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[dev.unified] cmd/compile: implement simple inline body pruning heuristic

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An important optimization in the existing export data format is the
pruning of unreachable inline bodies. That is, when re-exporting
transitively imported types, omitting the inline bodies for methods
that can't actually be needed due to importing that package.

The existing logic (implemented in typecheck/crawler.go) is fairly
sophisticated, but also relies on actually expanding inline bodies in
the process, which is undesirable. However, including all inline
bodies is also prohibitive for testing GOEXPERIMENT=unified against
very large Go code bases that impose size limits on build action
inputs.

As a short-term solution, this CL implements a simple heuristic for
GOEXPERIMENT=unified: include the inline bodies for all
locally-declared functions/methods, and for any imported
functions/methods that were inlined into this package.

Change-Id: I686964a0cd9262b77d3d5587f89cfbcfe8b2e521
Reviewed-on: https://go-review.googlesource.com/c/go/+/419675
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Matthew Dempsky 2022-07-26 21:52:42 -07:00
parent f2851c67fd
commit f995946094
4 changed files with 161 additions and 51 deletions
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35
src/cmd/compile/internal/noder/reader.go
View file

@ -897,6 +897,8 @@ func (r *reader) funcExt(name *ir.Name) {
typecheck.Func(fn)
if r.Bool() {
assert(name.Defn == nil)
fn.ABI = obj.ABI(r.Uint64())
// Escape analysis.
@ -911,7 +913,6 @@ func (r *reader) funcExt(name *ir.Name) {
Cost: int32(r.Len()),
CanDelayResults: r.Bool(),
}
r.addBody(name.Func)
}
} else {
r.addBody(name.Func)
@ -967,10 +968,26 @@ func (r *reader) pragmaFlag() ir.PragmaFlag {
// @@@ Function bodies
// bodyReader tracks where the serialized IR for a function's body can
// be found.
// bodyReader tracks where the serialized IR for a local or imported,
// generic function's body can be found.
var bodyReader = map[*ir.Func]pkgReaderIndex{}
// importBodyReader tracks where the serialized IR for an imported,
// static (i.e., non-generic) function body can be read.
var importBodyReader = map[*types.Sym]pkgReaderIndex{}
// bodyReaderFor returns the pkgReaderIndex for reading fn's
// serialized IR, and whether one was found.
func bodyReaderFor(fn *ir.Func) (pri pkgReaderIndex, ok bool) {
if fn.Nname.Defn != nil {
pri, ok = bodyReader[fn]
assert(ok) // must always be available
} else {
pri, ok = importBodyReader[fn.Sym()]
}
return
}
// todoBodies holds the list of function bodies that still need to be
// constructed.
var todoBodies []*ir.Func
@ -978,15 +995,13 @@ var todoBodies []*ir.Func
// addBody reads a function body reference from the element bitstream,
// and associates it with fn.
func (r *reader) addBody(fn *ir.Func) {
// addBody should only be called for local functions or imported
// generic functions; see comment in funcExt.
assert(fn.Nname.Defn != nil)
pri := pkgReaderIndex{r.p, r.Reloc(pkgbits.RelocBody), r.dict}
bodyReader[fn] = pri
if fn.Nname.Defn == nil {
// Don't read in function body for imported functions.
// See comment in funcExt.
return
}
if r.curfn == nil {
todoBodies = append(todoBodies, fn)
return
@ -2225,7 +2240,7 @@ func InlineCall(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExp
// TODO(mdempsky): Turn callerfn into an explicit parameter.
callerfn := ir.CurFunc
pri, ok := bodyReader[fn]
pri, ok := bodyReaderFor(fn)
if !ok {
// TODO(mdempsky): Reconsider this diagnostic's wording, if it's
// to be included in Go 1.20.