Transcript Chapter 8
Chapter 8 – Machine Instructions These are lecture notes to accompany the book SPARC Architecture, Assembly Language Programming, and C, by Richard P. Paul, 2nd edition, 2000. Updated Spring 2014 Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C Decoding Instructions • SPARC Instructions are 32 bits long op 31 30 29 0 • Bits <31:30> specify the “op” field • These first 2 bits indicate how the other bits should be handled. Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C Decoding Instructions • Instructions are classified according to “op” op 31 30 29 0 op Instruction class 00 Branch instructions 01 Call instructions 10 Format Three instructions 11 Format Three instructions Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C Format 1 Instructions 01 31 30 30 bit displacement 29 • Call instruction • The displacement must be word aligned • Address is calculated by right shifting displacement 2 positions Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C 0 Format 2 Instructions • branch 00 a 31 30 cond 29 28 op2 25 24 22 bit immediate 22 21 0 • sethi 00 31 30 rd 29 100 25 24 22 bit immediate 22 21 Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C 0 Branch Instructions • The branch is (or is not) taken based on the “cond” (condition) field. • op2 = 010 means integer condition code cond branch type cond branch type 0000 never 1000 always 0001 if equal to zero 1001 if not equal to zero 0010 if less than or equal to zero 1010 if greater than zero 0011 if less than zero 1011 if greater than or equal to zero 0100 if less or equal, unsigned 1100 if greater, unsigned 0101 if carry set 1101 if carry is clear 0110 if negative 1110 if positive 0111 if overflow is set 1111 if overflow is clear Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C Format 3 Instructions • 2 source registers 1x 31 30 rd 29 op3 25 24 rs1 19 18 0 14 13 12 rs2 5 4 0 • Immediate constant 1x 31 30 rd 29 op3 25 24 rs1 19 18 1 signed 13-bit # 14 13 12 5 4 Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C 0 Format Three Instructions • Not all possible bits patterns are used • op = 10 op3 Instruction op3 Instruction 000000 add 111000 jumpl 000001 and 111001 rett 000010 or 111010 ticc 000011 xor 111011 iflush 000100 sub 111100 save 000101 andn 111101 restore 000110 orn 111110 <unused> 000111 xnor 111111 <unused> 001000 addx See page 235 for a complete list Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C Format Three Instructions • Not all possible bits patterns are used • op = 11 op3 Instruction 000000 ld 000001 ldub 000010 lduh 000011 ldd 000100 st 000101 stb 000110 sth 000111 std 001000 <unused> See page 236 for a complete list Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C Register coding Register Synonyms Register Synonyms Register Synonyms Register Synonyms %g0 %r0 %o0 %r8 %l0 %r16 %i0 %r24 %g1 %r1 %o1 %r9 %l1 %r17 %i1 %r25 %g2 %r2 %o2 %r10 %l2 %r18 %i2 %r26 %g3 %r3 %o3 %r11 %l3 %r19 %i3 %r27 %g4 %r4 %o4 %r12 %l4 %r20 %i4 %r28 %g5 %5 %o5 %r13 %l5 %r21 %i5 %r29 %g6 %r6 %o6 %r14 %l6 %r22 %i6 %r30 %g7 %r7 %o7 %r15 %l7 %r23 %i7 %r31 Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C Load/Store instructions • Load and Store instructions have two references – a register and memory location • rd field – refers to the register component • rs1 field – refers to register for memory address • rs2 field/immediate – refers to offset for memory address Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C Load/Store examples ldub [%o3 + %l2], %o1 rd rs2 rs1 stb %l0, [%o1 + %o2] rd rs1 rs2 stb %o5, [%o1 + 50] rd rs1 immediate Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C Example • Decode the following commands: 0x9de3bfa0 0xd007bfec 0x92102004 0x90020009 0xd027bfec 0x81c7e008 0x81e80000 save %sp, -96, %sp ld [%fp-20], %o0 mov 4, %o1 add %o0, %o1, %o0 st %o0, [%fp-20] ret restore Richard P. Paul, SPARC Architecture, Assembly Language Programming, and C