mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
Alex Beregszaszi
GitHub
commit
b7fb1bc0a6
@ -9,11 +9,6 @@ This assembly language can also be used as "inline assembly" inside Solidity
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source code. We start with describing how to use inline assembly and how it
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differs from standalone assembly and then specify assembly itself.
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.. note::
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TODO: Write about how scoping rules of inline assembly are a bit different
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and the complications that arise when for example using internal functions
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of libraries. Furthermore, write about the symbols defined by the compiler.
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.. _inline-assembly:
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Inline Assembly
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@ -41,6 +36,11 @@ We now want to describe the inline assembly language in detail.
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at a low level. This discards several important safety
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features of Solidity.
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.. note::
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TODO: Write about how scoping rules of inline assembly are a bit different
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and the complications that arise when for example using internal functions
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of libraries. Furthermore, write about the symbols defined by the compiler.
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Example
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-------
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@ -156,6 +156,7 @@ Contents
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using-the-compiler.rst
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metadata.rst
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abi-spec.rst
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julia.rst
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style-guide.rst
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common-patterns.rst
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bugs.rst
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556
docs/julia.rst
Normal file
556
docs/julia.rst
Normal file
@ -0,0 +1,556 @@
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#################################################
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Joyfully Universal Language for (Inline) Assembly
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#################################################
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.. _julia:
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.. index:: ! assembly, ! asm, ! evmasm, ! julia
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JULIA is an intermediate language that can compile to various different backends
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(EVM 1.0, EVM 1.5 and eWASM are planned).
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Because of that, it is designed to be a usable common denominator of all three
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platforms.
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It can already be used for "inline assembly" inside Solidity and
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future versions of the Solidity compiler will even use JULIA as intermediate
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language. It should also be easy to build high-level optimizer stages for JULIA.
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The core components of JULIA are functions, blocks, variables, literals,
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for-loops, switch-statements, expressions and assignments to variables.
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JULIA is typed, both variables and literals must specify the type with postfix
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notation. The supported types are ``bool``, ``u8``, ``s8``, ``u32``, ``s32``,
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``u64``, ``s64``, ``u128``, ``s128``, ``u256`` and ``s256``.
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JULIA in itself does not even provide operators. If the EVM is targeted,
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opcodes will be available as built-in functions, but they can be reimplemented
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if the backend changes. For a list of mandatory built-in functions, see the section below.
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The following example program assumes that the EVM opcodes ``mul``, ``div``
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and ``mod`` are available either natively or as functions and computes exponentiation.
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.. code::
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{
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function power(base:u256, exponent:u256) -> result:u256
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{
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switch exponent
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case 0:u256 { result := 1:u256 }
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case 1:u256 { result := base }
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default:
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{
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result := power(mul(base, base), div(exponent, 2:u256))
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switch mod(exponent, 2:u256)
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case 1:u256 { result := mul(base, result) }
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}
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}
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}
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It is also possible to implement the same function using a for-loop
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instead of with recursion. Here, we need the EVM opcodes ``lt`` (less-than)
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and ``add`` to be available.
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.. code::
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{
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function power(base:u256, exponent:u256) -> result:u256
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{
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result := 1:u256
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for { let i := 0:u256 } lt(i, exponent) { i := add(i, 1:u256) }
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{
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result := mul(result, base)
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}
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}
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}
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Specification of JULIA
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======================
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JULIA code is described in this chapter. JULIA code is usually placed into a JULIA object, which is described in the following chapter.
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Grammar::
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Block = '{' Statement* '}'
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Statement =
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Block |
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FunctionDefinition |
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VariableDeclaration |
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Assignment |
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Expression |
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Switch |
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ForLoop |
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BreakContinue
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FunctionDefinition =
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'function' Identifier '(' TypedIdentifierList? ')'
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( '->' TypedIdentifierList )? Block
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VariableDeclaration =
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'let' TypedIdentifierList ( ':=' Expression )?
