cmd/compiler,internal/runtime/atomic: optimize Store{64,32,8} on loong64

On Loong64, AMSWAPDB{W,V} instructions are supported by default, and AMSWAPDB{B,H} [1]
is a new instruction added by LA664(Loongson 3A6000) and later microarchitectures.
Therefore, AMSWAPDB{W,V} (full barrier) is used to implement AtomicStore{32,64}, and
the traditional MOVB or the new AMSWAPDBB is used to implement AtomicStore8 according
to the CPU feature.

The StoreRelease barrier on Loong64 is "dbar 0x12", but it is still necessary to
ensure consistency in the order of Store/Load [2].

LoweredAtomicStorezero{32,64} was removed because on loong64 the constant "0" uses
the R0 register, and there is no performance difference between the implementations
of LoweredAtomicStorezero{32,64} and LoweredAtomicStore{32,64}.

goos: linux
goarch: loong64
pkg: internal/runtime/atomic
cpu: Loongson-3A5000-HV @ 2500.00MHz
                |  bench.old  |              bench.new              |
                |   sec/op    |   sec/op     vs base                |
AtomicStore64     19.61n ± 0%   13.61n ± 0%  -30.60% (p=0.000 n=20)
AtomicStore64-2   19.61n ± 0%   13.61n ± 0%  -30.57% (p=0.000 n=20)
AtomicStore64-4   19.62n ± 0%   13.61n ± 0%  -30.63% (p=0.000 n=20)
AtomicStore       19.61n ± 0%   13.61n ± 0%  -30.60% (p=0.000 n=20)
AtomicStore-2     19.62n ± 0%   13.61n ± 0%  -30.63% (p=0.000 n=20)
AtomicStore-4     19.62n ± 0%   13.62n ± 0%  -30.58% (p=0.000 n=20)
AtomicStore8      19.61n ± 0%   20.01n ± 0%   +2.04% (p=0.000 n=20)
AtomicStore8-2    19.62n ± 0%   20.02n ± 0%   +2.01% (p=0.000 n=20)
AtomicStore8-4    19.61n ± 0%   20.02n ± 0%   +2.09% (p=0.000 n=20)
geomean           19.61n        15.48n       -21.08%

goos: linux
goarch: loong64
pkg: internal/runtime/atomic
cpu: Loongson-3A6000 @ 2500.00MHz
                |  bench.old  |              bench.new              |
                |   sec/op    |   sec/op     vs base                |
AtomicStore64     18.03n ± 0%   12.81n ± 0%  -28.93% (p=0.000 n=20)
AtomicStore64-2   18.02n ± 0%   12.81n ± 0%  -28.91% (p=0.000 n=20)
AtomicStore64-4   18.01n ± 0%   12.81n ± 0%  -28.87% (p=0.000 n=20)
AtomicStore       18.02n ± 0%   12.81n ± 0%  -28.91% (p=0.000 n=20)
AtomicStore-2     18.01n ± 0%   12.81n ± 0%  -28.87% (p=0.000 n=20)
AtomicStore-4     18.01n ± 0%   12.81n ± 0%  -28.87% (p=0.000 n=20)
AtomicStore8      18.01n ± 0%   12.81n ± 0%  -28.87% (p=0.000 n=20)
AtomicStore8-2    18.01n ± 0%   12.81n ± 0%  -28.87% (p=0.000 n=20)
AtomicStore8-4    18.01n ± 0%   12.81n ± 0%  -28.87% (p=0.000 n=20)
geomean           18.01n        12.81n       -28.89%

[1]: https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html
[2]: https://gcc.gnu.org/git/?p=gcc.git;a=blob_plain;f=gcc/config/loongarch/sync.md

Change-Id: I4ae5e8dd0e6f026129b6e503990a763ed40c6097
Reviewed-on: https://go-review.googlesource.com/c/go/+/581356
Reviewed-by: sophie zhao <zhaoxiaolin@loongson.cn>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Qiqi Huang <huangqiqi@loongson.cn>
Reviewed-by: Meidan Li <limeidan@loongson.cn>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>

