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[dev.regabi] cmd/compile: introduce FwdRefAux for wrapping ir.Node as ssa.Aux

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OpFwdRef is the only SSA value that needs the ability to store an
arbitrary ir.Node in its Aux field. Every other SSA value always uses
an *ir.Name.

This CL introduces FwdRefAux, which wraps an ir.Node and implements
the ssa.Aux tag interface, so that a subsequent refactoring can change
ir.Node to not implement ssa.Aux.

Passes buildall w/ toolstash -cmp.

Updates #42982.

Change-Id: Id1475b28847579573cd376e82f28761d84cd1c23
Reviewed-on: https://go-review.googlesource.com/c/go/+/275788
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
This commit is contained in:
Matthew Dempsky 2020-12-06 18:10:34 -08:00
parent dcec658f6c
commit 1c8943a6ad
2 changed files with 14 additions and 6 deletions
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18
src/cmd/compile/internal/gc/phi.go
View File

@ -23,6 +23,14 @@ const smallBlocks = 500
const debugPhi = false
// FwdRefAux wraps an arbitrary ir.Node as an ssa.Aux for use with OpFwdref.
type FwdRefAux struct {
_ [0]func() // ensure ir.Node isn't compared for equality
N ir.Node
}
func (FwdRefAux) CanBeAnSSAAux() {}
// insertPhis finds all the places in the function where a phi is
// necessary and inserts them.
// Uses FwdRef ops to find all uses of variables, and s.defvars to find
@ -79,7 +87,7 @@ func (s *phiState) insertPhis() {
if v.Op != ssa.OpFwdRef {
continue
}
var_ := v.Aux.(ir.Node)
var_ := v.Aux.(FwdRefAux).N
// Optimization: look back 1 block for the definition.
if len(b.Preds) == 1 {
@ -319,7 +327,7 @@ func (s *phiState) resolveFwdRefs() {
if v.Op != ssa.OpFwdRef {
continue
}
n := s.varnum[v.Aux.(ir.Node)]
n := s.varnum[v.Aux.(FwdRefAux).N]
v.Op = ssa.OpCopy
v.Aux = nil
v.AddArg(values[n])
@ -450,7 +458,7 @@ func (s *simplePhiState) insertPhis() {
continue
}
s.fwdrefs = append(s.fwdrefs, v)
var_ := v.Aux.(ir.Node)
var_ := v.Aux.(FwdRefAux).N
if _, ok := s.defvars[b.ID][var_]; !ok {
s.defvars[b.ID][var_] = v // treat FwdDefs as definitions.
}
@ -464,7 +472,7 @@ loop:
v := s.fwdrefs[len(s.fwdrefs)-1]
s.fwdrefs = s.fwdrefs[:len(s.fwdrefs)-1]
b := v.Block
var_ := v.Aux.(ir.Node)
var_ := v.Aux.(FwdRefAux).N
if b == s.f.Entry {
// No variable should be live at entry.
s.s.Fatalf("Value live at entry. It shouldn't be. func %s, node %v, value %v", s.f.Name, var_, v)
@ -531,7 +539,7 @@ func (s *simplePhiState) lookupVarOutgoing(b *ssa.Block, t *types.Type, var_ ir.
}
}
// Generate a FwdRef for the variable and return that.
v := b.NewValue0A(line, ssa.OpFwdRef, t, var_)
v := b.NewValue0A(line, ssa.OpFwdRef, t, FwdRefAux{N: var_})
s.defvars[b.ID][var_] = v
s.s.addNamedValue(var_, v)
s.fwdrefs = append(s.fwdrefs, v)

2
src/cmd/compile/internal/gc/ssa.go
View File

@ -6051,7 +6051,7 @@ func (s *state) variable(name ir.Node, t *types.Type) *ssa.Value {
}
// Make a FwdRef, which records a value that's live on block input.
// We'll find the matching definition as part of insertPhis.
v = s.newValue0A(ssa.OpFwdRef, t, name)
v = s.newValue0A(ssa.OpFwdRef, t, FwdRefAux{N: name})
s.fwdVars[name] = v
s.addNamedValue(name, v)
return v