cannon: Remove unicorn references

cannon/docs/README.md

@@ -32,9 +32,8 @@ And as it executes each step, it can optionally produce the witness data for the
 The Cannon CLI is used to load a program into an initial state,
 transition it N steps quickly without witness generation, and 1 step while producing a witness.
 
-`mipsevm` is backed by the Unicorn emulator, but instrumented for proof generation,
-and handles delay-slots by isolating each individual instruction and tracking `nextPC`
-to emulate the delayed `PC` changes after delay-slot execution.
+`mipsevm` is instrumented for proof generation and handles delay-slots by isolating each individual instruction
+and tracking `nextPC` to emulate the delayed `PC` changes after delay-slot execution.
 
 ## Witness Data
 

cannon/mipsevm/evm_test.go

@@ -108,7 +108,7 @@ func TestEVM(t *testing.T) {
 				// TODO: maybe more readable to decode the evmPost state, and do attribute-wise comparison.
 				uniPost := us.state.EncodeWitness()
 				require.Equal(t, hexutil.Bytes(uniPost).String(), hexutil.Bytes(evmPost).String(),
-					"unicorn produced different state than EVM")
+					"mipsevm produced different state than EVM")
 			}
 			require.Equal(t, uint32(endAddr), state.PC, "must reach end")
 			// inspect test result
@@ -175,7 +175,7 @@ func TestHelloEVM(t *testing.T) {
 		// TODO: maybe more readable to decode the evmPost state, and do attribute-wise comparison.
 		uniPost := us.state.EncodeWitness()
 		require.Equal(t, hexutil.Bytes(uniPost).String(), hexutil.Bytes(evmPost).String(),
-			"unicorn produced different state than EVM")
+			"mipsevm produced different state than EVM")
 	}
 	end := time.Now()
 	delta := end.Sub(start)

cannon/mipsevm/memory.go

@@ -11,8 +11,7 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 )
 
-// Note: 2**12 = 4 KiB, the minimum page-size in Unicorn for mmap
-// as well as the Go runtime min phys page size.
+// Note: 2**12 = 4 KiB, the min phys page size in the Go runtime.
 const (
 	PageAddrSize = 12
 	PageKeySize  = 32 - PageAddrSize

cannon/mipsevm/mips.go

@@ -56,15 +56,6 @@ func (m *InstrumentedState) handleSyscall() error {
 			v0 = a0
 			//fmt.Printf("mmap hint 0x%x size 0x%x\n", v0, sz)
 		}
-		// Go does this thing where it first gets memory with PROT_NONE,
-		// and then mmaps with a hint with prot=3 (PROT_READ|WRITE).
-		// We can ignore the NONE case, to avoid duplicate/overlapping mmap calls to unicorn.
-		//prot := a2
-		//if prot != 0 {
-		//	if err := mu.MemMap(uint64(v0), uint64(sz)); err != nil {
-		//		log.Fatalf("mmap fail: %v", err)
-		//	}
-		//}
 	case 4045: // brk
 		v0 = 0x40000000
 	case 4120: // clone (not supported)