13 files changed, 210 insertions, 91 deletions

diff --git a/src/cmd/compile/internal/ir/symtab.go b/src/cmd/compile/internal/ir/symtab.go
index 3cdef10230..9a68c9055e 100644
--- a/src/cmd/compile/internal/ir/symtab.go
+++ b/src/cmd/compile/internal/ir/symtab.go
@@ -52,17 +52,18 @@ type symsStruct struct {
 	WBZero            *obj.LSym
 	WBMove            *obj.LSym
 	// Wasm
-	SigPanic        *obj.LSym
-	Staticuint64s   *obj.LSym
-	Typedmemmove    *obj.LSym
-	Udiv            *obj.LSym
-	WriteBarrier    *obj.LSym
-	Zerobase        *obj.LSym
-	ARM64HasATOMICS *obj.LSym
-	ARMHasVFPv4     *obj.LSym
-	X86HasFMA       *obj.LSym
-	X86HasPOPCNT    *obj.LSym
-	X86HasSSE41     *obj.LSym
+	SigPanic         *obj.LSym
+	Staticuint64s    *obj.LSym
+	Typedmemmove     *obj.LSym
+	Udiv             *obj.LSym
+	WriteBarrier     *obj.LSym
+	Zerobase         *obj.LSym
+	ARM64HasATOMICS  *obj.LSym
+	ARMHasVFPv4      *obj.LSym
+	Loong64HasLAM_BH *obj.LSym
+	X86HasFMA        *obj.LSym
+	X86HasPOPCNT     *obj.LSym
+	X86HasSSE41      *obj.LSym
 	// Wasm
 	WasmDiv *obj.LSym
 	// Wasm
diff --git a/src/cmd/compile/internal/loong64/ssa.go b/src/cmd/compile/internal/loong64/ssa.go
index 2dadda8860..7cdaa30ffe 100644
--- a/src/cmd/compile/internal/loong64/ssa.go
+++ b/src/cmd/compile/internal/loong64/ssa.go
@@ -614,33 +614,51 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 		p1.From.Type = obj.TYPE_CONST
 		p1.From.Offset = 0x14
 
-	case ssa.OpLOONG64LoweredAtomicStore8, ssa.OpLOONG64LoweredAtomicStore32, ssa.OpLOONG64LoweredAtomicStore64:
-		as := loong64.AMOVV
+	case ssa.OpLOONG64LoweredAtomicStore8,
+		ssa.OpLOONG64LoweredAtomicStore32,
+		ssa.OpLOONG64LoweredAtomicStore64:
+		// DBAR 0x12
+		// MOVx (Rarg1), Rout
+		// DBAR 0x18
+		movx := loong64.AMOVV
 		switch v.Op {
 		case ssa.OpLOONG64LoweredAtomicStore8:
-			as = loong64.AMOVB
+			movx = loong64.AMOVB
 		case ssa.OpLOONG64LoweredAtomicStore32:
-			as = loong64.AMOVW
+			movx = loong64.AMOVW
 		}
-		s.Prog(loong64.ADBAR)
-		p := s.Prog(as)
-		p.From.Type = obj.TYPE_REG
-		p.From.Reg = v.Args[1].Reg()
-		p.To.Type = obj.TYPE_MEM
-		p.To.Reg = v.Args[0].Reg()
-		s.Prog(loong64.ADBAR)
-	case ssa.OpLOONG64LoweredAtomicStorezero32, ssa.OpLOONG64LoweredAtomicStorezero64:
-		as := loong64.AMOVV
-		if v.Op == ssa.OpLOONG64LoweredAtomicStorezero32 {
-			as = loong64.AMOVW
+		p := s.Prog(loong64.ADBAR)
+		p.From.Type = obj.TYPE_CONST
+		p.From.Offset = 0x12
+
+		p1 := s.Prog(movx)
+		p1.From.Type = obj.TYPE_REG
+		p1.From.Reg = v.Args[1].Reg()
+		p1.To.Type = obj.TYPE_MEM
+		p1.To.Reg = v.Args[0].Reg()
+
+		p2 := s.Prog(loong64.ADBAR)
+		p2.From.Type = obj.TYPE_CONST
+		p2.From.Offset = 0x18
+
+	case ssa.OpLOONG64LoweredAtomicStore8Variant,
+		ssa.OpLOONG64LoweredAtomicStore32Variant,
+		ssa.OpLOONG64LoweredAtomicStore64Variant:
+		//AMSWAPx  Rarg1, (Rarg0), Rout
+		amswapx := loong64.AAMSWAPDBV
+		switch v.Op {
+		case ssa.OpLOONG64LoweredAtomicStore32Variant:
+			amswapx = loong64.AAMSWAPDBW
+		case ssa.OpLOONG64LoweredAtomicStore8Variant:
+			amswapx = loong64.AAMSWAPDBB
 		}
-		s.Prog(loong64.ADBAR)
-		p := s.Prog(as)
+		p := s.Prog(amswapx)
 		p.From.Type = obj.TYPE_REG
-		p.From.Reg = loong64.REGZERO
+		p.From.Reg = v.Args[1].Reg()
 		p.To.Type = obj.TYPE_MEM
 		p.To.Reg = v.Args[0].Reg()
-		s.Prog(loong64.ADBAR)
+		p.RegTo2 = loong64.REGZERO
+
 	case ssa.OpLOONG64LoweredAtomicExchange32, ssa.OpLOONG64LoweredAtomicExchange64:
 		// DBAR
 		// MOVV	Rarg1, Rtmp
diff --git a/src/cmd/compile/internal/ssa/_gen/LOONG64.rules b/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
index 7d78e3afa9..e351c2d402 100644
--- a/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
+++ b/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
@@ -436,6 +436,7 @@
 (AtomicLoadPtr ...) => (LoweredAtomicLoad64 ...)
 
