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[release-branch.go1.8] cmd/compile: add opcode flag hasSideEffects for do-not-remove
Added a flag to generic and various architectures' atomic operations that are judged to have observable side effects and thus cannot be dead-code-eliminated. Test requires GOMAXPROCS > 1 without preemption in loop. Fixes #19182. Change-Id: Id2230031abd2cca0bbb32fd68fc8a58fb912070f Reviewed-on: https://go-review.googlesource.com/39595 Run-TryBot: Austin Clements <[email protected]> TryBot-Result: Gobot Gobot <[email protected]> Reviewed-by: David Chase <[email protected]>
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+168
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‎src/cmd/compile/internal/ssa/deadcode.go

+1-1
Original file line numberDiff line numberDiff line change
@@ -64,7 +64,7 @@ func liveValues(f *Func, reachable []bool) []bool {
6464
q = append(q, v)
6565
}
6666
for _, v := range b.Values {
67-
if opcodeTable[v.Op].call && !live[v.ID] {
67+
if (opcodeTable[v.Op].call || opcodeTable[v.Op].hasSideEffects) && !live[v.ID] {
6868
live[v.ID] = true
6969
q = append(q, v)
7070
}

‎src/cmd/compile/internal/ssa/gen/AMD64Ops.go

+8-8
Original file line numberDiff line numberDiff line change
@@ -522,15 +522,15 @@ func init() {
522522
// store arg0 to arg1+auxint+aux, arg2=mem.
523523
// These ops return a tuple of <old contents of *(arg1+auxint+aux), memory>.
524524
// Note: arg0 and arg1 are backwards compared to MOVLstore (to facilitate resultInArg0)!
525-
{name: "XCHGL", argLength: 3, reg: gpstorexchg, asm: "XCHGL", aux: "SymOff", resultInArg0: true, faultOnNilArg1: true},
526-
{name: "XCHGQ", argLength: 3, reg: gpstorexchg, asm: "XCHGQ", aux: "SymOff", resultInArg0: true, faultOnNilArg1: true},
525+
{name: "XCHGL", argLength: 3, reg: gpstorexchg, asm: "XCHGL", aux: "SymOff", resultInArg0: true, faultOnNilArg1: true, hasSideEffects: true},
526+
{name: "XCHGQ", argLength: 3, reg: gpstorexchg, asm: "XCHGQ", aux: "SymOff", resultInArg0: true, faultOnNilArg1: true, hasSideEffects: true},
527527

528528
// Atomic adds.
529529
// *(arg1+auxint+aux) += arg0. arg2=mem.
530530
// Returns a tuple of <old contents of *(arg1+auxint+aux), memory>.
531531
// Note: arg0 and arg1 are backwards compared to MOVLstore (to facilitate resultInArg0)!
532-
{name: "XADDLlock", argLength: 3, reg: gpstorexchg, asm: "XADDL", typ: "(UInt32,Mem)", aux: "SymOff", resultInArg0: true, clobberFlags: true, faultOnNilArg1: true},
533-
{name: "XADDQlock", argLength: 3, reg: gpstorexchg, asm: "XADDQ", typ: "(UInt64,Mem)", aux: "SymOff", resultInArg0: true, clobberFlags: true, faultOnNilArg1: true},
532+
{name: "XADDLlock", argLength: 3, reg: gpstorexchg, asm: "XADDL", typ: "(UInt32,Mem)", aux: "SymOff", resultInArg0: true, clobberFlags: true, faultOnNilArg1: true, hasSideEffects: true},
533+
{name: "XADDQlock", argLength: 3, reg: gpstorexchg, asm: "XADDQ", typ: "(UInt64,Mem)", aux: "SymOff", resultInArg0: true, clobberFlags: true, faultOnNilArg1: true, hasSideEffects: true},
534534
{name: "AddTupleFirst32", argLength: 2}, // arg0=tuple <x,y>. Returns <x+arg1,y>.
535535
{name: "AddTupleFirst64", argLength: 2}, // arg0=tuple <x,y>. Returns <x+arg1,y>.
536536

