Attached Fuzzer test fails in current mainline:

$ build/linux-x86_64-server-fastdebug/images/jdk/bin/java -Xmx512m -XX:+UnlockDiagnosticVMOptions -XX:+StressIGVN -Xcomp -XX:CompileOnly=Test -XX:-TieredCompilation -XX:StressSeed=81931138 -cp 0017/ Test

# Internal Error (/home/shade/trunks/jdk/src/hotspot/share/opto/phaseX.cpp:1162), pid=2380570, tid=2380583
# assert(false) failed: infinite loop in PhaseIterGVN::transform_old

Current CompileTask:
C2: 365 6 !b Test::vMeth (499 bytes)

Stack: [0x00007ff68b638000,0x00007ff68b739000], sp=0x00007ff68b7340c0, free space=1008k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x1690c41] PhaseIterGVN::transform_old(Node*)+0x381
V [libjvm.so+0x1689a4e] PhaseIterGVN::optimize()+0x7e
V [libjvm.so+0xab4072] Compile::Optimize()+0x1c2
V [libjvm.so+0xab66ce] Compile::Compile(ciEnv*, ciMethod*, int, Options, DirectiveSet*)+0x127e
V [libjvm.so+0x8d58bb] C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x69b
V [libjvm.so+0xac80c8] CompileBroker::invoke_compiler_on_method(CompileTask*)+0xe48
V [libjvm.so+0xac8e38] CompileBroker::compiler_thread_loop()+0x648
V [libjvm.so+0x1a2ca0c] JavaThread::thread_main_inner()+0x28c
V [libjvm.so+0x1a33064] Thread::call_run()+0x104
V [libjvm.so+0x160a1cc] thread_native_entry(Thread*)+0x10c

Seems to only reproduce with a specific seed. Bisection points to JDK-8267687 as the cause.