 (AtomicStore(8|32|64) ...) => (LoweredAtomicStore(8|32|64)  ...)
+(AtomicStore(8|32|64)Variant ...) => (LoweredAtomicStore(8|32|64)Variant  ...)
 (AtomicStorePtrNoWB ...) => (LoweredAtomicStore64 ...)
 
 (AtomicExchange(32|64) ...) => (LoweredAtomicExchange(32|64) ...)
@@ -505,7 +506,6 @@
 	&& is32Bit(int64(off1)+int64(off2)) && (ptr.Op != OpSB || !config.ctxt.Flag_dynlink) =>
 	(MOV(B|H|W|V)storezero [off1+int32(off2)] {mergeSym(sym1,sym2)} ptr mem)
 
-(LoweredAtomicStore(32|64) ptr (MOVVconst [0]) mem) => (LoweredAtomicStorezero(32|64) ptr mem)
 (LoweredAtomicAdd32 ptr (MOVVconst [c]) mem) && is32Bit(c) => (LoweredAtomicAddconst32 [int32(c)] ptr mem)
 (LoweredAtomicAdd64 ptr (MOVVconst [c]) mem) && is32Bit(c) => (LoweredAtomicAddconst64 [c] ptr mem)
 
diff --git a/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go b/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go
index 4a7e67786b..a460882dca 100644
--- a/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go
+++ b/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go
@@ -431,9 +431,9 @@ func init() {
 		{name: "LoweredAtomicStore8", argLength: 3, reg: gpstore, faultOnNilArg0: true, hasSideEffects: true},
 		{name: "LoweredAtomicStore32", argLength: 3, reg: gpstore, faultOnNilArg0: true, hasSideEffects: true},
 		{name: "LoweredAtomicStore64", argLength: 3, reg: gpstore, faultOnNilArg0: true, hasSideEffects: true},
-		// store zero to arg0. arg1=mem. returns memory.
-		{name: "LoweredAtomicStorezero32", argLength: 2, reg: gpstore0, faultOnNilArg0: true, hasSideEffects: true},
-		{name: "LoweredAtomicStorezero64", argLength: 2, reg: gpstore0, faultOnNilArg0: true, hasSideEffects: true},
+		{name: "LoweredAtomicStore8Variant", argLength: 3, reg: gpstore, faultOnNilArg0: true, hasSideEffects: true},
+		{name: "LoweredAtomicStore32Variant", argLength: 3, reg: gpstore, faultOnNilArg0: true, hasSideEffects: true},
+		{name: "LoweredAtomicStore64Variant", argLength: 3, reg: gpstore, faultOnNilArg0: true, hasSideEffects: true},
 
