1 // Copyright 2015 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
8 "cmd/compile/internal/logopt"
9 "cmd/compile/internal/types"
11 "cmd/internal/obj/s390x"
23 type deadValueChoice bool
26 leaveDeadValues deadValueChoice = false
27 removeDeadValues = true
30 // deadcode indicates that rewrite should try to remove any values that become dead.
31 func applyRewrite(f *Func, rb blockRewriter, rv valueRewriter, deadcode deadValueChoice) {
32 // repeat rewrites until we find no more rewrites
33 pendingLines := f.cachedLineStarts // Holds statement boundaries that need to be moved to a new value/block
37 fmt.Printf("%s: rewriting for %s\n", f.pass.name, f.Name)
41 for _, b := range f.Blocks {
46 b0.Succs = append([]Edge{}, b.Succs...) // make a new copy, not aliasing
48 for i, c := range b.ControlValues() {
51 b.ReplaceControl(i, c)
57 fmt.Printf("rewriting %s -> %s\n", b0.LongString(), b.LongString())
60 for j, v := range b.Values {
65 v0.Args = append([]*Value{}, v.Args...) // make a new copy, not aliasing
67 if v.Uses == 0 && v.removeable() {
68 if v.Op != OpInvalid && deadcode == removeDeadValues {
69 // Reset any values that are now unused, so that we decrement
70 // the use count of all of its arguments.
71 // Not quite a deadcode pass, because it does not handle cycles.
72 // But it should help Uses==1 rules to fire.
76 // No point rewriting values which aren't used.
80 vchange := phielimValue(v)
81 if vchange && debug > 1 {
82 fmt.Printf("rewriting %s -> %s\n", v0.LongString(), v.LongString())
85 // Eliminate copy inputs.
86 // If any copy input becomes unused, mark it
87 // as invalid and discard its argument. Repeat
88 // recursively on the discarded argument.
89 // This phase helps remove phantom "dead copy" uses
90 // of a value so that a x.Uses==1 rule condition
92 for i, a := range v.Args {
98 // If a, a copy, has a line boundary indicator, attempt to find a new value
99 // to hold it. The first candidate is the value that will replace a (aa),
100 // if it shares the same block and line and is eligible.
101 // The second option is v, which has a as an input. Because aa is earlier in
102 // the data flow, it is the better choice.
103 if a.Pos.IsStmt() == src.PosIsStmt {
104 if aa.Block == a.Block && aa.Pos.Line() == a.Pos.Line() && aa.Pos.IsStmt() != src.PosNotStmt {
105 aa.Pos = aa.Pos.WithIsStmt()
106 } else if v.Block == a.Block && v.Pos.Line() == a.Pos.Line() && v.Pos.IsStmt() != src.PosNotStmt {
107 v.Pos = v.Pos.WithIsStmt()
109 // Record the lost line and look for a new home after all rewrites are complete.
110 // TODO: it's possible (in FOR loops, in particular) for statement boundaries for the same
111 // line to appear in more than one block, but only one block is stored, so if both end
112 // up here, then one will be lost.
113 pendingLines.set(a.Pos, int32(a.Block.ID))
115 a.Pos = a.Pos.WithNotStmt()
124 if vchange && debug > 1 {
125 fmt.Printf("rewriting %s -> %s\n", v0.LongString(), v.LongString())
128 // apply rewrite function
131 // If value changed to a poor choice for a statement boundary, move the boundary
132 if v.Pos.IsStmt() == src.PosIsStmt {
133 if k := nextGoodStatementIndex(v, j, b); k != j {
134 v.Pos = v.Pos.WithNotStmt()
135 b.Values[k].Pos = b.Values[k].Pos.WithIsStmt()
140 change = change || vchange
141 if vchange && debug > 1 {
142 fmt.Printf("rewriting %s -> %s\n", v0.LongString(), v.LongString())
150 // remove clobbered values
151 for _, b := range f.Blocks {
153 for i, v := range b.Values {
155 if v.Op == OpInvalid {
156 if v.Pos.IsStmt() == src.PosIsStmt {
157 pendingLines.set(vl, int32(b.ID))
162 if v.Pos.IsStmt() != src.PosNotStmt && pendingLines.get(vl) == int32(b.ID) {
163 pendingLines.remove(vl)
164 v.Pos = v.Pos.WithIsStmt()
171 if pendingLines.get(b.Pos) == int32(b.ID) {
172 b.Pos = b.Pos.WithIsStmt()
173 pendingLines.remove(b.Pos)
179 // Common functions called from rewriting rules
181 func is64BitFloat(t *types.Type) bool {
182 return t.Size() == 8 && t.IsFloat()
185 func is32BitFloat(t *types.Type) bool {
186 return t.Size() == 4 && t.IsFloat()
189 func is64BitInt(t *types.Type) bool {
190 return t.Size() == 8 && t.IsInteger()
193 func is32BitInt(t *types.Type) bool {
194 return t.Size() == 4 && t.IsInteger()
197 func is16BitInt(t *types.Type) bool {
198 return t.Size() == 2 && t.IsInteger()
201 func is8BitInt(t *types.Type) bool {
202 return t.Size() == 1 && t.IsInteger()
205 func isPtr(t *types.Type) bool {
206 return t.IsPtrShaped()
209 func isSigned(t *types.Type) bool {
213 // mergeSym merges two symbolic offsets. There is no real merging of
214 // offsets, we just pick the non-nil one.
215 func mergeSym(x, y Sym) Sym {
222 panic(fmt.Sprintf("mergeSym with two non-nil syms %v %v", x, y))
225 func canMergeSym(x, y Sym) bool {
226 return x == nil || y == nil
229 // canMergeLoadClobber reports whether the load can be merged into target without
230 // invalidating the schedule.
231 // It also checks that the other non-load argument x is something we
232 // are ok with clobbering.
233 func canMergeLoadClobber(target, load, x *Value) bool {
234 // The register containing x is going to get clobbered.
235 // Don't merge if we still need the value of x.
236 // We don't have liveness information here, but we can
237 // approximate x dying with:
238 // 1) target is x's only use.
239 // 2) target is not in a deeper loop than x.
243 loopnest := x.Block.Func.loopnest()
244 loopnest.calculateDepths()
245 if loopnest.depth(target.Block.ID) > loopnest.depth(x.Block.ID) {
248 return canMergeLoad(target, load)
251 // canMergeLoad reports whether the load can be merged into target without
252 // invalidating the schedule.
253 func canMergeLoad(target, load *Value) bool {
254 if target.Block.ID != load.Block.ID {
255 // If the load is in a different block do not merge it.
259 // We can't merge the load into the target if the load
260 // has more than one use.
265 mem := load.MemoryArg()
267 // We need the load's memory arg to still be alive at target. That
268 // can't be the case if one of target's args depends on a memory
269 // state that is a successor of load's memory arg.
