From 18369c489e9dc797e2f932160d72c2bf016c4591 Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Sun, 6 Sep 2020 15:26:03 +0300
Subject: [PATCH] compiler: do not allocate slotes for unused "_" vars
---
pkg/compiler/analysis.go | 6 +++++-
pkg/compiler/codegen.go | 14 ++++++++------
pkg/compiler/global_test.go | 16 ++++++++++++++++
3 files changed, 29 insertions(+), 7 deletions(-)
diff --git a/pkg/compiler/analysis.go b/pkg/compiler/analysis.go
index 190ea7511..11be72e32 100644
--- a/pkg/compiler/analysis.go
+++ b/pkg/compiler/analysis.go
@@ -112,7 +112,11 @@ func countGlobals(f ast.Node) (i int) {
case *ast.GenDecl:
if n.Tok == token.VAR {
for _, s := range n.Specs {
- i += len(s.(*ast.ValueSpec).Names)
+ for _, id := range s.(*ast.ValueSpec).Names {
+ if id.Name != "_" {
+ i++
+ }
+ }
}
}
return false
diff --git a/pkg/compiler/codegen.go b/pkg/compiler/codegen.go
index 710d58de6..bf01115ad 100644
--- a/pkg/compiler/codegen.go
+++ b/pkg/compiler/codegen.go
@@ -434,13 +434,15 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
switch t := spec.(type) {
case *ast.ValueSpec:
for _, id := range t.Names {
- if c.scope == nil {
- // it is a global declaration
- c.newGlobal("", id.Name)
- } else {
- c.scope.newLocal(id.Name)
+ if id.Name != "_" {
+ if c.scope == nil {
+ // it is a global declaration
+ c.newGlobal("", id.Name)
+ } else {
+ c.scope.newLocal(id.Name)
+ }
+ c.registerDebugVariable(id.Name, t.Type)
}
- c.registerDebugVariable(id.Name, t.Type)
}
for i := range t.Names {
if len(t.Values) != 0 {
diff --git a/pkg/compiler/global_test.go b/pkg/compiler/global_test.go
index b8ab1b045..434c22290 100644
--- a/pkg/compiler/global_test.go
+++ b/pkg/compiler/global_test.go
@@ -255,3 +255,19 @@ func TestConstDontUseSlots(t *testing.T) {
src := buf.String()
eval(t, src, big.NewInt(count))
}
+
+func TestUnderscoreVarsDontUseSlots(t *testing.T) {
+ const count = 128
+ buf := bytes.NewBufferString("package foo\n")
+ for i := 0; i < count; i++ {
+ buf.WriteString(fmt.Sprintf("var _, n%d = 1, 1\n", i))
+ }
+ buf.WriteString("func Main() int { sum := 0\n")
+ for i := 0; i < count; i++ {
+ buf.WriteString(fmt.Sprintf("sum += n%d\n", i))
+ }
+ buf.WriteString("return sum }")
+
+ src := buf.String()
+ eval(t, src, big.NewInt(count))
+}