From bda42a7a782dbcf4b123d617c5b60f3c848cbb82 Mon Sep 17 00:00:00 2001 From: Diogo Pinela Date: Thu, 5 Mar 2020 00:28:05 +0000 Subject: [PATCH] runtime: use staticuint64s instead of staticbytes for 1-length strings MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This was the last remaining use of staticbytes, so we can now delete it. The new code appears slightly faster on amd64: name old time/op new time/op delta SliceByteToString/1-4 6.29ns ± 2% 5.89ns ± 1% -6.46% (p=0.000 n=14+14) This may not be the case on the big-endian architectures, since they have to do an extra addition. Updates #37612 Change-Id: Icb84c5911ba025f798de152849992a55be99e4f3 Reviewed-on: https://go-review.googlesource.com/c/go/+/221979 Reviewed-by: Josh Bleecher Snyder Run-TryBot: Josh Bleecher Snyder TryBot-Result: Gobot Gobot --- src/runtime/iface.go | 36 ------------------------------------ src/runtime/string.go | 13 ++++++------- 2 files changed, 6 insertions(+), 43 deletions(-) diff --git a/src/runtime/iface.go b/src/runtime/iface.go index 892e5a400f..e4b0b6d3d3 100644 --- a/src/runtime/iface.go +++ b/src/runtime/iface.go @@ -527,42 +527,6 @@ func iterate_itabs(fn func(*itab)) { } } -// staticbytes is used to avoid convT2E for byte-sized values. -var staticbytes = [...]byte{ - 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, - 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, - 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, - 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, - 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, - 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, - 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, - 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, - 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, - 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, - 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, - 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, - 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, - 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, - 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, - 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, - 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, - 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, - 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, - 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, - 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, - 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, - 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, - 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, - 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, - 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, - 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, - 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, - 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, - 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, - 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, - 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, -} - // staticuint64s is used to avoid allocating in convTx for small integer values. var staticuint64s = [...]uint64{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, diff --git a/src/runtime/string.go b/src/runtime/string.go index 184245b105..7dc0bd789f 100644 --- a/src/runtime/string.go +++ b/src/runtime/string.go @@ -6,6 +6,7 @@ package runtime import ( "internal/bytealg" + "runtime/internal/sys" "unsafe" ) @@ -90,7 +91,11 @@ func slicebytetostring(buf *tmpBuf, b []byte) (str string) { msanread(unsafe.Pointer(&b[0]), uintptr(l)) } if l == 1 { - stringStructOf(&str).str = unsafe.Pointer(&staticbytes[b[0]]) + p := unsafe.Pointer(&staticuint64s[b[0]]) + if sys.BigEndian { + p = add(p, 7) + } + stringStructOf(&str).str = p stringStructOf(&str).len = 1 return } @@ -231,12 +236,6 @@ func stringStructOf(sp *string) *stringStruct { } func intstring(buf *[4]byte, v int64) (s string) { - if v >= 0 && v < runeSelf { - stringStructOf(&s).str = unsafe.Pointer(&staticbytes[v]) - stringStructOf(&s).len = 1 - return - } - var b []byte if buf != nil { b = buf[:] -- 2.50.0