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[dev.link] cmd/link: move findfunctab to a generated symbol

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Basically removes all allocation from findfunctab:

Findfunctab_GC                172kB ± 0%       0kB ± 0%   ~     (p=1.000 n=1+1)

Change-Id: I246f7d2751317886b658f7ef672fb30b3c519668
Reviewed-on: https://go-review.googlesource.com/c/go/+/239281
Run-TryBot: Jeremy Faller <jeremy@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Jeremy Faller 2020-06-22 11:11:12 -04:00
parent f033e23414
commit 1fdf5ba50c
1 changed files with 59 additions and 55 deletions
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20
src/cmd/link/internal/ld/pcln.go
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@ -585,9 +585,6 @@ const (
// a given text symbols is a container (outer sym).
func (ctxt *Link) findfunctab(container loader.Bitmap) {
ldr := ctxt.loader
t := ldr.CreateSymForUpdate("runtime.findfunctab", 0)
t.SetType(sym.SRODATA)
ldr.SetAttrLocal(t.Sym(), true)
// find min and max address
min := ldr.SymValue(ctxt.Textp[0])
@ -598,6 +595,13 @@ func (ctxt *Link) findfunctab(container loader.Bitmap) {
// that map to that subbucket.
n := int32((max - min + SUBBUCKETSIZE - 1) / SUBBUCKETSIZE)
nbuckets := int32((max - min + BUCKETSIZE - 1) / BUCKETSIZE)
size := 4*int64(nbuckets) + int64(n)
writeFindFuncTab := func(_ *Link, s loader.Sym) {
t := ldr.MakeSymbolUpdater(s)
indexes := make([]int32, n)
for i := int32(0); i < n; i++ {
indexes[i] = NOIDX
@ -637,11 +641,6 @@ func (ctxt *Link) findfunctab(container loader.Bitmap) {
idx++
}
// allocate table
nbuckets := int32((max - min + BUCKETSIZE - 1) / BUCKETSIZE)
t.Grow(4*int64(nbuckets) + int64(n))
// fill in table
for i := int32(0); i < nbuckets; i++ {
base := indexes[i*SUBBUCKETS]
@ -661,4 +660,9 @@ func (ctxt *Link) findfunctab(container loader.Bitmap) {
t.SetUint8(ctxt.Arch, int64(i)*(4+SUBBUCKETS)+4+int64(j), uint8(idx-base))
}
}
}
s := ctxt.createGeneratorSymbol("runtime.findfunctab", 0, sym.SRODATA, size, writeFindFuncTab)
ldr.SetAttrReachable(s, true)
ldr.SetAttrLocal(s, true)
}