From 496b8dbbfcd39cc51e1dfc1e9be90b7e61179009 Mon Sep 17 00:00:00 2001 From: Cherry Zhang Date: Thu, 25 Apr 2019 17:25:54 -0400 Subject: [PATCH] cmd, runtime: remove PC_F & PC_B globals on Wasm MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Following the previous CL, this removes more global variables on Wasm. PC_B is used mostly for intra-function jumps, and for a function telling its callee where to start or resume. This usage can be served by a parameter. The top level loop (wasm_pc_f_loop) uses PC_B for resuming a function. This value is either set by gogo, or loaded from the Go stack at function return. Instead of loading PC_B at each function return, we could make gogo stores PC_B at the same stack location, and let the top level loop do the load. This way, we don't need to use global PC_B to communicate with the top level loop, and we can replace global PC_B with a parameter. PC_F is similar. It is even more so in that the only reader is the top level loop. Let the top level loop read it from the stack, and we can get rid of PC_F entirely. PC_F and PC_B are used less entensively as SP, so this CL has smaller performance gain. Running on Chrome 74.0.3729.108 on Linux/AMD64, name old time/op new time/op delta BinaryTree17 16.6s ± 0% 16.2s ± 1% -2.59% (p=0.016 n=4+5) Fannkuch11 11.1s ± 1% 10.8s ± 0% -2.65% (p=0.008 n=5+5) FmtFprintfEmpty 231ns ± 1% 217ns ± 0% -6.06% (p=0.008 n=5+5) FmtFprintfString 407ns ± 3% 375ns ± 2% -7.81% (p=0.008 n=5+5) FmtFprintfInt 466ns ± 2% 430ns ± 0% -7.79% (p=0.016 n=5+4) FmtFprintfIntInt 719ns ± 2% 673ns ± 2% -6.37% (p=0.008 n=5+5) FmtFprintfPrefixedInt 706ns ± 1% 676ns ± 3% -4.31% (p=0.008 n=5+5) FmtFprintfFloat 1.01µs ± 1% 0.97µs ± 1% -4.30% (p=0.008 n=5+5) FmtManyArgs 2.67µs ± 1% 2.51µs ± 1% -5.95% (p=0.008 n=5+5) GobDecode 30.7ms ± 9% 31.3ms ±34% ~ (p=0.222 n=5+5) GobEncode 24.2ms ±23% 20.2ms ± 0% -16.36% (p=0.016 n=5+4) Gzip 852ms ± 0% 823ms ± 0% -3.38% (p=0.016 n=4+5) Gunzip 160ms ± 1% 151ms ± 1% -5.37% (p=0.008 n=5+5) JSONEncode 35.7ms ± 1% 34.3ms ± 1% -3.81% (p=0.008 n=5+5) JSONDecode 247ms ± 8% 254ms ± 7% ~ (p=0.548 n=5+5) Mandelbrot200 5.39ms ± 0% 5.41ms ± 0% +0.42% (p=0.008 n=5+5) GoParse 18.5ms ± 1% 18.3ms ± 2% ~ (p=0.343 n=4+4) RegexpMatchEasy0_32 424ns ± 2% 397ns ± 0% -6.23% (p=0.008 n=5+5) RegexpMatchEasy0_1K 2.88µs ± 0% 2.86µs ± 1% ~ (p=0.079 n=5+5) RegexpMatchEasy1_32 395ns ± 2% 370ns ± 1% -6.23% (p=0.008 n=5+5) RegexpMatchEasy1_1K 3.26µs ± 0% 3.19µs ± 1% -2.06% (p=0.008 n=5+5) RegexpMatchMedium_32 564ns ± 1% 532ns ± 0% -5.71% (p=0.008 n=5+5) RegexpMatchMedium_1K 146µs ± 2% 140µs ± 1% -4.62% (p=0.008 n=5+5) RegexpMatchHard_32 8.47µs ± 1% 7.91µs ± 1% -6.65% (p=0.008 n=5+5) RegexpMatchHard_1K 253µs ± 1% 236µs ± 2% -6.66% (p=0.008 n=5+5) Revcomp 1.78s ± 4% 1.76s ± 5% ~ (p=1.000 n=5+5) Template 292ms ±29% 269ms ± 5% ~ (p=0.690 n=5+5) TimeParse 1.61µs ± 4% 1.54µs ± 1% -4.42% (p=0.008 