cmd/compile: Drop references to Prog structs after each function

Don't accumulate a massive list of Prog structs during
compilation and write them all out at the end of compilation.
Instead, convert them to code+relocs (or data+relocs) after each
function is compiled.

Track down a few other places that were keeping Progs alive
and nil them out so the Progs get GCd promptly.

Saves ~20% in peak memory usage for the compiler.  Surprisingly not much
help speed-wise (only because we end up doing more GCs.  With a
compensating GOGC=120, it does help a bit), but this provides a base for
more changes (e.g. reusing a cache of Progs).

Change-Id: I838e01017c228995a687a8110d0cd67bf8596407
Reviewed-on: https://go-review.googlesource.com/19867
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/cmd/compile/internal/gc/dcl.go b/src/cmd/compile/internal/gc/dcl.go
index fc47a39ee62ee08919417c6079dd236beef5dbde..7e44a4756da50fa7e60f196fc4015a0c4f53eaaa 100644 (file)
--- a/src/cmd/compile/internal/gc/dcl.go
+++ b/src/cmd/compile/internal/gc/dcl.go
@@ -1449,8 +1449,13 @@ func funccompile(n *Node) {
        Funcdepth = n.Func.Depth + 1
        compile(n)
        Curfn = nil
+       Pc = nil
+       continpc = nil
+       breakpc = nil
        Funcdepth = 0
        dclcontext = PEXTERN
+       flushdata()
+       obj.Flushplist(Ctxt) // convert from Prog list to machine code
 }
 
 func funcsym(s *Sym) *Sym {

diff --git a/src/cmd/compile/internal/gc/gsubr.go b/src/cmd/compile/internal/gc/gsubr.go
index 30bf736e3eb961e97e2c4685e734a63d8c049a83..04e986562dd3f29223eae161179ced3bbd34886f 100644 (file)
--- a/src/cmd/compile/internal/gc/gsubr.go
+++ b/src/cmd/compile/internal/gc/gsubr.go
@@ -173,6 +173,18 @@ func dumpdata() {
        Clearp(Pc)
 }
 
+func flushdata() {
+       if dfirst == nil {
+               return
+       }
+       newplist()
+       *Pc = *dfirst
+       Pc = dpc
+       Clearp(Pc)
+       dfirst = nil
+       dpc = nil
+}
+
 // Fixup instructions after allocauto (formerly compactframe) has moved all autos around.
 func fixautoused(p *obj.Prog) {
        for lp := &p; ; {

diff --git a/src/cmd/internal/obj/objfile.go b/src/cmd/internal/obj/objfile.go
index 40c92dd15280720fa8b6b710964a6c5ee99fa362..3dc5152f544aabbe2e267bf6132652b19ff76f86 100644 (file)
--- a/src/cmd/internal/obj/objfile.go
+++ b/src/cmd/internal/obj/objfile.go
@@ -302,16 +302,22 @@ func Flushplist(ctxt *Link) {
                ctxt.Arch.Assemble(ctxt, s)
                fieldtrack(ctxt, s)
                linkpcln(ctxt, s)
+               s.Text = nil
+               s.Etext = nil
        }
 
        // Add to running list in ctxt.
-       if ctxt.Etext == nil {
-               ctxt.Text = text
-       } else {
-               ctxt.Etext.Next = text
+       if text != nil {
+               if ctxt.Text == nil {
+                       ctxt.Text = text
+               } else {
+                       ctxt.Etext.Next = text
+               }
+               ctxt.Etext = etext
        }
-       ctxt.Etext = etext
        ctxt.Plist = nil
+       ctxt.Plast = nil
+       ctxt.Curp = nil
 }
 
 func Writeobjfile(ctxt *Link, b *Biobuf) {