cmd/compile: optimize rule (x + x) << c to x << c+1 on loong64

Change-Id: I782f93510bba92ba60b298c1c1cde456c8bcec38
Reviewed-on: https://go-review.googlesource.com/c/go/+/697956
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>

3 files changed, 45 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/ssa/_gen/LOONG64.rules b/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
index efeeca652c..75b5e3806b 100644
--- a/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
+++ b/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
@@ -749,6 +749,9 @@
 (SRLVconst [rc] (MOVHUreg x)) && rc >= 16 => (MOVVconst [0])
 (SRLVconst [rc] (MOVBUreg x)) && rc >= 8 => (MOVVconst [0])
 
+// (x + x) << c -> x << c+1
+((SLLV|SLL)const [c] (ADDV x x)) => ((SLLV|SLL)const [c+1] x)
+
 // mul by constant
 (MULV _ (MOVVconst [0])) => (MOVVconst [0])
 (MULV x (MOVVconst [1])) => x
diff --git a/src/cmd/compile/internal/ssa/rewriteLOONG64.go b/src/cmd/compile/internal/ssa/rewriteLOONG64.go
index 6f29588f9a..df4ac818dd 100644
--- a/src/cmd/compile/internal/ssa/rewriteLOONG64.go
+++ b/src/cmd/compile/internal/ssa/rewriteLOONG64.go
@@ -468,6 +468,8 @@ func rewriteValueLOONG64(v *Value) bool {
 		return rewriteValueLOONG64_OpLOONG64SLLV(v)
 	case OpLOONG64SLLVconst:
 		return rewriteValueLOONG64_OpLOONG64SLLVconst(v)
+	case OpLOONG64SLLconst:
+		return rewriteValueLOONG64_OpLOONG64SLLconst(v)
 	case OpLOONG64SRA:
 		return rewriteValueLOONG64_OpLOONG64SRA(v)
 	case OpLOONG64SRAV:
@@ -6457,6 +6459,22 @@ func rewriteValueLOONG64_OpLOONG64SLLV(v *Value) bool {
 }
 func rewriteValueLOONG64_OpLOONG64SLLVconst(v *Value) bool {
 	v_0 := v.Args[0]
+	// match: (SLLVconst [c] (ADDV x x))
+	// result: (SLLVconst [c+1] x)
+	for {
+		c := auxIntToInt64(v.AuxInt)
+		if v_0.Op != OpLOONG64ADDV {
+			break
+		}
+		x := v_0.Args[1]
+		if x != v_0.Args[0] {
+			break
+		}
+		v.reset(OpLOONG64SLLVconst)
+		v.AuxInt = int64ToAuxInt(c + 1)
+		v.AddArg(x)
+		return true
+	}
 	// match: (SLLVconst [c] (MOVVconst [d]))
 	// result: (MOVVconst [d<<uint64(c)])
 	for {
@@ -6471,6 +6489,26 @@ func rewriteValueLOONG64_OpLOONG64SLLVconst(v *Value) bool {
 	}
 	return false
 }
+func rewriteValueLOONG64_OpLOONG64SLLconst(v *Value) bool {
+	v_0 := v.Args[0]
+	// match: (SLLconst [c] (ADDV x x))
+	// result: (SLLconst [c+1] x)
+	for {
+		c := auxIntToInt64(v.AuxInt)
+		if v_0.Op != OpLOONG64ADDV {
+			break
+		}
+		x := v_0.Args[1]
+		if x != v_0.Args[0] {
+			break
+		}
+		v.reset(OpLOONG64SLLconst)
+		v.AuxInt = int64ToAuxInt(c + 1)
+		v.AddArg(x)
+		return true
+	}
+	return false
+}
 func rewriteValueLOONG64_OpLOONG64SRA(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]
diff --git a/test/codegen/shift.go b/test/codegen/shift.go
index 0e4cf1ed8d..3ab0fcfabc 100644
--- a/test/codegen/shift.go
+++ b/test/codegen/shift.go
@@ -121,21 +121,25 @@ func rshConst64x32(v int64) int64 {
 
 func lshConst32x1Add(x int32) int32 {
 	// amd64:"SHLL\t[$]2"
+	// loong64:"SLL\t[$]2"
 	return (x + x) << 1
 }
 
 func lshConst64x1Add(x int64) int64 {
 	// amd64:"SHLQ\t[$]2"
+	// loong64:"SLLV\t[$]2"
 	return (x + x) << 1
 }
 
 func lshConst32x2Add(x int32) int32 {
 	// amd64:"SHLL\t[$]3"
+	// loong64:"SLL\t[$]3"
 	return (x + x) << 2
 }
 
 func lshConst64x2Add(x int64) int64 {
 	// amd64:"SHLQ\t[$]3"
+	// loong64:"SLLV\t[$]3"
 	return (x + x) << 2
 }