mirror of https://github.com/golang/go.git
cmd/compile: move addrescapes and moveToHeap to esc.go
They were used only in esc.go. 100% code movement. Also, remove the rather outdated comment at the top of gen.go. It's not really clear what gen.go is for any more. Change-Id: Iaedfe7015ef6f5c11c49f3e6721b15d779a00faa Reviewed-on: https://go-review.googlesource.com/41971 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Josh Bleecher Snyder
parent
14f3ca56ed
commit
fcee3777fd
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@ -2014,6 +2014,158 @@ recurse:
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e.pdepth--
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}
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// addrescapes tags node n as having had its address taken
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// by "increasing" the "value" of n.Esc to EscHeap.
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// Storage is allocated as necessary to allow the address
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// to be taken.
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func addrescapes(n *Node) {
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switch n.Op {
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default:
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// Unexpected Op, probably due to a previous type error. Ignore.
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case OIND, ODOTPTR:
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// Nothing to do.
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case ONAME:
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if n == nodfp {
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break
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}
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// if this is a tmpname (PAUTO), it was tagged by tmpname as not escaping.
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// on PPARAM it means something different.
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if n.Class() == PAUTO && n.Esc == EscNever {
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break
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}
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// If a closure reference escapes, mark the outer variable as escaping.
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if n.IsClosureVar() {
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addrescapes(n.Name.Defn)
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break
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}
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if n.Class() != PPARAM && n.Class() != PPARAMOUT && n.Class() != PAUTO {
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break
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}
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// This is a plain parameter or local variable that needs to move to the heap,
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// but possibly for the function outside the one we're compiling.
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// That is, if we have:
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//
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// func f(x int) {
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// func() {
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// global = &x
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// }
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// }
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//
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// then we're analyzing the inner closure but we need to move x to the
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// heap in f, not in the inner closure. Flip over to f before calling moveToHeap.
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oldfn := Curfn
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Curfn = n.Name.Curfn
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if Curfn.Func.Closure != nil && Curfn.Op == OCLOSURE {
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Curfn = Curfn.Func.Closure
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}
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ln := lineno
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lineno = Curfn.Pos
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moveToHeap(n)
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Curfn = oldfn
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lineno = ln
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// ODOTPTR has already been introduced,
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// so these are the non-pointer ODOT and OINDEX.
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// In &x[0], if x is a slice, then x does not
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// escape--the pointer inside x does, but that
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// is always a heap pointer anyway.
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case ODOT, OINDEX, OPAREN, OCONVNOP:
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if !n.Left.Type.IsSlice() {
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addrescapes(n.Left)
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}
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}
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}
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// moveToHeap records the parameter or local variable n as moved to the heap.
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func moveToHeap(n *Node) {
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if Debug['r'] != 0 {
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Dump("MOVE", n)
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}
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if compiling_runtime {
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yyerror("%v escapes to heap, not allowed in runtime.", n)
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}
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if n.Class() == PAUTOHEAP {
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Dump("n", n)
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Fatalf("double move to heap")
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}
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// Allocate a local stack variable to hold the pointer to the heap copy.
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// temp will add it to the function declaration list automatically.
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heapaddr := temp(types.NewPtr(n.Type))
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heapaddr.Sym = lookup("&" + n.Sym.Name)
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heapaddr.Orig.Sym = heapaddr.Sym
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// Unset AutoTemp to persist the &foo variable name through SSA to
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// liveness analysis.
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// TODO(mdempsky/drchase): Cleaner solution?
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heapaddr.Name.SetAutoTemp(false)
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// Parameters have a local stack copy used at function start/end
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// in addition to the copy in the heap that may live longer than
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// the function.
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if n.Class() == PPARAM || n.Class() == PPARAMOUT {
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if n.Xoffset == BADWIDTH {
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Fatalf("addrescapes before param assignment")
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}
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// We rewrite n below to be a heap variable (indirection of heapaddr).
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// Preserve a copy so we can still write code referring to the original,
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// and substitute that copy into the function declaration list
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// so that analyses of the local (on-stack) variables use it.