271 // For example, it would be invalid to merge load into target in
272 // the following situation because newmem has killed oldmem
273 // before target is reached:
274 // load = read ... oldmem
275 // newmem = write ... oldmem
276 // arg0 = read ... newmem
277 // target = add arg0 load
279 // If the argument comes from a different block then we can exclude
280 // it immediately because it must dominate load (which is in the
281 // same block as target).
283 for _, a := range target.Args {
284 if a != load && a.Block.ID == target.Block.ID {
285 args = append(args, a)
289 // memPreds contains memory states known to be predecessors of load's
290 // memory state. It is lazily initialized.
291 var memPreds map[*Value]bool
292 for i := 0; len(args) > 0; i++ {
295 // Give up if we have done a lot of iterations.
298 v := args[len(args)-1]
299 args = args[:len(args)-1]
300 if target.Block.ID != v.Block.ID {
301 // Since target and load are in the same block
302 // we can stop searching when we leave the block.
306 // A Phi implies we have reached the top of the block.
307 // The memory phi, if it exists, is always
308 // the first logical store in the block.
311 if v.Type.IsTuple() && v.Type.FieldType(1).IsMemory() {
312 // We could handle this situation however it is likely
316 if v.Op.SymEffect()&SymAddr != 0 {
317 // This case prevents an operation that calculates the
318 // address of a local variable from being forced to schedule
319 // before its corresponding VarDef.
325 // We don't want to combine the CMPQ with the load, because
326 // that would force the CMPQ to schedule before the VARDEF, which
327 // in turn requires the LEAQ to schedule before the VARDEF.
330 if v.Type.IsMemory() {
332 // Initialise a map containing memory states
333 // known to be predecessors of load's memory
335 memPreds = make(map[*Value]bool)
338 for i := 0; i < limit; i++ {
340 // The memory phi, if it exists, is always
341 // the first logical store in the block.
344 if m.Block.ID != target.Block.ID {
347 if !m.Type.IsMemory() {
351 if len(m.Args) == 0 {
358 // We can merge if v is a predecessor of mem.
360 // For example, we can merge load into target in the
361 // following scenario:
364 // load = read ... mem
365 // target = add x load
371 if len(v.Args) > 0 && v.Args[len(v.Args)-1] == mem {
372 // If v takes mem as an input then we know mem
373 // is valid at this point.
376 for _, a := range v.Args {
377 if target.Block.ID == a.Block.ID {
378 args = append(args, a)
386 // isSameCall reports whether sym is the same as the given named symbol
387 func isSameCall(sym interface{}, name string) bool {
388 fn := sym.(*AuxCall).Fn
389 return fn != nil && fn.String() == name
392 // nlz returns the number of leading zeros.
393 func nlz64(x int64) int { return bits.LeadingZeros64(uint64(x)) }
394 func nlz32(x int32) int { return bits.LeadingZeros32(uint32(x)) }
395 func nlz16(x int16) int { return bits.LeadingZeros16(uint16(x)) }
396 func nlz8(x int8) int { return bits.LeadingZeros8(uint8(x)) }
398 // ntzX returns the number of trailing zeros.
399 func ntz64(x int64) int { return bits.TrailingZeros64(uint64(x)) }
400 func ntz32(x int32) int { return bits.TrailingZeros32(uint32(x)) }
401 func ntz16(x int16) int { return bits.TrailingZeros16(uint16(x)) }
402 func ntz8(x int8) int { return bits.TrailingZeros8(uint8(x)) }
404 func oneBit(x int64) bool { return x&(x-1) == 0 && x != 0 }
405 func oneBit8(x int8) bool { return x&(x-1) == 0 && x != 0 }
406 func oneBit16(x int16) bool { return x&(x-1) == 0 && x != 0 }
407 func oneBit32(x int32) bool { return x&(x-1) == 0 && x != 0 }
408 func oneBit64(x int64) bool { return x&(x-1) == 0 && x != 0 }
410 // nto returns the number of trailing ones.
411 func nto(x int64) int64 {
412 return int64(ntz64(^x))
415 // logX returns logarithm of n base 2.
416 // n must be a positive power of 2 (isPowerOfTwoX returns true).
417 func log8(n int8) int64 {
418 return int64(bits.Len8(uint8(n))) - 1
420 func log16(n int16) int64 {
421 return int64(bits.Len16(uint16(n))) - 1
423 func log32(n int32) int64 {
424 return int64(bits.Len32(uint32(n))) - 1
426 func log64(n int64) int64 {
427 return int64(bits.Len64(uint64(n))) - 1
430 // log2uint32 returns logarithm in base 2 of uint32(n), with log2(0) = -1.
432 func log2uint32(n int64) int64 {
433 return int64(bits.Len32(uint32(n))) - 1
436 // isPowerOfTwo functions report whether n is a power of 2.
437 func isPowerOfTwo8(n int8) bool {
438 return n > 0 && n&(n-1) == 0
440 func isPowerOfTwo16(n int16) bool {
441 return n > 0 && n&(n-1) == 0
443 func isPowerOfTwo32(n int32) bool {
444 return n > 0 && n&(n-1) == 0
446 func isPowerOfTwo64(n int64) bool {
447 return n > 0 && n&(n-1) == 0
450 // isUint64PowerOfTwo reports whether uint64(n) is a power of 2.
451 func isUint64PowerOfTwo(in int64) bool {
453 return n > 0 && n&(n-1) == 0
456 // isUint32PowerOfTwo reports whether uint32(n) is a power of 2.
457 func isUint32PowerOfTwo(in int64) bool {
458 n := uint64(uint32(in))
459 return n > 0 && n&(n-1) == 0
462 // is32Bit reports whether n can be represented as a signed 32 bit integer.
463 func is32Bit(n int64) bool {
464 return n == int64(int32(n))
467 // is16Bit reports whether n can be represented as a signed 16 bit integer.
468 func is16Bit(n int64) bool {
469 return n == int64(int16(n))
472 // is8Bit reports whether n can be represented as a signed 8 bit integer.
473 func is8Bit(n int64) bool {
474 return n == int64(int8(n))
477 // isU8Bit reports whether n can be represented as an unsigned 8 bit integer.
478 func isU8Bit(n int64) bool {
479 return n == int64(uint8(n))
482 // isU12Bit reports whether n can be represented as an unsigned 12 bit integer.
483 func isU12Bit(n int64) bool {
484 return 0 <= n && n < (1<<12)
487 // isU16Bit reports whether n can be represented as an unsigned 16 bit integer.
488 func isU16Bit(n int64) bool {
489 return n == int64(uint16(n))
492 // isU32Bit reports whether n can be represented as an unsigned 32 bit integer.
493 func isU32Bit(n int64) bool {
494 return n == int64(uint32(n))
497 // is20Bit reports whether n can be represented as a signed 20 bit integer.
498 func is20Bit(n int64) bool {
499 return -(1<<19) <= n && n < (1<<19)
502 // b2i translates a boolean value to 0 or 1 for assigning to auxInt.
503 func b2i(b bool) int64 {
510 // b2i32 translates a boolean value to 0 or 1.
511 func b2i32(b bool) int32 {
518 // shiftIsBounded reports whether (left/right) shift Value v is known to be bounded.
