[1], mem, typ.Int, offset+ptrSize)
+
+ case OpSliceMake:
+ mem = storeArgOrLoad(pos, b, base, source.Args[0], mem, typ.BytePtr, offset)
+ pos = pos.WithNotStmt()
+ mem = storeArgOrLoad(pos, b, base, source.Args[1], mem, typ.Int, offset+ptrSize)
+ return storeArgOrLoad(pos, b, base, source.Args[2], mem, typ.Int, offset+2*ptrSize)
+ }
+
+ // For nodes that cannot be taken apart -- OpSelectN, other structure selectors.
+ switch t.Etype {
+ case types.TARRAY:
+ elt := t.Elem()
+ if source.Type != t && t.NumElem() == 1 && elt.Width == t.Width && t.Width == regSize {
+ t = removeTrivialWrapperTypes(t)
+ // it could be a leaf type, but the "leaf" could be complex64 (for example)
+ return storeArgOrLoad(pos, b, base, source, mem, t, offset)
+ }
+ for i := int64(0); i < t.NumElem(); i++ {
+ sel := source.Block.NewValue1I(pos, OpArraySelect, elt, i, source)
+ mem = storeArgOrLoad(pos, b, base, sel, mem, elt, offset+i*elt.Width)
+ pos = pos.WithNotStmt()
+ }
+ return mem
+
+ case types.TSTRUCT:
+ if source.Type != t && t.NumFields() == 1 && t.Field(0).Type.Width == t.Width && t.Width == regSize {
+ // This peculiar test deals with accesses to immediate interface data.
+ // It works okay because everything is the same size.
+ // Example code that triggers this can be found in go/constant/value.go, function ToComplex
+ // v119 (+881) = IData <intVal> v6
+ // v121 (+882) = StaticLECall <floatVal,mem> {AuxCall{"".itof([intVal,0])[floatVal,8]}} [16] v119 v1
+ // This corresponds to the generic rewrite rule "(StructSelect [0] (IData x)) => (IData x)"
+ // Guard against "struct{struct{*foo}}"
+ // Other rewriting phases create minor glitches when they transform IData, for instance the
+ // interface-typed Arg "x" of ToFloat in go/constant/value.go
+ // v6 (858) = Arg <Value> {x} (x[Value], x[Value])
+ // is rewritten by decomposeArgs into
+ // v141 (858) = Arg <uintptr> {x}
+ // v139 (858) = Arg <*uint8> {x} [8]
+ // because of a type case clause on line 862 of go/constant/value.go
+ // case intVal:
+ // return itof(x)
+ // v139 is later stored as an intVal == struct{val *big.Int} which naively requires the fields of
+ // of a *uint8, which does not succeed.
+ t = removeTrivialWrapperTypes(t)
+ // it could be a leaf type, but the "leaf" could be complex64 (for example)
+ return storeArgOrLoad(pos, b, base, source, mem, t, offset)
+ }
+
+ for i := 0; i < t.NumFields(); i++ {
+ fld := t.Field(i)
+ sel := source.Block.NewValue1I(pos, OpStructSelect, fld.Type, int64(i), source)
+ mem = storeArgOrLoad(pos, b, base, sel, mem, fld.Type, offset+fld.Offset)
+ pos = pos.WithNotStmt()
+ }
+ return mem
+
+ case types.TINT64, types.TUINT64:
+ if t.Width == regSize {
+ break
+ }
+ tHi, tLo := intPairTypes(t.Etype)
+ sel := source.Block.NewValue1(pos, OpInt64Hi, tHi, source)
+ mem = storeArgOrLoad(pos, b, base, sel, mem, tHi, offset+hiOffset)
+ pos = pos.WithNotStmt()
+ sel = source.Block.NewValue1(pos, OpInt64Lo, tLo, source)
