Revert "cmd/compile: optimize 386's math.bits.TrailingZeros16"

This reverts CL 189277. Reason for revert: broke 32-bit builders. Updates #33902 Change-Id: Ie5f180d0371a90e5057ed578c334372e5fc3a286 Reviewed-on: https://go-review.googlesource.com/c/go/+/192097 Run-TryBot: Bryan C. Mills <[email protected]> Reviewed-by: Daniel Martí <[email protected]>
golang · Aug 28, 2019 · 372b0ee · 372b0ee
1 parent bc92fe8
commit 372b0ee
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Showing 4 changed files with 1 addition and 22 deletions.
diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
@@ -3370,7 +3370,7 @@ func init() {
 		func(s *state, n *Node, args []*ssa.Value) *ssa.Value {
 			return s.newValue1(ssa.OpCtz16, types.Types[TINT], args[0])
 		},
-		sys.AMD64, sys.ARM, sys.I386, sys.ARM64, sys.Wasm)
+		sys.AMD64, sys.ARM, sys.ARM64, sys.Wasm)
 	addF("math/bits", "TrailingZeros16",
 		func(s *state, n *Node, args []*ssa.Value) *ssa.Value {
 			x := s.newValue1(ssa.OpZeroExt16to64, types.Types[TUINT64], args[0])

diff --git a/src/cmd/compile/internal/ssa/gen/386.rules b/src/cmd/compile/internal/ssa/gen/386.rules
@@ -66,8 +66,6 @@
 
 (Sqrt x) -> (SQRTSD x)
 
-(Ctz16 x) -> (BSFL (ORLconst <typ.UInt32> [0x10000] x))
-
 // Lowering extension
 (SignExt8to16  x) -> (MOVBLSX x)
 (SignExt8to32  x) -> (MOVBLSX x)

diff --git a/src/cmd/compile/internal/ssa/rewrite386.go b/src/cmd/compile/internal/ssa/rewrite386.go
diff --git a/test/codegen/mathbits.go b/test/codegen/mathbits.go
@@ -296,7 +296,6 @@ func TrailingZeros32(n uint32) int {
 
 func TrailingZeros16(n uint16) int {
 	// amd64:"BSFL","BTSL\\t\\$16"
-	// 386:"BSFL\t"
 	// arm:"ORR\t\\$65536","CLZ",-"MOVHU\tR"
 	// arm64:"ORR\t\\$65536","RBITW","CLZW",-"MOVHU\tR",-"RBIT\t",-"CLZ\t"
 	// s390x:"FLOGR","OR\t\\$65536"