深入理解计算机系统_3e 第四章家庭作业（部分） CS:APP3e chapter 4 homework

流水线部分只写了偶数题号的，这几天太浮躁，落下了好多课。。。

4.45

A. 不正确，当REG为%rsp时，这样会压入%rsp - 8而非%rsp

B. 对于 pushq REG:

movq REG, -8(%rsp)
subq $8, %rsp

4.46

A. 不正确，当REG为%rsp是，这样会使得%rsp的值为(%rsp) + 8 而非(%rsp)

B. 对于popq REG:

addq $8, %rsp
movq 8(%rsp), REG

4.47

A. （不知道这题有什么意义。。。）

/* Bubble sort: Array version */
void bubble_p(long *data, long count)
{
  long i, last;
  for(last = count - 1; last > 0; last--)
  {
    for(i = 0; i < last; i++)
    {
      if(*(data+i+1) < *(data+i))
      {
        long t = *(data+i+1);
        *(data+i+1) = *(data+i);
        *(data+i) = t;
      }
    }
  }
}

B. bubblesort.ys:

# Execution begins at address 0 
    .pos 0
    irmovq stack, %rsp      # Set up stack pointer
    call main       # Execute main program
    halt            # Terminate program 

# Array of 8 elements
    .align 8
data:   
    .quad 0xa000a000a000
    .quad 0x0b000b000b00
    .quad 0x00c000c000c0
    .quad 0x000d000d000d

main:   irmovq data,%rdi
    irmovq $4,%rsi
    call bubble_p       # bubble_p(data, 8)
    ret

# void bubble_p(long *data, long count)
# data in %rdi, count in %rsi
bubble_p:   
    rrmovq  %rsi, %r9
    irmovq  $1, %r11
    subq    %r11, %r9
    jmp L2
L4:
    rrmovq  %rdi, %rdx
    rrmovq  %rax, %rcx
    irmovq  $8, %r10
    loop:
         subq   %r11, %rcx
         jl end_loop
         addq   %r10, %rdx
         jmp loop
    end_loop:
    mrmovq  (%rdx), %r8
    rrmovq  %rdx, %rsi
    addq    %r10, %rsi
    mrmovq  (%rsi), %rcx
    rrmovq  %rcx, %r10
    subq    %r8, %r10
    jge L3
    rmmovq  %r8, (%rsi)
    rmmovq  %rcx, (%rdx)
L3:
    addq    %r11, %rax
    jmp L5
L6:
    xorq    %rax, %rax
L5:
    rrmovq  %rax, %r10
    subq    %r9, %r10
    jl  L4
    subq    %r11, %r9
L2:
    jg  L6
    ret

# Stack starts here and grows to lower addresses
    .pos 0x200
stack:

运行结果如下：

可以看到，之前由大到小的数组被排列成了由小到大的顺序。另外，0x01f0和0x01f8处是压入的两个返回地址，不是数组边界溢出。

4.48

书上6-11行为：

if(*(data+i+1) < *(data+i))
      {
        long t = *(data+i+1);
        *(data+i+1) = *(data+i);
        *(data+i) = t;
      }

其对应4.47里面的：

    mrmovq  (%rdx), %r8
    rrmovq  %rdx, %rsi
    addq    %r10, %rsi
    mrmovq  (%rsi), %rcx
    rrmovq  %rcx, %r10
    subq    %r8, %r10
    jge L3
    rmmovq  %r8, (%rsi)
    rmmovq  %rcx, (%rdx)

将其改为条件转移，使用了两个cmovl：

    mrmovq  (%rdx), %r8
    rrmovq  %rdx, %rsi
    addq    %r10, %rsi
    mrmovq  (%rsi), %rcx
    rrmovq  %rcx, %r10
    subq    %r8, %r10

    rrmovq  %rcx, %r10
    cmovl   %r8, %r10
    rmmovq  %r10, (%rsi)
    rrmovq  %r8, %r10
    cmovl   %rcx, %r10
    rmmovq  %r10, (%rdx)

运行结果如下：

4.49

这一题要求只能使用一个cmov指令实现书上的6-11行。我们首先分析一下4.48里面两条cmov冗余的地方：我们使用了两个cmovl ，其实这两个的条件码是一样的。于是我们可以使用一个cmovl 到一个寄存器A，然后在另一个寄存器B用算术运算将其线性关联起来（例如减法）。例如，如果我们要交换[A]，[B]，我们先将[A]存在%r1, -[A]存在%r2，cmovl [B], %r1，addq %r1, %r2，这时如果[A]大于[B]，%r1中为[B]，%r2中为[B]-[A]，否则%r1中为[A]，%r2中为0。随后，我们将%r1赋值给A，[B]-%r2赋值给B即可。

代码如下：

    mrmovq  (%rdx), %r8
    rrmovq  %rdx, %rsi
    addq    %r10, %rsi
    mrmovq  (%rsi), %rcx
    rrmovq  %rcx, %r10
    subq    %r8, %r10

    cmovl   %rcx, %r8
    xorq    %r12, %r12
    mrmovq  (%rdx), %r10
    subq    %r10, %r12
    addq    %r8, %r12
    rmmovq  %r8, (%rdx)
    subq    %r12, %rcx
    rmmovq  %rcx, (%rsi)

这里要注意一下，我这里为了方便使用了%r12寄存器，但是它是一个Callee saved的，所以我们要在bubblesort首尾分别加上pushq %r12和popq %r12 .