 		// atomic exchange.
 		// store arg1 to arg0. arg2=mem. returns <old content of *arg0, memory>.
diff --git a/src/cmd/compile/internal/ssa/_gen/genericOps.go b/src/cmd/compile/internal/ssa/_gen/genericOps.go
index 82f91320b3..0d136c2a98 100644
--- a/src/cmd/compile/internal/ssa/_gen/genericOps.go
+++ b/src/cmd/compile/internal/ssa/_gen/genericOps.go
@@ -633,7 +633,10 @@ var genericOps = []opData{
 	// But they are used for generating more efficient code on certain modern machines, with run-time CPU feature detection.
 	// On ARM64, these are used when the LSE hardware feature is available (either known at compile time or detected at runtime). If LSE is not available,
 	// then the basic atomic oprations are used instead.
-	// These are not currently used on any other platform.
+	{name: "AtomicStore8Variant", argLength: 3, typ: "Mem", hasSideEffects: true},  // Store arg1 to *arg0.  arg2=memory.  Returns memory.
+	{name: "AtomicStore32Variant", argLength: 3, typ: "Mem", hasSideEffects: true}, // Store arg1 to *arg0.  arg2=memory.  Returns memory.
+	{name: "AtomicStore64Variant", argLength: 3, typ: "Mem", hasSideEffects: true}, // Store arg1 to *arg0.  arg2=memory.  Returns memory.
+
 	{name: "AtomicAdd32Variant", argLength: 3, typ: "(UInt32,Mem)", hasSideEffects: true},          // Do *arg0 += arg1.  arg2=memory.  Returns sum and new memory.
 	{name: "AtomicAdd64Variant", argLength: 3, typ: "(UInt64,Mem)", hasSideEffects: true},          // Do *arg0 += arg1.  arg2=memory.  Returns sum and new memory.
 	{name: "AtomicExchange8Variant", argLength: 3, typ: "(UInt8,Mem)", hasSideEffects: true},       // Store arg1 to *arg0.  arg2=memory.  Returns old contents of *arg0 and new memory.
diff --git a/src/cmd/compile/internal/ssa/opGen.go b/src/cmd/compile/internal/ssa/opGen.go
index 93b96462a5..ac50769dff 100644
--- a/src/cmd/compile/internal/ssa/opGen.go
+++ b/src/cmd/compile/internal/ssa/opGen.go
@@ -1901,8 +1901,9 @@ const (
 	OpLOONG64LoweredAtomicStore8
 	OpLOONG64LoweredAtomicStore32
 	OpLOONG64LoweredAtomicStore64
-	OpLOONG64LoweredAtomicStorezero32
-	OpLOONG64LoweredAtomicStorezero64
+	OpLOONG64LoweredAtomicStore8Variant
+	OpLOONG64LoweredAtomicStore32Variant
+	OpLOONG64LoweredAtomicStore64Variant
 	OpLOONG64LoweredAtomicExchange32
 	OpLOONG64LoweredAtomicExchange64
 	OpLOONG64LoweredAtomicAdd32
@@ -3310,6 +3311,9 @@ const (
 	OpAtomicOr64value
 	OpAtomicOr32value
 	OpAtomicOr8value
+	OpAtomicStore8Variant
+	OpAtomicStore32Variant
+	OpAtomicStore64Variant
 	OpAtomicAdd32Variant
 	OpAtomicAdd64Variant
 	OpAtomicExchange8Variant
@@ -25501,23 +25505,37 @@ var opcodeTable = [...]opInfo{
 		},
 	},
 	{
-		name:           "LoweredAtomicStorezero32",
-		argLen:         2,
+		name:           "LoweredAtomicStore8Variant",
+		argLen:         3,
 		faultOnNilArg0: true,
 		hasSideEffects: true,
 		reg: regInfo{
 			inputs: []inputInfo{
+				{1, 1073741816},          // R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 g R23 R24 R25 R26 R27 R28 R29 R31
 				{0, 4611686019501129724}, // SP R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 g R23 R24 R25 R26 R27 R28 R29 R31 SB
 			},
 		},
 	},
 	{
-		name:           "LoweredAtomicStorezero64",
-		argLen:         2,
+		name:           "LoweredAtomicStore32Variant",
+		argLen:         3,
+		faultOnNilArg0: true,
+		hasSideEffects: true,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{1, 1073741816},          // R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 g R23 R24 R25 R26 R27 R28 R29 R31
+				{0, 4611686019501129724}, // SP R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 g R23 R24 R25 R26 R27 R28 R29 R31 SB
+			},
+		},
+	},
+	{
+		name:           "LoweredAtomicStore64Variant",
+		argLen:         3,
 		faultOnNilArg0: true,
 		hasSideEffects: true,
 		reg: regInfo{
 			inputs: []inputInfo{
+				{1, 1073741816},          // R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 g R23 R24 R25 R26 R27 R28 R29 R31
 				{0, 4611686019501129724}, // SP R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 g R23 R24 R25 R26 R27 R28 R29 R31 SB
 			},
 		},
@@ -41702,6 +41720,24 @@ var opcodeTable = [...]opInfo{
 		generic:        true,
 	},
 	{
+		name:           "AtomicStore8Variant",
+		argLen:         3,
+		hasSideEffects: true,
+		generic:        true,
+	},
+	{
+		name:           "AtomicStore32Variant",
+		argLen:         3,
+		hasSideEffects: true,
+		generic:        true,
+	},
+	{
+		name:           "AtomicStore64Variant",
+		argLen:         3,
+		hasSideEffects: true,
+		generic:        true,
+	},
+	{
 		name:           "AtomicAdd32Variant",
 		argLen:         3,
 		hasSideEffects: true,
diff --git a/src/cmd/compile/internal/ssa/rewriteLOONG64.go b/src/cmd/compile/internal/ssa/rewriteLOONG64.go
index 97f94729e7..3eaba1871e 100644
--- a/src/cmd/compile/internal/ssa/rewriteLOONG64.go
+++ b/src/cmd/compile/internal/ssa/rewriteLOONG64.go
@@ -79,12 +79,21 @@ func rewriteValueLOONG64(v *Value) bool {
 	case OpAtomicStore32:
 		v.Op = OpLOONG64LoweredAtomicStore32
 		return true
+	case OpAtomicStore32Variant:
+		v.Op = OpLOONG64LoweredAtomicStore32Variant
+		return true
 	case OpAtomicStore64:
 		v.Op = OpLOONG64LoweredAtomicStore64
 		return true
+	case OpAtomicStore64Variant:
+		v.Op = OpLOONG64LoweredAtomicStore64Variant
+		return true
 	case OpAtomicStore8:
 		v.Op = OpLOONG64LoweredAtomicStore8
 		return true
+	case OpAtomicStore8Variant:
+		v.Op = OpLOONG64LoweredAtomicStore8Variant
+		return true
 	case OpAtomicStorePtrNoWB:
 		v.Op = OpLOONG64LoweredAtomicStore64
 		return true
@@ -251,10 +260,6 @@ func rewriteValueLOONG64(v *Value) bool {
 		return rewriteValueLOONG64_OpLOONG64LoweredAtomicAdd32(v)
 	case OpLOONG64LoweredAtomicAdd64:
 		return rewriteValueLOONG64_OpLOONG64LoweredAtomicAdd64(v)
-	case OpLOONG64LoweredAtomicStore32:
-		return rewriteValueLOONG64_OpLOONG64LoweredAtomicStore32(v)
-	case OpLOONG64LoweredAtomicStore64:
-		return rewriteValueLOONG64_OpLOONG64LoweredAtomicStore64(v)
 	case OpLOONG64MASKEQZ:
 		return rewriteValueLOONG64_OpLOONG64MASKEQZ(v)
 	case OpLOONG64MASKNEZ:
@@ -1737,42 +1742,6 @@ func rewriteValueLOONG64_OpLOONG64LoweredAtomicAdd64(v *Value) bool {
 	}
 	return false
 }
-func rewriteValueLOONG64_OpLOONG64LoweredAtomicStore32(v *Value) bool {
-	v_2 := v.Args[2]
-	v_1 := v.Args[1]
-	v_0 := v.Args[0]
-	// match: (LoweredAtomicStore32 ptr (MOVVconst [0]) mem)
-	// result: (LoweredAtomicStorezero32 ptr mem)
-	for {
-		ptr := v_0
-		if v_1.Op != OpLOONG64MOVVconst || auxIntToInt64(v_1.AuxInt) != 0 {
-			break
-		}
-		mem := v_2
-		v.reset(OpLOONG64LoweredAtomicStorezero32)
-		v.AddArg2(ptr, mem)
-		return true
-	}
-	return false
-}
-func rewriteValueLOONG64_OpLOONG64LoweredAtomicStore64(v *Value) bool {
-	v_2 := v.Args[2]
-	v_1 := v.Args[1]
-	v_0 := v.Args[0]
-	// match: (LoweredAtomicStore64 ptr (MOVVconst [0]) mem)
-	// result: (LoweredAtomicStorezero64 ptr mem)
-	for {
-		ptr := v_0
-		if v_1.Op != OpLOONG64MOVVconst || auxIntToInt64(v_1.AuxInt) != 0 {
-			break
-		}
-		mem := v_2
-		v.reset(OpLOONG64LoweredAtomicStorezero64)
-		v.AddArg2(ptr, mem)
-		return true
-	}
-	return false
-}
 func rewriteValueLOONG64_OpLOONG64MASKEQZ(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]
diff --git a/src/cmd/compile/internal/ssagen/intrinsics.go b/src/cmd/compile/internal/ssagen/intrinsics.go
index 81caf0dfdf..9084c2f690 100644
--- a/src/cmd/compile/internal/ssagen/intrinsics.go
+++ b/src/cmd/compile/internal/ssagen/intrinsics.go
@@ -216,6 +216,8 @@ func initIntrinsics(cfg *intrinsicBuildConfig) {
 		sys.AMD64, sys.ARM64, sys.PPC64)
 