519 // A shift is bounded if it is shifting by less than the width of the shifted value.
520 func shiftIsBounded(v *Value) bool {
524 // truncate64Fto32F converts a float64 value to a float32 preserving the bit pattern
525 // of the mantissa. It will panic if the truncation results in lost information.
526 func truncate64Fto32F(f float64) float32 {
527 if !isExactFloat32(f) {
528 panic("truncate64Fto32F: truncation is not exact")
533 // NaN bit patterns aren't necessarily preserved across conversion
534 // instructions so we need to do the conversion manually.
535 b := math.Float64bits(f)
536 m := b & ((1 << 52) - 1) // mantissa (a.k.a. significand)
537 // | sign | exponent | mantissa |
538 r := uint32(((b >> 32) & (1 << 31)) | 0x7f800000 | (m >> (52 - 23)))
539 return math.Float32frombits(r)
542 // extend32Fto64F converts a float32 value to a float64 value preserving the bit
543 // pattern of the mantissa.
544 func extend32Fto64F(f float32) float64 {
545 if !math.IsNaN(float64(f)) {
548 // NaN bit patterns aren't necessarily preserved across conversion
549 // instructions so we need to do the conversion manually.
550 b := uint64(math.Float32bits(f))
551 // | sign | exponent | mantissa |
552 r := ((b << 32) & (1 << 63)) | (0x7ff << 52) | ((b & 0x7fffff) << (52 - 23))
553 return math.Float64frombits(r)
556 // DivisionNeedsFixUp reports whether the division needs fix-up code.
557 func DivisionNeedsFixUp(v *Value) bool {
561 // auxFrom64F encodes a float64 value so it can be stored in an AuxInt.
562 func auxFrom64F(f float64) int64 {
564 panic("can't encode a NaN in AuxInt field")
566 return int64(math.Float64bits(f))
569 // auxFrom32F encodes a float32 value so it can be stored in an AuxInt.
570 func auxFrom32F(f float32) int64 {
572 panic("can't encode a NaN in AuxInt field")
574 return int64(math.Float64bits(extend32Fto64F(f)))
577 // auxTo32F decodes a float32 from the AuxInt value provided.
578 func auxTo32F(i int64) float32 {
579 return truncate64Fto32F(math.Float64frombits(uint64(i)))
582 // auxTo64F decodes a float64 from the AuxInt value provided.
583 func auxTo64F(i int64) float64 {
584 return math.Float64frombits(uint64(i))
587 func auxIntToBool(i int64) bool {
593 func auxIntToInt8(i int64) int8 {
596 func auxIntToInt16(i int64) int16 {
599 func auxIntToInt32(i int64) int32 {
602 func auxIntToInt64(i int64) int64 {
605 func auxIntToUint8(i int64) uint8 {
608 func auxIntToFloat32(i int64) float32 {
609 return float32(math.Float64frombits(uint64(i)))
611 func auxIntToFloat64(i int64) float64 {
612 return math.Float64frombits(uint64(i))
614 func auxIntToValAndOff(i int64) ValAndOff {
617 func auxIntToArm64BitField(i int64) arm64BitField {
618 return arm64BitField(i)
620 func auxIntToInt128(x int64) int128 {
622 panic("nonzero int128 not allowed")
626 func auxIntToFlagConstant(x int64) flagConstant {
627 return flagConstant(x)
630 func auxIntToOp(cc int64) Op {
634 func boolToAuxInt(b bool) int64 {
640 func int8ToAuxInt(i int8) int64 {
643 func int16ToAuxInt(i int16) int64 {
646 func int32ToAuxInt(i int32) int64 {
649 func int64ToAuxInt(i int64) int64 {
652 func uint8ToAuxInt(i uint8) int64 {
653 return int64(int8(i))
655 func float32ToAuxInt(f float32) int64 {
656 return int64(math.Float64bits(float64(f)))
658 func float64ToAuxInt(f float64) int64 {
659 return int64(math.Float64bits(f))
661 func valAndOffToAuxInt(v ValAndOff) int64 {
664 func arm64BitFieldToAuxInt(v arm64BitField) int64 {
667 func int128ToAuxInt(x int128) int64 {
669 panic("nonzero int128 not allowed")
673 func flagConstantToAuxInt(x flagConstant) int64 {
677 func opToAuxInt(o Op) int64 {
681 func auxToString(i interface{}) string {
684 func auxToSym(i interface{}) Sym {
685 // TODO: kind of a hack - allows nil interface through
689 func auxToType(i interface{}) *types.Type {
690 return i.(*types.Type)
692 func auxToCall(i interface{}) *AuxCall {
695 func auxToS390xCCMask(i interface{}) s390x.CCMask {
696 return i.(s390x.CCMask)
698 func auxToS390xRotateParams(i interface{}) s390x.RotateParams {
699 return i.(s390x.RotateParams)
702 func stringToAux(s string) interface{} {
705 func symToAux(s Sym) interface{} {
708 func callToAux(s *AuxCall) interface{} {
711 func typeToAux(t *types.Type) interface{} {
714 func s390xCCMaskToAux(c s390x.CCMask) interface{} {
717 func s390xRotateParamsToAux(r s390x.RotateParams) interface{} {
721 // uaddOvf reports whether unsigned a+b would overflow.
722 func uaddOvf(a, b int64) bool {
723 return uint64(a)+uint64(b) < uint64(a)
726 // de-virtualize an InterCall
727 // 'sym' is the symbol for the itab
728 func devirt(v *Value, aux interface{}, sym Sym, offset int64) *AuxCall {
730 n, ok := sym.(*obj.LSym)
734 lsym := f.fe.DerefItab(n, offset)
735 if f.pass.debug > 0 {
737 f.Warnl(v.Pos, "de-virtualizing call")
739 f.Warnl(v.Pos, "couldn't de-virtualize call")
746 return StaticAuxCall(lsym, va.args, va.results)
749 // de-virtualize an InterLECall
750 // 'sym' is the symbol for the itab
751 func devirtLESym(v *Value, aux interface{}, sym Sym, offset int64) *obj.LSym {
752 n, ok := sym.(*obj.LSym)
758 lsym := f.fe.DerefItab(n, offset)
759 if f.pass.debug > 0 {
761 f.Warnl(v.Pos, "de-virtualizing call")
763 f.Warnl(v.Pos, "couldn't de-virtualize call")
772 func devirtLECall(v *Value, sym *obj.LSym) *Value {
773 v.Op = OpStaticLECall
774 v.Aux.(*AuxCall).Fn = sym
779 // isSamePtr reports whether p1 and p2 point to the same address.
780 func isSamePtr(p1, p2 *Value) bool {
789 return p1.AuxInt == p2.AuxInt && isSamePtr(p1.Args[0], p2.Args[0])
790 case OpAddr, OpLocalAddr:
791 // OpAddr's 0th arg is either OpSP or OpSB, which means that it is uniquely identified by its Op.
792 // Checking for value equality only works after [z]cse has run.
