cmd/compile: WIP implement codegen of count-{leading,trailing}-ones o…

…n loong64

tests TODO

Updates golang#59120

Change-Id: Icde85d717999600954244c1105b7c55759d3469f

src/cmd/compile/internal/loong64/ssa.go

@@ -353,6 +353,10 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 		ssa.OpLOONG64CTZV,
 		ssa.OpLOONG64CLZW,
 		ssa.OpLOONG64CLZV,
+		ssa.OpLOONG64CTOW,
+		ssa.OpLOONG64CTOV,
+		ssa.OpLOONG64CLOW,
+		ssa.OpLOONG64CLOV,
 		ssa.OpLOONG64REVB2H,
 		ssa.OpLOONG64REVB2W,
 		ssa.OpLOONG64REVBV,

src/cmd/compile/internal/ssa/_gen/LOONG64.rules

@@ -126,8 +126,12 @@
 // unary ops
 (Neg(64|32|16|8) ...) => (NEGV ...)
 (Neg(32|64)F ...) => (NEG(F|D) ...)
-(Ctz(32|64) ...) => (CTZ(W|V) ...)
+(Ctz32 (Com32 x)) => (CTOW x)
+(Ctz64 (Com64 x)) => (CTOV x)
+(Ctz(32|64) x) => (CTZ(W|V) x)
 (Ctz(8|16|32|64)NonZero ...) => (Ctz(8|16|32|64) ...)
+(BitLen64 <t> (Com64 x)) => (NEGV <t> (SUBVconst <t> [64] (CLOV <t> x)))
+(BitLen32 <t> (Com32 x)) => (NEGV <t> (SUBVconst <t> [32] (CLOW <t> x)))
 (BitLen64 <t> x) => (NEGV <t> (SUBVconst <t> [64] (CLZV <t> x)))
 (BitLen32 <t> x) => (NEGV <t> (SUBVconst <t> [32] (CLZW <t> x)))
 (Bswap(16|32|64) ...) => (REVB(2H|2W|V) ...)
@@ -619,6 +623,9 @@
 (OR  x x) => x
 (XOR x x) => (MOVVconst [0])
 
+// recognize and fold counting of leading/trailing ones
+(C(TZW|TZV|LZW|LZV) (NOR (MOVVconst [0]) x)) => (C(TOW|TOV|LOW|LOV) x)
+
 // remove redundant *const ops
 (ADDVconst [0]  x) => x
 (SUBVconst [0]  x) => x

src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go

@@ -196,6 +196,10 @@ func init() {
 		{name: "CTZV", argLength: 1, reg: gp11, asm: "CTZV"},     // Count trailing (low order) zeroes (returns 0-64)
 		{name: "CLZW", argLength: 1, reg: gp11, asm: "CLZW"},     // Count leading (high order) zeroes (returns 0-32)
 		{name: "CLZV", argLength: 1, reg: gp11, asm: "CLZV"},     // Count leading (high order) zeroes (returns 0-64)
+		{name: "CTOW", argLength: 1, reg: gp11, asm: "CTOW"},     // Count trailing (low order) ones (returns 0-32)
+		{name: "CTOV", argLength: 1, reg: gp11, asm: "CTOV"},     // Count trailing (low order) ones (returns 0-64)
+		{name: "CLOW", argLength: 1, reg: gp11, asm: "CLOW"},     // Count leading (high order) ones (returns 0-32)
+		{name: "CLOV", argLength: 1, reg: gp11, asm: "CLOV"},     // Count leading (high order) ones (returns 0-64)
 		{name: "REVB2H", argLength: 1, reg: gp11, asm: "REVB2H"}, // Swap bytes: 0x11223344 -> 0x22114433 (sign extends to 64 bits)
 		{name: "REVB2W", argLength: 1, reg: gp11, asm: "REVB2W"}, // Swap bytes: 0x1122334455667788 -> 0x4433221188776655
 		{name: "REVBV", argLength: 1, reg: gp11, asm: "REVBV"},   // Swap bytes: 0x1122334455667788 -> 0x8877665544332211