 	/******** internal/runtime/atomic ********/
+	type atomicOpEmitter func(s *state, n *ir.CallExpr, args []*ssa.Value, op ssa.Op, typ types.Kind, needReturn bool)
+
 	addF("internal/runtime/atomic", "Load",
 		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 			v := s.newValue2(ssa.OpAtomicLoad32, types.NewTuple(types.Types[types.TUINT32], types.TypeMem), args[0], s.mem())
@@ -264,19 +266,19 @@ func initIntrinsics(cfg *intrinsicBuildConfig) {
 			s.vars[memVar] = s.newValue3(ssa.OpAtomicStore32, types.TypeMem, args[0], args[1], s.mem())
 			return nil
 		},
-		sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
+		sys.AMD64, sys.ARM64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
 	addF("internal/runtime/atomic", "Store8",
 		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 			s.vars[memVar] = s.newValue3(ssa.OpAtomicStore8, types.TypeMem, args[0], args[1], s.mem())
 			return nil
 		},
-		sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
+		sys.AMD64, sys.ARM64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
 	addF("internal/runtime/atomic", "Store64",
 		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 			s.vars[memVar] = s.newValue3(ssa.OpAtomicStore64, types.TypeMem, args[0], args[1], s.mem())
 			return nil
 		},
-		sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
+		sys.AMD64, sys.ARM64, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
 	addF("internal/runtime/atomic", "StorepNoWB",
 		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 			s.vars[memVar] = s.newValue3(ssa.OpAtomicStorePtrNoWB, types.TypeMem, args[0], args[1], s.mem())
@@ -296,6 +298,70 @@ func initIntrinsics(cfg *intrinsicBuildConfig) {
 		},
 		sys.PPC64)
 
