cmd/compile: internal compiler error: live values in unreachable block #81771

$ gotip version
go version go1.28-devel_8fc7e764 Fri Sep 25 19:44:14 2026 -0700 linux/amd64

package p

import "simd/archsimd"

type S struct {
	f archsimd.Float32x8
}

type I interface {
	M(S) rune
}

func f(i I) rune {
	for range []int{} {
		_ = i.M(S{(archsimd.Float32x8{})})
	}
	return i.M(S{(archsimd.Float32x8{})})
}

$ GOEXPERIMENT=simd gotip build crash.go 
# command-line-arguments
./crash.go:14:17: internal compiler error: 'f': live values in unreachable block b6: [v25]

goroutine 13 [running]:
runtime/debug.Stack()
	../desktop/gotip/src/runtime/debug/stack.go:26 +0x5e
cmd/compile/internal/base.FatalfAt({0xf53c93b8?, 0x32c7?}, {0x32c7f53c9358, 0x2d}, {0x32c7f53c2990, 0x3, 0x3})
	../desktop/gotip/src/cmd/compile/internal/base/print.go:232 +0x18b
cmd/compile/internal/base.Fatalf(...)
	../desktop/gotip/src/cmd/compile/internal/base/print.go:197
cmd/compile/internal/ssagen.(*ssafn).Fatalf(0x32c7f536a940?, {0x5c6cddd8?, 0x2576606a?}, {0x105907e, 0x27}, {0x32c7f5274660, 0x2, 0x18?})
	../desktop/gotip/src/cmd/compile/internal/ssagen/ssa.go:8066 +0x185
cmd/compile/internal/ssa.(*Func).FatalfWithPos(0x32c7f49ac380, {0x1?, 0x0?}, {0x105907e, 0x27}, {0x32c7f5274660, 0x2, 0x2})
	../desktop/gotip/src/cmd/compile/internal/ssa/func.go:801 +0x190
cmd/compile/internal/ssa.(*Block).Fatalf(...)
	../desktop/gotip/src/cmd/compile/internal/ssa/block.go:478
cmd/compile/internal/ssacompile.deadcode(0x32c7f49ac380)
	../desktop/gotip/src/cmd/compile/internal/ssacompile/deadcode.go:152 +0xedf
cmd/compile/internal/ssacompile.Compiler.Compile({}, 0x32c7f49ac380, {0x1a0a148, 0x0})
	../desktop/gotip/src/cmd/compile/internal/ssacompile/compile.go:112 +0xa6d
...