CS/COE0447 Computer Organization & Assembly LanguageTopics to cover in Chapter 2MIPS Operations/OperandsMIPS ArithmeticMIPS RegistersGeneral-Purpose RegistersInstruction EncodingMIPS Instruction FormatsR-Format InstructionsR-Format ExampleM I P S Reference Data: CORE INSTRUCTION SETR-Format Instructions (REMINDER)Slide 13R-Format ExampleI-Format InstructionsSlide 16I-Format ExampleSlide 18Slide 19Executing the addi instructionLogic InstructionsDealing with ImmediatesLong ImmediatesMemory Transfer InstructionsAddress CalculationMachine Code ExampleMemory ViewMemory OrganizationPeer Instruction: $s3=i, $s4=j, $s5=@APeer InstructionMore on AlignmentShift InstructionsControlControl, cont’dSlide 38Slide 39Instruction FormatInstruction Format, cont’dMIPS Addressing ModesSummaryRegister Usage ConventionStack and Frame Pointers“C Program” Down to “Numbers”To Produce an ExecutableAn AssemblerAn Object FileAssembler DirectivesCode ExampleMacro ExampleLinkerProcedure CallsSPIMHigh-Level Lang. vs. AssemblyInterpreter vs. CompilerCompiler StructureCompiler Structure, cont’dSlide 60Code Example (AST)Code Example (IR)Code Example (CFG)Code Example (CFG), cont’dCode Example (Reg. Alloc.)Compiler ExampleOptimization and Compile TimeBuilding a CompilerSlide 691CS/COE0447Computer Organization & Assembly LanguageChapter 2 Part 12Topics to cover in Chapter 2•MIPS operations and operands•MIPS registers•Memory view•Instruction encoding•Arithmetic operations•Logic operations•Memory transfer operations3MIPS Operations/Operands•“Operation” (instruction)•“Operand”•MIPS operations–Arithmetic operations (integer/floating-point) (add, sub,…)–Logical operations (and, or,…)–Shift operations (shift a certain number of bits to the left or right)–Compare operations (do something if one operand is less than another,…)–Load/stores to transfer data from/to memory–Branch/jump operations–System control operations/coprocessor operations•MIPS operands–General-purpose registers–Fixed registers, e.g., HI/LO registers–Memory location–Immediate value4MIPS Arithmetic•<op> <rdestination> <rsource1> <rsource2>•All arithmetic instructions have 3 operands–Operand order is fixed: destination first–32 registers (page 2 of green card)•Examples–add $t0, $s0, $s2 # $t0 = $s0 + $s2–sub $s0, $t0, $t1 # $s0 = $t0 – $t1 rd rs rt5MIPS Registersr0r1r2r3r4r5r6r7r8r9r10r11r12r13r14r15r16r17r18r19r20r21r22r23r24r25r26r27r28r29r30r31$zero$at$v0$v1$a0$a1$a2$a3$t0$t1$t2$t3$t4$t5$t6$t7HILOPC$s1$s2$s3$s4$s5$s6$s7$t8$t9$k0$k1$gp$sp$fp$ra$s0General-Purpose Registers Special-Purpose Registers32 bits 32 bits 32 bits6General-Purpose Registers•GPR: all can be used as operands in instructions•Still, conventions and limitations exist to keep GPRs from being used arbitrarily–r0, termed $zero, always has a value “0”–r31, termed $ra (return address), is reserved for subroutine call/return–Etc. (we’ll see others later)–Register usage and related software conventions are summarized in “application binary interface” (ABI), which is important when writing system software such as an assembler and a compiler7Instruction Encoding•Instructions are encoded in binary numbers–Assembler translates assembly programs into binary numbers–Machine decodes binary numbers to figure out what the instruction is–MIPS has “fixed” 32-bit instruction encoding•MIPS has several instruction formats–R-format: arithmetic instructions–I-format: transfer/branch/immediate format–J-format: jump instruction format–(FI/FR-format: floating-point instruction format)(later chapter)8MIPS Instruction FormatsName Fields Comments6 bits 5 bits 5 bits 5 bits 5 bits 6 bits All MIPS instructions 32 bitsR-format op rs rt rd shamt funct Arithmetic/logic instruction formatI-format op rs rt address/immediate Transfer, branch, immediate formatJ-format op target address Jump instruction format9R-Format Instructions•Define “fields” of the following number of bits each: 6 + 5 + 5 + 5 + 5 + 6 = 326 5 5 5 65opcode rs rt rd functshamt•For simplicity, each field has a name:For shift instructions:“shift amount”10R-Format Example •MIPS Instruction:add $8,$9,$10Binary number per field representation:Decimal number per field representation:hex representation: decimal representation:On Green Card: Format in column 1, opcodes in column 3(Let’s look and then come back)11M I P S Reference Data: CORE INSTRUCTION SETNAME MNE-MON-ICFOR-MATOPERATION (in Verilog)OPCODE/ FUNCT (hex)Add add R R[rd] = R[rs] + R[rt] (1) 0 / 20hex Add Immediate addi I R[rt] = R[rs] + SignExtImm (1)(2) 8hex Branch On Equal beq I if(R[rs]==R[rt]) PC=PC+4+ BranchAddr (4) 4hex(1) May cause overflow exception(2) SignExtImm = { 16{immediate[15]}, immediate }(3) ZeroExtImm = { 16{1b’0}, immediate }(4) BranchAddr = { 14{immediate[15]}, immediate, 2’b0}Later12R-Format Instructions (REMINDER)•Define “fields” of the following number of bits each: 6 + 5 + 5 + 5 + 5 + 6 = 326 5 5 5 65opcode rs rt rd functshamt•For simplicity, each field has a name:13R-Format Example •MIPS Instruction:add $8,$9,$10Binary number per field representation:Decimal number per field representation:Now let’s fill this in14R-Format Example•MIPS Instruction:add $8,$9,$100 9 10 8 320Binary number per field representation:Decimal number per field representation:hex representation: 012A 4020hexdecimal representation: 19,546,144ten000000 01001 01010 01000 10000000000hex15I-Format Instructions•Define “fields” of the following number of bits each: 6 + 5 + 5 + 16 = 326 5 5 16opcode rs rt immediate•For simplicity, each field has a name:Let’s do an example using addi16M I P S Reference Data: CORE INSTRUCTION SETNAME MNE-MON-ICFOR-MATOPERATION (in Verilog)OPCODE/ FUNCT (hex)Add add R R[rd] = R[rs] + R[rt] (1) 0 / 20hex Add Immediate addi I R[rt] = R[rs] + SignExtImm (1)(2) 8hex Branch On Equal beq I if(R[rs]==R[rt]) PC=PC+4+ BranchAddr (4) 4hex(1) May cause overflow exception(2) SignExtImm = { 16{immediate[15]}, immediate }(3) ZeroExtImm = { 16{1b’0}, immediate }(4) BranchAddr = { 14{immediate[15]}, immediate, 2’b0}17I-Format Example •MIPS Instruction:addi $8,$9,7Binary number per field representation:Decimal number per field representation:18I-Format Example •MIPS Instruction:addi $8,$9,7Binary number per field