Add Context Structure to Affect State Dependent Liftings #617
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lkorenc
suggested changes
Aug 15, 2022
include/remill/Arch/Arch.h
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| @@ -281,14 +285,16 @@ class Arch { | |||
| // walk up, one byte at a time, to `MaxInstructionSize(false)` | |||
| // bytes being passed to the decoder, until you successfully decode | |||
| // or ultimately fail. | |||
| virtual bool DecodeInstruction(uint64_t address, std::string_view instr_bytes, | |||
| Instruction &inst) const = 0; | |||
| virtual std::optional<DecodingContext::ContextMap> | |||
include/remill/Arch/Arch.h
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| inst.in_delay_slot = true; | ||
| return this->DecodeInstruction(address, instr_bytes, inst); | ||
| return this->DecodeInstruction(address, instr_bytes, inst, context); |
include/remill/Arch/ArchBase.h
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| protected: | ||
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| /// A simple mixin for a default decoder with a null context and the default insdtruction lifter; | ||
| class DefaultContextAndLifter : virtual public remill::Arch { |
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virtual inheritance is a big hammer we may not need here - think how to make it without.
| uint64_t GetContextValue(const std::string &context_reg) const; | ||
| DecodingContext PutContextReg(std::string creg, uint64_t value) const; | ||
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| static ContextMap UniformContextMapping(DecodingContext cst); |
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What is the advantage of using this compared to simply passing the "raw" unordered_map around?
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The context map? the lambda allows the decoders to encode arbitrary computations over successor addresses
lib/Arch/Context.cpp
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| DecodingContext::ContextMap | ||
| DecodingContext::UniformContextMapping(DecodingContext cst) { | ||
| return [cst](uint64_t ctx) -> DecodingContext { return cst; }; |
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you are doing two copies, move cst into lambda.
lib/BC/TraceLifter.cpp
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| @@ -345,7 +345,9 @@ bool TraceLifter::Impl::Lift( | |||
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| inst.Reset(); | |||
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| (void) arch->DecodeInstruction(inst_addr, inst_bytes, inst); | |||
| // TODO(Ian): not passing context around in trace lifter | |||
| (void) arch->DecodeInstruction(inst_addr, inst_bytes, inst, | |||
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std::ignore = value_dont_care_about()
lkorenc
reviewed
Aug 15, 2022
lib/Arch/Arch.cpp
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| inst.SetLifter(std::make_unique<remill::InstructionLifter>( | ||
| this, this->GetInstrinsicTable())); | ||
| return this->ArchDecodeInstruction(address, instr_bytes, inst); | ||
| if (this->ArchDecodeInstruction(address, instr_bytes, inst)) { | ||
| return [](uint64_t x) -> DecodingContext { return DecodingContext(); }; |
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Drop x - unused arguments do not need names.
lkorenc
reviewed
Aug 15, 2022
lib/Arch/Sleigh/Arch.cpp
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| return this->ArchDecodeInstruction(address, instr_bytes, inst); | ||
| if (const_cast<SleighArch *>(this)->DecodeInstructionImpl( | ||
| address, instr_bytes, inst)) { | ||
| return [this](uint64_t x) -> DecodingContext { |
lkorenc
suggested changes
Aug 17, 2022
lib/Arch/Arch.cpp
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| @@ -863,7 +863,7 @@ DefaultContextAndLifter::DecodeInstruction(uint64_t address, | |||
| inst.SetLifter(std::make_unique<remill::InstructionLifter>( | |||
| this, this->GetInstrinsicTable())); | |||
| if (this->ArchDecodeInstruction(address, instr_bytes, inst)) { | |||
| return [](uint64_t x) -> DecodingContext { return DecodingContext(); }; | |||
| return [](uint64_t _) -> DecodingContext { return DecodingContext(); }; | |||
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Just [](uint64_t) -> DecodingContext { ... }.
No need for _. (In other changes as well)
As a sidenote, -> DecodingContext can also be dropped, I think compiler should be able to deduce this, but I can understand if you want to keep it as part of docs.
lkorenc
approved these changes
Aug 17, 2022
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