793 return p1.Aux == p2.Aux && p1.Args[0].Op == p2.Args[0].Op
795 return p1.Args[1] == p2.Args[1] && isSamePtr(p1.Args[0], p2.Args[0])
800 func isStackPtr(v *Value) bool {
801 for v.Op == OpOffPtr || v.Op == OpAddPtr {
804 return v.Op == OpSP || v.Op == OpLocalAddr
807 // disjoint reports whether the memory region specified by [p1:p1+n1)
808 // does not overlap with [p2:p2+n2).
809 // A return value of false does not imply the regions overlap.
810 func disjoint(p1 *Value, n1 int64, p2 *Value, n2 int64) bool {
811 if n1 == 0 || n2 == 0 {
817 baseAndOffset := func(ptr *Value) (base *Value, offset int64) {
818 base, offset = ptr, 0
819 for base.Op == OpOffPtr {
820 offset += base.AuxInt
825 p1, off1 := baseAndOffset(p1)
826 p2, off2 := baseAndOffset(p2)
827 if isSamePtr(p1, p2) {
828 return !overlap(off1, n1, off2, n2)
830 // p1 and p2 are not the same, so if they are both OpAddrs then
831 // they point to different variables.
832 // If one pointer is on the stack and the other is an argument
833 // then they can't overlap.
835 case OpAddr, OpLocalAddr:
836 if p2.Op == OpAddr || p2.Op == OpLocalAddr || p2.Op == OpSP {
839 return p2.Op == OpArg && p1.Args[0].Op == OpSP
841 if p2.Op == OpSP || p2.Op == OpLocalAddr {
845 return p2.Op == OpAddr || p2.Op == OpLocalAddr || p2.Op == OpArg || p2.Op == OpSP
850 // moveSize returns the number of bytes an aligned MOV instruction moves
851 func moveSize(align int64, c *Config) int64 {
853 case align%8 == 0 && c.PtrSize == 8:
863 // mergePoint finds a block among a's blocks which dominates b and is itself
864 // dominated by all of a's blocks. Returns nil if it can't find one.
865 // Might return nil even if one does exist.
866 func mergePoint(b *Block, a ...*Value) *Block {
867 // Walk backward from b looking for one of the a's blocks.
873 for _, x := range a {
878 if len(b.Preds) > 1 {
879 // Don't know which way to go back. Abort.
885 return nil // too far away
887 // At this point, r is the first value in a that we find by walking backwards.
888 // if we return anything, r will be it.
891 // Keep going, counting the other a's that we find. They must all dominate r.
894 for _, x := range a {
900 // Found all of a in a backwards walk. We can return r.
903 if len(b.Preds) > 1 {
910 return nil // too far away
913 // clobber invalidates values. Returns true.
914 // clobber is used by rewrite rules to:
915 // A) make sure the values are really dead and never used again.
916 // B) decrement use counts of the values' args.
917 func clobber(vv ...*Value) bool {
918 for _, v := range vv {
920 // Note: leave v.Block intact. The Block field is used after clobber.
925 // clobberIfDead resets v when use count is 1. Returns true.
926 // clobberIfDead is used by rewrite rules to decrement
927 // use counts of v's args when v is dead and never used.
928 func clobberIfDead(v *Value) bool {
932 // Note: leave v.Block intact. The Block field is used after clobberIfDead.
936 // noteRule is an easy way to track if a rule is matched when writing
937 // new ones. Make the rule of interest also conditional on
938 // noteRule("note to self: rule of interest matched")
939 // and that message will print when the rule matches.
940 func noteRule(s string) bool {
945 // countRule increments Func.ruleMatches[key].
946 // If Func.ruleMatches is non-nil at the end
947 // of compilation, it will be printed to stdout.
948 // This is intended to make it easier to find which functions
949 // which contain lots of rules matches when developing new rules.
950 func countRule(v *Value, key string) bool {
952 if f.ruleMatches == nil {
953 f.ruleMatches = make(map[string]int)
959 // warnRule generates compiler debug output with string s when
960 // v is not in autogenerated code, cond is true and the rule has fired.
961 func warnRule(cond bool, v *Value, s string) bool {
962 if pos := v.Pos; pos.Line() > 1 && cond {
963 v.Block.Func.Warnl(pos, s)
968 // for a pseudo-op like (LessThan x), extract x
969 func flagArg(v *Value) *Value {
970 if len(v.Args) != 1 || !v.Args[0].Type.IsFlags() {
976 // arm64Negate finds the complement to an ARM64 condition code,
977 // for example Equal -> NotEqual or LessThan -> GreaterEqual
979 // TODO: add floating-point conditions
980 func arm64Negate(op Op) Op {
982 case OpARM64LessThan:
983 return OpARM64GreaterEqual
984 case OpARM64LessThanU:
985 return OpARM64GreaterEqualU
986 case OpARM64GreaterThan:
987 return OpARM64LessEqual
988 case OpARM64GreaterThanU:
989 return OpARM64LessEqualU
990 case OpARM64LessEqual:
991 return OpARM64GreaterThan
992 case OpARM64LessEqualU:
993 return OpARM64GreaterThanU
994 case OpARM64GreaterEqual:
995 return OpARM64LessThan
996 case OpARM64GreaterEqualU:
997 return OpARM64LessThanU
999 return OpARM64NotEqual
1000 case OpARM64NotEqual:
1002 case OpARM64LessThanF:
1003 return OpARM64GreaterEqualF
1004 case OpARM64GreaterThanF:
1005 return OpARM64LessEqualF
1006 case OpARM64LessEqualF:
1007 return OpARM64GreaterThanF
1008 case OpARM64GreaterEqualF:
1009 return OpARM64LessThanF
1011 panic("unreachable")
1015 // arm64Invert evaluates (InvertFlags op), which
1016 // is the same as altering the condition codes such
1017 // that the same result would be produced if the arguments
1018 // to the flag-generating instruction were reversed, e.g.
1019 // (InvertFlags (CMP x y)) -> (CMP y x)
1021 // TODO: add floating-point conditions
1022 func arm64Invert(op Op) Op {
1024 case OpARM64LessThan:
1025 return OpARM64GreaterThan
1026 case OpARM64LessThanU:
1027 return OpARM64GreaterThanU
1028 case OpARM64GreaterThan:
1029 return OpARM64LessThan
1030 case OpARM64GreaterThanU:
1031 return OpARM64LessThanU
1032 case OpARM64LessEqual:
1033 return OpARM64GreaterEqual
1034 case OpARM64LessEqualU:
1035 return OpARM64GreaterEqualU
1036 case OpARM64GreaterEqual:
1037 return OpARM64LessEqual
1038 case OpARM64GreaterEqualU:
1039 return OpARM64LessEqualU
1040 case OpARM64Equal, OpARM64NotEqual:
1042 case OpARM64LessThanF:
1043 return OpARM64GreaterThanF
1044 case OpARM64GreaterThanF:
1045 return OpARM64LessThanF
1046 case OpARM64LessEqualF:
1047 return OpARM64GreaterEqualF
1048 case OpARM64GreaterEqualF:
1049 return OpARM64LessEqualF
1051 panic("unreachable")
1055 // evaluate an ARM64 op against a flags value
1056 // that is potentially constant; return 1 for true,
1057 // -1 for false, and 0 for not constant.