n=5+5) TimeFormat 1.66µs ± 3% 1.58µs ± 1% -5.22% (p=0.008 n=5+5) [Geo mean] 232µs 221µs -4.54% name old speed new speed delta GobDecode 25.0MB/s ± 8% 25.1MB/s ±27% ~ (p=0.222 n=5+5) GobEncode 32.8MB/s ±21% 38.0MB/s ± 0% +15.84% (p=0.016 n=5+4) Gzip 22.8MB/s ± 0% 23.6MB/s ± 0% +3.49% (p=0.016 n=4+5) Gunzip 121MB/s ± 1% 128MB/s ± 1% +5.68% (p=0.008 n=5+5) JSONEncode 54.4MB/s ± 1% 56.5MB/s ± 1% +3.97% (p=0.008 n=5+5) JSONDecode 7.88MB/s ± 8% 7.65MB/s ± 8% ~ (p=0.548 n=5+5) GoParse 3.07MB/s ± 8% 3.00MB/s ±22% ~ (p=0.579 n=5+5) RegexpMatchEasy0_32 75.6MB/s ± 2% 80.5MB/s ± 0% +6.58% (p=0.008 n=5+5) RegexpMatchEasy0_1K 356MB/s ± 0% 358MB/s ± 1% ~ (p=0.095 n=5+5) RegexpMatchEasy1_32 81.1MB/s ± 2% 86.5MB/s ± 1% +6.69% (p=0.008 n=5+5) RegexpMatchEasy1_1K 314MB/s ± 0% 320MB/s ± 0% +2.10% (p=0.008 n=5+5) RegexpMatchMedium_32 1.77MB/s ± 1% 1.88MB/s ± 0% +6.09% (p=0.016 n=5+4) RegexpMatchMedium_1K 6.99MB/s ± 2% 7.33MB/s ± 1% +4.83% (p=0.008 n=5+5) RegexpMatchHard_32 3.78MB/s ± 1% 4.04MB/s ± 1% +7.04% (p=0.008 n=5+5) RegexpMatchHard_1K 4.04MB/s ± 1% 4.33MB/s ± 2% +7.17% (p=0.008 n=5+5) Revcomp 143MB/s ± 4% 145MB/s ± 5% ~ (p=1.000 n=5+5) Template 6.77MB/s ±24% 7.22MB/s ± 5% ~ (p=0.690 n=5+5) [Geo mean] 24.4MB/s 25.4MB/s +4.18% Change-Id: Ib80716e62992aec28b2c4a96af280c278f83aa49 Reviewed-on: https://go-review.googlesource.com/c/go/+/173980 Run-TryBot: Cherry Zhang TryBot-Result: Gobot Gobot Reviewed-by: Richard Musiol --- src/cmd/internal/obj/wasm/a.out.go | 8 +- src/cmd/internal/obj/wasm/wasmobj.go | 134 +++++++++++++++++++-------- src/cmd/link/internal/wasm/asm.go | 23 +++-- src/runtime/asm_wasm.s | 15 +-- src/runtime/rt0_js_wasm.s | 52 ++++++----- 5 files changed, 145 insertions(+), 87 deletions(-) diff --git a/src/cmd/internal/obj/wasm/a.out.go b/src/cmd/internal/obj/wasm/a.out.go index c686f1d6f0..823777d4fb 100644 --- a/src/cmd/internal/obj/wasm/a.out.go +++ b/src/cmd/internal/obj/wasm/a.out.go @@ -250,9 +250,7 @@ const ( const ( // globals - REG_PC_F = obj.RBaseWasm + iota - REG_PC_B - REG_SP // SP is currently 32-bit, until 64-bit memory operations are available + REG_SP = obj.RBaseWasm + iota // SP is currently 32-bit, until 64-bit memory operations are available REG_CTXT REG_g // RET* are used by runtime.return0 and runtime.reflectcall. These functions pass return values in registers. @@ -296,9 +294,11 @@ const ( REG_F14 REG_F15 + REG_PC_B // also first parameter, i32 + MAXREG - MINREG = REG_PC_F + MINREG = REG_SP REGSP = REG_SP REGCTXT = REG_CTXT REGG = REG_g diff --git a/src/cmd/internal/obj/wasm/wasmobj.go b/src/cmd/internal/obj/wasm/wasmobj.go index 0ad883470e..a6388b9ee7 100644 --- a/src/cmd/internal/obj/wasm/wasmobj.go +++ b/src/cmd/internal/obj/wasm/wasmobj.go @@ -16,8 +16,6 @@ import ( ) var Register = map[string]int16{ - "PC_F": REG_PC_F, - "PC_B": REG_PC_B, "SP": REG_SP, "CTXT": REG_CTXT, "g": REG_g, @@ -60,6 +58,8 @@ var Register = map[string]int16{ "F13": REG_F13, "F14": REG_F14, "F15": REG_F15, + + "PC_B": REG_PC_B, } var registerNames []string @@ -368,20 +368,31 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { break } - // reset PC_B to function entry - p = appendp(p, AI32Const, constAddr(0)) - p = appendp(p, ASet, regAddr(REG_PC_B)) - // low-level WebAssembly call to function switch jmp.To.Type { case obj.TYPE_MEM: + if !notUsePC_B[jmp.To.Sym.Name] { + // Set PC_B parameter to function entry. + p = appendp(p, AI32Const, constAddr(0)) + } p = appendp(p, ACall, jmp.To) + case obj.TYPE_NONE: // (target PC is on stack) p = appendp(p, AI32WrapI64) p = appendp(p, AI32Const, constAddr(16)) // only needs PC_F bits (16-31), PC_B bits (0-15) are zero p = appendp(p, AI32ShrU) + + // Set PC_B parameter to function entry. + // We need to push this before pushing the target PC_F, + // so temporarily pop PC_F, using our REG_PC_B as a + // scratch register, and push it back after pushing 0. + p = appendp(p, ASet, regAddr(REG_PC_B)) + p = appendp(p, AI32Const, constAddr(0)) + p = appendp(p, AGet, regAddr(REG_PC_B)) + p = appendp(p, ACallIndirect) + default: panic("bad target for JMP") } @@ -419,20 +430,31 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { }) p = appendp(p, AI64Store, constAddr(0)) - // reset PC_B to function entry - p = appendp(p, AI32Const, constAddr(0)) - p = appendp(p, ASet, regAddr(REG_PC_B)) - // low-level WebAssembly call to function switch call.To.Type { case obj.TYPE_MEM: + if !notUsePC_B[call.To.Sym.Name] { + // Set PC_B parameter to function entry. + p = appendp(p, AI32Const, constAddr(0)) + } p = appendp(p, ACall, call.To) + case obj.TYPE_NONE: // (target PC is on stack) p = appendp(p, AI32WrapI64) p = appendp(p, AI32Const, constAddr(16)) // only needs PC_F bits (16-31), PC_B bits (0-15) are zero p = appendp(p, AI32ShrU) + + // Set PC_B parameter to function entry. + // We need to push this before pushing the target PC_F, + // so temporarily pop PC_F, using our PC_B as a + // scratch register, and push it back after pushing 0. + p = appendp(p, ASet, regAddr(REG_PC_B)) + p = appendp(p, AI32Const, constAddr(0)) + p = appendp(p, AGet, regAddr(REG_PC_B)) + p = appendp(p, ACallIndirect) + default: panic("bad target for CALL") } @@ -465,7 +487,13 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { // jump to before the call if jmpdefer has reset the return address to the call's PC if call.To.Sym == deferreturn { - p = appendp(p, AGet, regAddr(REG_PC_B)) + // get PC_B from -8(SP) + p = appendp(p, AGet, regAddr(REG_SP)) + p = appendp(p, AI32Const, constAddr(8)) + p = appendp(p, AI32Sub) + p = appendp(p, AI32Load16U, constAddr(0)) + p = appendp(p, ATee, regAddr(REG_PC_B)) + p = appendp(p, AI32Const, constAddr(call.Pc)) p = appendp(p, AI32Eq) p = appendp(p, ABrIf, constAddr(0)) @@ -487,9 +515,8 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { } if ret.To.Type == obj.TYPE_MEM { - // reset PC_B to function entry + // Set PC_B parameter to function entry. p = appendp(p, AI32Const, constAddr(0)) - p = appendp(p, ASet, regAddr(REG_PC_B)) // low-level WebAssembly call to function p = appendp(p, ACall, ret.To) @@ -497,16 +524,6 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { break } - // read return PC_F from Go stack - p = appendp(p, AGet, regAddr(REG_SP)) - p = appendp(p, AI32Load16U, constAddr(2)) - p = appendp(p, ASet, regAddr(REG_PC_F)) - - // read return PC_B from Go stack - p = appendp(p, AGet, regAddr(REG_SP)) - p = appendp(p, AI32Load16U, constAddr(0)) - p = appendp(p, ASet, regAddr(REG_PC_B)) - // SP += 8 p = appendp(p, AGet, regAddr(REG_SP)) p = appendp(p, AI32Const, constAddr(8)) @@ -771,16 +788,38 @@ func countRegisters(s *obj.LSym) (numI, numF int16) { return } +// Most of the Go functions has a single parameter (PC_B) in +// Wasm ABI. This is a list of exceptions. +var notUsePC_B = map[string]bool{ + "_rt0_wasm_js": true, + "wasm_export_run": true, + "wasm_export_resume": true, + "wasm_export_getsp": true, + "wasm_pc_f_loop": true, + "runtime.wasmMove": true, + "runtime.wasmZero": true, + "runtime.wasmDiv": true, + "runtime.wasmTruncS": true, + "runtime.wasmTruncU": true, + "runtime.gcWriteBarrier": true, + "cmpbody": true, + "memeqbody": true, + "memcmp": true, + "memchr": true, +} + func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { w := new(bytes.Buffer) hasLocalSP := false + hasPC_B := false var r0, f0 int16 // Function starts with declaration of locals: numbers and types. // Some functions use a special calling convention. switch s.Name { - case "wasm_export_run", "runtime.wasmMove", "runtime.wasmZero", "runtime.wasmDiv", "runtime.wasmTruncS", "runtime.wasmTruncU", "memeqbody": + case "_rt0_wasm_js", "wasm_export_run", "wasm_export_resume", "wasm_export_getsp", "wasm_pc_f_loop", + "runtime.wasmMove", "runtime.wasmZero", "runtime.wasmDiv", "runtime.wasmTruncS", "runtime.wasmTruncU", "memeqbody": writeUleb128(w, 0) // number of sets of locals case "memchr", "memcmp": writeUleb128(w, 1) // number of sets of locals @@ -797,9 +836,10 @@ func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { default: // Normal calling convention: No WebAssembly parameters. First local variable is local SP cache. hasLocalSP = true + hasPC_B = true numI, numF := countRegisters(s) - r0 = 1 - f0 = 1 + numI + r0 = 2 + f0 = 2 + numI numTypes := 1 if numI > 0 { @@ -826,6 +866,7 @@ func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { // Copy SP from its global variable into a local variable. Accessing a local variable is more efficient. updateLocalSP(w) } + for p := s.Func.Text; p != nil; p = p.Link { switch p.As { case AGet: @@ -836,10 +877,16 @@ func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { switch { case reg == REG_SP && hasLocalSP: w.WriteByte(0x20) // local.get - writeUleb128(w, 0) // local SP - case reg >= REG_PC_F && reg <= REG_PAUSE: + writeUleb128(w, 1) // local SP + case reg >= REG_SP && reg <= REG_PAUSE: w.WriteByte(0x23) // global.get - writeUleb128(w, uint64(reg-REG_PC_F)) + writeUleb128(w, uint64(reg-REG_SP)) + case reg == REG_PC_B: + if !hasPC_B { + panic(fmt.Sprintf("PC_B is not used in %s", s.Name)) + } + w.WriteByte(0x20) // local.get (i32) + writeUleb128(w, 0) // local PC_B case reg >= REG_R0 && reg <= REG_R15: w.WriteByte(0x20) // local.get (i64) writeUleb128(w, uint64(r0+(reg-REG_R0))) @@ -857,21 +904,26 @@ func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { } reg := p.To.Reg switch { - case reg >= REG_PC_F && reg <= REG_PAUSE: + case reg >= REG_SP && reg <= REG_PAUSE: if reg == REG_SP && hasLocalSP { w.WriteByte(0x22) // local.tee - writeUleb128(w, 0) // local SP + writeUleb128(w, 1) // local SP } w.WriteByte(0x24) // global.set - writeUleb128(w, uint64(reg-REG_PC_F)) - case reg >= REG_R0 && reg <= REG_F15: + writeUleb128(w, uint64(reg-REG_SP)) + case reg >= REG_R0 && reg <= REG_PC_B: if p.Link.As == AGet && p.Link.From.Reg == reg { w.WriteByte(0x22) // local.tee p = p.Link } else { w.WriteByte(0x21) // local.set } - if reg <= REG_R15 { + if reg == REG_PC_B { + if !hasPC_B { + panic(fmt.Sprintf("PC_B is not used in %s", s.Name)) + } + writeUleb128(w, 0) // local PC_B + } else if reg <= REG_R15 { writeUleb128(w, uint64(r0+(reg-REG_R0))) } else { writeUleb128(w, uint64(f0+(reg-REG_F0))) @@ -887,6 +939,12 @@ func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { } reg := p.To.Reg switch { + case reg == REG_PC_B: + if !hasPC_B { + panic(fmt.Sprintf("PC_B is not used in %s", s.Name)) + } + w.WriteByte(0x22) // local.tee (i32) + writeUleb128(w, 0) // local PC_B case reg >= REG_R0 && reg <= REG_R15: w.WriteByte(0x22) // local.tee (i64) writeUleb128(w, uint64(r0+(reg-REG_R0))) @@ -1036,10 +1094,10 @@ func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) { } func updateLocalSP(w *bytes.Buffer) { - w.WriteByte(0x23) // global.get - writeUleb128(w, uint64(REG_SP-REG_PC_F)) // SP - w.WriteByte(0x21) // local.set - writeUleb128(w, 0) // local SP + w.WriteByte(0x23) // global.get + writeUleb128(w, 0) // global SP + w.WriteByte(0x21) // local.set + writeUleb128(w, 1) // local SP } func align(as obj.As) uint64 { diff --git a/src/cmd/link/internal/wasm/asm.go b/src/cmd/link/internal/wasm/asm.go index c80e81e5b3..54b265cb19 100644 --- a/src/cmd/link/internal/wasm/asm.go +++ b/src/cmd/link/internal/wasm/asm.go @@ -102,10 +102,11 @@ func asmb2(ctxt *ld.Link) { } types := []*wasmFuncType{ - // For normal Go functions the return value is + // For normal Go functions, the single parameter is PC_B, + // the return value is // 0 if the function returned normally or // 1 if the stack needs to be unwound. - {Results: []byte{I32}}, + {Params: []byte{I32}, Results: []byte{I32}}, } // collect host imports (functions that get imported from the WebAssembly host, usually JavaScript) @@ -320,16 +321,14 @@ func writeGlobalSec(ctxt *ld.Link) { sizeOffset := writeSecHeader(ctxt, sectionGlobal) globalRegs := []byte{ - I32, // 0: PC_F - I32, // 1: PC_B - I32, // 2: SP - I64, // 3: CTXT - I64, // 4: g - I64, // 5: RET0 - I64, // 6: RET1 - I64, // 7: RET2 - I64, // 8: RET3 - I32, // 9: PAUSE + I32, // 0: SP + I64, // 1: CTXT + I64, // 2: g + I64, // 3: RET0 + I64, // 4: RET1 + I64, // 5: RET2 + I64, // 6: RET3 + I32, // 7: PAUSE } writeUleb128(ctxt.Out, uint64(len(globalRegs))) // number of globals diff --git a/src/runtime/asm_wasm.s b/src/runtime/asm_wasm.s index a10c89d298..8f3964f08b 100644 --- a/src/runtime/asm_wasm.s +++ b/src/runtime/asm_wasm.s @@ -37,17 +37,12 @@ TEXT runtime·gogo(SB), NOSPLIT, $0-8 MOVD gobuf_g(R0), g MOVD gobuf_sp(R0), SP + // Put target PC at -8(SP), wasm_pc_f_loop will pick it up + Get SP + I32Const $8 + I32Sub I64Load gobuf_pc(R0) - I32WrapI64 - I32Const $16 - I32ShrU - Set PC_F - - I64Load gobuf_pc(R0) - I64Const $0xFFFF - I64And - I32WrapI64 - Set PC_B + I64Store $0 MOVD gobuf_ret(R0), RET0 MOVD gobuf_ctxt(R0), CTXT diff --git a/src/runtime/rt0_js_wasm.s b/src/runtime/rt0_js_wasm.s index c4efd9637c..b22c46e2e9 100644 --- a/src/runtime/rt0_js_wasm.s +++ b/src/runtime/rt0_js_wasm.s @@ -31,14 +31,9 @@ TEXT wasm_export_run(SB),NOSPLIT,$0 I64ExtendI32U I64Store $8 - I32Const $runtime·rt0_go(SB) - I32Const $16 - I32ShrU - Set PC_F - - I32Const $0 - Set PC_B - + I32Const $0 // entry PC_B + Call runtime·rt0_go(SB) + Drop Call wasm_pc_f_loop(SB) Return @@ -46,14 +41,9 @@ TEXT wasm_export_run(SB),NOSPLIT,$0 // wasm_export_resume gets called from JavaScript. It resumes the execution of Go code until it needs to wait for // an event. TEXT wasm_export_resume(SB),NOSPLIT,$0 - I32Const $runtime·handleEvent(SB) - I32Const $16 - I32ShrU - Set PC_F - I32Const $0 - Set PC_B - + Call runtime·handleEvent(SB) + Drop Call wasm_pc_f_loop(SB) Return @@ -63,15 +53,30 @@ TEXT wasm_pc_f_loop(SB),NOSPLIT,$0 // The WebAssembly stack may unwind, e.g. when switching goroutines. // The Go stack on the linear memory is then used to jump to the correct functions // with this loop, without having to restore the full WebAssembly stack. -loop: - Loop - Get PC_F - CallIndirect $0 - Drop +// It is expected to have a pending call before entering the loop, so check PAUSE first. + Get PAUSE + I32Eqz + If + loop: + Loop + // Get PC_B & PC_F from -8(SP) + Get SP + I32Const $8 + I32Sub + I32Load16U $0 // PC_B - Get PAUSE - I32Eqz - BrIf loop + Get SP + I32Const $8 + I32Sub + I32Load16U $2 // PC_F + + CallIndirect $0 + Drop + + Get PAUSE + I32Eqz + BrIf loop + End End I32Const $0 @@ -91,6 +96,7 @@ TEXT runtime·pause(SB), NOSPLIT, $0-8 RETUNWIND TEXT runtime·exit(SB), NOSPLIT, $0-4 + I32Const $0 Call runtime·wasmExit(SB) Drop I32Const $1