cmd/compile/internal/ssa: BenchmarkCSEPass panics

[cherrymui]

What version of Go are you using (go version)?
go version devel +4b6e560 Sun May 22 01:41:05 2016 +0000 darwin/amd64

$ go test -v -run=XXX -bench=CSEPass cmd/compile/internal/ssa
panic: runtime error: index out of range

goroutine 6 [running]:
panic(0x223380, 0xc4200100b0)
    /Users/cherryyz/src/go-tip/src/runtime/panic.go:500 +0x18c
cmd/compile/internal/ssa.(*sortbyentry).Less(0xc42048a240, 0x0, 0x7d, 0x30)
    <autogenerated>:144 +0xba
sort.medianOfThree(0x36d2e0, 0xc42048a240, 0x0, 0x7d, 0xfa)
    /Users/cherryyz/src/go-tip/src/sort/sort.go:74 +0x3f
sort.doPivot(0x36d2e0, 0xc42048a240, 0x0, 0x3e8, 0xc4205d0000, 0x3e8)
    /Users/cherryyz/src/go-tip/src/sort/sort.go:99 +0x5e4
sort.quickSort(0x36d2e0, 0xc42048a240, 0x0, 0x3e8, 0x13)
    /Users/cherryyz/src/go-tip/src/sort/sort.go:188 +0x73
sort.Sort(0x36d2e0, 0xc42048a240)
    /Users/cherryyz/src/go-tip/src/sort/sort.go:222 +0x76
cmd/compile/internal/ssa.cse(0xc420092000)
    /Users/cherryyz/src/go-tip/src/cmd/compile/internal/ssa/cse.go:140 +0x109a
cmd/compile/internal/ssa.benchFnPass(0xc4200d2140, 0x2910b8, 0x3e8, 0x291128)
    /Users/cherryyz/src/go-tip/src/cmd/compile/internal/ssa/passbm_test.go:42 +0x15e
cmd/compile/internal/ssa.BenchmarkCSEPass(0xc4200d2140)
    /Users/cherryyz/src/go-tip/src/cmd/compile/internal/ssa/passbm_test.go:20 +0x42
testing.(*B).runN(0xc4200d2140, 0x1)
    /Users/cherryyz/src/go-tip/src/testing/benchmark.go:139 +0xa0
testing.(*B).run1.func1(0xc4200d2140)
    /Users/cherryyz/src/go-tip/src/testing/benchmark.go:208 +0x50
created by testing.(*B).run1
    /Users/cherryyz/src/go-tip/src/testing/benchmark.go:209 +0x6f
exit status 2
FAIL    cmd/compile/internal/ssa    0.057s