1058 func ccARM64Eval(op Op, flags *Value) int {
1060 if fop == OpARM64InvertFlags {
1061 return -ccARM64Eval(op, flags.Args[0])
1063 if fop != OpARM64FlagConstant {
1066 fc := flagConstant(flags.AuxInt)
1067 b2i := func(b bool) int {
1076 case OpARM64NotEqual:
1078 case OpARM64LessThan:
1080 case OpARM64LessThanU:
1081 return b2i(fc.ult())
1082 case OpARM64GreaterThan:
1084 case OpARM64GreaterThanU:
1085 return b2i(fc.ugt())
1086 case OpARM64LessEqual:
1088 case OpARM64LessEqualU:
1089 return b2i(fc.ule())
1090 case OpARM64GreaterEqual:
1092 case OpARM64GreaterEqualU:
1093 return b2i(fc.uge())
1098 // logRule logs the use of the rule s. This will only be enabled if
1099 // rewrite rules were generated with the -log option, see gen/rulegen.go.
1100 func logRule(s string) {
1101 if ruleFile == nil {
1102 // Open a log file to write log to. We open in append
1103 // mode because all.bash runs the compiler lots of times,
1104 // and we want the concatenation of all of those logs.
1105 // This means, of course, that users need to rm the old log
1106 // to get fresh data.
1107 // TODO: all.bash runs compilers in parallel. Need to synchronize logging somehow?
1108 w, err := os.OpenFile(filepath.Join(os.Getenv("GOROOT"), "src", "rulelog"),
1109 os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
1115 _, err := fmt.Fprintln(ruleFile, s)
1121 var ruleFile io.Writer
1123 func min(x, y int64) int64 {
1130 func isConstZero(v *Value) bool {
1134 case OpConst64, OpConst32, OpConst16, OpConst8, OpConstBool, OpConst32F, OpConst64F:
1135 return v.AuxInt == 0
1140 // reciprocalExact64 reports whether 1/c is exactly representable.
1141 func reciprocalExact64(c float64) bool {
1142 b := math.Float64bits(c)
1143 man := b & (1<<52 - 1)
1145 return false // not a power of 2, denormal, or NaN
1147 exp := b >> 52 & (1<<11 - 1)
1148 // exponent bias is 0x3ff. So taking the reciprocal of a number
1149 // changes the exponent to 0x7fe-exp.
1154 return false // ±inf
1156 return false // exponent is not representable
1162 // reciprocalExact32 reports whether 1/c is exactly representable.
1163 func reciprocalExact32(c float32) bool {
1164 b := math.Float32bits(c)
1165 man := b & (1<<23 - 1)
1167 return false // not a power of 2, denormal, or NaN
1169 exp := b >> 23 & (1<<8 - 1)
1170 // exponent bias is 0x7f. So taking the reciprocal of a number
1171 // changes the exponent to 0xfe-exp.
1176 return false // ±inf
1178 return false // exponent is not representable
1184 // check if an immediate can be directly encoded into an ARM's instruction
1185 func isARMImmRot(v uint32) bool {
1186 for i := 0; i < 16; i++ {
1196 // overlap reports whether the ranges given by the given offset and
1197 // size pairs overlap.
1198 func overlap(offset1, size1, offset2, size2 int64) bool {
1199 if offset1 >= offset2 && offset2+size2 > offset1 {
1202 if offset2 >= offset1 && offset1+size1 > offset2 {
1208 func areAdjacentOffsets(off1, off2, size int64) bool {
1209 return off1+size == off2 || off1 == off2+size
1212 // check if value zeroes out upper 32-bit of 64-bit register.
1213 // depth limits recursion depth. In AMD64.rules 3 is used as limit,
1214 // because it catches same amount of cases as 4.
1215 func zeroUpper32Bits(x *Value, depth int) bool {
1217 case OpAMD64MOVLconst, OpAMD64MOVLload, OpAMD64MOVLQZX, OpAMD64MOVLloadidx1,
1218 OpAMD64MOVWload, OpAMD64MOVWloadidx1, OpAMD64MOVBload, OpAMD64MOVBloadidx1,
1219 OpAMD64MOVLloadidx4, OpAMD64ADDLload, OpAMD64SUBLload, OpAMD64ANDLload,
1220 OpAMD64ORLload, OpAMD64XORLload, OpAMD64CVTTSD2SL,
1221 OpAMD64ADDL, OpAMD64ADDLconst, OpAMD64SUBL, OpAMD64SUBLconst,
1222 OpAMD64ANDL, OpAMD64ANDLconst, OpAMD64ORL, OpAMD64ORLconst,
1223 OpAMD64XORL, OpAMD64XORLconst, OpAMD64NEGL, OpAMD64NOTL,
1224 OpAMD64SHRL, OpAMD64SHRLconst, OpAMD64SARL, OpAMD64SARLconst,
1225 OpAMD64SHLL, OpAMD64SHLLconst:
1228 return x.Type.Width == 4
1229 case OpPhi, OpSelect0, OpSelect1:
1230 // Phis can use each-other as an arguments, instead of tracking visited values,
1231 // just limit recursion depth.
1235 for i := range x.Args {
1236 if !zeroUpper32Bits(x.Args[i], depth-1) {
1246 // zeroUpper48Bits is similar to zeroUpper32Bits, but for upper 48 bits
1247 func zeroUpper48Bits(x *Value, depth int) bool {
1249 case OpAMD64MOVWQZX, OpAMD64MOVWload, OpAMD64MOVWloadidx1, OpAMD64MOVWloadidx2:
1252 return x.Type.Width == 2
1253 case OpPhi, OpSelect0, OpSelect1:
1254 // Phis can use each-other as an arguments, instead of tracking visited values,
1255 // just limit recursion depth.
1259 for i := range x.Args {
1260 if !zeroUpper48Bits(x.Args[i], depth-1) {
1270 // zeroUpper56Bits is similar to zeroUpper32Bits, but for upper 56 bits
1271 func zeroUpper56Bits(x *Value, depth int) bool {
1273 case OpAMD64MOVBQZX, OpAMD64MOVBload, OpAMD64MOVBloadidx1:
1276 return x.Type.Width == 1
1277 case OpPhi, OpSelect0, OpSelect1:
1278 // Phis can use each-other as an arguments, instead of tracking visited values,
1279 // just limit recursion depth.
1283 for i := range x.Args {
1284 if !zeroUpper56Bits(x.Args[i], depth-1) {
1294 // isInlinableMemmove reports whether the given arch performs a Move of the given size
1295 // faster than memmove. It will only return true if replacing the memmove with a Move is
1296 // safe, either because Move is small or because the arguments are disjoint.
1297 // This is used as a check for replacing memmove with Move ops.