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Assignment =
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IdentifierList ':=' Expression
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Expression =
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FunctionCall | Identifier | Literal
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Switch =
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'switch' Expression Case* ( 'default' Block )?
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Case =
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'case' Literal Block
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ForLoop =
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'for' Block Expression Block Block
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BreakContinue =
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'break' | 'continue'
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FunctionCall =
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Identifier '(' ( Expression ( ',' Expression )* )? ')'
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Identifier = [a-zA-Z_$] [a-zA-Z_0-9]*
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IdentifierList = Identifier ( ',' Identifier)*
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TypeName = Identifier | BuiltinTypeName
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BuiltinTypeName = 'bool' | [us] ( '8' | '32' | '64' | '128' | '256' )
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TypedIdentifierList = Identifier ':' TypeName ( ',' Identifier ':' TypeName )*
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Literal =
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(NumberLiteral | StringLiteral | HexLiteral | TrueLiteral | FalseLiteral) ':' TypeName
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NumberLiteral = HexNumber | DecimalNumber
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HexLiteral = 'hex' ('"' ([0-9a-fA-F]{2})* '"' | '\'' ([0-9a-fA-F]{2})* '\'')
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StringLiteral = '"' ([^"\r\n\\] | '\\' .)* '"'
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TrueLiteral = 'true'
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FalseLiteral = 'false'
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HexNumber = '0x' [0-9a-fA-F]+
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DecimalNumber = [0-9]+
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Restrictions on the Grammar
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---------------------------
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Switches must have at least one case (including the default case).
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If all possible values of the expression is covered, the default case should
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not be allowed (i.e. a switch with a ``bool`` expression and having both a
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true and false case should not allow a default case).
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Every expression evaluates to zero or more values. Identifiers and Literals
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evaluate to exactly
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one value and function calls evaluate to a number of values equal to the
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number of return values of the function called.
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In variable declarations and assignments, the right-hand-side expression
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(if present) has to evaluate to a number of values equal to the number of
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variables on the left-hand-side.
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This is the only situation where an expression evaluating
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to more than one value is allowed.
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Expressions that are also statements (i.e. at the block level) have to
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evaluate to zero values.
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In all other situations, expressions have to evaluate to exactly one value.
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The ``continue`` and ``break`` statements can only be used inside loop bodies
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and have to be in the same function as the loop (or both have to be at the
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top level).
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The condition part of the for-loop has to evaluate to exactly one value.
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Literals cannot be larger than the their type. The largest type defined is 256-bit wide.
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Scoping Rules
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-------------
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Scopes in JULIA are tied to Blocks (exceptions are functions and the for loop
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as explained below) and all declarations
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(``FunctionDefinition``, ``VariableDeclaration``)
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introduce new identifiers into these scopes.
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Identifiers are visible in
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the block they are defined in (including all sub-nodes and sub-blocks).
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As an exception, identifiers defined in the "init" part of the for-loop
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(the first block) are visible in all other parts of the for-loop
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(but not outside of the loop).
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Identifiers declared in the other parts of the for loop respect the regular
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syntatical scoping rules.
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The parameters and return parameters of functions are visible in the
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function body and their names cannot overlap.
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Variables can only be referenced after their declaration. In particular,
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variables cannot be referenced in the right hand side of their own variable
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declaration.
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Functions can be referenced already before their declaration (if they are visible).
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Shadowing is disallowed, i.e. you cannot declare an identifier at a point
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where another identifier with the same name is also visible, even if it is
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not accessible.
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Inside functions, it is not possible to access a variable that was declared
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outside of that function.
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Formal Specification
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--------------------
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We formally specify JULIA by providing an evaluation function E overloaded
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on the various nodes of the AST. Any functions can have side effects, so
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E takes two state objects and the AST node and returns two new
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state objects and a variable number of other values.
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The two state objects are the global state object
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(which in the context of the EVM is the memory, storage and state of the
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blockchain) and the local state object (the state of local variables, i.e. a
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segment of the stack in the EVM).
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If the AST node is a statement, E returns the two state objects and a "mode",
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which is used for the ``break`` and ``continue`` statements.
