From f9fb4579e1766246d615566dec202bcd54e096a7 Mon Sep 17 00:00:00 2001 From: Josh Bleecher Snyder Date: Sat, 18 Mar 2017 08:11:49 -0700 Subject: [PATCH] cmd/compile: disable typPtr caching in the backend MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The only new Types that the backend introduces are pointers to Types generated by the frontend. Usually, when we generate a *T, we cache the resulting Type in T, to avoid recreating it later. However, that caching is not concurrency safe. Rather than add mutexes, this CL disables that caching before starting the backend. The backend generates few enough new *Ts that the performance impact of this is small, particularly if we pre-create some commonly used *Ts. Updates #15756 name old alloc/op new alloc/op delta Template 40.3MB ± 0% 40.4MB ± 0% +0.18% (p=0.001 n=10+10) Unicode 29.8MB ± 0% 29.8MB ± 0% +0.11% (p=0.043 n=10+9) GoTypes 114MB ± 0% 115MB ± 0% +0.33% (p=0.000 n=9+10) SSA 855MB ± 0% 859MB ± 0% +0.40% (p=0.000 n=10+10) Flate 25.7MB ± 0% 25.8MB ± 0% +0.35% (p=0.000 n=10+10) GoParser 31.9MB ± 0% 32.1MB ± 0% +0.58% (p=0.000 n=10+10) Reflect 79.6MB ± 0% 79.9MB ± 0% +0.31% (p=0.000 n=10+10) Tar 26.9MB ± 0% 26.9MB ± 0% +0.21% (p=0.000 n=10+10) XML 42.5MB ± 0% 42.7MB ± 0% +0.52% (p=0.000 n=10+9) name old allocs/op new allocs/op delta Template 394k ± 1% 393k ± 0% ~ (p=0.529 n=10+10) Unicode 319k ± 1% 319k ± 0% ~ (p=0.720 n=10+9) GoTypes 1.15M ± 0% 1.15M ± 0% +0.14% (p=0.035 n=10+10) SSA 7.53M ± 0% 7.56M ± 0% +0.45% (p=0.000 n=9+10) Flate 238k ± 0% 238k ± 1% ~ (p=0.579 n=10+10) GoParser 318k ± 1% 320k ± 1% +0.64% (p=0.001 n=10+10) Reflect 1.00M ± 0% 1.00M ± 0% ~ (p=0.393 n=10+10) Tar 254k ± 0% 254k ± 1% ~ (p=0.075 n=10+10) XML 395k ± 0% 397k ± 0% +0.44% (p=0.001 n=10+9) Change-Id: I6c031ed4f39108f26969c5712b73aa2fc08cd10a Reviewed-on: https://go-review.googlesource.com/38417 Run-TryBot: Josh Bleecher Snyder TryBot-Result: Gobot Gobot Reviewed-by: Matthew Dempsky --- src/cmd/compile/internal/gc/ssa.go | 15 +++++++++++++++ src/cmd/compile/internal/gc/type.go | 11 +++++++++-- 2 files changed, 24 insertions(+), 2 deletions(-) diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go index 6726bdd621..fb4cad9139 100644 --- a/src/cmd/compile/internal/gc/ssa.go +++ b/src/cmd/compile/internal/gc/ssa.go @@ -46,6 +46,21 @@ func initssaconfig() { Float64Ptr: typPtr(Types[TFLOAT64]), BytePtrPtr: typPtr(typPtr(Types[TUINT8])), } + // Generate a few pointer types that are uncommon in the frontend but common in the backend. + // Caching is disabled in the backend, so generating these here avoids allocations. + _ = typPtr(Types[TINTER]) // *interface{} + _ = typPtr(typPtr(Types[TSTRING])) // **string + _ = typPtr(typPtr(idealstring)) // **string + _ = typPtr(typSlice(Types[TINTER])) // *[]interface{} + _ = typPtr(typPtr(bytetype)) // **byte + _ = typPtr(typSlice(bytetype)) // *[]byte + _ = typPtr(typSlice(Types[TSTRING])) // *[]string + _ = typPtr(typSlice(idealstring)) // *[]string + _ = typPtr(typPtr(typPtr(Types[TUINT8]))) // ***uint8 + _ = typPtr(Types[TINT16]) // *int16 + _ = typPtr(Types[TINT64]) // *int64 + _ = typPtr(errortype) // *error + typPtrCacheEnabled = false ssaConfig = ssa.NewConfig(thearch.LinkArch.Name, types, Ctxt, Debug['N'] == 0) if thearch.LinkArch.Name == "386" { ssaConfig.Set387(thearch.Use387) diff --git a/src/cmd/compile/internal/gc/type.go b/src/cmd/compile/internal/gc/type.go index f9e3b60d7b..49d222507b 100644 --- a/src/cmd/compile/internal/gc/type.go +++ b/src/cmd/compile/internal/gc/type.go @@ -487,6 +487,11 @@ func typMap(k, v *Type) *Type { return t } +// typPtrCacheEnabled controls whether *T Types are cached in T. +// Caching is disabled just before starting the backend. +// This allows the backend to run concurrently. +var typPtrCacheEnabled = true + // typPtr returns the pointer type pointing to t. func typPtr(elem *Type) *Type { if elem == nil { @@ -501,14 +506,16 @@ func typPtr(elem *Type) *Type { } if Tptr == 0 { - Fatalf("typPtr: Tptr not intialized") + Fatalf("typPtr: Tptr not initialized") } t := typ(Tptr) t.Extra = PtrType{Elem: elem} t.Width = int64(Widthptr) t.Align = uint8(Widthptr) - elem.ptrTo = t + if typPtrCacheEnabled { + elem.ptrTo = t + } return t }