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

Fixes golang#75479

Change-Id: I362d3e49090e94f91a840dd5a475978b59222a00
Reviewed-on: https://go-review.googlesource.com/c/go/+/704135
Reviewed-by: Mark Freeman <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>
Reviewed-by: Meidan Li <[email protected]>
Reviewed-by: abner chenc <[email protected]>

Author: sophie-zhao

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])

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.

src/cmd/compile/internal/ssa/rewriteLOONG64.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
 }