1298 func isInlinableMemmove(dst, src *Value, sz int64, c *Config) bool {
1299 // It is always safe to convert memmove into Move when its arguments are disjoint.
1300 // Move ops may or may not be faster for large sizes depending on how the platform
1301 // lowers them, so we only perform this optimization on platforms that we know to
1302 // have fast Move ops.
1305 return sz <= 16 || (sz < 1024 && disjoint(dst, sz, src, sz))
1306 case "386", "arm64":
1308 case "s390x", "ppc64", "ppc64le":
1309 return sz <= 8 || disjoint(dst, sz, src, sz)
1310 case "arm", "mips", "mips64", "mipsle", "mips64le":
1316 // logLargeCopy logs the occurrence of a large copy.
1317 // The best place to do this is in the rewrite rules where the size of the move is easy to find.
1318 // "Large" is arbitrarily chosen to be 128 bytes; this may change.
1319 func logLargeCopy(v *Value, s int64) bool {
1323 if logopt.Enabled() {
1324 logopt.LogOpt(v.Pos, "copy", "lower", v.Block.Func.Name, fmt.Sprintf("%d bytes", s))
1329 // hasSmallRotate reports whether the architecture has rotate instructions
1330 // for sizes < 32-bit. This is used to decide whether to promote some rotations.
1331 func hasSmallRotate(c *Config) bool {
1333 case "amd64", "386":
1340 func newPPC64ShiftAuxInt(sh, mb, me, sz int64) int32 {
1341 if sh < 0 || sh >= sz {
1342 panic("PPC64 shift arg sh out of range")
1344 if mb < 0 || mb >= sz {
1345 panic("PPC64 shift arg mb out of range")
1347 if me < 0 || me >= sz {
1348 panic("PPC64 shift arg me out of range")
1350 return int32(sh<<16 | mb<<8 | me)
1353 func GetPPC64Shiftsh(auxint int64) int64 {
1354 return int64(int8(auxint >> 16))
1357 func GetPPC64Shiftmb(auxint int64) int64 {
1358 return int64(int8(auxint >> 8))
1361 func GetPPC64Shiftme(auxint int64) int64 {
1362 return int64(int8(auxint))
1365 // Test if this value can encoded as a mask for a rlwinm like
1366 // operation. Masks can also extend from the msb and wrap to
1367 // the lsb too. That is, the valid masks are 32 bit strings
1368 // of the form: 0..01..10..0 or 1..10..01..1 or 1...1
1369 func isPPC64WordRotateMask(v64 int64) bool {
1370 // Isolate rightmost 1 (if none 0) and add.
1373 // Likewise, for the wrapping case.
1375 vpn := (vn & -vn) + vn
1376 return (v&vp == 0 || vn&vpn == 0) && v != 0
1379 // Compress mask and and shift into single value of the form
1380 // me | mb<<8 | rotate<<16 | nbits<<24 where me and mb can
1381 // be used to regenerate the input mask.
1382 func encodePPC64RotateMask(rotate, mask, nbits int64) int64 {
1383 var mb, me, mbn, men int
1385 // Determine boundaries and then decode them
1386 if mask == 0 || ^mask == 0 || rotate >= nbits {
1387 panic("Invalid PPC64 rotate mask")
1388 } else if nbits == 32 {
1389 mb = bits.LeadingZeros32(uint32(mask))
1390 me = 32 - bits.TrailingZeros32(uint32(mask))
1391 mbn = bits.LeadingZeros32(^uint32(mask))
1392 men = 32 - bits.TrailingZeros32(^uint32(mask))
1394 mb = bits.LeadingZeros64(uint64(mask))
1395 me = 64 - bits.TrailingZeros64(uint64(mask))
1396 mbn = bits.LeadingZeros64(^uint64(mask))
1397 men = 64 - bits.TrailingZeros64(^uint64(mask))
1399 // Check for a wrapping mask (e.g bits at 0 and 63)
1400 if mb == 0 && me == int(nbits) {
1401 // swap the inverted values
1405 return int64(me) | int64(mb<<8) | int64(rotate<<16) | int64(nbits<<24)
1408 // The inverse operation of encodePPC64RotateMask. The values returned as
1409 // mb and me satisfy the POWER ISA definition of MASK(x,y) where MASK(mb,me) = mask.
1410 func DecodePPC64RotateMask(sauxint int64) (rotate, mb, me int64, mask uint64) {
1411 auxint := uint64(sauxint)
1412 rotate = int64((auxint >> 16) & 0xFF)
1413 mb = int64((auxint >> 8) & 0xFF)
1414 me = int64((auxint >> 0) & 0xFF)
1415 nbits := int64((auxint >> 24) & 0xFF)
1416 mask = ((1 << uint(nbits-mb)) - 1) ^ ((1 << uint(nbits-me)) - 1)
1421 mask = uint64(uint32(mask))
1424 // Fixup ME to match ISA definition. The second argument to MASK(..,me)
1426 me = (me - 1) & (nbits - 1)
1430 // This verifies that the mask is a set of
1431 // consecutive bits including the least
1433 func isPPC64ValidShiftMask(v int64) bool {
1434 if (v != 0) && ((v+1)&v) == 0 {
1440 func getPPC64ShiftMaskLength(v int64) int64 {
1441 return int64(bits.Len64(uint64(v)))
1444 // Decompose a shift right into an equivalent rotate/mask,
1445 // and return mask & m.
1446 func mergePPC64RShiftMask(m, s, nbits int64) int64 {
1447 smask := uint64((1<<uint(nbits))-1) >> uint(s)
1448 return m & int64(smask)
1451 // Combine (ANDconst [m] (SRWconst [s])) into (RLWINM [y]) or return 0
1452 func mergePPC64AndSrwi(m, s int64) int64 {
1453 mask := mergePPC64RShiftMask(m, s, 32)
1454 if !isPPC64WordRotateMask(mask) {
1457 return encodePPC64RotateMask(32-s, mask, 32)
1460 // Test if a shift right feeding into a CLRLSLDI can be merged into RLWINM.
1461 // Return the encoded RLWINM constant, or 0 if they cannot be merged.
1462 func mergePPC64ClrlsldiSrw(sld, srw int64) int64 {
1463 mask_1 := uint64(0xFFFFFFFF >> uint(srw))
1464 // for CLRLSLDI, it's more convient to think of it as a mask left bits then rotate left.
1465 mask_2 := uint64(0xFFFFFFFFFFFFFFFF) >> uint(GetPPC64Shiftmb(int64(sld)))
1467 // Rewrite mask to apply after the final left shift.
1468 mask_3 := (mask_1 & mask_2) << uint(GetPPC64Shiftsh(sld))
1471 r_2 := GetPPC64Shiftsh(sld)
1472 r_3 := (r_1 + r_2) & 31 // This can wrap.
1474 if uint64(uint32(mask_3)) != mask_3 || mask_3 == 0 {
1477 return encodePPC64RotateMask(int64(r_3), int64(mask_3), 32)
1480 // Test if a RLWINM feeding into a CLRLSLDI can be merged into RLWINM. Return
1481 // the encoded RLWINM constant, or 0 if they cannot be merged.