+ return storeArgOrLoad(pos, b, base, sel, mem, tLo, offset+lowOffset)
+
+ case types.TINTER:
+ sel := source.Block.NewValue1(pos, OpITab, typ.BytePtr, source)
+ mem = storeArgOrLoad(pos, b, base, sel, mem, typ.BytePtr, offset)
+ pos = pos.WithNotStmt()
+ sel = source.Block.NewValue1(pos, OpIData, typ.BytePtr, source)
+ return storeArgOrLoad(pos, b, base, sel, mem, typ.BytePtr, offset+ptrSize)
+
+ case types.TSTRING:
+ sel := source.Block.NewValue1(pos, OpStringPtr, typ.BytePtr, source)
+ mem = storeArgOrLoad(pos, b, base, sel, mem, typ.BytePtr, offset)
+ pos = pos.WithNotStmt()
+ sel = source.Block.NewValue1(pos, OpStringLen, typ.Int, source)
+ return storeArgOrLoad(pos, b, base, sel, mem, typ.Int, offset+ptrSize)
+
+ case types.TSLICE:
+ et := types.NewPtr(t.Elem())
+ sel := source.Block.NewValue1(pos, OpSlicePtr, et, source)
+ mem = storeArgOrLoad(pos, b, base, sel, mem, et, offset)
+ pos = pos.WithNotStmt()
+ sel = source.Block.NewValue1(pos, OpSliceLen, typ.Int, source)
+ mem = storeArgOrLoad(pos, b, base, sel, mem, typ.Int, offset+ptrSize)
+ sel = source.Block.NewValue1(pos, OpSliceCap, typ.Int, source)
+ return storeArgOrLoad(pos, b, base, sel, mem, typ.Int, offset+2*ptrSize)
+
+ case types.TCOMPLEX64:
+ sel := source.Block.NewValue1(pos, OpComplexReal, typ.Float32, source)
+ mem = storeArgOrLoad(pos, b, base, sel, mem, typ.Float32, offset)
+ pos = pos.WithNotStmt()
+ sel = source.Block.NewValue1(pos, OpComplexImag, typ.Float32, source)
+ return storeArgOrLoad(pos, b, base, sel, mem, typ.Float32, offset+4)
+
+ case types.TCOMPLEX128:
+ sel := source.Block.NewValue1(pos, OpComplexReal, typ.Float64, source)
+ mem = storeArgOrLoad(pos, b, base, sel, mem, typ.Float64, offset)
+ pos = pos.WithNotStmt()
+ sel = source.Block.NewValue1(pos, OpComplexImag, typ.Float64, source)
+ return storeArgOrLoad(pos, b, base, sel, mem, typ.Float64, offset+8)
+ }
+
+ dst := offsetFrom(base, offset, types.NewPtr(t))
+ x := b.NewValue3A(pos, OpStore, types.TypeMem, t, dst, source, mem)
+ if debug {
+ fmt.Printf("\t\tstoreArg returns %s\n", x.LongString())
+ }
+ return x
+ }
+
+ // rewriteArgs removes all the Args from a call and converts the call args into appropriate
+ // stores (or later, register movement). Extra args for interface and closure calls are ignored,
+ // but removed.
+ rewriteArgs := func(v *Value, firstArg int) *Value {
+ // Thread the stores on the memory arg
+ aux := v.Aux.(*AuxCall)
+ pos := v.Pos.WithNotStmt()
+ m0 := v.Args[len(v.Args)-1]
+ mem := m0
+ for i, a := range v.Args {
+ if i < firstArg {
+ continue
+ }
+ if a == m0 { // mem is last.
+ break
+ }
+ auxI := int64(i - firstArg)
+ if a.Op == OpDereference {
+ if a.MemoryArg() != m0 {
+ f.Fatalf("Op...LECall and OpDereference have mismatched mem, %s and %s", v.LongString(), a.LongString())
+ }
+ // "Dereference" of addressed (probably not-SSA-eligible) value becomes Move
+ // TODO this will be more complicated with registers in the picture.