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stackcopy := newname(n.Sym)
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stackcopy.SetAddable(false)
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stackcopy.Type = n.Type
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stackcopy.Xoffset = n.Xoffset
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stackcopy.SetClass(n.Class())
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stackcopy.Name.Param.Heapaddr = heapaddr
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if n.Class() == PPARAMOUT {
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// Make sure the pointer to the heap copy is kept live throughout the function.
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// The function could panic at any point, and then a defer could recover.
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// Thus, we need the pointer to the heap copy always available so the
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// post-deferreturn code can copy the return value back to the stack.
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// See issue 16095.
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heapaddr.SetIsOutputParamHeapAddr(true)
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}
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n.Name.Param.Stackcopy = stackcopy
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// Substitute the stackcopy into the function variable list so that
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// liveness and other analyses use the underlying stack slot
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// and not the now-pseudo-variable n.
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found := false
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for i, d := range Curfn.Func.Dcl {
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if d == n {
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Curfn.Func.Dcl[i] = stackcopy
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found = true
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break
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}
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// Parameters are before locals, so can stop early.
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// This limits the search even in functions with many local variables.
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if d.Class() == PAUTO {
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break
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}
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}
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if !found {
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Fatalf("cannot find %v in local variable list", n)
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}
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Curfn.Func.Dcl = append(Curfn.Func.Dcl, n)
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}
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// Modify n in place so that uses of n now mean indirection of the heapaddr.
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n.SetClass(PAUTOHEAP)
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n.Xoffset = 0
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n.Name.Param.Heapaddr = heapaddr
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n.Esc = EscHeap
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if Debug['m'] != 0 {
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fmt.Printf("%v: moved to heap: %v\n", n.Line(), n)
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}
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}
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// This special tag is applied to uintptr variables
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// that we believe may hold unsafe.Pointers for
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// calls into assembly functions.
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@ -2,15 +2,12 @@
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Portable half of code generator; mainly statements and control flow.
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package gc
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import (
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"cmd/compile/internal/types"
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"cmd/internal/obj"
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"cmd/internal/src"
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"fmt"
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"strconv"
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)
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@ -18,74 +15,6 @@ func Sysfunc(name string) *obj.LSym {
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return Runtimepkg.Lookup(name).Linksym()
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}
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// addrescapes tags node n as having had its address taken
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// by "increasing" the "value" of n.Esc to EscHeap.
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// Storage is allocated as necessary to allow the address
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// to be taken.
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func addrescapes(n *Node) {
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switch n.Op {
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default:
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// Unexpected Op, probably due to a previous type error. Ignore.
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case OIND, ODOTPTR:
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// Nothing to do.
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case ONAME:
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if n == nodfp {
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break
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}
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// if this is a tmpname (PAUTO), it was tagged by tmpname as not escaping.
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// on PPARAM it means something different.
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if n.Class() == PAUTO && n.Esc == EscNever {
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break
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}
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// If a closure reference escapes, mark the outer variable as escaping.
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if n.IsClosureVar() {
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addrescapes(n.Name.Defn)
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break
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}
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if n.Class() != PPARAM && n.Class() != PPARAMOUT && n.Class() != PAUTO {
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break
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}
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// This is a plain parameter or local variable that needs to move to the heap,
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// but possibly for the function outside the one we're compiling.
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// That is, if we have:
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//
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// func f(x int) {
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// func() {
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// global = &x
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// }
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// }
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//
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// then we're analyzing the inner closure but we need to move x to the
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// heap in f, not in the inner closure. Flip over to f before calling moveToHeap.
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oldfn := Curfn
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Curfn = n.Name.Curfn
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if Curfn.Func.Closure != nil && Curfn.Op == OCLOSURE {
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Curfn = Curfn.Func.Closure
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}
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ln := lineno
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lineno = Curfn.Pos
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moveToHeap(n)
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Curfn = oldfn
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lineno = ln
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// ODOTPTR has already been introduced,
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// so these are the non-pointer ODOT and OINDEX.