@@ -553,12 +553,12 @@ func init() {
553553
// JEQ ...
554554
// but we can't do that because memory-using ops can't generate flags yet
555555
// (flagalloc wants to move flag-generating instructions around).
556-
{name: "CMPXCHGLlock", argLength: 4, reg: cmpxchg, asm: "CMPXCHGL", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true},
557-
{name: "CMPXCHGQlock", argLength: 4, reg: cmpxchg, asm: "CMPXCHGQ", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true},
556+
{name: "CMPXCHGLlock", argLength: 4, reg: cmpxchg, asm: "CMPXCHGL", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true},
557+
{name: "CMPXCHGQlock", argLength: 4, reg: cmpxchg, asm: "CMPXCHGQ", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true},
558558

559559
// Atomic memory updates.
560-
{name: "ANDBlock", argLength: 3, reg: gpstore, asm: "ANDB", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true}, // *(arg0+auxint+aux) &= arg1
561-
{name: "ORBlock", argLength: 3, reg: gpstore, asm: "ORB", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true}, // *(arg0+auxint+aux) |= arg1
560+
{name: "ANDBlock", argLength: 3, reg: gpstore, asm: "ANDB", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true}, // *(arg0+auxint+aux) &= arg1
561+
{name: "ORBlock", argLength: 3, reg: gpstore, asm: "ORB", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true}, // *(arg0+auxint+aux) |= arg1
562562
}
563563

564564
var AMD64blocks = []blockData{

‎src/cmd/compile/internal/ssa/gen/ARM64Ops.go

+10-10
Original file line numberDiff line numberDiff line change
@@ -456,25 +456,25 @@ func init() {
456456

457457
// atomic stores.
458458
// store arg1 to arg0. arg2=mem. returns memory. auxint must be zero.
459-
{name: "STLR", argLength: 3, reg: gpstore, asm: "STLR", faultOnNilArg0: true},
460-
{name: "STLRW", argLength: 3, reg: gpstore, asm: "STLRW", faultOnNilArg0: true},
459+
{name: "STLR", argLength: 3, reg: gpstore, asm: "STLR", faultOnNilArg0: true, hasSideEffects: true},
460+
{name: "STLRW", argLength: 3, reg: gpstore, asm: "STLRW", faultOnNilArg0: true, hasSideEffects: true},
461461

462462
// atomic exchange.
463463
// store arg1 to arg0. arg2=mem. returns <old content of *arg0, memory>. auxint must be zero.
464464
// LDAXR (Rarg0), Rout
465465
// STLXR Rarg1, (Rarg0), Rtmp
466466
// CBNZ Rtmp, -2(PC)
467-
{name: "LoweredAtomicExchange64", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true},
468-
{name: "LoweredAtomicExchange32", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true},
467+
{name: "LoweredAtomicExchange64", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true, hasSideEffects: true},
468+
{name: "LoweredAtomicExchange32", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true, hasSideEffects: true},
469469

470470
// atomic add.
471471
// *arg0 += arg1. arg2=mem. returns <new content of *arg0, memory>. auxint must be zero.
472472
// LDAXR (Rarg0), Rout
473473
// ADD Rarg1, Rout
474474
// STLXR Rout, (Rarg0), Rtmp
475475
// CBNZ Rtmp, -3(PC)
476-
{name: "LoweredAtomicAdd64", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true},
477-
{name: "LoweredAtomicAdd32", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true},
476+
{name: "LoweredAtomicAdd64", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true, hasSideEffects: true},
477+
{name: "LoweredAtomicAdd32", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true, hasSideEffects: true},
478478

479479
// atomic compare and swap.
480480
// arg0 = pointer, arg1 = old value, arg2 = new value, arg3 = memory. auxint must be zero.
@@ -490,17 +490,17 @@ func init() {
490490
// STLXR Rarg2, (Rarg0), Rtmp
491491
// CBNZ Rtmp, -4(PC)
492492
// CSET EQ, Rout
493-
{name: "LoweredAtomicCas64", argLength: 4, reg: gpcas, resultNotInArgs: true, clobberFlags: true, faultOnNilArg0: true},
494-
{name: "LoweredAtomicCas32", argLength: 4, reg: gpcas, resultNotInArgs: true, clobberFlags: true, faultOnNilArg0: true},
493+
{name: "LoweredAtomicCas64", argLength: 4, reg: gpcas, resultNotInArgs: true, clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true},
494+
{name: "LoweredAtomicCas32", argLength: 4, reg: gpcas, resultNotInArgs: true, clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true},
495495

