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Split memcopy into three functions.

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This commit is contained in:
chriseth 2016-12-11 17:51:17 +01:00
parent 4184525d4a
commit bfa4f45116
3 changed files with 78 additions and 53 deletions
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9
libsolidity/codegen/ArrayUtils.cpp
View File

@ -335,9 +335,14 @@ void ArrayUtils::copyArrayToMemory(ArrayType const& _sourceType, bool _padToWord
if (baseSize > 1)
m_context << u256(baseSize) << Instruction::MUL;
// stack: <target> <source> <size>
//@TODO do not use ::CALL if less than 32 bytes?
m_context << Instruction::DUP1 << Instruction::DUP4 << Instruction::DUP4;
utils.memoryCopy();
// We can resort to copying full 32 bytes only if
// - the length is known to be a multiple of 32 or
// - we will pad to full 32 bytes later anyway.
if (((baseSize % 32) == 0) || _padToWordBoundaries)
utils.memoryCopy32();
else
utils.memoryCopy();
m_context << Instruction::SWAP1 << Instruction::POP;
// stack: <target> <size>

112
libsolidity/codegen/CompilerUtils.cpp
View File

@ -298,61 +298,73 @@ void CompilerUtils::zeroInitialiseMemoryArray(ArrayType const& _type)
m_context << Instruction::SWAP1 << Instruction::POP;
}
void CompilerUtils::memoryCopy(bool _useIdentityPrecompile)
void CompilerUtils::memoryCopyPrecompile()
{
//@TODO do not use ::CALL if less than 32 bytes?
// Stack here: size target source
if (!_useIdentityPrecompile)
{
m_context.appendInlineAssembly(R"(
{
// expects three locals: src, dst, len
m_context.appendInlineAssembly(R"(
{
let words := div(add(len, 31), 32)
let cost := add(15, mul(3, words))
jumpi(invalidJumpLabel, iszero(call(cost, $identityContractAddress, 0, src, len, dst, len)))
}
)",
{ "len", "dst", "src" },
map<string, string> {
{ "$identityContractAddress", toString(identityContractAddress) }
}
);
m_context << Instruction::POP << Instruction::POP << Instruction::POP;
}
// copy 32 bytes at once
start32:
jumpi(end32, lt(len, 32))
mstore(dst, mload(src))
dst := add(dst, 32)
src := add(src, 32)
len := sub(len, 32)
jump(start32)
end32:
void CompilerUtils::memoryCopy32()
{
// Stack here: size target source
// copy the remainder (0 < len < 32)
let mask := sub(exp(256, sub(32, len)), 1)
let srcpart := and(mload(src), not(mask))
let dstpart := and(mload(dst), mask)
mstore(dst, or(srcpart, dstpart))
}
)",
{ "len", "dst", "src" }
);
m_context << Instruction::POP;
m_context << Instruction::POP;
m_context << Instruction::POP;
return;
}
else
{
m_context.appendInlineAssembly(R"(
{
let words := div(add(len, 31), 32)
let cost := add(15, mul(3, words))
jump(invalidJumpLabel, iszero(call(cost, $identityContractAddress, 0, src, len, dst, len)))
}
)",
{ "len", "dst", "src" },
map<string, string> {
{ "$identityContractAddress", toString(identityContractAddress) }
}
);
m_context << Instruction::POP;
m_context << Instruction::POP;
m_context << Instruction::POP;
return;
}
m_context.appendInlineAssembly(R"(
{
jumpi(end, eq(len, 0))
start:
mstore(dst, mload(src))
jumpi(end, iszero(gt(len, 32)))
dst := add(dst, 32)
src := add(src, 32)
len := sub(len, 32)
jump(start)
end:
}
)",
{ "len", "dst", "src" }
);
m_context << Instruction::POP << Instruction::POP << Instruction::POP;
}
void CompilerUtils::memoryCopy()
{
// Stack here: size target source
m_context.appendInlineAssembly(R"(
{
// copy 32 bytes at once
start32:
jumpi(end32, lt(len, 32))
mstore(dst, mload(src))
dst := add(dst, 32)
src := add(src, 32)
len := sub(len, 32)
jump(start32)
end32:
// copy the remainder (0 < len < 32)
let mask := sub(exp(256, sub(32, len)), 1)
let srcpart := and(mload(src), not(mask))
let dstpart := and(mload(dst), mask)
mstore(dst, or(srcpart, dstpart))
}
)",
{ "len", "dst", "src" }
);
m_context << Instruction::POP << Instruction::POP << Instruction::POP;
}
void CompilerUtils::splitExternalFunctionType(bool _leftAligned)

10
libsolidity/codegen/CompilerUtils.h
View File

@ -112,7 +112,15 @@ public:
/// Uses a CALL to the identity contract to perform a memory-to-memory copy.
/// Stack pre: <size> <target> <source>
/// Stack post:
void memoryCopy(bool _useIdentityPrecompile = false);
void memoryCopyPrecompile();
/// Copies full 32 byte words in memory (regions cannot overlap), i.e. may copy more than length.
/// Stack pre: <size> <target> <source>
/// Stack post:
void memoryCopy32();
/// Copies data in memory (regions cannot overlap).
/// Stack pre: <size> <target> <source>
/// Stack post:
void memoryCopy();
/// Converts the combined and left-aligned (right-aligned if @a _rightAligned is true)
/// external function type <address><function identifier> into two stack slots: