cmd/internal/gc: transitive inlining
Inlining refuses to inline bodies containing an actual function call, so that
if that call or a child uses runtime.Caller it cannot observe
the inlining.
However, inlining was also refusing to inline bodies that contained
function calls that were themselves inlined away. For example:
func f() int {
return f1()
}
func f1() int {
return f2()
}
func f2() int {
return 2
}
The f2 call in f1 would be inlined, but the f1 call in f would not,
because f1's call to f2 blocked the inlining, despite itself eventually
being inlined away.
Account properly for this kind of transitive inlining and enable.
Also bump the inlining budget a bit, so that the runtime's
heapBits.next is inlined.
This reduces the time for '6g *.go' in html/template by around 12% (!).
(For what it's worth, closing Chrome reduces the time by about 17%.)
Change-Id: If1aa673bf3e583082dcfb5f223e67355c984bfc1
Reviewed-on: https://go-review.googlesource.com/5952
Reviewed-by: Austin Clements <austin@google.com>
diff --git a/src/cmd/internal/gc/inl.go b/src/cmd/internal/gc/inl.go
index 8b088a7..57a0ab6 100644
--- a/src/cmd/internal/gc/inl.go
+++ b/src/cmd/internal/gc/inl.go
@@ -15,7 +15,6 @@
// 2: early typechecking of all imported bodies
// 3: allow variadic functions
// 4: allow non-leaf functions , (breaks runtime.Caller)
-// 5: transitive inlining
//
// At some point this may get another default and become switch-offable with -N.
//
@@ -125,8 +124,9 @@
}
}
- budget := 40 // allowed hairyness
- if ishairylist(fn.Nbody, &budget) {
+ const maxBudget = 80
+ budget := maxBudget // allowed hairyness
+ if ishairylist(fn.Nbody, &budget) || budget < 0 {
return
}
@@ -136,6 +136,7 @@
fn.Nname.Inl = fn.Nbody
fn.Nbody = inlcopylist(fn.Nname.Inl)
fn.Nname.Inldcl = inlcopylist(fn.Nname.Defn.Dcl)
+ fn.Nname.InlCost = int32(maxBudget - budget)
// hack, TODO, check for better way to link method nodes back to the thing with the ->inl
// this is so export can find the body of a method
@@ -165,12 +166,42 @@
return false
}
- // Things that are too hairy, irrespective of the budget
switch n.Op {
+ // Call is okay if inlinable and we have the budget for the body.
+ case OCALLFUNC:
+ if n.Left.Inl != nil {
+ *budget -= int(n.Left.InlCost)
+ break
+ }
+ if n.Left.Op == ONAME && n.Left.Left != nil && n.Left.Left.Op == OTYPE && n.Left.Right != nil && n.Left.Right.Op == ONAME { // methods called as functions
+ if n.Left.Sym.Def != nil && n.Left.Sym.Def.Inl != nil {
+ *budget -= int(n.Left.Sym.Def.InlCost)
+ break
+ }
+ }
+ if Debug['l'] < 4 {
+ return true
+ }
+
+ // Call is okay if inlinable and we have the budget for the body.
+ case OCALLMETH:
+ if n.Left.Type == nil {
+ Fatal("no function type for [%p] %v\n", n.Left, Nconv(n.Left, obj.FmtSign))
+ }
+ if n.Left.Type.Nname == nil {
+ Fatal("no function definition for [%p] %v\n", n.Left.Type, Tconv(n.Left.Type, obj.FmtSign))
+ }
+ if n.Left.Type.Nname.Inl != nil {
+ *budget -= int(n.Left.Type.Nname.InlCost)
+ break
+ }
+ if Debug['l'] < 4 {
+ return true
+ }
+
+ // Things that are too hairy, irrespective of the budget
case OCALL,
- OCALLFUNC,
OCALLINTER,
- OCALLMETH,
OPANIC,
ORECOVER:
if Debug['l'] < 4 {
@@ -778,20 +809,20 @@
inlfn = saveinlfn
// transitive inlining
- // TODO do this pre-expansion on fn->inl directly. requires
- // either supporting exporting statemetns with complex ninits
- // or saving inl and making inlinl
- if Debug['l'] >= 5 {
- body := fn.Inl
- fn.Inl = nil // prevent infinite recursion
- inlnodelist(call.Nbody)
- for ll := call.Nbody; ll != nil; ll = ll.Next {
- if ll.N.Op == OINLCALL {
- inlconv2stmt(ll.N)
- }
+ // might be nice to do this before exporting the body,
+ // but can't emit the body with inlining expanded.
+ // instead we emit the things that the body needs
+ // and each use must redo the inlining.
+ // luckily these are small.
+ body = fn.Inl
+ fn.Inl = nil // prevent infinite recursion (shouldn't happen anyway)
+ inlnodelist(call.Nbody)
+ for ll := call.Nbody; ll != nil; ll = ll.Next {
+ if ll.N.Op == OINLCALL {
+ inlconv2stmt(ll.N)
}
- fn.Inl = body
}
+ fn.Inl = body
if Debug['m'] > 2 {
fmt.Printf("%v: After inlining %v\n\n", n.Line(), Nconv(*np, obj.FmtSign))