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If the AST node is an expression, E returns the two state objects and
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as many values as the expression evaluates to.
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The exact nature of the global state is unspecified for this high level
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description. The local state ``L`` is a mapping of identifiers ``i`` to values ``v``,
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denoted as ``L[i] = v``.
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For an identifier ``v``, let ``$v`` be the name of the identifier.
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We will use a destructuring notation for the AST nodes.
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.. code::
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E(G, L, <{St1, ..., Stn}>: Block) =
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let G1, L1, mode = E(G, L, St1, ..., Stn)
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let L2 be a restriction of L1 to the identifiers of L
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G1, L2, mode
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E(G, L, St1, ..., Stn: Statement) =
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if n is zero:
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G, L, regular
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else:
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let G1, L1, mode = E(G, L, St1)
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if mode is regular then
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E(G1, L1, St2, ..., Stn)
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otherwise
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G1, L1, mode
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E(G, L, FunctionDefinition) =
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G, L, regular
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E(G, L, <let var1, ..., varn := rhs>: VariableDeclaration) =
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E(G, L, <var1, ..., varn := rhs>: Assignment)
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E(G, L, <let var1, ..., varn>: VariableDeclaration) =
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let L1 be a copy of L where L1[$vari] = 0 for i = 1, ..., n
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G, L1, regular
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E(G, L, <var1, ..., varn := rhs>: Assignment) =
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let G1, L1, v1, ..., vn = E(G, L, rhs)
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let L2 be a copy of L1 where L2[$vari] = vi for i = 1, ..., n
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G, L2, regular
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E(G, L, <for { i1, ..., in } condition post body>: ForLoop) =
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if n >= 1:
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let G1, L1, mode = E(G, L, i1, ..., in)
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// mode has to be regular due to the syntactic restrictions
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let G2, L2, mode = E(G1, L1, for {} condition post body)
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// mode has to be regular due to the syntactic restrictions
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let L3 be the restriction of L2 to only variables of L
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G2, L3, regular
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else:
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let G1, L1, v = E(G, L, condition)
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if v is false:
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G1, L1, regular
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else:
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let G2, L2, mode = E(G1, L, body)
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if mode is break:
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G2, L2, regular
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else:
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G3, L3, mode = E(G2, L2, post)
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E(G3, L3, for {} condition post body)
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E(G, L, break: BreakContinue) =
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G, L, break
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E(G, L, continue: BreakContinue) =
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G, L, continue
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E(G, L, <switch condition case l1:t1 st1 ... case ln:tn stn>: Switch) =
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E(G, L, switch condition case l1:t1 st1 ... case ln:tn stn default {}) =
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E(G, L, <switch condition case l1:t1 st1 ... case ln:tn stn default st'>: Switch) =
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let G0, L0, v = E(G, L, condition)
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// i = 1 .. n
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// Evaluate literals, context doesn't matter
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let _, _, v1 = E(G0, L0, l1)
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...
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let _, _, vn = E(G0, L0, ln)
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if there exists smallest i such that vi = v:
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E(G0, L0, sti)
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else:
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E(G0, L0, st')
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E(G, L, <name>: Identifier) =
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G, L, L[$name]
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E(G, L, <fname(arg1, ..., argn)>: FunctionCall) =
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G1, L1, vn = E(G, L, argn)
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...
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G(n-1), L(n-1), v2 = E(G(n-2), L(n-2), arg2)
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Gn, Ln, v1 = E(G(n-1), L(n-1), arg1)
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Let <function fname (param1, ..., paramn) -> ret1, ..., retm block>
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be the function of name $fname visible at the point of the call.
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Let L' be a new local state such that
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L'[$parami] = vi and L'[$reti] = 0 for all i.
