From: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Date: Sun, 8 Sep 2024 14:45:36 +0000 (+0700)
Subject: cmd/compile/internal/typecheck: simplify tcSlice
X-Git-Tag: go1.24rc1~925
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=d7521704cebccd36c16df6f4ac229e3a757ed055;p=gostls13.git

cmd/compile/internal/typecheck: simplify tcSlice

types2 handles all constant-related bounds checks in user Go code now,
so it's safe to remove all constants checking in tcSlice function.

Change-Id: Ia0dd4928d7122a6f62df10436bb4a3675ebf3357
Reviewed-on: https://go-review.googlesource.com/c/go/+/611676
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Tim King <taking@google.com>
---

diff --git a/src/cmd/compile/internal/typecheck/expr.go b/src/cmd/compile/internal/typecheck/expr.go
index eb92797259..2eec8d41ad 100644
--- a/src/cmd/compile/internal/typecheck/expr.go
+++ b/src/cmd/compile/internal/typecheck/expr.go
@@ -788,19 +788,15 @@ func tcSlice(n *ir.SliceExpr) ir.Node {
 		return n
 	}
 
-	if n.Low != nil && !checksliceindex(l, n.Low, tp) {
+	if n.Low != nil && !checksliceindex(n.Low) {
 		n.SetType(nil)
 		return n
 	}
-	if n.High != nil && !checksliceindex(l, n.High, tp) {
+	if n.High != nil && !checksliceindex(n.High) {
 		n.SetType(nil)
 		return n
 	}
-	if n.Max != nil && !checksliceindex(l, n.Max, tp) {
-		n.SetType(nil)
-		return n
-	}
-	if !checksliceconst(n.Low, n.High) || !checksliceconst(n.Low, n.Max) || !checksliceconst(n.High, n.Max) {
+	if n.Max != nil && !checksliceindex(n.Max) {
 		n.SetType(nil)
 		return n
 	}
diff --git a/src/cmd/compile/internal/typecheck/typecheck.go b/src/cmd/compile/internal/typecheck/typecheck.go
index 5d041b1939..cb48bfd7e3 100644
--- a/src/cmd/compile/internal/typecheck/typecheck.go
+++ b/src/cmd/compile/internal/typecheck/typecheck.go
@@ -7,7 +7,6 @@ package typecheck
 import (
 	"fmt"
 	"go/constant"
-	"go/token"
 	"strings"
 
 	"cmd/compile/internal/base"
@@ -681,7 +680,7 @@ func RewriteMultiValueCall(n ir.InitNode, call ir.Node) {
 	}
 }
 
-func checksliceindex(l ir.Node, r ir.Node, tp *types.Type) bool {
+func checksliceindex(r ir.Node) bool {
 	t := r.Type()
 	if t == nil {
 		return false
@@ -690,33 +689,6 @@ func checksliceindex(l ir.Node, r ir.Node, tp *types.Type) bool {
 		base.Errorf("invalid slice index %v (type %v)", r, t)
 		return false
 	}
-
-	if r.Op() == ir.OLITERAL {
-		x := r.Val()
-		if constant.Sign(x) < 0 {
-			base.Errorf("invalid slice index %v (index must be non-negative)", r)
-			return false
-		} else if tp != nil && tp.NumElem() >= 0 && constant.Compare(x, token.GTR, constant.MakeInt64(tp.NumElem())) {
-			base.Errorf("invalid slice index %v (out of bounds for %d-element array)", r, tp.NumElem())
-			return false
-		} else if ir.IsConst(l, constant.String) && constant.Compare(x, token.GTR, constant.MakeInt64(int64(len(ir.StringVal(l))))) {
-			base.Errorf("invalid slice index %v (out of bounds for %d-byte string)", r, len(ir.StringVal(l)))
-			return false
-		} else if ir.ConstOverflow(x, types.Types[types.TINT]) {
-			base.Errorf("invalid slice index %v (index too large)", r)
-			return false
-		}
-	}
-
-	return true
-}
-
-func checksliceconst(lo ir.Node, hi ir.Node) bool {
-	if lo != nil && hi != nil && lo.Op() == ir.OLITERAL && hi.Op() == ir.OLITERAL && constant.Compare(lo.Val(), token.GTR, hi.Val()) {
-		base.Errorf("invalid slice index: %v > %v", lo, hi)
-		return false
-	}
-
 	return true
 }