+	makeAtomicGuardedIntrinsicLoong64common := func(op0, op1 ssa.Op, typ types.Kind, emit atomicOpEmitter, needReturn bool) intrinsicBuilder {
+		return func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
+			// Target Atomic feature is identified by dynamic detection
+			addr := s.entryNewValue1A(ssa.OpAddr, types.Types[types.TBOOL].PtrTo(), ir.Syms.Loong64HasLAM_BH, s.sb)
+			v := s.load(types.Types[types.TBOOL], addr)
+			b := s.endBlock()
+			b.Kind = ssa.BlockIf
+			b.SetControl(v)
+			bTrue := s.f.NewBlock(ssa.BlockPlain)
+			bFalse := s.f.NewBlock(ssa.BlockPlain)
+			bEnd := s.f.NewBlock(ssa.BlockPlain)
+			b.AddEdgeTo(bTrue)
+			b.AddEdgeTo(bFalse)
+			b.Likely = ssa.BranchLikely
+
+			// We have atomic instructions - use it directly.
+			s.startBlock(bTrue)
+			emit(s, n, args, op1, typ, needReturn)
+			s.endBlock().AddEdgeTo(bEnd)
+
+			// Use original instruction sequence.
+			s.startBlock(bFalse)
+			emit(s, n, args, op0, typ, needReturn)
+			s.endBlock().AddEdgeTo(bEnd)
+
+			// Merge results.
+			s.startBlock(bEnd)
+
+			if needReturn {
+				return s.variable(n, types.Types[typ])
+			} else {
+				return nil
+			}
+		}
+	}
+
+	makeAtomicStoreGuardedIntrinsicLoong64 := func(op0, op1 ssa.Op, typ types.Kind, emit atomicOpEmitter) intrinsicBuilder {
+		return makeAtomicGuardedIntrinsicLoong64common(op0, op1, typ, emit, false)
+	}
+
+	atomicStoreEmitterLoong64 := func(s *state, n *ir.CallExpr, args []*ssa.Value, op ssa.Op, typ types.Kind, needReturn bool) {
+		v := s.newValue3(op, types.NewTuple(types.Types[typ], types.TypeMem), args[0], args[1], s.mem())
+		s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
+		if needReturn {
+			s.vars[n] = s.newValue1(ssa.OpSelect0, types.Types[typ], v)
+		}
+	}
+
+	addF("internal/runtime/atomic", "Store8",
+		makeAtomicStoreGuardedIntrinsicLoong64(ssa.OpAtomicStore8, ssa.OpAtomicStore8Variant, types.TUINT8, atomicStoreEmitterLoong64),
+		sys.Loong64)
+	addF("internal/runtime/atomic", "Store",
+		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
+			s.vars[memVar] = s.newValue3(ssa.OpAtomicStore32Variant, types.TypeMem, args[0], args[1], s.mem())
+			return nil
+		},
+		sys.Loong64)
+	addF("internal/runtime/atomic", "Store64",
+		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
+			s.vars[memVar] = s.newValue3(ssa.OpAtomicStore64Variant, types.TypeMem, args[0], args[1], s.mem())
+			return nil
+		},
+		sys.Loong64)
+
 	addF("internal/runtime/atomic", "Xchg8",
 		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 			v := s.newValue3(ssa.OpAtomicExchange8, types.NewTuple(types.Types[types.TUINT8], types.TypeMem), args[0], args[1], s.mem())
@@ -318,8 +384,6 @@ func initIntrinsics(cfg *intrinsicBuildConfig) {
 		},
 		sys.AMD64, sys.Loong64, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
 