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Let G'', L'', mode = E(Gn, L', block)
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G'', Ln, L''[$ret1], ..., L''[$retm]
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E(G, L, l: HexLiteral) = G, L, hexString(l),
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where hexString decodes l from hex and left-aligns it into 32 bytes
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E(G, L, l: StringLiteral) = G, L, utf8EncodeLeftAligned(l),
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where utf8EncodeLeftAligned performs a utf8 encoding of l
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and aligns it left into 32 bytes
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E(G, L, n: HexNumber) = G, L, hex(n)
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where hex is the hexadecimal decoding function
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E(G, L, n: DecimalNumber) = G, L, dec(n),
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where dec is the decimal decoding function
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Type Conversion Functions
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-------------------------
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JULIA has no support for implicit type conversion and therefore functions exists to provide explicit conversion.
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When converting a larger type to a shorter type a runtime exception can occur in case of an overflow.
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The following type conversion functions must be available:
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- ``u32tobool(x:u32) -> y:bool``
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- ``booltou32(x:bool) -> y:u32``
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- ``u32tou64(x:u32) -> y:u64``
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- ``u64tou32(x:u64) -> y:u32``
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- etc. (TBD)
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Low-level Functions
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||||
-------------------
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The following functions must be available:
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+---------------------------------------------------------------------------------------------------------------+
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| *Arithmetics* |
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+---------------------------------------------------------------------------------------------------------------+
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| addu256(x:u256, y:u256) -> z:u256 | x + y |
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+---------------------------------------------------------------------------------------------------------------+
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| subu256(x:u256, y:u256) -> z:u256 | x - y |
|
||||
+---------------------------------------------------------------------------------------------------------------+
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||||
| mulu256(x:u256, y:u256) -> z:u256 | x * y |
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||||
+---------------------------------------------------------------------------------------------------------------+
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||||
| divu256(x:u256, y:u256) -> z:u256 | x / y |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| divs256(x:s256, y:s256) -> z:s256 | x / y, for signed numbers in two's complement |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| modu256(x:u256, y:u256) -> z:u256 | x % y |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| mods256(x:s256, y:s256) -> z:s256 | x % y, for signed numbers in two's complement |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| signextendu256(i:u256, x:u256) -> z:u256 | sign extend from (i*8+7)th bit counting from least significant |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| expu256(x:u256, y:u256) -> z:u256 | x to the power of y |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| addmodu256(x:u256, y:u256, m:u256) -> z:u256| (x + y) % m with arbitrary precision arithmetics |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| mulmodu256(x:u256, y:u256, m:u256) -> z:u256| (x * y) % m with arbitrary precision arithmetics |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| ltu256(x:u256, y:u256) -> z:bool | 1 if x < y, 0 otherwise |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| gtu256(x:u256, y:u256) -> z:bool | 1 if x > y, 0 otherwise |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| sltu256(x:s256, y:s256) -> z:bool | 1 if x < y, 0 otherwise, for signed numbers in two's complement |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| sgtu256(x:s256, y:s256) -> z:bool | 1 if x > y, 0 otherwise, for signed numbers in two's complement |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| equ256(x:u256, y:u256) -> z:bool | 1 if x == y, 0 otherwise |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| notu256(x:u256) -> z:u256 | ~x, every bit of x is negated |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| andu256(x:u256, y:u256) -> z:u256 | bitwise and of x and y |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| oru256(x:u256, y:u256) -> z:u256 | bitwise or of x and y |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| xoru256(x:u256, y:u256) -> z:u256 | bitwise xor of x and y |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| shlu256(x:u256, y:u256) -> z:u256 | logical left shift of x by y |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| shru256(x:u256, y:u256) -> z:u256 | logical right shift of x by y |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| saru256(x:u256, y:u256) -> z:u256 | arithmetic right shift of x by y |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| byte(n:u256, x:u256) -> v:u256 | nth byte of x, where the most significant byte is the 0th byte |
|
||||
| Cannot this be just replaced by and256(shr256(n, x), 0xff) and let it be optimised out by the EVM backend? |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| *Memory and storage* |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| mload(p:u256) -> v:u256 | mem[p..(p+32)) |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| mstore(p:u256, v:u256) | mem[p..(p+32)) := v |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| mstore8(p:u256, v:u256) | mem[p] := v & 0xff - only modifies a single byte |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| sload(p:u256) -> v:u256 | storage[p] |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| sstore(p:u256, v:u256) | storage[p] := v |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| msize() -> size:u256 | size of memory, i.e. largest accessed memory index, albeit due |
