From b6b8b2fe6ef8ceb727c7a157750cdd4e61393489 Mon Sep 17 00:00:00 2001
From: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Date: Mon, 22 Dec 2025 18:49:17 +0700
Subject: cmd/compile: handle propagating an out-of-range jump table index

For an out-of-range jump table index, the constant facts should not be
propagated to the destinations.

Fixes #76950

Change-Id: Iff29814cb466c7aaa432cec212e5387665c45afc
Reviewed-on: https://go-review.googlesource.com/c/go/+/731860
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---
 src/cmd/compile/internal/ssa/sccp.go | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'src/cmd')

diff --git a/src/cmd/compile/internal/ssa/sccp.go b/src/cmd/compile/internal/ssa/sccp.go
index 9b958d0454..7ef8d6b7c1 100644
--- a/src/cmd/compile/internal/ssa/sccp.go
+++ b/src/cmd/compile/internal/ssa/sccp.go
@@ -507,6 +507,10 @@ func (t *worklist) propagate(block *Block) {
 				branchIdx = 1 - condLattice.val.AuxInt
 			} else {
 				branchIdx = condLattice.val.AuxInt
+				if branchIdx < 0 || branchIdx >= int64(len(block.Succs)) {
+					// unreachable code, do nothing then
+					break
+				}
 			}
 			t.edges = append(t.edges, block.Succs[branchIdx])
 		} else {
-- 
cgit v1.3-5-g45d5