Add support for remote state reads

Zilliqa / scilla-compiler

Compile Scilla to LLVM-IR

GNU General Public License v3.0

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Add support for remote state reads #61

Closed vaivaswatha closed 3 years ago

vaivaswatha commented 3 years ago

https://github.com/Zilliqa/scilla/pull/967

vaivaswatha commented 3 years ago

See commit message: https://github.com/Zilliqa/scilla-compiler/commit/b8b97d32a05b78676a4962a0f5b02b9c92041785.

In addition to explicit remote state load and map get, code must be generated for dynamic type checking. This involves:

During deployment, any Address typed fields in contract parameters must be scanned and ensured that each field specified exists.
During transition execution, any Address typed transition parameter must be first scanned and each field specified must exist.

vaivaswatha commented 3 years ago

See commit message: b8b97d3.

In addition to explicit remote state load and map get, code must be generated for dynamic type checking. This involves:

During deployment, any Address typed fields in contract parameters must be scanned and ensured that each field specified exists.

During transition execution, any Address typed transition parameter must be first scanned and each field specified must exist.

Quoting @jjcnn 's response to this on slack:

Not quite: It's any address in a contract/transition parameter, even if it's buried in a map or an ADT value. In the interpreter the work is done by assert_literal_type: >https://github.com/Zilliqa/scilla/blob/994b231fd1a4be37639a9ac86194296e6022946f/src/base/TypeUtil.ml#L672 It's called from init_contract (for deployment) and check_message_entries (for transition invocation) in Eval.ml.

vaivaswatha commented 3 years ago

After a discussion with Jacob:

Generating code for dynamic type checking will likely be too tedious, especially since we've to check assignability and not equality of types.
We'll go against the idea mentioned in https://github.com/Zilliqa/scilla-compiler/commit/b8b97d32a05b78676a4962a0f5b02b9c92041785 commit message and carry over Address types till LLVM code generation. Type descriptors will be extended to accommodate Address types and the VM taught to handle and test assignability of these types. Actual code generation of Address values can still be just as if they were ByStr20 values. It's just the type system that'll be extended.

vaivaswatha commented 3 years ago

Implemented with #64, #65, #66. Closing.