Nearly the same as JDK-8285437. MachNode size should match in scratch emission and real emission phases. The address of the local char buffer is a random value, but when RVC is enabled, the `movptr`, containing `lui+addi+slli+addi+slli`, with another dangling `addi` at last to load the immediate address of the special local char buffer may get compressed depending on the char buffer's different addresses. So the size may at last mismatch. Due to this part containing implicit fixed-length semantics, it shall be a reasonable fix to add an ImcompressibleRegion for this special position.

`test/hotspot/jtreg/testlibrary_tests/ir_framework/tests/TestDFlags.java` in hotspot tier4 can reflect this issue. It contains a `vm.flagless` so it didn't run in my local environment until recently.