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cmd/compile: use cache in front of type assert runtime call

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That way we don't need to call into the runtime for every
type assertion (to an interface type).

name           old time/op  new time/op  delta
TypeAssert-24  3.78ns ± 3%  1.00ns ± 1%  -73.53%  (p=0.000 n=10+8)

Change-Id: I0ba308aaf0f24a5495b4e13c814d35af0c58bfde
Reviewed-on: https://go-review.googlesource.com/c/go/+/529316
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
This commit is contained in:
Keith Randall 2023-09-18 13:31:49 -07:00
parent b455e239ae
commit cbcf8efa5f
7 changed files with 239 additions and 30 deletions
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7
src/cmd/compile/internal/walk/expr.go
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@ -731,10 +731,15 @@ func walkDotType(n *ir.TypeAssertExpr, init *ir.Nodes) ir.Node {
lsym := types.LocalPkg.Lookup(fmt.Sprintf(".typeAssert.%d", typeAssertGen)).LinksymABI(obj.ABI0)
typeAssertGen++
off := 0
off = objw.SymPtr(lsym, off, typecheck.LookupRuntimeVar("emptyTypeAssertCache"), 0)
off = objw.SymPtr(lsym, off, reflectdata.TypeSym(n.Type()).Linksym(), 0)
off = objw.Bool(lsym, off, n.Op() == ir.ODOTTYPE2) // CanFail
off += types.PtrSize - 1
objw.Global(lsym, int32(off), obj.LOCAL|obj.NOPTR)
objw.Global(lsym, int32(off), obj.LOCAL)
// Set the type to be just a single pointer, as the cache pointer is the
// only one that GC needs to see.
lsym.Gotype = reflectdata.TypeLinksym(types.Types[types.TUINT8].PtrTo())
n.Descriptor = lsym
}
return n