1482 func mergePPC64ClrlsldiRlwinm(sld int32, rlw int64) int64 {
1483 r_1, _, _, mask_1 := DecodePPC64RotateMask(rlw)
1484 // for CLRLSLDI, it's more convient to think of it as a mask left bits then rotate left.
1485 mask_2 := uint64(0xFFFFFFFFFFFFFFFF) >> uint(GetPPC64Shiftmb(int64(sld)))
1487 // combine the masks, and adjust for the final left shift.
1488 mask_3 := (mask_1 & mask_2) << uint(GetPPC64Shiftsh(int64(sld)))
1489 r_2 := GetPPC64Shiftsh(int64(sld))
1490 r_3 := (r_1 + r_2) & 31 // This can wrap.
1492 // Verify the result is still a valid bitmask of <= 32 bits.
1493 if !isPPC64WordRotateMask(int64(mask_3)) || uint64(uint32(mask_3)) != mask_3 {
1496 return encodePPC64RotateMask(r_3, int64(mask_3), 32)
1499 // Compute the encoded RLWINM constant from combining (SLDconst [sld] (SRWconst [srw] x)),
1500 // or return 0 if they cannot be combined.
1501 func mergePPC64SldiSrw(sld, srw int64) int64 {
1502 if sld > srw || srw >= 32 {
1505 mask_r := uint32(0xFFFFFFFF) >> uint(srw)
1506 mask_l := uint32(0xFFFFFFFF) >> uint(sld)
1507 mask := (mask_r & mask_l) << uint(sld)
1508 return encodePPC64RotateMask((32-srw+sld)&31, int64(mask), 32)
1511 // Convenience function to rotate a 32 bit constant value by another constant.
1512 func rotateLeft32(v, rotate int64) int64 {
1513 return int64(bits.RotateLeft32(uint32(v), int(rotate)))
1516 // encodes the lsb and width for arm(64) bitfield ops into the expected auxInt format.
1517 func armBFAuxInt(lsb, width int64) arm64BitField {
1518 if lsb < 0 || lsb > 63 {
1519 panic("ARM(64) bit field lsb constant out of range")
1521 if width < 1 || width > 64 {
1522 panic("ARM(64) bit field width constant out of range")
1524 return arm64BitField(width | lsb<<8)
1527 // returns the lsb part of the auxInt field of arm64 bitfield ops.
1528 func (bfc arm64BitField) getARM64BFlsb() int64 {
1529 return int64(uint64(bfc) >> 8)
1532 // returns the width part of the auxInt field of arm64 bitfield ops.
1533 func (bfc arm64BitField) getARM64BFwidth() int64 {
1534 return int64(bfc) & 0xff
1537 // checks if mask >> rshift applied at lsb is a valid arm64 bitfield op mask.
1538 func isARM64BFMask(lsb, mask, rshift int64) bool {
1539 shiftedMask := int64(uint64(mask) >> uint64(rshift))
1540 return shiftedMask != 0 && isPowerOfTwo64(shiftedMask+1) && nto(shiftedMask)+lsb < 64
1543 // returns the bitfield width of mask >> rshift for arm64 bitfield ops
1544 func arm64BFWidth(mask, rshift int64) int64 {
1545 shiftedMask := int64(uint64(mask) >> uint64(rshift))
1546 if shiftedMask == 0 {
1547 panic("ARM64 BF mask is zero")
1549 return nto(shiftedMask)
1552 // sizeof returns the size of t in bytes.
1553 // It will panic if t is not a *types.Type.
1554 func sizeof(t interface{}) int64 {
1555 return t.(*types.Type).Size()
1558 // registerizable reports whether t is a primitive type that fits in
1559 // a register. It assumes float64 values will always fit into registers
1560 // even if that isn't strictly true.
1561 func registerizable(b *Block, typ *types.Type) bool {
1562 if typ.IsPtrShaped() || typ.IsFloat() {
1565 if typ.IsInteger() {
1566 return typ.Size() <= b.Func.Config.RegSize
1571 // needRaceCleanup reports whether this call to racefuncenter/exit isn't needed.
1572 func needRaceCleanup(sym *AuxCall, v *Value) bool {
1577 if !isSameCall(sym, "runtime.racefuncenter") && !isSameCall(sym, "runtime.racefuncenterfp") && !isSameCall(sym, "runtime.racefuncexit") {
1580 for _, b := range f.Blocks {
1581 for _, v := range b.Values {
1584 // Check for racefuncenter/racefuncenterfp will encounter racefuncexit and vice versa.
1585 // Allow calls to panic*
1586 s := v.Aux.(*AuxCall).Fn.String()
1588 case "runtime.racefuncenter", "runtime.racefuncenterfp", "runtime.racefuncexit",
1589 "runtime.panicdivide", "runtime.panicwrap",
1590 "runtime.panicshift":
1593 // If we encountered any call, we need to keep racefunc*,
1594 // for accurate stacktraces.
1596 case OpPanicBounds, OpPanicExtend:
1597 // Note: these are panic generators that are ok (like the static calls above).
1598 case OpClosureCall, OpInterCall:
1599 // We must keep the race functions if there are any other call types.
1604 if isSameCall(sym, "runtime.racefuncenter") {
1605 // If we're removing racefuncenter, remove its argument as well.
1606 if v.Args[0].Op != OpStore {
1609 mem := v.Args[0].Args[2]
1610 v.Args[0].reset(OpCopy)
1611 v.Args[0].AddArg(mem)
1616 // symIsRO reports whether sym is a read-only global.
1617 func symIsRO(sym interface{}) bool {
1618 lsym := sym.(*obj.LSym)
1619 return lsym.Type == objabi.SRODATA && len(lsym.R) == 0
1622 // symIsROZero reports whether sym is a read-only global whose data contains all zeros.
1623 func symIsROZero(sym Sym) bool {
1624 lsym := sym.(*obj.LSym)
1625 if lsym.Type != objabi.SRODATA || len(lsym.R) != 0 {
1628 for _, b := range lsym.P {
1636 // read8 reads one byte from the read-only global sym at offset off.
1637 func read8(sym interface{}, off int64) uint8 {
1638 lsym := sym.(*obj.LSym)
1639 if off >= int64(len(lsym.P)) || off < 0 {
1640 // Invalid index into the global sym.
1641 // This can happen in dead code, so we don't want to panic.
1642 // Just return any value, it will eventually get ignored.
1649 // read16 reads two bytes from the read-only global sym at offset off.
1650 func read16(sym interface{}, off int64, byteorder binary.ByteOrder) uint16 {
1651 lsym := sym.(*obj.LSym)
1652 // lsym.P is written lazily.
1653 // Bytes requested after the end of lsym.P are 0.
1655 if 0 <= off && off < int64(len(lsym.P)) {
1658 buf := make([]byte, 2)
1660 return byteorder.Uint16(buf)
1663 // read32 reads four bytes from the read-only global sym at offset off.
