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Optimizations for stack checks when no over/under flow is present #2709

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Optimizations for stack checks when no over/under flow is present #2709

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3ba1eb5
kevm-pyk/evm: use function, not macro, for stack under/over-flow
ehildenb Feb 24, 2025
386c5d1
kevm-pyk/evm: optimize for non-overflow cases on stack checks
ehildenb Feb 24, 2025
51deb06
kevm-pyk/evm.md: optimize for non-underflow stack check
ehildenb Feb 24, 2025
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21 changes: 16 additions & 5 deletions kevm-pyk/src/kevm_pyk/kproj/evm-semantics/evm.md
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Expand Up @@ -377,11 +377,22 @@ The `#next [_]` operator initiates execution by:
- `#stackDelta` is the delta the stack will have after the opcode executes.

```k
syntax Bool ::= #stackUnderflow ( WordStack , OpCode ) [symbol(#stackUnderflow), macro]
| #stackOverflow ( WordStack , OpCode ) [symbol(#stackOverflow), macro]
// --------------------------------------------------------------------------------------
rule #stackUnderflow(WS, OP:OpCode) => #sizeWordStack(WS) <Int #stackNeeded(OP)
rule #stackOverflow (WS, OP) => (#stackDelta(OP) >Int 0) andBool (#sizeWordStack(WS) +Int #stackDelta(OP) >Int 1024)
syntax Bool ::= #stackUnderflow ( WordStack , OpCode ) [symbol(#stackUnderflow), function, total]
| #stackOverflow ( WordStack , OpCode ) [symbol(#stackOverflow), function, total]
// ------------------------------------------------------------------------------------------------
rule #stackUnderflow( _WS , _POP:PushOp ) => false
rule #stackUnderflow( _WS , _IOP:InvalidOp ) => false
rule #stackUnderflow( _WS , _NOP:NullStackOp ) => false
rule #stackUnderflow( _W0 : _WS , _UOP:UnStackOp ) => false
rule #stackUnderflow( _W0 : _W1 : _WS , BOP:BinStackOp ) => false requires notBool isLogOp(BOP)
rule #stackUnderflow( _W0 : _W1 : _W2 : _WS , _TOP:TernStackOp ) => false
rule #stackUnderflow( _W0 : _W1 : _W2 : _W3 : _WS , _QOP:QuadStackOp ) => false
rule #stackUnderflow( _W0 : _W1 : _W2 : _W3 : _W4 : _W5 : _W6 : _WS , _CSOP:CallSixOp ) => false
rule #stackUnderflow( _W0 : _W1 : _W2 : _W3 : _W4 : _W5 : _W6 : _W7 : _WS , COP:CallOp ) => false requires notBool isCallSixOp(COP)
rule #stackUnderflow(WS, OP:OpCode) => #sizeWordStack(WS) <Int #stackNeeded(OP) [owise]

rule #stackOverflow(_WS, OP) => false requires #stackDelta(OP) <=Int 0
rule #stackOverflow(WS, OP) => 1024 <Int #sizeWordStack(WS) +Int #stackDelta(OP) [owise]

syntax Int ::= #stackNeeded ( OpCode ) [symbol(#stackNeeded), function]
// -----------------------------------------------------------------------
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