From: Xiaolin Zhao <zhaoxiaolin@loongson.cn>
Date: Tue, 16 Sep 2025 07:27:42 +0000 (+0800)
Subject: cmd/compile: fix the issue of shift amount exceeding the valid range
X-Git-Tag: go1.26rc1~837
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=78ef487a6f;p=gostls13.git

cmd/compile: fix the issue of shift amount exceeding the valid range

Fixes #75479

Change-Id: I362d3e49090e94f91a840dd5a475978b59222a00
Reviewed-on: https://go-review.googlesource.com/c/go/+/704135
Reviewed-by: Mark Freeman <markfreeman@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Meidan Li <limeidan@loongson.cn>
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
---

diff --git a/src/cmd/compile/internal/ssa/_gen/LOONG64.rules b/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
index d0a64364d6..0d2384143c 100644
--- a/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
+++ b/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
@@ -717,7 +717,8 @@
 (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)
+((SLLV|SLL)const <t> [c] (ADDV x x)) && c < t.Size() * 8 - 1  => ((SLLV|SLL)const [c+1] x)
+((SLLV|SLL)const <t> [c] (ADDV x x)) && c >= t.Size() * 8 - 1 => (MOVVconst [0])
 
 // mul by constant
 (MULV _ (MOVVconst [0])) => (MOVVconst [0])
diff --git a/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go b/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go
index 0d5e0eb76f..a3db4def56 100644
--- a/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go
+++ b/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go
@@ -247,7 +247,7 @@ func init() {
 		{name: "SLL", argLength: 2, reg: gp21, asm: "SLL"},                        // arg0 << arg1, shift amount is mod 32
 		{name: "SLLV", argLength: 2, reg: gp21, asm: "SLLV"},                      // arg0 << arg1, shift amount is mod 64
 		{name: "SLLconst", argLength: 1, reg: gp11, asm: "SLL", aux: "Int64"},     // arg0 << auxInt, auxInt should be in the range 0 to 31.
-		{name: "SLLVconst", argLength: 1, reg: gp11, asm: "SLLV", aux: "Int64"},   // arg0 << auxInt
+		{name: "SLLVconst", argLength: 1, reg: gp11, asm: "SLLV", aux: "Int64"},   // arg0 << auxInt, auxInt should be in the range 0 to 63.
 		{name: "SRL", argLength: 2, reg: gp21, asm: "SRL"},                        // arg0 >> arg1, shift amount is mod 32
 		{name: "SRLV", argLength: 2, reg: gp21, asm: "SRLV"},                      // arg0 >> arg1, unsigned, shift amount is mod 64
 		{name: "SRLconst", argLength: 1, reg: gp11, asm: "SRL", aux: "Int64"},     // arg0 >> auxInt, auxInt should be in the range 0 to 31.
diff --git a/src/cmd/compile/internal/ssa/rewriteLOONG64.go b/src/cmd/compile/internal/ssa/rewriteLOONG64.go
index 6a9b723c8c..3990b2833b 100644
--- a/src/cmd/compile/internal/ssa/rewriteLOONG64.go
+++ b/src/cmd/compile/internal/ssa/rewriteLOONG64.go
@@ -6561,15 +6561,17 @@ func rewriteValueLOONG64_OpLOONG64SLLV(v *Value) bool {
 }
 func rewriteValueLOONG64_OpLOONG64SLLVconst(v *Value) bool {
 	v_0 := v.Args[0]
-	// match: (SLLVconst [c] (ADDV x x))
+	// match: (SLLVconst <t> [c] (ADDV x x))
+	// cond: c < t.Size() * 8 - 1
 	// result: (SLLVconst [c+1] x)
 	for {
+		t := v.Type
 		c := auxIntToInt64(v.AuxInt)
 		if v_0.Op != OpLOONG64ADDV {
 			break
 		}
 		x := v_0.Args[1]
-		if x != v_0.Args[0] {
+		if x != v_0.Args[0] || !(c < t.Size()*8-1) {
 			break
 		}
 		v.reset(OpLOONG64SLLVconst)
@@ -6577,6 +6579,23 @@ func rewriteValueLOONG64_OpLOONG64SLLVconst(v *Value) bool {
 		v.AddArg(x)
 		return true
 	}
+	// match: (SLLVconst <t> [c] (ADDV x x))
+	// cond: c >= t.Size() * 8 - 1
+	// result: (MOVVconst [0])
+	for {
+		t := v.Type
+		c := auxIntToInt64(v.AuxInt)
+		if v_0.Op != OpLOONG64ADDV {
+			break
+		}
+		x := v_0.Args[1]
+		if x != v_0.Args[0] || !(c >= t.Size()*8-1) {
+			break
+		}
+		v.reset(OpLOONG64MOVVconst)
+		v.AuxInt = int64ToAuxInt(0)
+		return true
+	}
 	// match: (SLLVconst [c] (MOVVconst [d]))
 	// result: (MOVVconst [d<<uint64(c)])
 	for {
@@ -6593,15 +6612,17 @@ func rewriteValueLOONG64_OpLOONG64SLLVconst(v *Value) bool {
 }
 func rewriteValueLOONG64_OpLOONG64SLLconst(v *Value) bool {
 	v_0 := v.Args[0]
-	// match: (SLLconst [c] (ADDV x x))
+	// match: (SLLconst <t> [c] (ADDV x x))
+	// cond: c < t.Size() * 8 - 1
 	// result: (SLLconst [c+1] x)
 	for {
+		t := v.Type
 		c := auxIntToInt64(v.AuxInt)
 		if v_0.Op != OpLOONG64ADDV {
 			break
 		}
 		x := v_0.Args[1]
-		if x != v_0.Args[0] {
+		if x != v_0.Args[0] || !(c < t.Size()*8-1) {
 			break
 		}
 		v.reset(OpLOONG64SLLconst)
@@ -6609,6 +6630,23 @@ func rewriteValueLOONG64_OpLOONG64SLLconst(v *Value) bool {
 		v.AddArg(x)
 		return true
 	}
+	// match: (SLLconst <t> [c] (ADDV x x))
+	// cond: c >= t.Size() * 8 - 1
+	// result: (MOVVconst [0])
+	for {
+		t := v.Type
+		c := auxIntToInt64(v.AuxInt)
+		if v_0.Op != OpLOONG64ADDV {
+			break
+		}
+		x := v_0.Args[1]
+		if x != v_0.Args[0] || !(c >= t.Size()*8-1) {
+			break
+		}
+		v.reset(OpLOONG64MOVVconst)
+		v.AuxInt = int64ToAuxInt(0)
+		return true
+	}
 	return false
 }
 func rewriteValueLOONG64_OpLOONG64SRA(v *Value) bool {
diff --git a/test/codegen/shift.go b/test/codegen/shift.go
index 7385058726..4b0885a4dd 100644
--- a/test/codegen/shift.go
+++ b/test/codegen/shift.go
@@ -148,11 +148,13 @@ func lshConst64x2Add(x int64) int64 {
 }
 
 func lshConst32x31Add(x int32) int32 {
+	// loong64:-"SLL\t","MOVV\tR0"
 	// riscv64:-"SLLI","MOV\t[$]0"
 	return (x + x) << 31
 }
 
 func lshConst64x63Add(x int64) int64 {
+	// loong64:-"SLLV","MOVV\tR0"
 	// riscv64:-"SLLI","MOV\t[$]0"
 	return (x + x) << 63
 }