运行结果如下：

4.50

代码如下：

# Execution begins at address 0 
    .pos 0
    irmovq stack, %rsp      # Set up stack pointer
    call main       # Execute main program
    halt            # Terminate program 

# Array of 8 elements
    .align 8
vals:   
    .quad 0x000000000000
    .quad 0x000000000000
    .quad 0x000000000000
    .quad 0x000000000000
    .quad 0x000000000000
    .quad 0x000000000000
    .quad 0x000000000000
    .quad 0x000000000000

jump_table:
    .quad L1
    .quad L4
    .quad L2
    .quad L3
    .quad L4
    .quad L2

main:   
    irmovq  vals, %r12

    irmovq  $-1,%rdi
    call switchv        # switchv(-1)
    rmmovq  %rax, (%r12)

    irmovq  $0,%rdi
    call switchv        # switchv(0)
    rmmovq  %rax, 0x8(%r12)

    irmovq  $1,%rdi
    call switchv        # switchv(1)
    rmmovq  %rax, 0x10(%r12)

    irmovq  $2,%rdi
    call switchv        # switchv(2)
    rmmovq  %rax, 0x18(%r12)

    irmovq  $3,%rdi
    call switchv        # switchv(3)
    rmmovq  %rax, 0x20(%r12)

    irmovq  $4,%rdi
    call switchv        # switchv(4)
    rmmovq  %rax, 0x28(%r12)

    irmovq  $5,%rdi
    call switchv        # switchv(5)
    rmmovq  %rax, 0x30(%r12)

    irmovq  $6,%rdi
    call switchv        # switchv(6)
    rmmovq  %rax, 0x38(%r12)

    ret

# long switchv(long idx)
# idx in %rdi
switchv:
    rrmovq %rdi, %r8
    irmovq $5, %r9
    subq %r9, %r8
    jg L4
    andq %rdi, %rdi
    jl L4
    irmovq jump_table, %r8
    irmovq $8, %r9
    irmovq $1, %r10
loop:
    subq %r10, %rdi
    jl endloop
    addq %r9, %r8
    jmp loop
endloop:
    mrmovq (%r8), %r8
    pushq %r8
    ret 

L1:             # case 0
    irmovq 0xaaa, %rax
    ret
L2:             #case 2 or case 5
    irmovq 0xbbb, %rax
    ret
L3:
    irmovq 0xccc, %rax  #case 3
    ret
L4:
    irmovq 0xddd, %rax  #default
    ret

# Stack starts here and grows to lower addresses
    .pos 0x400
stack:

这里要特别注意到原来的stack为0x200，这个时候的代码量会导致代码区段淹没到栈的部分，所以要将stack的位置增高一些。

运行结果如下：

4.51

iaddq V, rB

Fetch:

? icode:ifun <-- M1[PC]

? rA:rB <-- M1[PC+1]

? valC <-- M8[PC+2]

? valP <-- PC+10

Decode:

? valB <-- R[rB]

Execute:

? ValE <-- valB + valC

Memory:

Write back:

? R[rB] <-- valE

PC update:

? PC <-- valP

4.52

由4.51 ，在seq-full.hcl中添加IIADDQ，得到如下代码：

#/* $begin seq-all-hcl */
####################################################################
#  HCL Description of Control for Single Cycle Y86-64 Processor SEQ   #
#  Copyright (C) Randal E. Bryant, David R. O‘Hallaron, 2010       #
####################################################################

## Your task is to implement the iaddq instruction
## The file contains a declaration of the icodes
## for iaddq (IIADDQ)
## Your job is to add the rest of the logic to make it work

####################################################################
#    C Include‘s.  Don‘t alter these                               #
####################################################################

quote ‘#include <stdio.h>‘
quote ‘#include "isa.h"‘
quote ‘#include "sim.h"‘
quote ‘int sim_main(int argc, char *argv[]);‘
quote ‘word_t gen_pc(){return 0;}‘
quote ‘int main(int argc, char *argv[])‘
quote ‘  {plusmode=0;return sim_main(argc,argv);}‘

####################################################################
#    Declarations.  Do not change/remove/delete any of these       #
####################################################################

##### Symbolic representation of Y86-64 Instruction Codes #############
wordsig INOP    ‘I_NOP‘
wordsig IHALT   ‘I_HALT‘
wordsig IRRMOVQ ‘I_RRMOVQ‘
wordsig IIRMOVQ ‘I_IRMOVQ‘
wordsig IRMMOVQ ‘I_RMMOVQ‘
wordsig IMRMOVQ ‘I_MRMOVQ‘
wordsig IOPQ    ‘I_ALU‘
wordsig IJXX    ‘I_JMP‘
wordsig ICALL   ‘I_CALL‘
wordsig IRET    ‘I_RET‘
wordsig IPUSHQ  ‘I_PUSHQ‘
wordsig IPOPQ   ‘I_POPQ‘
# Instruction code for iaddq instruction
wordsig IIADDQ  ‘I_IADDQ‘

##### Symbolic represenations of Y86-64 function codes                  #####
wordsig FNONE    ‘F_NONE‘        # Default function code