+ source := a.Args[0]
+ dst := f.ConstOffPtrSP(source.Type, aux.OffsetOfArg(auxI), sp)
+ if a.Uses == 1 && a.Block == v.Block {
+ a.reset(OpMove)
+ a.Pos = pos
+ a.Type = types.TypeMem
+ a.Aux = aux.TypeOfArg(auxI)
+ a.AuxInt = aux.SizeOfArg(auxI)
+ a.SetArgs3(dst, source, mem)
+ mem = a
+ } else {
+ mem = v.Block.NewValue3A(pos, OpMove, types.TypeMem, aux.TypeOfArg(auxI), dst, source, mem)
+ mem.AuxInt = aux.SizeOfArg(auxI)
+ }
+ } else {
+ if debug {
+ fmt.Printf("storeArg %s, %v, %d\n", a.LongString(), aux.TypeOfArg(auxI), aux.OffsetOfArg(auxI))
+ }
+ mem = storeArgOrLoad(pos, v.Block, sp, a, mem, aux.TypeOfArg(auxI), aux.OffsetOfArg(auxI))
+ }
+ }
+ v.resetArgs()
+ return mem
+ }
+
+ // TODO if too slow, whole program iteration can be replaced w/ slices of appropriate values, accumulated in first loop here.
+
+ // Step 0: rewrite the calls to convert incoming args to stores.
+ for _, b := range f.Blocks {
+ for _, v := range b.Values {
+ switch v.Op {
+ case OpStaticLECall:
+ mem := rewriteArgs(v, 0)
+ v.SetArgs1(mem)
+ case OpClosureLECall:
+ code := v.Args[0]
+ context := v.Args[1]
+ mem := rewriteArgs(v, 2)
+ v.SetArgs3(code, context, mem)
+ case OpInterLECall:
+ code := v.Args[0]
+ mem := rewriteArgs(v, 1)
+ v.SetArgs2(code, mem)
+ }
+ }
+ }
+
+ for i, name := range f.Names {
+ t := name.Type
+ if isAlreadyExpandedAggregateType(t) {
+ for j, v := range f.NamedValues[name] {
+ if v.Op == OpSelectN || v.Op == OpArg && isAlreadyExpandedAggregateType(v.Type) {
+ ns := namedSelects[v]
+ namedSelects[v] = append(ns, namedVal{locIndex: i, valIndex: j})
+ }
+ }
+ }
+ }
+
+ // Step 1: any stores of aggregates remaining are believed to be sourced from call results or args.
+ // Decompose those stores into a series of smaller stores, adding selection ops as necessary.
+ for _, b := range f.Blocks {
+ for _, v := range b.Values {
+ if v.Op == OpStore {
+ t := v.Aux.(*types.Type)
+ source := v.Args[1]
+ tSrc := source.Type
+ iAEATt := isAlreadyExpandedAggregateType(t)
+
+ if !iAEATt {
+ // guarding against store immediate struct into interface data field -- store type is *uint8
+ // TODO can this happen recursively?
+ iAEATt = isAlreadyExpandedAggregateType(tSrc)
+ if iAEATt {
+ t = tSrc
+ }
+ }
+ if iAEATt {
+ if debug {
+ fmt.Printf("Splitting store %s\n", v.LongString())
+ }
+ dst, mem := v.Args[0], v.Args[2]
+ mem = storeArgOrLoad(v.Pos, b, dst, source, mem, t, 0)
+ v.copyOf(mem)
+ }
+ }
+ }
+ }
+
+ val2Preds := make(map[*Value]int32) // Used to accumulate dependency graph of selection operations for topological ordering.
+
+ // Step 2: transform or accumulate selection operations for rewrite in topological order.
+ //
+ // Aggregate types that have already (in earlier phases) been transformed must be lowered comprehensively to finish
+ // the transformation (user-defined structs and arrays, slices, strings, interfaces, complex, 64-bit on 32-bit architectures),
+ //
+ // Any select-for-addressing applied to call results can be transformed directly.
