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[dev.regabi] cmd/compile: clean up Order.copyExpr TODO

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Just a little cleaner to read.

Passes buildall w/ toolstash -cmp.

Change-Id: I27b9f09bf6756f74f1c01794444518ded1a7d625
Reviewed-on: https://go-review.googlesource.com/c/go/+/274106
Trust: Russ Cox <rsc@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Russ Cox 2020-11-29 11:16:20 -05:00
parent 7c9b6b1ca2
commit 5fc192af56
1 changed files with 35 additions and 30 deletions
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65
src/cmd/compile/internal/gc/order.go
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@ -93,21 +93,26 @@ func (o *Order) newTemp(t *types.Type, clear bool) ir.Node {
// copyExpr behaves like newTemp but also emits
// code to initialize the temporary to the value n.
//
// The clear argument is provided for use when the evaluation
// of tmp = n turns into a function call that is passed a pointer
// to the temporary as the output space. If the call blocks before
// tmp has been written, the garbage collector will still treat the
// temporary as live, so we must zero it before entering that call.
func (o *Order) copyExpr(n ir.Node) ir.Node {
return o.copyExpr1(n, false)
}
// copyExprClear is like copyExpr but clears the temp before assignment.
// It is provided for use when the evaluation of tmp = n turns into
// a function call that is passed a pointer to the temporary as the output space.
// If the call blocks before tmp has been written,
// the garbage collector will still treat the temporary as live,
// so we must zero it before entering that call.
// Today, this only happens for channel receive operations.
// (The other candidate would be map access, but map access
// returns a pointer to the result data instead of taking a pointer
// to be filled in.)
// TODO(rsc): t == n.Type() always; remove parameter.
func (o *Order) copyExpr(n ir.Node, t *types.Type, clear bool) ir.Node {
if t != n.Type() {
panic("copyExpr")
}
func (o *Order) copyExprClear(n ir.Node) ir.Node {
return o.copyExpr1(n, true)
}
func (o *Order) copyExpr1(n ir.Node, clear bool) ir.Node {
t := n.Type()
v := o.newTemp(t, clear)
a := ir.Nod(ir.OAS, v, n)
a = typecheck(a, ctxStmt)
@ -137,7 +142,7 @@ func (o *Order) cheapExpr(n ir.Node) ir.Node {
return typecheck(a, ctxExpr)
}
return o.copyExpr(n, n.Type(), false)
return o.copyExpr(n)
}
// safeExpr returns a safe version of n.
@ -224,7 +229,7 @@ func (o *Order) addrTemp(n ir.Node) ir.Node {
if isaddrokay(n) {
return n
}
return o.copyExpr(n, n.Type(), false)
return o.copyExpr(n)
}
// mapKeyTemp prepares n to be a key in a map runtime call and returns n.
@ -493,7 +498,7 @@ func (o *Order) call(n ir.Node) {
// by copying it into a temp and marking that temp
// still alive when we pop the temp stack.
if arg.Op() == ir.OCONVNOP && arg.Left().Type().IsUnsafePtr() {
x := o.copyExpr(arg.Left(), arg.Left().Type(), false)
x := o.copyExpr(arg.Left())
arg.SetLeft(x)
x.Name().SetAddrtaken(true) // ensure SSA keeps the x variable
n.PtrBody().Append(typecheck(ir.Nod(ir.OVARLIVE, x, nil), ctxStmt))
@ -555,10 +560,10 @@ func (o *Order) mapAssign(n ir.Node) {
switch {
case m.Op() == ir.OINDEXMAP:
if !ir.IsAutoTmp(m.Left()) {
m.SetLeft(o.copyExpr(m.Left(), m.Left().Type(), false))
m.SetLeft(o.copyExpr(m.Left()))
}
if !ir.IsAutoTmp(m.Right()) {
m.SetRight(o.copyExpr(m.Right(), m.Right().Type(), false))
m.SetRight(o.copyExpr(m.Right()))
}
fallthrough
