This gets redundant allocations eliminated fine:

    @Benchmark
    public Object arr_const_2() {
        Object o;
        o = new int[10];
        o = new int[10];
        return o;
    }

...and here they are not:

    @Benchmark
    public Object arr_var_2() {
        Object o;
        o = new int[size];
        o = new int[size];
        return o;
    }

This seems to affect e.g. JavaGrande. 

Benchmarks:
 http://cr.openjdk.java.net/~shade/8180290/MultiAlloc.java
 http://cr.openjdk.java.net/~shade/8180290/benchmarks.jar

Perf data:
 http://cr.openjdk.java.net/~shade/8180290/perf.txt