Missing RETURNPRIVATE in TAC for Inline Assembly Switch Case

[pc9527zxx]

Description

Gigahorse's TAC output incorrectly handles inline assembly switch statements in a Solidity contract. The switchFunc in the provided contract uses inline assembly to check the function selector, returning 0x...01 for 0xa9059cbb (transfer) and 0x...00 otherwise. In the TAC file, when the selector matches 0xa9059cbb and enters the corresponding block (e.g., 0x5c), there is no RETURNPRIVATE instruction to handle the return value, causing analysis errors.

Steps to Reproduce

1. Contract:

   // SPDX-License-Identifier: MIT
   pragma solidity ^0.8.20;
   
   contract Switch {
       function switchFunc() public pure returns (bytes32 result) {
           assembly {
               let selector := shr(224, calldataload(0))
               switch selector
                   case 0xa9059cbb {
                       result := 0x0000000000000000000000000000000000000000000000000000000000000001
                   }
                   default {
                       result := 0x0000000000000000000000000000000000000000000000000000000000000000
                   }
           }
       }
   }

2. Runtime Bytecode:

   0x6080604052348015600e575f80fd5b50600436106026575f3560e01c8063ecc56f2f14602a575b5f80fd5b60306044565b604051603b9190607c565b60405180910390f35b5f803560e01c8063a9059cbb8114605c575f92506061565b600192505b505090565b5f819050919050565b6076816066565b82525050565b5f602082019050608d5f830184606f565b9291505056fea26469706673582212205d3632ef267ecc641af94231ff154a370ca81f4bfe4730698d849be01a4afecd64736f6c63430008140033
   

3. TAC Output:

   Begin block 0xd5B0x2a
   prev=[0x44B0x2a], succ=[0x30]
   =================================
   0xd6S0x2a: vd6V2a(0x5c) = CONST 
   0xd7S0x2a: CALLPRIVATE vd6V2a(0x5c), v4aV2a, v4aV2a, v45V2a(0x0), v2b(0x30)
   
   function transfer(address,uint256)(v5carg0, v5carg1, v5carg2(0x0), v5carg3) public {
       Begin block 0x5c
       prev=[], succ=[0x610x5c]
       =================================
       0x5d: v5d(0x1) = CONST 
   
       Begin block 0x610x5c
       prev=[0x5c], succ=[]
       =================================
       0x650x5c: JUMP v5carg3
   }
   

[sifislag]

Thanks for the report, I will check it out.