case instrumenting && n.Op() == ir.OAS2FUNC && !ir.IsBlank(m):
@ -617,7 +622,7 @@ func (o *Order) stmt(n ir.Node) {
if l1.Op() == ir.OINDEXMAP {
l2.SetIndexMapLValue(false)
}
l2 = o.copyExpr(l2, l2.Type(), false)
l2 = o.copyExpr(l2)
r := ir.NodAt(n.Pos(), n.SubOp(), l2, n.Right())
r = typecheck(r, ctxExpr)
r = o.expr(r, nil)
@ -802,7 +807,7 @@ func (o *Order) stmt(n ir.Node) {
r = typecheck(r, ctxExpr)
}
n.SetRight(o.copyExpr(r, r.Type(), false))
n.SetRight(o.copyExpr(r))
case types.TMAP:
if isMapClear(n) {
@ -817,7 +822,7 @@ func (o *Order) stmt(n ir.Node) {
// TODO(rsc): Make tmp = literal expressions reuse tmp.
// For maps tmp is just one word so it hardly matters.
r := n.Right()
n.SetRight(o.copyExpr(r, r.Type(), false))
n.SetRight(o.copyExpr(r))
// prealloc[n] is the temp for the iterator.
// hiter contains pointers and needs to be zeroed.
@ -898,7 +903,7 @@ func (o *Order) stmt(n ir.Node) {
recv.SetLeft(o.expr(recv.Left(), nil))
if recv.Left().Op() != ir.ONAME {
recv.SetLeft(o.copyExpr(recv.Left(), recv.Left().Type(), false))
recv.SetLeft(o.copyExpr(recv.Left()))
}
// Introduce temporary for receive and move actual copy into case body.
@ -956,11 +961,11 @@ func (o *Order) stmt(n ir.Node) {
r.SetLeft(o.expr(r.Left(), nil))
if !ir.IsAutoTmp(r.Left()) {
r.SetLeft(o.copyExpr(r.Left(), r.Left().Type(), false))
r.SetLeft(o.copyExpr(r.Left()))
}
r.SetRight(o.expr(r.Right(), nil))
if !ir.IsAutoTmp(r.Right()) {
r.SetRight(o.copyExpr(r.Right(), r.Right().Type(), false))
r.SetRight(o.copyExpr(r.Right()))
}
}
}
@ -988,7 +993,7 @@ func (o *Order) stmt(n ir.Node) {
if instrumenting {
// Force copying to the stack so that (chan T)(nil) <- x
// is still instrumented as a read of x.
n.SetRight(o.copyExpr(n.Right(), n.Right().Type(), false))
n.SetRight(o.copyExpr(n.Right()))
} else {
n.SetRight(o.addrTemp(n.Right()))
}
@ -1134,7 +1139,7 @@ func (o *Order) expr(n, lhs ir.Node) ir.Node {
// key must be addressable
n.SetRight(o.mapKeyTemp(n.Left().Type(), n.Right()))
if needCopy {
n = o.copyExpr(n, n.Type(), false)
n = o.copyExpr(n)
}
// concrete type (not interface) argument might need an addressable
@ -1159,7 +1164,7 @@ func (o *Order) expr(n, lhs ir.Node) ir.Node {
o.init(n.Left())
o.call(n.Left())
if lhs == nil || lhs.Op() != ir.ONAME || instrumenting {
n = o.copyExpr(n, n.Type(), false)
n = o.copyExpr(n)
}
} else {
n.SetLeft(o.expr(n.Left(), nil))
@ -1229,7 +1234,7 @@ func (o *Order) expr(n, lhs ir.Node) ir.Node {
}
if lhs == nil || lhs.Op() != ir.ONAME || instrumenting {
n = o.copyExpr(n, n.Type(), false)
n = o.copyExpr(n)
}
case ir.OAPPEND:
@ -1242,7 +1247,7 @@ func (o *Order) expr(n, lhs ir.Node) ir.Node {
}
if lhs == nil || lhs.Op() != ir.ONAME && !samesafeexpr(lhs, n.List().First()) {
n = o.copyExpr(n, n.Type(), false)
n = o.copyExpr(n)
}
case ir.OSLICE, ir.OSLICEARR, ir.OSLICESTR, ir.OSLICE3, ir.OSLICE3ARR:
@ -1256,7 +1261,7 @@ func (o *Order) expr(n, lhs ir.Node) ir.Node {
max = o.cheapExpr(max)
n.SetSliceBounds(low, high, max)
if lhs == nil || lhs.Op() != ir.ONAME && !samesafeexpr(lhs, n.Left()) {
n = o.copyExpr(n, n.Type(), false)
n = o.copyExpr(n)
}
case ir.OCLOSURE:
@ -1283,12 +1288,12 @@ func (o *Order) expr(n, lhs ir.Node) ir.Node {
case ir.ODOTTYPE, ir.ODOTTYPE2:
n.SetLeft(o.expr(n.Left(), nil))
if !isdirectiface(n.Type()) || instrumenting {
n = o.copyExpr(n, n.Type(), true)
n = o.copyExprClear(n)
}
case ir.ORECV:
n.SetLeft(o.expr(n.Left(), nil))
n = o.copyExpr(n, n.Type(), true)
n = o.copyExprClear(n)
case ir.OEQ, ir.ONE, ir.OLT, ir.OLE, ir.OGT, ir.OGE:
n.SetLeft(o.expr(n.Left(), nil))