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https://github.com/pezkuwichain/revive.git
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xermicus
40e97d11eb
Existing test coverage didn't catch a signed remainder overflow semantics edge case behavior where at least one the operators is being constant folded by LLVM instead of solc. This PR fixes the SREM translation bug and adds missing test coverage for division ops with constants. Closes #524 --------- Signed-off-by: xermicus <cyrill@parity.io>
22 lines
801 B
Plaintext
22 lines
801 B
Plaintext
/// Probe: `addmod(a, b, 0)` — LLVM `urem ..., 0` is UB; EVM defines ADDMOD
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/// with modulus = 0 as 0. The stdlib `__addmod` runtime function guards this.
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/// Question is whether LLVM constant-folds through the guard at O3.
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object "AddModZeroProbe" {
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code {
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let size := datasize("AddModZeroProbe_deployed")
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codecopy(0, dataoffset("AddModZeroProbe_deployed"), size)
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return(0, size)
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}
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object "AddModZeroProbe_deployed" {
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code {
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let tag := calldataload(0)
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let a := calldataload(32)
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let b := calldataload(64)
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// 0 modulus, obfuscated so revive can't pre-fold
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let modulus := sub(shl(8, 1), shl(8, 1))
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mstore(0, xor(addmod(a, b, modulus), tag))
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return(0, 32)
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}
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}
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}
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