##### Symbolic representation of Y86-64 Registers referenced explicitly #####
wordsig RRSP     ‘REG_RSP‘      # Stack Pointer
wordsig RNONE    ‘REG_NONE‘     # Special value indicating "no register"

##### ALU Functions referenced explicitly                            #####
wordsig ALUADD  ‘A_ADD‘     # ALU should add its arguments

##### Possible instruction status values                             #####
wordsig SAOK    ‘STAT_AOK‘  # Normal execution
wordsig SADR    ‘STAT_ADR‘  # Invalid memory address
wordsig SINS    ‘STAT_INS‘  # Invalid instruction
wordsig SHLT    ‘STAT_HLT‘  # Halt instruction encountered

##### Signals that can be referenced by control logic ####################

##### Fetch stage inputs        #####
wordsig pc ‘pc‘             # Program counter
##### Fetch stage computations      #####
wordsig imem_icode ‘imem_icode‘     # icode field from instruction memory
wordsig imem_ifun  ‘imem_ifun‘      # ifun field from instruction memory
wordsig icode     ‘icode‘       # Instruction control code
wordsig ifun      ‘ifun‘        # Instruction function
wordsig rA    ‘ra‘          # rA field from instruction
wordsig rB    ‘rb‘          # rB field from instruction
wordsig valC      ‘valc‘        # Constant from instruction
wordsig valP      ‘valp‘        # Address of following instruction
boolsig imem_error ‘imem_error‘     # Error signal from instruction memory
boolsig instr_valid ‘instr_valid‘   # Is fetched instruction valid?

##### Decode stage computations     #####
wordsig valA    ‘vala‘          # Value from register A port
wordsig valB    ‘valb‘          # Value from register B port

##### Execute stage computations    #####
wordsig valE    ‘vale‘          # Value computed by ALU
boolsig Cnd ‘cond‘          # Branch test

##### Memory stage computations     #####
wordsig valM    ‘valm‘          # Value read from memory
boolsig dmem_error ‘dmem_error‘     # Error signal from data memory


####################################################################
#    Control Signal Definitions.                                   #
####################################################################

################ Fetch Stage     ###################################

# Determine instruction code
word icode = [
    imem_error: INOP;
    1: imem_icode;      # Default: get from instruction memory
];

# Determine instruction function
word ifun = [
    imem_error: FNONE;
    1: imem_ifun;       # Default: get from instruction memory
];

bool instr_valid = icode in 
    { INOP, IHALT, IRRMOVQ, IIRMOVQ, IIADDQ, IRMMOVQ, IMRMOVQ,
           IOPQ, IJXX, ICALL, IRET, IPUSHQ, IPOPQ };

# Does fetched instruction require a regid byte?
bool need_regids =
    icode in { IRRMOVQ, IOPQ, IPUSHQ, IPOPQ, 
             IIRMOVQ, IIADDQ, IRMMOVQ, IMRMOVQ };

# Does fetched instruction require a constant word?
bool need_valC =
    icode in { IIRMOVQ, IIADDQ, IRMMOVQ, IMRMOVQ, IJXX, ICALL };

################ Decode Stage    ###################################

## What register should be used as the A source?
word srcA = [
    icode in { IRRMOVQ, IRMMOVQ, IOPQ, IPUSHQ  } : rA;
    icode in { IPOPQ, IRET } : RRSP;
    1 : RNONE; # Don‘t need register
];

## What register should be used as the B source?
word srcB = [
    icode in { IOPQ, IRMMOVQ, IMRMOVQ, IIADDQ  } : rB;
    icode in { IPUSHQ, IPOPQ, ICALL, IRET } : RRSP;
    1 : RNONE;  # Don‘t need register
];

## What register should be used as the E destination?
word dstE = [
    icode in { IRRMOVQ } && Cnd : rB;
    icode in { IIRMOVQ, IOPQ, IIADDQ} : rB;
    icode in { IPUSHQ, IPOPQ, ICALL, IRET } : RRSP;
    1 : RNONE;  # Don‘t write any register
];

## What register should be used as the M destination?
word dstM = [
    icode in { IMRMOVQ, IPOPQ } : rA;
    1 : RNONE;  # Don‘t write any register
];

################ Execute Stage   ###################################

## Select input A to ALU
word aluA = [
    icode in { IRRMOVQ, IOPQ } : valA;
    icode in { IIRMOVQ, IRMMOVQ, IMRMOVQ, IIADDQ } : valC;
    icode in { ICALL, IPUSHQ } : -8;
    icode in { IRET, IPOPQ } : 8;
    # Other instructions don‘t need ALU
];

## Select input B to ALU
word aluB = [
    icode in { IRMMOVQ, IMRMOVQ, IOPQ, ICALL, 
              IPUSHQ, IRET, IPOPQ, IIADDQ } : valB;
    icode in { IRRMOVQ, IIRMOVQ } : 0;
    # Other instructions don‘t need ALU
];