496496
// atomic and/or.
497497
// *arg0 &= (|=) arg1. arg2=mem. returns memory. auxint must be zero.
498498
// LDAXRB (Rarg0), Rtmp
499499
// AND/OR Rarg1, Rtmp
500500
// STLXRB Rtmp, (Rarg0), Rtmp
501501
// CBNZ Rtmp, -3(PC)
502-
{name: "LoweredAtomicAnd8", argLength: 3, reg: gpstore, asm: "AND", faultOnNilArg0: true},
503-
{name: "LoweredAtomicOr8", argLength: 3, reg: gpstore, asm: "ORR", faultOnNilArg0: true},
502+
{name: "LoweredAtomicAnd8", argLength: 3, reg: gpstore, asm: "AND", faultOnNilArg0: true, hasSideEffects: true},
503+
{name: "LoweredAtomicOr8", argLength: 3, reg: gpstore, asm: "ORR", faultOnNilArg0: true, hasSideEffects: true},
504504
}
505505

506506
blocks := []blockData{

‎src/cmd/compile/internal/ssa/gen/MIPSOps.go

+8-8
Original file line numberDiff line numberDiff line change
@@ -267,8 +267,8 @@ func init() {
267267
// SYNC
268268
// MOVW Rarg1, (Rarg0)
269269
// SYNC
270-
{name: "LoweredAtomicStore", argLength: 3, reg: gpstore, faultOnNilArg0: true},
271-
{name: "LoweredAtomicStorezero", argLength: 2, reg: gpstore0, faultOnNilArg0: true},
270+
{name: "LoweredAtomicStore", argLength: 3, reg: gpstore, faultOnNilArg0: true, hasSideEffects: true},
271+
{name: "LoweredAtomicStorezero", argLength: 2, reg: gpstore0, faultOnNilArg0: true, hasSideEffects: true},
272272

273273
// atomic exchange.
274274
// store arg1 to arg0. arg2=mem. returns <old content of *arg0, memory>.
@@ -278,7 +278,7 @@ func init() {
278278
// SC Rtmp, (Rarg0)
279279
// BEQ Rtmp, -3(PC)
280280
// SYNC
281-
{name: "LoweredAtomicExchange", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true},
281+
{name: "LoweredAtomicExchange", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true, hasSideEffects: true},
282282

283283
// atomic add.
284284
// *arg0 += arg1. arg2=mem. returns <new content of *arg0, memory>.
@@ -289,8 +289,8 @@ func init() {
289289
// BEQ Rtmp, -3(PC)
290290
// SYNC
291291
// ADDU Rarg1, Rout
292-
{name: "LoweredAtomicAdd", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true},
293-
{name: "LoweredAtomicAddconst", argLength: 2, reg: regInfo{inputs: []regMask{gpspsbg}, outputs: []regMask{gp}}, aux: "Int32", resultNotInArgs: true, faultOnNilArg0: true},
292+
{name: "LoweredAtomicAdd", argLength: 3, reg: gpxchg, resultNotInArgs: true, faultOnNilArg0: true, hasSideEffects: true},
293+
{name: "LoweredAtomicAddconst", argLength: 2, reg: regInfo{inputs: []regMask{gpspsbg}, outputs: []regMask{gp}}, aux: "Int32", resultNotInArgs: true, faultOnNilArg0: true, hasSideEffects: true},
294294

