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yul: Set non movable flag to true in simplification rule for byte of right-shifted expression

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This commit is contained in:
Bhargava Shastry 2020-08-02 13:29:19 +02:00 committed by chriseth
parent 08791ab0d4
commit 5100effeec
7 changed files with 74 additions and 2 deletions
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1
Changelog.md
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@ -7,6 +7,7 @@ Compiler Features:
Bugfixes:
* Optimizer: Keep side-effects of ``x`` in ``byte(a, shr(b, x))`` even if the constants ``a`` and ``b`` would make the expression zero unconditionally. This optimizer rule is very hard if not impossible to trigger in a way that it can result in invalid code, though.
* SMTChecker: Fix internal error on fixed bytes index access.

15
libevmasm/RuleList.h
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@ -581,9 +581,20 @@ std::vector<SimplificationRule<Pattern>> simplificationRuleListPart7(
rules.push_back({
Builtins::BYTE(A, Builtins::SHR(B, X)),
[=]() -> Pattern { return A.d() < B.d() / 8 ? Word(0) : Builtins::BYTE(A.d() - B.d() / 8, X); },
[=]() -> Pattern { return Word(0); },
true,
[=] {
return B.d() % 8 == 0 && A.d() < Pattern::WordSize / 8 && B.d() <= Pattern::WordSize && A.d() < B.d() / 8;
}
});
rules.push_back({
Builtins::BYTE(A, Builtins::SHR(B, X)),
[=]() -> Pattern { return Builtins::BYTE(A.d() - B.d() / 8, X); },
false,
[=] { return B.d() % 8 == 0 && A.d() < Pattern::WordSize / 8 && B.d() <= Pattern::WordSize; }
[=] {
return B.d() % 8 == 0 && A.d() < Pattern::WordSize / 8 && B.d() <= Pattern::WordSize && A.d() >= B.d() / 8;
}
});
return rules;

10
test/libyul/yulInterpreterTests/pop_byte_shr_call.yul Normal file
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@ -0,0 +1,10 @@
{
pop(byte(0, shr(0x8, call(0, 0, 0, 0, 0, 0, 0))))
}
// ====
// EVMVersion: >=constantinople
// ----
// Trace:
// CALL(0, 0, 0, 0, 0, 0, 0)
// Memory dump:
// Storage dump:

11
test/libyul/yulInterpreterTests/pop_byte_shr_func.yul Normal file
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@ -0,0 +1,11 @@
{
function f() -> x { mstore(0, 0x1337) }
pop(byte(0, shr(0x8, f())))
}
// ====
// EVMVersion: >=constantinople
// ----
// Trace:
// Memory dump:
// 0: 0000000000000000000000000000000000000000000000000000000000001337
// Storage dump:

11
test/libyul/yulOptimizerTests/expressionSimplifier/pop_byte_shr_call.yul Normal file
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@ -0,0 +1,11 @@
{
pop(byte(0, shr(0x8, call(0, 0, 0, 0, 0, 0, 0))))
}
// ====
// EVMVersion: >=constantinople
// ----
// step: expressionSimplifier
//
// {
// pop(byte(0, shr(0x8, call(0, 0, 0, 0, 0, 0, 0))))
// }

14
test/libyul/yulOptimizerTests/expressionSimplifier/pop_byte_shr_func.yul Normal file
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@ -0,0 +1,14 @@
{
function f() -> x { mstore(0, 1337) }
pop(byte(0, shr(0x8, f())))
}
// ====
// EVMVersion: >=constantinople
// ----
// step: expressionSimplifier
//
// {
// function f() -> x
// { mstore(0, 1337) }
// pop(byte(0, shr(0x8, f())))
// }

14
test/libyul/yulOptimizerTests/expressionSimplifier/pop_byte_shr_func_trivial.yul Normal file
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@ -0,0 +1,14 @@
{
function f() -> x {}
pop(byte(0, shr(0x8, f())))
}
// ====
// EVMVersion: >=constantinople
// ----
// step: expressionSimplifier
//
// {
// function f() -> x
// { }
// pop(byte(0, shr(0x8, f())))
// }