|
||||
| | due to the memory extension function, which extends by words, |
|
||||
| | this will always be a multiple of 32 bytes |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| *Execution control* |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| create(v:u256, p:u256, s:u256) | create new contract with code mem[p..(p+s)) and send v wei |
|
||||
| | and return the new address |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| call(g:u256, a:u256, v:u256, in:u256, | call contract at address a with input mem[in..(in+insize)) |
|
||||
| insize:u256, out:u256, | providing g gas and v wei and output area |
|
||||
| outsize:u256) | mem[out..(out+outsize)) returning 0 on error (eg. out of gas) |
|
||||
| -> r:u256 | and 1 on success |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| callcode(g:u256, a:u256, v:u256, in:u256, | identical to ``call`` but only use the code from a |
|
||||
| insize:u256, out:u256, | and stay in the context of the |
|
||||
| outsize:u256) -> r:u256 | current contract otherwise |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| delegatecall(g:u256, a:u256, in:u256, | identical to ``callcode``, |
|
||||
| insize:u256, out:u256, | but also keep ``caller`` |
|
||||
| outsize:u256) -> r:u256 | and ``callvalue`` |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| stop() | stop execution, identical to return(0,0) |
|
||||
| Perhaps it would make sense retiring this as it equals to return(0,0). It can be an optimisation by the EVM |
|
||||
| backend. |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| abort() | abort (equals to invalid instruction on EVM) |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| return(p:u256, s:u256) | end execution, return data mem[p..(p+s)) |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| revert(p:u256, s:u256) | end execution, revert state changes, return data mem[p..(p+s)) |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| selfdestruct(a:u256) | end execution, destroy current contract and send funds to a |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| log0(p:u256, s:u256) | log without topics and data mem[p..(p+s)) |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| log1(p:u256, s:u256, t1:u256) | log with topic t1 and data mem[p..(p+s)) |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| log2(p:u256, s:u256, t1:u256, t2:u256) | log with topics t1, t2 and data mem[p..(p+s)) |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| log3(p:u256, s:u256, t1:u256, t2:u256, | log with topics t, t2, t3 and data mem[p..(p+s)) |
|
||||
| t3:u256) | |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| log4(p:u256, s:u256, t1:u256, t2:u256, | log with topics t1, t2, t3, t4 and data mem[p..(p+s)) |
|
||||
| t3:u256, t4:u256) | |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| *State queries* |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| blockcoinbase() -> address:u256 | current mining beneficiary |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| blockdifficulty() -> difficulty:u256 | difficulty of the current block |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| blockgaslimit() -> limit:u256 | block gas limit of the current block |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| blockhash(b:u256) -> hash:u256 | hash of block nr b - only for last 256 blocks excluding current |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| blocknumber() -> block:u256 | current block number |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| blocktimestamp() -> timestamp:u256 | timestamp of the current block in seconds since the epoch |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| txorigin() -> address:u256 | transaction sender |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| txgasprice() -> price:u256 | gas price of the transaction |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| gasleft() -> gas:u256 | gas still available to execution |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| balance(a:u256) -> v:u256 | wei balance at address a |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| this() -> address:u256 | address of the current contract / execution context |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| caller() -> address:u256 | call sender (excluding delegatecall) |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| callvalue() -> v:u256 | wei sent together with the current call |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| calldataload(p:u256) -> v:u256 | call data starting from position p (32 bytes) |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| calldatasize() -> v:u256 | size of call data in bytes |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| calldatacopy(t:u256, f:u256, s:u256) | copy s bytes from calldata at position f to mem at position t |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| codesize() -> size:u256 | size of the code of the current contract / execution context |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| codecopy(t:u256, f:u256, s:u256) | copy s bytes from code at position f to mem at position t |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| extcodesize(a:u256) -> size:u256 | size of the code at address a |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| extcodecopy(a:u256, t:u256, f:u256, s:u256) | like codecopy(t, f, s) but take code at address a |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| *Others* |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| discardu256(unused:u256) | discard value |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| splitu256tou64(x:u256) -> (x1:u64, x2:u64, | split u256 to four u64's |
|
||||
| x3:u64, x4:u64) | |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| combineu64tou256(x1:u64, x2:u64, x3:u64, | combine four u64's into a single u256 |
|
||||
| x4:u64) -> (x:u256) | |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
| sha3(p:u256, s:u256) -> v:u256 | keccak(mem[p...(p+s))) |
|
||||
+---------------------------------------------------------------------------------------------------------------+
|
||||
|
||||
Backends
|
||||
--------
|
||||
|
||||
Backends or targets are the translators from JULIA to a specific bytecode. Each of the backends can expose functions
|
||||
prefixed with the name of the backend. We reserve ``evm_`` and ``ewasm_`` prefixes for the two proposed backends.