295295
// atomic compare and swap.
296296
// arg0 = pointer, arg1 = old value, arg2 = new value, arg3 = memory.
@@ -308,7 +308,7 @@ func init() {
308308
// SC Rout, (Rarg0)
309309
// BEQ Rout, -4(PC)
310310
// SYNC
311-
{name: "LoweredAtomicCas", argLength: 4, reg: gpcas, resultNotInArgs: true, faultOnNilArg0: true},
311+
{name: "LoweredAtomicCas", argLength: 4, reg: gpcas, resultNotInArgs: true, faultOnNilArg0: true, hasSideEffects: true},
312312

313313
// atomic and/or.
314314
// *arg0 &= (|=) arg1. arg2=mem. returns memory.
@@ -318,8 +318,8 @@ func init() {
318318
// SC Rtmp, (Rarg0)
319319
// BEQ Rtmp, -3(PC)
320320
// SYNC
321-
{name: "LoweredAtomicAnd", argLength: 3, reg: gpstore, asm: "AND", faultOnNilArg0: true},
322-
{name: "LoweredAtomicOr", argLength: 3, reg: gpstore, asm: "OR", faultOnNilArg0: true},
321+
{name: "LoweredAtomicAnd", argLength: 3, reg: gpstore, asm: "AND", faultOnNilArg0: true, hasSideEffects: true},
322+
{name: "LoweredAtomicOr", argLength: 3, reg: gpstore, asm: "OR", faultOnNilArg0: true, hasSideEffects: true},
323323

324324
// large or unaligned zeroing
325325
// arg0 = address of memory to zero (in R1, changed as side effect)

‎src/cmd/compile/internal/ssa/gen/S390XOps.go

+8-8
Original file line numberDiff line numberDiff line change
@@ -429,14 +429,14 @@ func init() {
429429

430430
// Atomic stores. These are just normal stores.
431431
// store arg1 to arg0+auxint+aux. arg2=mem.
432-
{name: "MOVWatomicstore", argLength: 3, reg: gpstore, asm: "MOVW", aux: "SymOff", typ: "Mem", clobberFlags: true, faultOnNilArg0: true},
433-
{name: "MOVDatomicstore", argLength: 3, reg: gpstore, asm: "MOVD", aux: "SymOff", typ: "Mem", clobberFlags: true, faultOnNilArg0: true},
432+
{name: "MOVWatomicstore", argLength: 3, reg: gpstore, asm: "MOVW", aux: "SymOff", typ: "Mem", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true},
433+
{name: "MOVDatomicstore", argLength: 3, reg: gpstore, asm: "MOVD", aux: "SymOff", typ: "Mem", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true},
434434

435435
// Atomic adds.
436436
// *(arg0+auxint+aux) += arg1. arg2=mem.
437437
// Returns a tuple of <old contents of *(arg0+auxint+aux), memory>.
438-
{name: "LAA", argLength: 3, reg: gpstorelaa, asm: "LAA", typ: "(UInt32,Mem)", aux: "SymOff", faultOnNilArg0: true},
439-
{name: "LAAG", argLength: 3, reg: gpstorelaa, asm: "LAAG", typ: "(UInt64,Mem)", aux: "SymOff", faultOnNilArg0: true},
438+
{name: "LAA", argLength: 3, reg: gpstorelaa, asm: "LAA", typ: "(UInt32,Mem)", aux: "SymOff", faultOnNilArg0: true, hasSideEffects: true},
439+
{name: "LAAG", argLength: 3, reg: gpstorelaa, asm: "LAAG", typ: "(UInt64,Mem)", aux: "SymOff", faultOnNilArg0: true, hasSideEffects: true},
440440
{name: "AddTupleFirst32", argLength: 2}, // arg0=tuple <x,y>. Returns <x+arg1,y>.
441441
{name: "AddTupleFirst64", argLength: 2}, // arg0=tuple <x,y>. Returns <x+arg1,y>.
442442

@@ -461,13 +461,13 @@ func init() {
461461
// BEQ ...
462462
// but we can't do that because memory-using ops can't generate flags yet
463463
// (flagalloc wants to move flag-generating instructions around).
464-
{name: "LoweredAtomicCas32", argLength: 4, reg: cas, asm: "CS", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true},
465-
{name: "LoweredAtomicCas64", argLength: 4, reg: cas, asm: "CSG", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true},
464+
{name: "LoweredAtomicCas32", argLength: 4, reg: cas, asm: "CS", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true},
465+
{name: "LoweredAtomicCas64", argLength: 4, reg: cas, asm: "CSG", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true},
466466

