src/cmd/compile/internal/ssa/loopbce.go |  7 +++++++
 test/fixedbugs/issue63955.go            | 22 ++++++++++++++++++++++

diff --git a/src/cmd/compile/internal/ssa/loopbce.go b/src/cmd/compile/internal/ssa/loopbce.go
index d92566f2d3eb456b690f5a70e79b1d45878ec4e9..696930fed8e65048f91e044468b3f8962b5e3421 100644
--- a/src/cmd/compile/internal/ssa/loopbce.go
+++ b/src/cmd/compile/internal/ssa/loopbce.go
@@ -130,6 +130,13 @@ 			ind, limit = limit, ind
 			less = false
 		}
 
+		if ind.Block != b {
+			// TODO: Could be extended to include disjointed loop headers.
+			// I don't think this is causing missed optimizations in real world code often.
+			// See https://go.dev/issue/63955
+			continue
+		}
+
 		// Expect the increment to be a nonzero constant.
 		if inc.Op != OpConst64 {
 			continue
diff --git a/test/fixedbugs/issue63955.go b/test/fixedbugs/issue63955.go
new file mode 100644
index 0000000000000000000000000000000000000000..258e874220f0efa4f26a80bb3548ba9bd7861870
--- /dev/null
+++ b/test/fixedbugs/issue63955.go
@@ -0,0 +1,22 @@
+// compile
+
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package j
+
+func f(try func() int, shouldInc func() bool, N func(int) int) {
+	var n int
+loop: // we want to have 3 preds here, the function entry and both gotos
+	if v := try(); v == 42 || v == 1337 { // the two || are to trick findIndVar
+		if n < 30 { // this aims to be the matched block
+			if shouldInc() {
+				n++
+				goto loop
+			}
+			n = N(n) // try to prevent some block joining
+			goto loop
+		}
+	}
+}