1664 func read32(sym interface{}, off int64, byteorder binary.ByteOrder) uint32 {
1665 lsym := sym.(*obj.LSym)
1667 if 0 <= off && off < int64(len(lsym.P)) {
1670 buf := make([]byte, 4)
1672 return byteorder.Uint32(buf)
1675 // read64 reads eight bytes from the read-only global sym at offset off.
1676 func read64(sym interface{}, off int64, byteorder binary.ByteOrder) uint64 {
1677 lsym := sym.(*obj.LSym)
1679 if 0 <= off && off < int64(len(lsym.P)) {
1682 buf := make([]byte, 8)
1684 return byteorder.Uint64(buf)
1687 // sequentialAddresses reports true if it can prove that x + n == y
1688 func sequentialAddresses(x, y *Value, n int64) bool {
1689 if x.Op == Op386ADDL && y.Op == Op386LEAL1 && y.AuxInt == n && y.Aux == nil &&
1690 (x.Args[0] == y.Args[0] && x.Args[1] == y.Args[1] ||
1691 x.Args[0] == y.Args[1] && x.Args[1] == y.Args[0]) {
1694 if x.Op == Op386LEAL1 && y.Op == Op386LEAL1 && y.AuxInt == x.AuxInt+n && x.Aux == y.Aux &&
1695 (x.Args[0] == y.Args[0] && x.Args[1] == y.Args[1] ||
1696 x.Args[0] == y.Args[1] && x.Args[1] == y.Args[0]) {
1699 if x.Op == OpAMD64ADDQ && y.Op == OpAMD64LEAQ1 && y.AuxInt == n && y.Aux == nil &&
1700 (x.Args[0] == y.Args[0] && x.Args[1] == y.Args[1] ||
1701 x.Args[0] == y.Args[1] && x.Args[1] == y.Args[0]) {
1704 if x.Op == OpAMD64LEAQ1 && y.Op == OpAMD64LEAQ1 && y.AuxInt == x.AuxInt+n && x.Aux == y.Aux &&
1705 (x.Args[0] == y.Args[0] && x.Args[1] == y.Args[1] ||
1706 x.Args[0] == y.Args[1] && x.Args[1] == y.Args[0]) {
1712 // flagConstant represents the result of a compile-time comparison.
1713 // The sense of these flags does not necessarily represent the hardware's notion
1714 // of a flags register - these are just a compile-time construct.
1715 // We happen to match the semantics to those of arm/arm64.
1716 // Note that these semantics differ from x86: the carry flag has the opposite
1717 // sense on a subtraction!
1718 // On amd64, C=1 represents a borrow, e.g. SBB on amd64 does x - y - C.
1719 // On arm64, C=0 represents a borrow, e.g. SBC on arm64 does x - y - ^C.
1720 // (because it does x + ^y + C).
1721 // See https://en.wikipedia.org/wiki/Carry_flag#Vs._borrow_flag
1722 type flagConstant uint8
1724 // N reports whether the result of an operation is negative (high bit set).
1725 func (fc flagConstant) N() bool {
1729 // Z reports whether the result of an operation is 0.
1730 func (fc flagConstant) Z() bool {
1734 // C reports whether an unsigned add overflowed (carry), or an
1735 // unsigned subtract did not underflow (borrow).
1736 func (fc flagConstant) C() bool {
1740 // V reports whether a signed operation overflowed or underflowed.
1741 func (fc flagConstant) V() bool {
1745 func (fc flagConstant) eq() bool {
1748 func (fc flagConstant) ne() bool {
1751 func (fc flagConstant) lt() bool {
1752 return fc.N() != fc.V()
1754 func (fc flagConstant) le() bool {
1755 return fc.Z() || fc.lt()
1757 func (fc flagConstant) gt() bool {
1758 return !fc.Z() && fc.ge()
1760 func (fc flagConstant) ge() bool {
1761 return fc.N() == fc.V()
1763 func (fc flagConstant) ult() bool {
1766 func (fc flagConstant) ule() bool {
1767 return fc.Z() || fc.ult()
1769 func (fc flagConstant) ugt() bool {
1770 return !fc.Z() && fc.uge()
1772 func (fc flagConstant) uge() bool {
1776 func (fc flagConstant) ltNoov() bool {
1777 return fc.lt() && !fc.V()
1779 func (fc flagConstant) leNoov() bool {
1780 return fc.le() && !fc.V()
1782 func (fc flagConstant) gtNoov() bool {
1783 return fc.gt() && !fc.V()
1785 func (fc flagConstant) geNoov() bool {
1786 return fc.ge() && !fc.V()
1789 func (fc flagConstant) String() string {
1790 return fmt.Sprintf("N=%v,Z=%v,C=%v,V=%v", fc.N(), fc.Z(), fc.C(), fc.V())
1793 type flagConstantBuilder struct {
1800 func (fcs flagConstantBuilder) encode() flagConstant {
1817 // Note: addFlags(x,y) != subFlags(x,-y) in some situations:
1818 // - the results of the C flag are different
1819 // - the results of the V flag when y==minint are different
1821 // addFlags64 returns the flags that would be set from computing x+y.
1822 func addFlags64(x, y int64) flagConstant {
1823 var fcb flagConstantBuilder
1826 fcb.C = uint64(x+y) < uint64(x)
1827 fcb.V = x >= 0 && y >= 0 && x+y < 0 || x < 0 && y < 0 && x+y >= 0
1831 // subFlags64 returns the flags that would be set from computing x-y.
1832 func subFlags64(x, y int64) flagConstant {
1833 var fcb flagConstantBuilder
1836 fcb.C = uint64(y) <= uint64(x) // This code follows the arm carry flag model.
1837 fcb.V = x >= 0 && y < 0 && x-y < 0 || x < 0 && y >= 0 && x-y >= 0
1841 // addFlags32 returns the flags that would be set from computing x+y.
1842 func addFlags32(x, y int32) flagConstant {
1843 var fcb flagConstantBuilder
1846 fcb.C = uint32(x+y) < uint32(x)
1847 fcb.V = x >= 0 && y >= 0 && x+y < 0 || x < 0 && y < 0 && x+y >= 0
1851 // subFlags32 returns the flags that would be set from computing x-y.
1852 func subFlags32(x, y int32) flagConstant {
1853 var fcb flagConstantBuilder
1856 fcb.C = uint32(y) <= uint32(x) // This code follows the arm carry flag model.
1857 fcb.V = x >= 0 && y < 0 && x-y < 0 || x < 0 && y >= 0 && x-y >= 0
1861 // logicFlags64 returns flags set to the sign/zeroness of x.
1862 // C and V are set to false.
1863 func logicFlags64(x int64) flagConstant {
1864 var fcb flagConstantBuilder
1870 // logicFlags32 returns flags set to the sign/zeroness of x.
1871 // C and V are set to false.
1872 func logicFlags32(x int32) flagConstant {
1873 var fcb flagConstantBuilder