diff options
author | Cherry Zhang <cherryyz@google.com> | 2020-04-21 18:50:49 -0400 |
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committer | Cherry Zhang <cherryyz@google.com> | 2020-04-22 14:40:35 +0000 |
commit | 9570fc8f7155a668c0e868d5757ac7b0774e8340 (patch) | |
tree | 317b0ecbcfb26921ce3a177dcf71066f00bbe603 /src/cmd/link/internal/loader/loader.go | |
parent | 7a22f11e962a88813f945e227d3d67d94f3dc094 (diff) | |
download | go-9570fc8f7155a668c0e868d5757ac7b0774e8340.tar.gz go-9570fc8f7155a668c0e868d5757ac7b0774e8340.zip |
[dev.link] cmd/link: reduce memory usage for storing symbol section information
Currently, we use a dense array to store symbol's sections. The
array element is a *sym.Section, which takes 8 bytes per symbol
on a 64-bit machine. And the array is created upfront.
To reduce memory usage, use a 16-bit index for sections, so we
store 2 bytes per symbol. The array is pointerless, reducing GC
work. Also create the array lazily.
This reduces some memory usage: linking cmd/compile,
name old alloc/op new alloc/op delta
Loadlib_GC 42.1MB ± 0% 36.2MB ± 0% -14.01% (p=0.008 n=5+5)
name old live-B new live-B delta
Loadlib_GC 16.8M ± 0% 15.4M ± 0% -8.36% (p=0.008 n=5+5)
Archive_GC 98.2M ± 0% 97.2M ± 0% -1.02% (p=0.008 n=5+5) # at the end
Change-Id: If8c41eded8859660bca648c5e6fdf5830810fbf6
Reviewed-on: https://go-review.googlesource.com/c/go/+/229306
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Diffstat (limited to 'src/cmd/link/internal/loader/loader.go')
-rw-r--r-- | src/cmd/link/internal/loader/loader.go | 34 |
1 files changed, 30 insertions, 4 deletions
diff --git a/src/cmd/link/internal/loader/loader.go b/src/cmd/link/internal/loader/loader.go index 75477fd819..9fd2bb28b6 100644 --- a/src/cmd/link/internal/loader/loader.go +++ b/src/cmd/link/internal/loader/loader.go @@ -198,7 +198,9 @@ type Loader struct { payloadBatch []extSymPayload payloads []*extSymPayload // contents of linker-materialized external syms values []int64 // symbol values, indexed by global sym index - sects []*sym.Section // symbol's section, indexed by global index + + sects []*sym.Section // sections + symSects []uint16 // symbol's section, index to sects array itablink map[Sym]struct{} // itablink[j] defined if j is go.itablink.* @@ -326,6 +328,7 @@ func NewLoader(flags uint32, elfsetstring elfsetstringFunc) *Loader { builtinSyms: make([]Sym, nbuiltin), flags: flags, elfsetstring: elfsetstring, + sects: []*sym.Section{nil}, // reserve index 0 for nil section } } @@ -990,7 +993,6 @@ func (l *Loader) growValues(reqLen int) { curLen := len(l.values) if reqLen > curLen { l.values = append(l.values, make([]int64, reqLen+1-curLen)...) - l.sects = append(l.sects, make([]*sym.Section, reqLen+1-curLen)...) } } @@ -1053,12 +1055,35 @@ func (l *Loader) SetSymAlign(i Sym, align int32) { // SymValue returns the section of the i-th symbol. i is global index. func (l *Loader) SymSect(i Sym) *sym.Section { - return l.sects[i] + return l.sects[l.symSects[i]] } // SetSymValue sets the section of the i-th symbol. i is global index. func (l *Loader) SetSymSect(i Sym, sect *sym.Section) { - l.sects[i] = sect + if int(i) >= len(l.symSects) { + l.symSects = append(l.symSects, make([]uint16, l.NSym()-len(l.symSects))...) + } + l.symSects[i] = sect.Index +} + +// growSects grows the slice used to store symbol sections. +func (l *Loader) growSects(reqLen int) { + curLen := len(l.symSects) + if reqLen > curLen { + l.symSects = append(l.symSects, make([]uint16, reqLen+1-curLen)...) + } +} + +// NewSection creates a new (output) section. +func (l *Loader) NewSection() *sym.Section { + sect := new(sym.Section) + idx := len(l.sects) + if idx != int(uint16(idx)) { + panic("too many sections created") + } + sect.Index = uint16(idx) + l.sects = append(l.sects, sect) + return sect } // SymDynImplib returns the "dynimplib" attribute for the specified @@ -1842,6 +1867,7 @@ func preprocess(arch *sys.Arch, s *sym.Symbol) { func (l *Loader) LoadFull(arch *sys.Arch, syms *sym.Symbols) { // create all Symbols first. l.growSyms(l.NSym()) + l.growSects(l.NSym()) nr := 0 // total number of sym.Reloc's we'll need for _, o := range l.objs[1:] { |