CL-USER> (disassemble (compile nil (lambda (x)				    
				                     (loop for i below (length x)
					                       do (setf (aref x i) (floor (aref x i) 2))))))
; disassembly for (LAMBDA (X))
; Size: 336 bytes. Origin: #x536C0115                         ; (LAMBDA (X))
; 115:       498B4510         MOV RAX, [R13+16]               ; thread.binding-stack-pointer
; 119:       488945F8         MOV [RBP-8], RAX
; 11D:       4883EC10         SUB RSP, 16
; 121:       488B55F0         MOV RDX, [RBP-16]
; 125:       B902000000       MOV ECX, 2
; 12A:       48892C24         MOV [RSP], RBP
; 12E:       488BEC           MOV RBP, RSP
; 131:       B8901AA052       MOV EAX, #x52A01A90             ; LENGTH
; 136:       FFD0             CALL RAX
; 138:       488955E0         MOV [RBP-32], RDX
; 13C:       48C745E800000000 MOV QWORD PTR [RBP-24], 0
; 144:       E9F2000000       JMP L4
; 149:       0F1F8000000000   NOP
; 150: L0:   488B45E8         MOV RAX, [RBP-24]
; 154:       488945D8         MOV [RBP-40], RAX
; 158:       488B7DE8         MOV RDI, [RBP-24]
; 15C:       488B4DF0         MOV RCX, [RBP-16]
; 160:       488D41F1         LEA RAX, [RCX-15]
; 164:       A80F             TEST AL, 15
; 166:       7506             JNE L1
; 168:       8A00             MOV AL, [RAX]
; 16A:       2C85             SUB AL, -123
; 16C:       3C71             CMP AL, 113
; 16E: L1:   0F83E8000000     JNB L7
; 174:       488B55F0         MOV RDX, [RBP-16]
; 178:       4883EC10         SUB RSP, 16
; 17C:       B904000000       MOV ECX, 4
; 181:       48892C24         MOV [RSP], RBP
; 185:       488BEC           MOV RBP, RSP
; 188:       B822BE3550       MOV EAX, #x5035BE22             ; #<FDEFN SB-KERNEL:HAIRY-DATA-VECTOR-REF/CHECK-BOUNDS>
; 18D:       FFD0             CALL RAX
; 18F:       4C8BC2           MOV R8, RDX
; 192:       4C8945D0         MOV [RBP-48], R8
; 196:       498D40F1         LEA RAX, [R8-15]
; 19A:       A801             TEST AL, 1
; 19C:       7515             JNE L2
; 19E:       3C0A             CMP AL, 10
; 1A0:       7411             JEQ L2
; 1A2:       A80F             TEST AL, 15
; 1A4:       0F85AF000000     JNE L6
; 1AA:       80381D           CMP BYTE PTR [RAX], 29
; 1AD:       0F87A6000000     JNBE L6
; 1B3: L2:   498BD0           MOV RDX, R8
; 1B6:       4883EC10         SUB RSP, 16
; 1BA:       BF04000000       MOV EDI, 4
; 1BF:       B904000000       MOV ECX, 4
; 1C4:       48892C24         MOV [RSP], RBP
; 1C8:       488BEC           MOV RBP, RSP
; 1CB:       B8A2483550       MOV EAX, #x503548A2             ; #<FDEFN TRUNCATE>
; 1D0:       FFD0             CALL RAX
; 1D2:       4C8B45D0         MOV R8, [RBP-48]
; 1D6:       4C8BCA           MOV R9, RDX
; 1D9:       4C894DC8         MOV [RBP-56], R9
; 1DD:       488BD7           MOV RDX, RDI
; 1E0:       31FF             XOR EDI, EDI
; 1E2:       FF14254001A052   CALL QWORD PTR [#x52A00140]     ; SB-VM::GENERIC-=
; 1E9:       4C8B4DC8         MOV R9, [RBP-56]
; 1ED:       4C8B45D0         MOV R8, [RBP-48]
; 1F1:       7461             JEQ L5
; 1F3:       31FF             XOR EDI, EDI
; 1F5:       498BD0           MOV RDX, R8
; 1F8:       FF14253001A052   CALL QWORD PTR [#x52A00130]     ; SB-VM::GENERIC-<
; 1FF:       4C8B4DC8         MOV R9, [RBP-56]
; 203:       7D4F             JNL L5
; 205:       BF02000000       MOV EDI, 2
; 20A:       498BD1           MOV RDX, R9
; 20D:       FF14251801A052   CALL QWORD PTR [#x52A00118]     ; SB-VM::GENERIC--
; 214:       488BF2           MOV RSI, RDX
; 217: L3:   4883EC10         SUB RSP, 16
; 21B:       488B55F0         MOV RDX, [RBP-16]
; 21F:       488B7DD8         MOV RDI, [RBP-40]
; 223:       B906000000       MOV ECX, 6
; 228:       48892C24         MOV [RSP], RBP
; 22C:       488BEC           MOV RBP, RSP
; 22F:       B8A20D3750       MOV EAX, #x50370DA2             ; #<FDEFN SB-KERNEL:HAIRY-DATA-VECTOR-SET/CHECK-BOUNDS>
; 234:       FFD0             CALL RAX
; 236:       488345E802       ADD QWORD PTR [RBP-24], 2
; 23B: L4:   488B45E8         MOV RAX, [RBP-24]
; 23F:       483B45E0         CMP RAX, [RBP-32]
; 243:       0F8C07FFFFFF     JL L0
; 249:       BA17011050       MOV EDX, #x50100117             ; NIL
; 24E:       488BE5           MOV RSP, RBP
; 251:       F8               CLC
; 252:       5D               POP RBP
; 253:       C3               RET
; 254: L5:   498BF1           MOV RSI, R9
; 257:       EBBE             JMP L3
; 259: L6:   CC5D             INT3 93                         ; OBJECT-NOT-REAL-ERROR
; 25B:       20               BYTE #X20                       ; R8(d)
; 25C: L7:   488B45F0         MOV RAX, [RBP-16]
; 260:       CC53             INT3 83                         ; OBJECT-NOT-VECTOR-ERROR
; 262:       00               BYTE #X00                       ; RAX(d)
; 263:       CC10             INT3 16                         ; Invalid argument count trap
NIL
CL-USER> (disassemble (compile nil (lambda (x)
				                     (declare (type (simple-array fixnum (*)) x)
					                          (optimize speed))
				                     (loop for i below (length x)
					                       do (setf (aref x i) (floor (aref x i) 2))))))
; disassembly for (LAMBDA (X))
; Size: 59 bytes. Origin: #x536AFE8C                          ; (LAMBDA (X))
; 8C:       488B72F9         MOV RSI, [RDX-7]
; 90:       31C9             XOR ECX, ECX
; 92:       EB21             JMP L1
; 94:       660F1F840000000000 NOP
; 9D:       0F1F00           NOP
; A0: L0:   488B5C8A01       MOV RBX, [RDX+RCX*4+1]
; A5:       48D1FB           SAR RBX, 1
; A8:       4883E3FE         AND RBX, -2
; AC:       48895C8A01       MOV [RDX+RCX*4+1], RBX
; B1:       4883C102         ADD RCX, 2
; B5: L1:   4839F1           CMP RCX, RSI
; B8:       7CE6             JL L0
; BA:       BA17011050       MOV EDX, #x50100117              ; NIL
; BF:       488BE5           MOV RSP, RBP
; C2:       F8               CLC
; C3:       5D               POP RBP
; C4:       C3               RET
; C5:       CC10             INT3 16                          ; Invalid argument count trap