+ for _, b := range f.Blocks {
+ for _, v := range b.Values {
+ // Accumulate chains of selectors for processing in topological order
+ switch v.Op {
+ case OpStructSelect, OpArraySelect,
+ OpIData, OpITab,
+ OpStringPtr, OpStringLen,
+ OpSlicePtr, OpSliceLen, OpSliceCap,
+ OpComplexReal, OpComplexImag,
+ OpInt64Hi, OpInt64Lo:
+ w := v.Args[0]
+ switch w.Op {
+ case OpStructSelect, OpArraySelect, OpSelectN, OpArg:
+ val2Preds[w] += 1
+ if debug {
+ fmt.Printf("v2p[%s] = %d\n", w.LongString(), val2Preds[w])
+ }
+ }
+ fallthrough
+
+ case OpSelectN:
+ if _, ok := val2Preds[v]; !ok {
+ val2Preds[v] = 0
+ if debug {
+ fmt.Printf("v2p[%s] = %d\n", v.LongString(), val2Preds[v])
+ }
+ }
+
+ case OpArg:
+ if !isAlreadyExpandedAggregateType(v.Type) {
+ continue
+ }
+ if _, ok := val2Preds[v]; !ok {
+ val2Preds[v] = 0
+ if debug {
+ fmt.Printf("v2p[%s] = %d\n", v.LongString(), val2Preds[v])
+ }
+ }
+
+ case OpSelectNAddr:
+ // Do these directly, there are no chains of selectors.
+ call := v.Args[0]
+ which := v.AuxInt
+ aux := call.Aux.(*AuxCall)
+ pt := v.Type
+ off := offsetFrom(sp, aux.OffsetOfResult(which), pt)
+ v.copyOf(off)
+ }
+ }
+ }
+
+ // Step 3: Compute topological order of selectors,
+ // then process it in reverse to eliminate duplicates,
+ // then forwards to rewrite selectors.
+ //
+ // All chains of selectors end up in same block as the call.
+
+ // Compilation must be deterministic, so sort after extracting first zeroes from map.
+ // Sorting allows dominators-last order within each batch,
+ // so that the backwards scan for duplicates will most often find copies from dominating blocks (it is best-effort).
+ var toProcess []*Value
+ less := func(i, j int) bool {
+ vi, vj := toProcess[i], toProcess[j]
+ bi, bj := vi.Block, vj.Block
+ if bi == bj {
+ return vi.ID < vj.ID
+ }
+ return sdom.domorder(bi) > sdom.domorder(bj) // reverse the order to put dominators last.
+ }
+
+ // Accumulate order in allOrdered
+ var allOrdered []*Value
+ for v, n := range val2Preds {
+ if n == 0 {
+ allOrdered = append(allOrdered, v)
+ }
+ }
+ last := 0 // allOrdered[0:last] has been top-sorted and processed
+ for len(val2Preds) > 0 {
+ toProcess = allOrdered[last:]
+ last = len(allOrdered)
+ sort.SliceStable(toProcess, less)
+ for _, v := range toProcess {
+ delete(val2Preds, v)
+ if v.Op == OpArg {
+ continue // no Args[0], hence done.
+ }
+ w := v.Args[0]
+ n, ok := val2Preds[w]
+ if !ok {
+ continue
+ }
+ if n == 1 {
+ allOrdered = append(allOrdered, w)
+ delete(val2Preds, w)
+ continue
+ }
+ val2Preds[w] = n - 1
+ }
+ }
+
+ common = make(map[selKey]*Value)
+ // Rewrite duplicate selectors as copies where possible.