467467
// Lowered atomic swaps, emulated using compare-and-swap.
468468
// store arg1 to arg0+auxint+aux, arg2=mem.
469-
{name: "LoweredAtomicExchange32", argLength: 3, reg: exchange, asm: "CS", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true},
470-
{name: "LoweredAtomicExchange64", argLength: 3, reg: exchange, asm: "CSG", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true},
469+
{name: "LoweredAtomicExchange32", argLength: 3, reg: exchange, asm: "CS", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true},
470+
{name: "LoweredAtomicExchange64", argLength: 3, reg: exchange, asm: "CSG", aux: "SymOff", clobberFlags: true, faultOnNilArg0: true, hasSideEffects: true},
471471

472472
// find leftmost one
473473
{

‎src/cmd/compile/internal/ssa/gen/genericOps.go

+14-14
Original file line numberDiff line numberDiff line change
@@ -460,20 +460,20 @@ var genericOps = []opData{
460460
// Atomic loads return a new memory so that the loads are properly ordered
461461
// with respect to other loads and stores.
462462
// TODO: use for sync/atomic at some point.
463-
{name: "AtomicLoad32", argLength: 2, typ: "(UInt32,Mem)"}, // Load from arg0. arg1=memory. Returns loaded value and new memory.
464-
{name: "AtomicLoad64", argLength: 2, typ: "(UInt64,Mem)"}, // Load from arg0. arg1=memory. Returns loaded value and new memory.
465-
{name: "AtomicLoadPtr", argLength: 2, typ: "(BytePtr,Mem)"}, // Load from arg0. arg1=memory. Returns loaded value and new memory.
466-
{name: "AtomicStore32", argLength: 3, typ: "Mem"}, // Store arg1 to *arg0. arg2=memory. Returns memory.
467-
{name: "AtomicStore64", argLength: 3, typ: "Mem"}, // Store arg1 to *arg0. arg2=memory. Returns memory.
468-
{name: "AtomicStorePtrNoWB", argLength: 3, typ: "Mem"}, // Store arg1 to *arg0. arg2=memory. Returns memory.
469-
{name: "AtomicExchange32", argLength: 3, typ: "(UInt32,Mem)"}, // Store arg1 to *arg0. arg2=memory. Returns old contents of *arg0 and new memory.
470-
{name: "AtomicExchange64", argLength: 3, typ: "(UInt64,Mem)"}, // Store arg1 to *arg0. arg2=memory. Returns old contents of *arg0 and new memory.
471-
{name: "AtomicAdd32", argLength: 3, typ: "(UInt32,Mem)"}, // Do *arg0 += arg1. arg2=memory. Returns sum and new memory.
472-
{name: "AtomicAdd64", argLength: 3, typ: "(UInt64,Mem)"}, // Do *arg0 += arg1. arg2=memory. Returns sum and new memory.
473-
{name: "AtomicCompareAndSwap32", argLength: 4, typ: "(Bool,Mem)"}, // if *arg0==arg1, then set *arg0=arg2. Returns true iff store happens and new memory.
474-
{name: "AtomicCompareAndSwap64", argLength: 4, typ: "(Bool,Mem)"}, // if *arg0==arg1, then set *arg0=arg2. Returns true iff store happens and new memory.
475-
{name: "AtomicAnd8", argLength: 3, typ: "Mem"}, // *arg0 &= arg1. arg2=memory. Returns memory.
476-
{name: "AtomicOr8", argLength: 3, typ: "Mem"}, // *arg0 |= arg1. arg2=memory. Returns memory.
463+
{name: "AtomicLoad32", argLength: 2, typ: "(UInt32,Mem)"}, // Load from arg0. arg1=memory. Returns loaded value and new memory.
464+
{name: "AtomicLoad64", argLength: 2, typ: "(UInt64,Mem)"}, // Load from arg0. arg1=memory. Returns loaded value and new memory.
465+
{name: "AtomicLoadPtr", argLength: 2, typ: "(BytePtr,Mem)"}, // Load from arg0. arg1=memory. Returns loaded value and new memory.
466+
{name: "AtomicStore32", argLength: 3, typ: "Mem", hasSideEffects: true}, // Store arg1 to *arg0. arg2=memory. Returns memory.
467+
{name: "AtomicStore64", argLength: 3, typ: "Mem", hasSideEffects: true}, // Store arg1 to *arg0. arg2=memory. Returns memory.
468+
{name: "AtomicStorePtrNoWB", argLength: 3, typ: "Mem", hasSideEffects: true}, // Store arg1 to *arg0. arg2=memory. Returns memory.
469+
{name: "AtomicExchange32", argLength: 3, typ: "(UInt32,Mem)", hasSideEffects: true}, // Store arg1 to *arg0. arg2=memory. Returns old contents of *arg0 and new memory.
470+
{name: "AtomicExchange64", argLength: 3, typ: "(UInt64,Mem)", hasSideEffects: true}, // Store arg1 to *arg0. arg2=memory. Returns old contents of *arg0 and new memory.
471+
{name: "AtomicAdd32", argLength: 3, typ: "(UInt32,Mem)", hasSideEffects: true}, // Do *arg0 += arg1. arg2=memory. Returns sum and new memory.
472+
{name: "AtomicAdd64", argLength: 3, typ: "(UInt64,Mem)", hasSideEffects: true}, // Do *arg0 += arg1. arg2=memory. Returns sum and new memory.
473+
{name: "AtomicCompareAndSwap32", argLength: 4, typ: "(Bool,Mem)", hasSideEffects: true}, // if *arg0==arg1, then set *arg0=arg2. Returns true iff store happens and new memory.
474+
{name: "AtomicCompareAndSwap64", argLength: 4, typ: "(Bool,Mem)", hasSideEffects: true}, // if *arg0==arg1, then set *arg0=arg2. Returns true iff store happens and new memory.
475+
{name: "AtomicAnd8", argLength: 3, typ: "Mem", hasSideEffects: true}, // *arg0 &= arg1. arg2=memory. Returns memory.
476+
{name: "AtomicOr8", argLength: 3, typ: "Mem", hasSideEffects: true}, // *arg0 |= arg1. arg2=memory. Returns memory.
477477
}
478478