|
||||
|
||||
Backend: EVM
|
||||
------------
|
||||
|
||||
The EVM target will have all the underlying EVM opcodes exposed with the `evm_` prefix.
|
||||
|
||||
Backend: "EVM 1.5"
|
||||
------------------
|
||||
|
||||
TBD
|
||||
|
||||
Backend: eWASM
|
||||
--------------
|
||||
|
||||
TBD
|
||||
|
||||
Specification of JULIA Object
|
||||
=============================
|
||||
|
||||
Grammar::
|
||||
|
||||
TopLevelObject = 'object' '{' Code? ( Object | Data )* '}'
|
||||
Object = 'object' StringLiteral '{' Code? ( Object | Data )* '}'
|
||||
Code = 'code' Block
|
||||
Data = 'data' StringLiteral HexLiteral
|
||||
HexLiteral = 'hex' ('"' ([0-9a-fA-F]{2})* '"' | '\'' ([0-9a-fA-F]{2})* '\'')
|
||||
StringLiteral = '"' ([^"\r\n\\] | '\\' .)* '"'
|
||||
|
||||
Above, ``Block`` refers to ``Block`` in the JULIA code grammar explained in the previous chapter.
|
||||
|
||||
An example JULIA Object is shown below:
|
||||
|
||||
..code::
|
||||
|
||||
// Code consists of a single object. A single "code" node is the code of the object.
|
||||
// Every (other) named object or data section is serialized and
|
||||
// made accessible to the special built-in functions datacopy / dataoffset / datasize
|
||||
object {
|
||||
code {
|
||||
let size = datasize("runtime")
|
||||
let offset = allocate(size)
|
||||
// This will turn into a memory->memory copy for eWASM and
|
||||
// a codecopy for EVM
|
||||
datacopy(dataoffset("runtime"), offset, size)
|
||||
// this is a constructor and the runtime code is returned
|
||||
return(offset, size)
|
||||
}
|
||||
|
||||
data "Table2" hex"4123"
|
||||
|
||||
object "runtime" {
|
||||
code {
|
||||
// runtime code
|
||||
|
||||
let size = datasize("Contract2")
|
||||
let offset = allocate(size)
|
||||
// This will turn into a memory->memory copy for eWASM and
|
||||
// a codecopy for EVM
|
||||
datacopy(dataoffset("Contract2"), offset, size)
|
||||
// constructor parameter is a single number 0x1234
|
||||
mstore(add(offset, size), 0x1234)
|
||||
create(offset, add(size, 32))
|
||||
}
|
||||
|
||||
// Embedded object. Use case is that the outside is a factory contract,
|
||||
// and Contract2 is the code to be created by the factory
|
||||
object "Contract2" {
|
||||
code {
|
||||
// code here ...
|
||||
}
|
||||
|
||||
object "runtime" {
|
||||
code {
|
||||
// code here ...
|
||||
}
|
||||
}
|
||||
|
||||
data "Table1" hex"4123"
|
||||
}
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user