compiler/jvmci/compilerToVM/DisassembleCodeBlobTest.java assumes immutable code

compiler/jvmci/compilerToVM/DisassembleCodeBlobTest.java has been failing intermittently in the loom repo for the last few weeks. The typical output is:

----------System.err:(16/2068)----------
java.lang.RuntimeException: CompileCodeTestCase{executable=protected compiler.jvmci.compilerToVM.CompileCodeTestCase$Dummy(), bci=-1} : 3nd invocation returned different value from 2nd: expected 0x00007f41098d8360: 8984 2400 | a0fe ff55 | 4883 ec10 | 9090 9090 | 4181 7f1c | 0000 0000 | 0f84 0500 to equal 0x00007f41098d8360: 8984 2400 | a0fe ff55 | 4883 ec10 | 9090 9090 | 4181 7f1c | 0200 0000 | 0f84 0500
at jdk.test.lib.Asserts.fail(Asserts.java:594)
at jdk.test.lib.Asserts.assertEquals(Asserts.java:205)
at jdk.test.lib.Asserts.assertEQ(Asserts.java:178)
at compiler.jvmci.compilerToVM.DisassembleCodeBlobTest.check(DisassembleCodeBlobTest.java:112)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at compiler.jvmci.compilerToVM.DisassembleCodeBlobTest.main(DisassembleCodeBlobTest.java:66)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:577)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:1496)

JavaTest Message: Test threw exception: java.lang.RuntimeException: CompileCodeTestCase{executable=protected compiler.jvmci.compilerToVM.CompileCodeTestCase$Dummy(), bci=-1} : 3nd invocation returned different value from 2nd: expected 0x00007f41098d8360: 8984 2400 | a0fe ff55 | 4883 ec10 | 9090 9090 | 4181 7f1c | 0000 0000 | 0f84 0500 to equal 0x00007f41098d8360: 8984 2400 | a0fe ff55 | 4883 ec10 | 9090 9090 | 4181 7f1c | 0200 0000 | 0f84 0500
JavaTest Message: shutting down test