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[dev.ssa] cmd/compile: implement static data generation

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The existing backend recognizes special
assignment statements as being implementable
with static data rather than code.
Unfortunately, it assumes that it is in the middle
of codegen; it emits data and modifies the AST.

This does not play well with SSA's two-phase
bootstrapping approach, in which we attempt to
compile code but fall back to the existing backend
if something goes wrong.

To work around this:

* Add the ability to inquire about static data
without side-effects.
* Save the static data required for a function.
* Emit that static data during SSA codegen.

Change-Id: I2e8a506c866ea3e27dffb597095833c87f62d87e
Reviewed-on: https://go-review.googlesource.com/12790
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2015-07-28 10:56:39 -07:00
parent 2a5e6c47bc
commit 6b41665039
4 changed files with 55 additions and 21 deletions
Download patch file Download diff file Expand all files Collapse all files

39
src/cmd/compile/internal/gc/sinit.go
View file

@ -1236,6 +1236,7 @@ func getlit(lit *Node) int {
return -1
}
// stataddr sets nam to the static address of n and reports whether it succeeeded.
func stataddr(nam *Node, n *Node) bool {
if n == nil {
return false
@ -1408,7 +1409,9 @@ func entry(p *InitPlan) *InitEntry {
return &p.E[len(p.E)-1]
}
func gen_as_init(n *Node) bool {
// gen_as_init attempts to emit static data for n and reports whether it succeeded.
// If reportOnly is true, it does not emit static data and does not modify the AST.
func gen_as_init(n *Node, reportOnly bool) bool {
var nr *Node
var nl *Node
var nam Node
@ -1457,7 +1460,9 @@ func gen_as_init(n *Node) bool {
case OSLICEARR:
if nr.Right.Op == OKEY && nr.Right.Left == nil && nr.Right.Right == nil {
nr = nr.Left
gused(nil) // in case the data is the dest of a goto
if !reportOnly {
gused(nil) // in case the data is the dest of a goto
}
nl := nr
if nr == nil || nr.Op != OADDR {
goto no
@ -1472,16 +1477,18 @@ func gen_as_init(n *Node) bool {
goto no
}
nam.Xoffset += int64(Array_array)
gdata(&nam, nl, int(Types[Tptr].Width))
if !reportOnly {
nam.Xoffset += int64(Array_array)
gdata(&nam, nl, int(Types[Tptr].Width))
nam.Xoffset += int64(Array_nel) - int64(Array_array)
var nod1 Node
Nodconst(&nod1, Types[TINT], nr.Type.Bound)
gdata(&nam, &nod1, Widthint)
nam.Xoffset += int64(Array_nel) - int64(Array_array)
var nod1 Node
Nodconst(&nod1, Types[TINT], nr.Type.Bound)
gdata(&nam, &nod1, Widthint)
nam.Xoffset += int64(Array_cap) - int64(Array_nel)
gdata(&nam, &nod1, Widthint)
nam.Xoffset += int64(Array_cap) - int64(Array_nel)
gdata(&nam, &nod1, Widthint)
}
return true
}
@ -1512,13 +1519,19 @@ func gen_as_init(n *Node) bool {
TPTR64,
TFLOAT32,
TFLOAT64:
gdata(&nam, nr, int(nr.Type.Width))
if !reportOnly {
gdata(&nam, nr, int(nr.Type.Width))
}
case TCOMPLEX64, TCOMPLEX128:
gdatacomplex(&nam, nr.Val().U.(*Mpcplx))
if !reportOnly {
gdatacomplex(&nam, nr.Val().U.(*Mpcplx))
}
case TSTRING:
gdatastring(&nam, nr.Val().U.(string))
if !reportOnly {
gdatastring(&nam, nr.Val().U.(string))
}
}
return true