479479
// kind control successors implicit exit

‎src/cmd/compile/internal/ssa/gen/main.go

+4
Original file line numberDiff line numberDiff line change
@@ -52,6 +52,7 @@ type opData struct {
5252
faultOnNilArg0 bool // this op will fault if arg0 is nil (and aux encodes a small offset)
5353
faultOnNilArg1 bool // this op will fault if arg1 is nil (and aux encodes a small offset)
5454
usesScratch bool // this op requires scratch memory space
55+
hasSideEffects bool // for "reasons", not to be eliminated. E.g., atomic store, #19182.
5556
}
5657

5758
type blockData struct {
@@ -208,6 +209,9 @@ func genOp() {
208209
if v.usesScratch {
209210
fmt.Fprintln(w, "usesScratch: true,")
210211
}
212+
if v.hasSideEffects {
213+
fmt.Fprintln(w, "hasSideEffects: true,")
214+
}
211215
if a.name == "generic" {
212216
fmt.Fprintln(w, "generic:true,")
213217
fmt.Fprintln(w, "},") // close op

‎src/cmd/compile/internal/ssa/op.go

+1
Original file line numberDiff line numberDiff line change
@@ -34,6 +34,7 @@ type opInfo struct {
3434
faultOnNilArg0 bool // this op will fault if arg0 is nil (and aux encodes a small offset)
3535
faultOnNilArg1 bool // this op will fault if arg1 is nil (and aux encodes a small offset)
3636
usesScratch bool // this op requires scratch memory space
37+
hasSideEffects bool // for "reasons", not to be eliminated. E.g., atomic store, #19182.
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}
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type inputInfo struct {

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