## Set the ALU function
word alufun = [
    icode == IOPQ : ifun;
    1 : ALUADD;
];

## Should the condition codes be updated?
bool set_cc = icode in { IOPQ, IIADDQ };

################ Memory Stage    ###################################

## Set read control signal
bool mem_read = icode in { IMRMOVQ, IPOPQ, IRET };

## Set write control signal
bool mem_write = icode in { IRMMOVQ, IPUSHQ, ICALL };

## Select memory address
word mem_addr = [
    icode in { IRMMOVQ, IPUSHQ, ICALL, IMRMOVQ } : valE;
    icode in { IPOPQ, IRET } : valA;
    # Other instructions don‘t need address
];

## Select memory input data
word mem_data = [
    # Value from register
    icode in { IRMMOVQ, IPUSHQ } : valA;
    # Return PC
    icode == ICALL : valP;
    # Default: Don‘t write anything
];

## Determine instruction status
word Stat = [
    imem_error || dmem_error : SADR;
    !instr_valid: SINS;
    icode == IHALT : SHLT;
    1 : SAOK;
];

################ Program Counter Update ############################

## What address should instruction be fetched at

word new_pc = [
    # Call.  Use instruction constant
    icode == ICALL : valC;
    # Taken branch.  Use instruction constant
    icode == IJXX && Cnd : valC;
    # Completion of RET instruction.  Use value from stack
    icode == IRET : valM;
    # Default: Use incremented PC
    1 : valP;
];
#/* $end seq-all-hcl */

运行结果如下：

4.54

pipe-full.hcl:

#/* $begin pipe-all-hcl */
####################################################################
#    HCL Description of Control for Pipelined Y86-64 Processor     #
#    Copyright (C) Randal E. Bryant, David R. O‘Hallaron, 2014     #
####################################################################

## Your task is to implement the iaddq instruction
## The file contains a declaration of the icodes
## for iaddq (IIADDQ)
## Your job is to add the rest of the logic to make it work

####################################################################
#    C Include‘s.  Don‘t alter these                               #
####################################################################

quote ‘#include <stdio.h>‘
quote ‘#include "isa.h"‘
quote ‘#include "pipeline.h"‘
quote ‘#include "stages.h"‘
quote ‘#include "sim.h"‘
quote ‘int sim_main(int argc, char *argv[]);‘
quote ‘int main(int argc, char *argv[]){return sim_main(argc,argv);}‘

####################################################################
#    Declarations.  Do not change/remove/delete any of these       #
####################################################################

##### Symbolic representation of Y86-64 Instruction Codes #############
wordsig INOP    ‘I_NOP‘
wordsig IHALT   ‘I_HALT‘
wordsig IRRMOVQ ‘I_RRMOVQ‘
wordsig IIRMOVQ ‘I_IRMOVQ‘
wordsig IRMMOVQ ‘I_RMMOVQ‘
wordsig IMRMOVQ ‘I_MRMOVQ‘
wordsig IOPQ    ‘I_ALU‘
wordsig IJXX    ‘I_JMP‘
wordsig ICALL   ‘I_CALL‘
wordsig IRET    ‘I_RET‘
wordsig IPUSHQ  ‘I_PUSHQ‘
wordsig IPOPQ   ‘I_POPQ‘
# Instruction code for iaddq instruction
wordsig IIADDQ  ‘I_IADDQ‘

##### Symbolic represenations of Y86-64 function codes            #####
wordsig FNONE    ‘F_NONE‘        # Default function code

##### Symbolic representation of Y86-64 Registers referenced      #####
wordsig RRSP     ‘REG_RSP‘           # Stack Pointer
wordsig RNONE    ‘REG_NONE‘          # Special value indicating "no register"

##### ALU Functions referenced explicitly ##########################
wordsig ALUADD  ‘A_ADD‘          # ALU should add its arguments

##### Possible instruction status values                       #####
wordsig SBUB    ‘STAT_BUB‘  # Bubble in stage
wordsig SAOK    ‘STAT_AOK‘  # Normal execution
wordsig SADR    ‘STAT_ADR‘  # Invalid memory address
wordsig SINS    ‘STAT_INS‘  # Invalid instruction
wordsig SHLT    ‘STAT_HLT‘  # Halt instruction encountered

##### Signals that can be referenced by control logic ##############

##### Pipeline Register F ##########################################

wordsig F_predPC ‘pc_curr->pc‘       # Predicted value of PC

##### Intermediate Values in Fetch Stage ###########################

wordsig imem_icode  ‘imem_icode‘      # icode field from instruction memory
wordsig imem_ifun   ‘imem_ifun‘       # ifun  field from instruction memory
wordsig f_icode ‘if_id_next->icode‘  # (Possibly modified) instruction code
wordsig f_ifun  ‘if_id_next->ifun‘   # Fetched instruction function
wordsig f_valC  ‘if_id_next->valc‘   # Constant data of fetched instruction
wordsig f_valP  ‘if_id_next->valp‘   # Address of following instruction
boolsig imem_error ‘imem_error‘      # Error signal from instruction memory
boolsig instr_valid ‘instr_valid‘    # Is fetched instruction valid?