+ for i := len(allOrdered) - 1; i >= 0; i-- {
+ v := allOrdered[i]
+ if v.Op == OpArg {
+ continue
+ }
+ w := v.Args[0]
+ if w.Op == OpCopy {
+ for w.Op == OpCopy {
+ w = w.Args[0]
+ }
+ v.SetArg(0, w)
+ }
+ typ := v.Type
+ if typ.IsMemory() {
+ continue // handled elsewhere, not an indexable result
+ }
+ size := typ.Width
+ offset := int64(0)
+ switch v.Op {
+ case OpStructSelect:
+ if w.Type.Etype == types.TSTRUCT {
+ offset = w.Type.FieldOff(int(v.AuxInt))
+ } else { // Immediate interface data artifact, offset is zero.
+ f.Fatalf("Expand calls interface data problem, func %s, v=%s, w=%s\n", f.Name, v.LongString(), w.LongString())
+ }
+ case OpArraySelect:
+ offset = size * v.AuxInt
+ case OpSelectN:
+ offset = w.Aux.(*AuxCall).OffsetOfResult(v.AuxInt)
+ case OpInt64Hi:
+ offset = hiOffset
+ case OpInt64Lo:
+ offset = lowOffset
+ case OpStringLen, OpSliceLen, OpIData:
+ offset = ptrSize
+ case OpSliceCap:
+ offset = 2 * ptrSize
+ case OpComplexImag:
+ offset = size
+ }
+ sk := selKey{from: w, size: size, offset: offset, typ: typ}
+ dupe := common[sk]
+ if dupe == nil {
+ common[sk] = v
+ } else if sdom.IsAncestorEq(dupe.Block, v.Block) {
+ v.copyOf(dupe)
+ } else {
+ // Because values are processed in dominator order, the old common[s] will never dominate after a miss is seen.
+ // Installing the new value might match some future values.
+ common[sk] = v
+ }
+ }
+
+ // Indices of entries in f.Names that need to be deleted.
+ var toDelete []namedVal
+
+ // Rewrite selectors.
+ for i, v := range allOrdered {
+ if debug {
+ b := v.Block
+ fmt.Printf("allOrdered[%d] = b%d, %s, uses=%d\n", i, b.ID, v.LongString(), v.Uses)
+ }
+ if v.Uses == 0 {
+ v.reset(OpInvalid)
+ continue
+ }
+ if v.Op == OpCopy {
+ continue
+ }
+ locs := rewriteSelect(v, v, 0)
+ // Install new names.
+ if v.Type.IsMemory() {
+ continue
+ }
+ // Leaf types may have debug locations
+ if !isAlreadyExpandedAggregateType(v.Type) {
+ for _, l := range locs {
+ f.NamedValues[l] = append(f.NamedValues[l], v)
+ }
+ f.Names = append(f.Names, locs...)
+ continue
+ }
+ // Not-leaf types that had debug locations need to lose them.
+ if ns, ok := namedSelects[v]; ok {
+ toDelete = append(toDelete, ns...)
+ }
+ }
+
+ deleteNamedVals(f, toDelete)
+
+ // Step 4: rewrite the calls themselves, correcting the type
+ for _, b := range f.Blocks {
+ for _, v := range b.Values {
+ switch v.Op {
+ case OpStaticLECall:
+ v.Op = OpStaticCall
+ v.Type = types.TypeMem
+ case OpClosureLECall:
+ v.Op = OpClosureCall
+ v.Type = types.TypeMem
+ case OpInterLECall:
+ v.Op = OpInterCall
+ v.Type = types.TypeMem
+ }
+ }
+ }
+
+ // Step 5: elide any copies introduced.
+ for _, b := range f.Blocks {
+ for _, v := range b.Values {
+ for i, a := range v.Args {
+ if a.Op != OpCopy {
+ continue
+ }
+ aa := copySource(a)
+ v.SetArg(i, aa)
+ for a.Uses == 0 {
+ b := a.Args[0]
+ a.reset(OpInvalid)
+ a = b
+ }
+ }
+ }
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-09-27 17:21:12 +0000