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# Copyright (C) 2010 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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Notes on updating the sets of defined opcodes and instruction formats
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##########
If you want to add, delete, or change opcodes:
* Update the file bytecode.txt, in this directory.
* Run the regen-all script, in this directory. This will regenerate a
number of tables, definitions, and declarations in the code, in
dalvik/dx, dalvik/libdex, and libcore/dalvik.
* Implement/update the opcode in C in vm/mterp/c/...
* Verify new code by running with "dalvik.vm.execution-mode = int:portable"
or "-Xint:portable".
* Implement/update the instruction in assembly in vm/mterp/{arm*,x86*}/...
* Verify by enabling the assembly (e.g. ARM) handler for that instruction
in mterp/config-* and running "int:fast" as above.
* Implement/update the instruction in
vm/compiler/codegen/{arm,x86}/CodegenDriver.c.
* Rebuild the interpreter code. See the notes in vm/mterp/ReadMe.txt for
details.
* Look in the directory vm/analysis at the files CodeVerify.c,
DexVerify.c, and Optimize.c. You may need to update them to account
for your changes.
* If you change anything here, be sure to try running the system with
the verifier enabled (which is in fact the default).
##########
If you want to add, delete, or change instruction formats:
This is a more manual affair than changing opcodes.
* Update the file bytecode.txt, and run regen-all, as per above.
* Update the instruction format list in libdex/InstrUtils.h.
* Update dexDecodeInstruction() in libdex/InstrUtils.c.
* Update dumpInstruction() and its helper code in dexdump/DexDump.c.
* Update the switch inside dvmCompilerMIR2LIR() in
vm/compiler/codegen/{arm,x86}/CodegenDriver.c. (There may be other
architectures to deal with too.)
##########
Testing your work:
The Dalvik VM tests (in the vm/tests directory) provide a convenient
way to test most of the above without doing any rebuilds. In
particular, test 003-omnibus-opcodes will exercise most of the
opcodes.