##### Pipeline Register D ##########################################
wordsig D_icode ‘if_id_curr->icode‘   # Instruction code
wordsig D_rA ‘if_id_curr->ra‘        # rA field from instruction
wordsig D_rB ‘if_id_curr->rb‘        # rB field from instruction
wordsig D_valP ‘if_id_curr->valp‘     # Incremented PC

##### Intermediate Values in Decode Stage  #########################

wordsig d_srcA   ‘id_ex_next->srca‘  # srcA from decoded instruction
wordsig d_srcB   ‘id_ex_next->srcb‘  # srcB from decoded instruction
wordsig d_rvalA ‘d_regvala‘      # valA read from register file
wordsig d_rvalB ‘d_regvalb‘      # valB read from register file

##### Pipeline Register E ##########################################
wordsig E_icode ‘id_ex_curr->icode‘   # Instruction code
wordsig E_ifun  ‘id_ex_curr->ifun‘    # Instruction function
wordsig E_valC  ‘id_ex_curr->valc‘    # Constant data
wordsig E_srcA  ‘id_ex_curr->srca‘    # Source A register ID
wordsig E_valA  ‘id_ex_curr->vala‘    # Source A value
wordsig E_srcB  ‘id_ex_curr->srcb‘    # Source B register ID
wordsig E_valB  ‘id_ex_curr->valb‘    # Source B value
wordsig E_dstE ‘id_ex_curr->deste‘    # Destination E register ID
wordsig E_dstM ‘id_ex_curr->destm‘    # Destination M register ID

##### Intermediate Values in Execute Stage #########################
wordsig e_valE ‘ex_mem_next->vale‘  # valE generated by ALU
boolsig e_Cnd ‘ex_mem_next->takebranch‘ # Does condition hold?
wordsig e_dstE ‘ex_mem_next->deste‘      # dstE (possibly modified to be RNONE)

##### Pipeline Register M                  #########################
wordsig M_stat ‘ex_mem_curr->status‘     # Instruction status
wordsig M_icode ‘ex_mem_curr->icode‘    # Instruction code
wordsig M_ifun  ‘ex_mem_curr->ifun‘ # Instruction function
wordsig M_valA  ‘ex_mem_curr->vala‘      # Source A value
wordsig M_dstE ‘ex_mem_curr->deste‘ # Destination E register ID
wordsig M_valE  ‘ex_mem_curr->vale‘      # ALU E value
wordsig M_dstM ‘ex_mem_curr->destm‘ # Destination M register ID
boolsig M_Cnd ‘ex_mem_curr->takebranch‘ # Condition flag
boolsig dmem_error ‘dmem_error‘         # Error signal from instruction memory

##### Intermediate Values in Memory Stage ##########################
wordsig m_valM ‘mem_wb_next->valm‘  # valM generated by memory
wordsig m_stat ‘mem_wb_next->status‘    # stat (possibly modified to be SADR)

##### Pipeline Register W ##########################################
wordsig W_stat ‘mem_wb_curr->status‘     # Instruction status
wordsig W_icode ‘mem_wb_curr->icode‘    # Instruction code
wordsig W_dstE ‘mem_wb_curr->deste‘ # Destination E register ID
wordsig W_valE  ‘mem_wb_curr->vale‘      # ALU E value
wordsig W_dstM ‘mem_wb_curr->destm‘ # Destination M register ID
wordsig W_valM  ‘mem_wb_curr->valm‘ # Memory M value

####################################################################
#    Control Signal Definitions.                                   #
####################################################################

################ Fetch Stage     ###################################

## What address should instruction be fetched at
word f_pc = [
    # Mispredicted branch.  Fetch at incremented PC
    M_icode == IJXX && !M_Cnd : M_valA;
    # Completion of RET instruction
    W_icode == IRET : W_valM;
    # Default: Use predicted value of PC
    1 : F_predPC;
];

## Determine icode of fetched instruction
word f_icode = [
    imem_error : INOP;
    1: imem_icode;
];

# Determine ifun
word f_ifun = [
    imem_error : FNONE;
    1: imem_ifun;
];

# Is instruction valid?
bool instr_valid = f_icode in 
    { INOP, IHALT, IRRMOVQ, IIRMOVQ, IRMMOVQ, IMRMOVQ,
      IOPQ, IJXX, ICALL, IRET, IPUSHQ, IPOPQ, IIADDQ };

# Determine status code for fetched instruction
word f_stat = [
    imem_error: SADR;
    !instr_valid : SINS;
    f_icode == IHALT : SHLT;
    1 : SAOK;
];

# Does fetched instruction require a regid byte?
bool need_regids =
    f_icode in { IRRMOVQ, IOPQ, IPUSHQ, IPOPQ, 
             IIRMOVQ, IRMMOVQ, IMRMOVQ, IIADDQ };

# Does fetched instruction require a constant word?
bool need_valC =
    f_icode in { IIRMOVQ, IRMMOVQ, IMRMOVQ, IJXX, ICALL, IIADDQ };

# Predict next value of PC
word f_predPC = [
    f_icode in { IJXX, ICALL } : f_valC;
    1 : f_valP;
];

################ Decode Stage ######################################


## What register should be used as the A source?
word d_srcA = [
    D_icode in { IRRMOVQ, IRMMOVQ, IOPQ, IPUSHQ  } : D_rA;
    D_icode in { IPOPQ, IRET } : RRSP;
    1 : RNONE; # Don‘t need register
];

## What register should be used as the B source?
word d_srcB = [
    D_icode in { IOPQ, IRMMOVQ, IMRMOVQ, IIADDQ } : D_rB;
    D_icode in { IPUSHQ, IPOPQ, ICALL, IRET } : RRSP;
    1 : RNONE;  # Don‘t need register
];