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// In &x[0], if x is a slice, then x does not
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// escape--the pointer inside x does, but that
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// is always a heap pointer anyway.
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case ODOT, OINDEX, OPAREN, OCONVNOP:
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if !n.Left.Type.IsSlice() {
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addrescapes(n.Left)
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}
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}
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}
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// isParamStackCopy reports whether this is the on-stack copy of a
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// function parameter that moved to the heap.
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func (n *Node) isParamStackCopy() bool {
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@ -98,90 +27,6 @@ func (n *Node) isParamHeapCopy() bool {
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return n.Op == ONAME && n.Class() == PAUTOHEAP && n.Name.Param.Stackcopy != nil
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}
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// moveToHeap records the parameter or local variable n as moved to the heap.
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func moveToHeap(n *Node) {
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if Debug['r'] != 0 {
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Dump("MOVE", n)
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}
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if compiling_runtime {
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yyerror("%v escapes to heap, not allowed in runtime.", n)
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}
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if n.Class() == PAUTOHEAP {
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Dump("n", n)
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Fatalf("double move to heap")
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}
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// Allocate a local stack variable to hold the pointer to the heap copy.
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// temp will add it to the function declaration list automatically.
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heapaddr := temp(types.NewPtr(n.Type))
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heapaddr.Sym = lookup("&" + n.Sym.Name)
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heapaddr.Orig.Sym = heapaddr.Sym
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// Unset AutoTemp to persist the &foo variable name through SSA to
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// liveness analysis.
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// TODO(mdempsky/drchase): Cleaner solution?
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heapaddr.Name.SetAutoTemp(false)
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// Parameters have a local stack copy used at function start/end
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// in addition to the copy in the heap that may live longer than
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// the function.
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if n.Class() == PPARAM || n.Class() == PPARAMOUT {
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if n.Xoffset == BADWIDTH {
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Fatalf("addrescapes before param assignment")
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}
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// We rewrite n below to be a heap variable (indirection of heapaddr).
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// Preserve a copy so we can still write code referring to the original,
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// and substitute that copy into the function declaration list
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// so that analyses of the local (on-stack) variables use it.
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stackcopy := newname(n.Sym)
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stackcopy.SetAddable(false)
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stackcopy.Type = n.Type
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stackcopy.Xoffset = n.Xoffset
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stackcopy.SetClass(n.Class())
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stackcopy.Name.Param.Heapaddr = heapaddr
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if n.Class() == PPARAMOUT {
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// Make sure the pointer to the heap copy is kept live throughout the function.
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// The function could panic at any point, and then a defer could recover.
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// Thus, we need the pointer to the heap copy always available so the
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// post-deferreturn code can copy the return value back to the stack.
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// See issue 16095.
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heapaddr.SetIsOutputParamHeapAddr(true)
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}
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n.Name.Param.Stackcopy = stackcopy
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// Substitute the stackcopy into the function variable list so that
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// liveness and other analyses use the underlying stack slot
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// and not the now-pseudo-variable n.
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found := false
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for i, d := range Curfn.Func.Dcl {
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if d == n {
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Curfn.Func.Dcl[i] = stackcopy
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found = true
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break
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}
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// Parameters are before locals, so can stop early.
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// This limits the search even in functions with many local variables.
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if d.Class() == PAUTO {
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break
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}
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}
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if !found {
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Fatalf("cannot find %v in local variable list", n)
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}
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Curfn.Func.Dcl = append(Curfn.Func.Dcl, n)
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}
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// Modify n in place so that uses of n now mean indirection of the heapaddr.
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n.SetClass(PAUTOHEAP)
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n.Xoffset = 0
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n.Name.Param.Heapaddr = heapaddr
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n.Esc = EscHeap
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if Debug['m'] != 0 {
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fmt.Printf("%v: moved to heap: %v\n", n.Line(), n)
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}
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}
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// autotmpname returns the name for an autotmp variable numbered n.
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func autotmpname(n int) string {
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// Give each tmp a different name so that they can be registerized.
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