-	type atomicOpEmitter func(s *state, n *ir.CallExpr, args []*ssa.Value, op ssa.Op, typ types.Kind, needReturn bool)
-
 	makeAtomicGuardedIntrinsicARM64common := func(op0, op1 ssa.Op, typ types.Kind, emit atomicOpEmitter, needReturn bool) intrinsicBuilder {
 
 		return func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index ba09216f8f..156190614c 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -145,11 +145,12 @@ func InitConfig() {
 	ir.Syms.TypeAssert = typecheck.LookupRuntimeFunc("typeAssert")
 	ir.Syms.WBZero = typecheck.LookupRuntimeFunc("wbZero")
 	ir.Syms.WBMove = typecheck.LookupRuntimeFunc("wbMove")
-	ir.Syms.X86HasPOPCNT = typecheck.LookupRuntimeVar("x86HasPOPCNT")       // bool
-	ir.Syms.X86HasSSE41 = typecheck.LookupRuntimeVar("x86HasSSE41")         // bool
-	ir.Syms.X86HasFMA = typecheck.LookupRuntimeVar("x86HasFMA")             // bool
-	ir.Syms.ARMHasVFPv4 = typecheck.LookupRuntimeVar("armHasVFPv4")         // bool
-	ir.Syms.ARM64HasATOMICS = typecheck.LookupRuntimeVar("arm64HasATOMICS") // bool
+	ir.Syms.X86HasPOPCNT = typecheck.LookupRuntimeVar("x86HasPOPCNT")         // bool
+	ir.Syms.X86HasSSE41 = typecheck.LookupRuntimeVar("x86HasSSE41")           // bool
+	ir.Syms.X86HasFMA = typecheck.LookupRuntimeVar("x86HasFMA")               // bool
+	ir.Syms.ARMHasVFPv4 = typecheck.LookupRuntimeVar("armHasVFPv4")           // bool
+	ir.Syms.ARM64HasATOMICS = typecheck.LookupRuntimeVar("arm64HasATOMICS")   // bool
+	ir.Syms.Loong64HasLAM_BH = typecheck.LookupRuntimeVar("loong64HasLAM_BH") // bool
 	ir.Syms.Staticuint64s = typecheck.LookupRuntimeVar("staticuint64s")
 	ir.Syms.Typedmemmove = typecheck.LookupRuntimeFunc("typedmemmove")
 	ir.Syms.Udiv = typecheck.LookupRuntimeVar("udiv")                 // asm func with special ABI
diff --git a/src/cmd/compile/internal/typecheck/_builtin/runtime.go b/src/cmd/compile/internal/typecheck/_builtin/runtime.go
index 6761432530..df1421d457 100644
--- a/src/cmd/compile/internal/typecheck/_builtin/runtime.go
+++ b/src/cmd/compile/internal/typecheck/_builtin/runtime.go
@@ -289,5 +289,6 @@ var x86HasSSE41 bool
 var x86HasFMA bool
 var armHasVFPv4 bool
 var arm64HasATOMICS bool
+var loong64HasLAM_BH bool
 