## What register should be used as the E destination?
word d_dstE = [
    D_icode in { IRRMOVQ, IIRMOVQ, IOPQ, IIADDQ} : D_rB;
    D_icode in { IPUSHQ, IPOPQ, ICALL, IRET } : RRSP;
    1 : RNONE;  # Don‘t write any register
];

## What register should be used as the M destination?
word d_dstM = [
    D_icode in { IMRMOVQ, IPOPQ } : D_rA;
    1 : RNONE;  # Don‘t write any register
];

## What should be the A value?
## Forward into decode stage for valA
word d_valA = [
    D_icode in { ICALL, IJXX } : D_valP; # Use incremented PC
    d_srcA == e_dstE : e_valE;    # Forward valE from execute
    d_srcA == M_dstM : m_valM;    # Forward valM from memory
    d_srcA == M_dstE : M_valE;    # Forward valE from memory
    d_srcA == W_dstM : W_valM;    # Forward valM from write back
    d_srcA == W_dstE : W_valE;    # Forward valE from write back
    1 : d_rvalA;  # Use value read from register file
];

word d_valB = [
    d_srcB == e_dstE : e_valE;    # Forward valE from execute
    d_srcB == M_dstM : m_valM;    # Forward valM from memory
    d_srcB == M_dstE : M_valE;    # Forward valE from memory
    d_srcB == W_dstM : W_valM;    # Forward valM from write back
    d_srcB == W_dstE : W_valE;    # Forward valE from write back
    1 : d_rvalB;  # Use value read from register file
];

################ Execute Stage #####################################

## Select input A to ALU
word aluA = [
    E_icode in { IRRMOVQ, IOPQ } : E_valA;
    E_icode in { IIRMOVQ, IRMMOVQ, IMRMOVQ, IIADDQ } : E_valC;
    E_icode in { ICALL, IPUSHQ } : -8;
    E_icode in { IRET, IPOPQ } : 8;
    # Other instructions don‘t need ALU
];

## Select input B to ALU
word aluB = [
    E_icode in { IRMMOVQ, IMRMOVQ, IOPQ, ICALL, 
             IPUSHQ, IRET, IPOPQ, IIADDQ } : E_valB;
    E_icode in { IRRMOVQ, IIRMOVQ } : 0;
    # Other instructions don‘t need ALU
];

## Set the ALU function
word alufun = [
    E_icode == IOPQ : E_ifun;
    1 : ALUADD;
];

## Should the condition codes be updated?
bool set_cc = (E_icode == IOPQ || E_icode == IIADDQ) &&
    # State changes only during normal operation
    !m_stat in { SADR, SINS, SHLT } && !W_stat in { SADR, SINS, SHLT };

## Generate valA in execute stage
word e_valA = E_valA;    # Pass valA through stage

## Set dstE to RNONE in event of not-taken conditional move
word e_dstE = [
    E_icode == IRRMOVQ && !e_Cnd : RNONE;
    1 : E_dstE;
];

################ Memory Stage ######################################

## Select memory address
word mem_addr = [
    M_icode in { IRMMOVQ, IPUSHQ, ICALL, IMRMOVQ } : M_valE;
    M_icode in { IPOPQ, IRET } : M_valA;
    # Other instructions don‘t need address
];

## Set read control signal
bool mem_read = M_icode in { IMRMOVQ, IPOPQ, IRET };

## Set write control signal
bool mem_write = M_icode in { IRMMOVQ, IPUSHQ, ICALL };

#/* $begin pipe-m_stat-hcl */
## Update the status
word m_stat = [
    dmem_error : SADR;
    1 : M_stat;
];
#/* $end pipe-m_stat-hcl */

## Set E port register ID
word w_dstE = W_dstE;

## Set E port value
word w_valE = W_valE;

## Set M port register ID
word w_dstM = W_dstM;

## Set M port value
word w_valM = W_valM;

## Update processor status
word Stat = [
    W_stat == SBUB : SAOK;
    1 : W_stat;
];

################ Pipeline Register Control #########################

# Should I stall or inject a bubble into Pipeline Register F?
# At most one of these can be true.
bool F_bubble = 0;
bool F_stall =
    # Conditions for a load/use hazard
    E_icode in { IMRMOVQ, IPOPQ } &&
     E_dstM in { d_srcA, d_srcB } ||
    # Stalling at fetch while ret passes through pipeline
    IRET in { D_icode, E_icode, M_icode };

# Should I stall or inject a bubble into Pipeline Register D?
# At most one of these can be true.
bool D_stall = 
    # Conditions for a load/use hazard
    E_icode in { IMRMOVQ, IPOPQ } &&
     E_dstM in { d_srcA, d_srcB };

bool D_bubble =
    # Mispredicted branch
    (E_icode == IJXX && !e_Cnd) ||
    # Stalling at fetch while ret passes through pipeline
    # but not condition for a load/use hazard
    !(E_icode in { IMRMOVQ, IPOPQ } && E_dstM in { d_srcA, d_srcB }) &&
      IRET in { D_icode, E_icode, M_icode };

