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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>
31 lines
1.3 KiB
Plaintext
31 lines
1.3 KiB
Plaintext
/// Both-constant DIV variants. The selector index is read from calldata[0..32]
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/// and dispatched to a branch with two literal operands. Compiled directly via
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/// revive's Yul-to-LLVM path (bypassing solc's Yul optimizer) so the literals
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/// reach LLVM intact and exercise revive's "two literal operands" codegen path.
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object "DivBothConst" {
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code {
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let size := datasize("DivBothConst_deployed")
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codecopy(0, dataoffset("DivBothConst_deployed"), size)
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return(0, size)
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}
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object "DivBothConst_deployed" {
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code {
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let which := calldataload(0)
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// `tag` is XORed into the result so that any poison/undef LLVM
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// produces from a UB-triggering const-fold propagates and diverges
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// from EVM, instead of coincidentally returning 0 and masking it.
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let tag := calldataload(32)
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let r := 0
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switch which
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case 0 { r := div(5, 5) }
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case 1 { r := div(5, 1) }
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case 2 { r := div(0, 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff) }
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case 3 { r := div(5, 2) }
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case 4 { r := div(1, 0) }
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default { revert(0, 0) }
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mstore(0, xor(r, tag))
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return(0, 32)
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}
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}
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}
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