 func asanregisterglobals(unsafe.Pointer, uintptr)
diff --git a/src/cmd/compile/internal/typecheck/builtin.go b/src/cmd/compile/internal/typecheck/builtin.go
index 0a0e5917f6..1d7f84903f 100644
--- a/src/cmd/compile/internal/typecheck/builtin.go
+++ b/src/cmd/compile/internal/typecheck/builtin.go
@@ -237,6 +237,7 @@ var runtimeDecls = [...]struct {
 	{"x86HasFMA", varTag, 6},
 	{"armHasVFPv4", varTag, 6},
 	{"arm64HasATOMICS", varTag, 6},
+	{"loong64HasLAM_BH", varTag, 6},
 	{"asanregisterglobals", funcTag, 130},
 }
 
diff --git a/src/cmd/internal/goobj/builtinlist.go b/src/cmd/internal/goobj/builtinlist.go
index a18e944c6b..f091d77622 100644
--- a/src/cmd/internal/goobj/builtinlist.go
+++ b/src/cmd/internal/goobj/builtinlist.go
@@ -215,6 +215,7 @@ var builtins = [...]struct {
 	{"runtime.x86HasFMA", 0},
 	{"runtime.armHasVFPv4", 0},
 	{"runtime.arm64HasATOMICS", 0},
+	{"runtime.loong64HasLAM_BH", 0},
 	{"runtime.asanregisterglobals", 1},
 	{"runtime.deferproc", 1},
 	{"runtime.deferprocStack", 1},
diff --git a/src/cmd/internal/obj/loong64/doc.go b/src/cmd/internal/obj/loong64/doc.go
index 6ec53e7a17..e4c33f6525 100644
--- a/src/cmd/internal/obj/loong64/doc.go
+++ b/src/cmd/internal/obj/loong64/doc.go
@@ -88,5 +88,29 @@ Examples:
 	MOVB R6, (R4)(R5)  <=>  stx.b R6, R5, R5
 	MOVV R6, (R4)(R5)  <=>  stx.d R6, R5, R5
 	MOVV F6, (R4)(R5)  <=>  fstx.d F6, R5, R5
+
+# Special instruction encoding definition and description on LoongArch
+
+ 1. DBAR hint encoding for LA664(Loongson 3A6000) and later micro-architectures, paraphrased
+    from the Linux kernel implementation: https://git.kernel.org/torvalds/c/e031a5f3f1ed
+
+    - Bit4: ordering or completion (0: completion, 1: ordering)
+    - Bit3: barrier for previous read (0: true, 1: false)
+    - Bit2: barrier for previous write (0: true, 1: false)
+    - Bit1: barrier for succeeding read (0: true, 1: false)
+    - Bit0: barrier for succeeding write (0: true, 1: false)
+    - Hint 0x700: barrier for "read after read" from the same address
+
+    Traditionally, on microstructures that do not support dbar grading such as LA464
+    (Loongson 3A5000, 3C5000) all variants are treated as “dbar 0” (full barrier).
+
+2. Notes on using atomic operation instructions
+
+  - AM*_DB.W[U]/V[U] instructions such as AMSWAPDBW not only complete the corresponding
+    atomic operation sequence, but also implement the complete full data barrier function.
+
+  - When using the AM*_.W[U]/D[U] instruction, registers rd and rj cannot be the same,
+    otherwise an exception is triggered, and rd and rk cannot be the same, otherwise
+    the execution result is uncertain.
 */
 package loong64