# Should I stall or inject a bubble into Pipeline Register E?
# At most one of these can be true.
bool E_stall = 0;
bool E_bubble =
    # Mispredicted branch
    (E_icode == IJXX && !e_Cnd) ||
    # Conditions for a load/use hazard
    E_icode in { IMRMOVQ, IPOPQ } &&
     E_dstM in { d_srcA, d_srcB};

# Should I stall or inject a bubble into Pipeline Register M?
# At most one of these can be true.
bool M_stall = 0;
# Start injecting bubbles as soon as exception passes through memory stage
bool M_bubble = m_stat in { SADR, SINS, SHLT } || W_stat in { SADR, SINS, SHLT };

# Should I stall or inject a bubble into Pipeline Register W?
bool W_stall = W_stat in { SADR, SINS, SHLT };
bool W_bubble = 0;
#/* $end pipe-all-hcl */

运行结果如下：

4.56

pipe-btfnt.hcl:

#/* $begin pipe-all-hcl */
####################################################################
#    HCL Description of Control for Pipelined Y86-64 Processor     #
#    Copyright (C) Randal E. Bryant, David R. O‘Hallaron, 2014     #
####################################################################

## Your task is to modify the design so that conditional branches are
## predicted as being taken when backward and not-taken when forward
## The code here is nearly identical to that for the normal pipeline.  
## Comments starting with keyword "BBTFNT" have been added at places
## relevant to the exercise.

####################################################################
#    C Include‘s.  Don‘t alter these                               #
####################################################################

quote ‘#include <stdio.h>‘
quote ‘#include "isa.h"‘
quote ‘#include "pipeline.h"‘
quote ‘#include "stages.h"‘
quote ‘#include "sim.h"‘
quote ‘int sim_main(int argc, char *argv[]);‘
quote ‘int main(int argc, char *argv[]){return sim_main(argc,argv);}‘

####################################################################
#    Declarations.  Do not change/remove/delete any of these       #
####################################################################

##### Symbolic representation of Y86-64 Instruction Codes #############
wordsig INOP    ‘I_NOP‘
wordsig IHALT   ‘I_HALT‘
wordsig IRRMOVQ ‘I_RRMOVQ‘
wordsig IIRMOVQ ‘I_IRMOVQ‘
wordsig IRMMOVQ ‘I_RMMOVQ‘
wordsig IMRMOVQ ‘I_MRMOVQ‘
wordsig IOPQ    ‘I_ALU‘
wordsig IJXX    ‘I_JMP‘
wordsig ICALL   ‘I_CALL‘
wordsig IRET    ‘I_RET‘
wordsig IPUSHQ  ‘I_PUSHQ‘
wordsig IPOPQ   ‘I_POPQ‘

##### Symbolic represenations of Y86-64 function codes            #####
wordsig FNONE    ‘F_NONE‘        # Default function code

##### Symbolic representation of Y86-64 Registers referenced      #####
wordsig RRSP     ‘REG_RSP‘           # Stack Pointer
wordsig RNONE    ‘REG_NONE‘          # Special value indicating "no register"

##### ALU Functions referenced explicitly ##########################
wordsig ALUADD  ‘A_ADD‘          # ALU should add its arguments
## BBTFNT: For modified branch prediction, need to distinguish
## conditional vs. unconditional branches
##### Jump conditions referenced explicitly
wordsig UNCOND ‘C_YES‘               # Unconditional transfer

##### Possible instruction status values                       #####
wordsig SBUB    ‘STAT_BUB‘  # Bubble in stage
wordsig SAOK    ‘STAT_AOK‘  # Normal execution
wordsig SADR    ‘STAT_ADR‘  # Invalid memory address
wordsig SINS    ‘STAT_INS‘  # Invalid instruction
wordsig SHLT    ‘STAT_HLT‘  # Halt instruction encountered

##### Signals that can be referenced by control logic ##############

##### Pipeline Register F ##########################################

wordsig F_predPC ‘pc_curr->pc‘       # Predicted value of PC

##### Intermediate Values in Fetch Stage ###########################

wordsig imem_icode  ‘imem_icode‘      # icode field from instruction memory
wordsig imem_ifun   ‘imem_ifun‘       # ifun  field from instruction memory
wordsig f_icode ‘if_id_next->icode‘  # (Possibly modified) instruction code
wordsig f_ifun  ‘if_id_next->ifun‘   # Fetched instruction function
wordsig f_valC  ‘if_id_next->valc‘   # Constant data of fetched instruction
wordsig f_valP  ‘if_id_next->valp‘   # Address of following instruction
boolsig imem_error ‘imem_error‘      # Error signal from instruction memory
boolsig instr_valid ‘instr_valid‘    # Is fetched instruction valid?

