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[ewasm] Clean up opcodes/builtins in the binary encoder

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Also make sure that `i32.drop/i64.drop` won't silently drop its arguments, as they may have side-effects.
This commit is contained in:
Alex Beregszaszi
2020-12-01 12:50:54 +00:00
parent a29a7ad680
commit 04cf4867fe
6 changed files with 30 additions and 44 deletions
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libyul/backends/wasm/BinaryTransform.cpp
+22 -36
View File
@@ -107,33 +107,24 @@ bytes toBytes(Export _export)
return toBytes(uint8_t(_export));
}
// NOTE: This is a subset of WebAssembly opcodes.
// Those available as a builtin are listed further down.
enum class Opcode: uint8_t
{
Unreachable = 0x00,
Nop = 0x01,
Block = 0x02,
Loop = 0x03,
If = 0x04,
Else = 0x05,
Try = 0x06,
Catch = 0x07,
Throw = 0x08,
Rethrow = 0x09,
BrOnExn = 0x0a,
End = 0x0b,
Br = 0x0c,
BrIf = 0x0d,
BrTable = 0x0e,
BrTable = 0x0e, // Not used yet.
Return = 0x0f,
Call = 0x10,
CallIndirect = 0x11,
ReturnCall = 0x12,
ReturnCallIndirect = 0x13,
Drop = 0x1a,
Select = 0x1b,
CallIndirect = 0x11, // Not used yet.
LocalGet = 0x20,
LocalSet = 0x21,
LocalTee = 0x22,
LocalTee = 0x22, // Not used yet.
GlobalGet = 0x23,
GlobalSet = 0x24,
I32Const = 0x41,
@@ -156,6 +147,10 @@ Opcode constOpcodeFor(ValueType _type)
}
static map<string, uint8_t> const builtins = {
{"unreachable", 0x00},
{"nop", 0x01},
{"i32.drop", 0x1a},
{"i64.drop", 0x1a},
{"i32.select", 0x1b},
{"i64.select", 0x1b},
{"i32.load", 0x28},
@@ -381,30 +376,21 @@ bytes BinaryTransform::operator()(BuiltinCall const& _call)
return toBytes(Opcode::I64Const) + lebEncodeSigned(static_cast<int64_t>(m_subModulePosAndSize.at(name).second));
}
yulAssert(builtins.count(_call.functionName), "Builtin " + _call.functionName + " not found");
// NOTE: the dialect ensures we have the right amount of arguments
bytes args = visit(_call.arguments);
bytes ret = move(args) + toBytes(builtins.at(_call.functionName));
if (
_call.functionName.find(".load") != string::npos ||
_call.functionName.find(".store") != string::npos
)
// Alignment hint and offset. Interpreters ignore the alignment. JITs/AOTs can take it
// into account to generate more efficient code but if the hint is invalid it could
// actually be more expensive. It's best to hint at 1-byte alignment if we don't plan
// to control the memory layout accordingly.
ret += bytes{{0, 0}}; // 2^0 == 1-byte alignment
if (_call.functionName == "unreachable")
return toBytes(Opcode::Unreachable);
else if (_call.functionName == "nop")
return toBytes(Opcode::Nop);
else if (_call.functionName == "i32.drop" || _call.functionName == "i64.drop")
return toBytes(Opcode::Drop);
else
{
yulAssert(builtins.count(_call.functionName), "Builtin " + _call.functionName + " not found");
bytes ret = move(args) + toBytes(builtins.at(_call.functionName));
if (
_call.functionName.find(".load") != string::npos ||
_call.functionName.find(".store") != string::npos
)
// Alignment hint and offset. Interpreters ignore the alignment. JITs/AOTs can take it
// into account to generate more efficient code but if the hint is invalid it could
// actually be more expensive. It's best to hint at 1-byte alignment if we don't plan
// to control the memory layout accordingly.
ret += bytes{{0, 0}}; // 2^0 == 1-byte alignment
return ret;
}
return ret;
}
bytes BinaryTransform::operator()(FunctionCall const& _call)
libyul/backends/wasm/WasmDialect.h
+1 -1
View File
@@ -38,7 +38,7 @@ struct Object;
*
* Builtin functions are a subset of the wasm instructions.
*
* There is a builtin function `i32.drop` that takes an i32, while `drop` takes i64.
* There is a builtin function `i32.drop` that takes an i32, while `i64.drop` takes i64.
*
*/
struct WasmDialect: public Dialect