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[dev.regabi] cmd/compile: simplify stack temp initialization

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This CL simplifies the previous one a little bit further, by combining
reordering stack-temporary initialization and getting rid of an
unneeded temporary variable. (Does not pass toolstash -cmp.)

Change-Id: I17799dfe368484f33a8ddd0ab4f68647d6262147
Reviewed-on: https://go-review.googlesource.com/c/go/+/284225
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
This commit is contained in:
Matthew Dempsky 2021-01-16 19:35:39 -08:00
parent ba0e8a92fa
commit 7ce2a8383d
2 changed files with 13 additions and 23 deletions
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17
src/cmd/compile/internal/walk/complit.go
View File

@ -344,21 +344,18 @@ func slicelit(ctxt initContext, n *ir.CompLitExpr, var_ ir.Node, init *ir.Nodes)
if !types.Identical(t, x.Type()) {
panic("dotdotdot base type does not match order's assigned type")
}
a = initStackTemp(init, x, vstat != nil)
a = initStackTemp(init, x, vstat)
} else if n.Esc() == ir.EscNone {
if vstat == nil {
// TODO(mdempsky): Remove this useless temporary.
// It's only needed to keep toolstash happy.
typecheck.Temp(t)
}
a = initStackTemp(init, typecheck.Temp(t), vstat != nil)
a = initStackTemp(init, typecheck.Temp(t), vstat)
} else {
a = ir.NewUnaryExpr(base.Pos, ir.ONEW, ir.TypeNode(t))
}
appendWalkStmt(init, ir.NewAssignStmt(base.Pos, vauto, a))
if vstat != nil {
// copy static to heap (4)
if vstat != nil && n.Prealloc == nil && n.Esc() != ir.EscNone {
// If we allocated on the heap with ONEW, copy the static to the
// heap (4). We skip this for stack temporaries, because
// initStackTemp already handled the copy.
a = ir.NewStarExpr(base.Pos, vauto)
appendWalkStmt(init, ir.NewAssignStmt(base.Pos, a, vstat))
}
@ -535,7 +532,7 @@ func anylit(n ir.Node, var_ ir.Node, init *ir.Nodes) {
var r ir.Node
if n.Prealloc != nil {
// n.Prealloc is stack temporary used as backing store.
r = initStackTemp(init, n.Prealloc, false)
r = initStackTemp(init, n.Prealloc, nil)
} else {
r = ir.NewUnaryExpr(base.Pos, ir.ONEW, ir.TypeNode(n.X.Type()))
r.SetEsc(n.Esc())

19
src/cmd/compile/internal/walk/temp.go
View File

@ -12,19 +12,12 @@ import (
)
// initStackTemp appends statements to init to initialize the given
// temporary variable, and then returns the expression &tmp. If vardef
// is true, then the variable is initialized with OVARDEF, and the
// caller must ensure the variable is later assigned before use;
// otherwise, it's zero initialized.
//
// TODO(mdempsky): Change callers to provide tmp's initial value,
// rather than just vardef, to make this safer/easier to use.
func initStackTemp(init *ir.Nodes, tmp *ir.Name, vardef bool) *ir.AddrExpr {
if vardef {
init.Append(ir.NewUnaryExpr(base.Pos, ir.OVARDEF, tmp))
} else {
appendWalkStmt(init, ir.NewAssignStmt(base.Pos, tmp, nil))
// temporary variable to val, and then returns the expression &tmp.
func initStackTemp(init *ir.Nodes, tmp *ir.Name, val ir.Node) *ir.AddrExpr {
if val != nil && !types.Identical(tmp.Type(), val.Type()) {
base.Fatalf("bad initial value for %L: %L", tmp, val)
}
appendWalkStmt(init, ir.NewAssignStmt(base.Pos, tmp, val))
return typecheck.Expr(typecheck.NodAddr(tmp)).(*ir.AddrExpr)
}
@ -32,7 +25,7 @@ func initStackTemp(init *ir.Nodes, tmp *ir.Name, vardef bool) *ir.AddrExpr {
// allocated temporary variable of the given type. Statements to
// zero-initialize tmp are appended to init.
func stackTempAddr(init *ir.Nodes, typ *types.Type) *ir.AddrExpr {
return initStackTemp(init, typecheck.Temp(typ), false)
return initStackTemp(init, typecheck.Temp(typ), nil)
}
// stackBufAddr returns thte expression &tmp, where tmp is a newly