##### Pipeline Register D ##########################################
wordsig D_icode ‘if_id_curr->icode‘   # Instruction code
wordsig D_rA ‘if_id_curr->ra‘        # rA field from instruction
wordsig D_rB ‘if_id_curr->rb‘        # rB field from instruction
wordsig D_valP ‘if_id_curr->valp‘     # Incremented PC

##### Intermediate Values in Decode Stage  #########################

wordsig d_srcA   ‘id_ex_next->srca‘  # srcA from decoded instruction
wordsig d_srcB   ‘id_ex_next->srcb‘  # srcB from decoded instruction
wordsig d_rvalA ‘d_regvala‘      # valA read from register file
wordsig d_rvalB ‘d_regvalb‘      # valB read from register file

##### Pipeline Register E ##########################################
wordsig E_icode ‘id_ex_curr->icode‘   # Instruction code
wordsig E_ifun  ‘id_ex_curr->ifun‘    # Instruction function
wordsig E_valC  ‘id_ex_curr->valc‘    # Constant data
wordsig E_srcA  ‘id_ex_curr->srca‘    # Source A register ID
wordsig E_valA  ‘id_ex_curr->vala‘    # Source A value
wordsig E_srcB  ‘id_ex_curr->srcb‘    # Source B register ID
wordsig E_valB  ‘id_ex_curr->valb‘    # Source B value
wordsig E_dstE ‘id_ex_curr->deste‘    # Destination E register ID
wordsig E_dstM ‘id_ex_curr->destm‘    # Destination M register ID

##### Intermediate Values in Execute Stage #########################
wordsig e_valE ‘ex_mem_next->vale‘  # valE generated by ALU
boolsig e_Cnd ‘ex_mem_next->takebranch‘ # Does condition hold?
wordsig e_dstE ‘ex_mem_next->deste‘      # dstE (possibly modified to be RNONE)

##### Pipeline Register M                  #########################
wordsig M_stat ‘ex_mem_curr->status‘     # Instruction status
wordsig M_icode ‘ex_mem_curr->icode‘    # Instruction code
wordsig M_ifun  ‘ex_mem_curr->ifun‘ # Instruction function
wordsig M_valA  ‘ex_mem_curr->vala‘      # Source A value
wordsig M_dstE ‘ex_mem_curr->deste‘ # Destination E register ID
wordsig M_valE  ‘ex_mem_curr->vale‘      # ALU E value
wordsig M_dstM ‘ex_mem_curr->destm‘ # Destination M register ID
boolsig M_Cnd ‘ex_mem_curr->takebranch‘ # Condition flag
boolsig dmem_error ‘dmem_error‘         # Error signal from instruction memory

##### Intermediate Values in Memory Stage ##########################
wordsig m_valM ‘mem_wb_next->valm‘  # valM generated by memory
wordsig m_stat ‘mem_wb_next->status‘    # stat (possibly modified to be SADR)

##### Pipeline Register W ##########################################
wordsig W_stat ‘mem_wb_curr->status‘     # Instruction status
wordsig W_icode ‘mem_wb_curr->icode‘    # Instruction code
wordsig W_dstE ‘mem_wb_curr->deste‘ # Destination E register ID
wordsig W_valE  ‘mem_wb_curr->vale‘      # ALU E value
wordsig W_dstM ‘mem_wb_curr->destm‘ # Destination M register ID
wordsig W_valM  ‘mem_wb_curr->valm‘ # Memory M value

####################################################################
#    Control Signal Definitions.                                   #
####################################################################

################ Fetch Stage     ###################################

## What address should instruction be fetched at
word f_pc = [
    # Mispredicted branch.  Fetch at incremented PC
    # backward
    M_icode == IJXX && M_ifun != UNCOND && M_valE < M_valA && !M_Cnd : M_valA;
    # forward
    M_icode == IJXX && M_ifun != UNCOND && M_valE >= M_valA && M_Cnd : M_valE;
    # Completion of RET instruction
    W_icode == IRET : W_valM;
    # Default: Use predicted value of PC
    1 : F_predPC;
];

## Determine icode of fetched instruction
word f_icode = [
    imem_error : INOP;
    1: imem_icode;
];

# Determine ifun
word f_ifun = [
    imem_error : FNONE;
    1: imem_ifun;
];

# Is instruction valid?
bool instr_valid = f_icode in 
    { INOP, IHALT, IRRMOVQ, IIRMOVQ, IRMMOVQ, IMRMOVQ,
      IOPQ, IJXX, ICALL, IRET, IPUSHQ, IPOPQ };

# Determine status code for fetched instruction
word f_stat = [
    imem_error: SADR;
    !instr_valid : SINS;
    f_icode == IHALT : SHLT;
    1 : SAOK;
];

# Does fetched instruction require a regid byte?
bool need_regids =
    f_icode in { IRRMOVQ, IOPQ, IPUSHQ, IPOPQ, 
             IIRMOVQ, IRMMOVQ, IMRMOVQ };

# Does fetched instruction require a constant word?
bool need_valC =
    f_icode in { IIRMOVQ, IRMMOVQ, IMRMOVQ, IJXX, ICALL };

# Predict next value of PC
word f_predPC = [
    # BBTFNT: This is where you‘ll change the branch prediction rule
    f_icode == IJXX && f_ifun != UNCOND && f_valC < f_valP : f_valC;
    f_icode == IJXX && f_ifun != UNCOND && f_valC >= f_valP : f_valP;
    f_icode in { IJXX, ICALL } : f_valC;
    1 : f_valP;
];

################ Decode Stage ######################################


## What register should be used as the A source?
word d_srcA = [
    D_icode in { IRRMOVQ, IRMMOVQ, IOPQ, IPUSHQ  } : D_rA;
    D_icode in { IPOPQ, IRET } : RRSP;
    1 : RNONE; # Don‘t need register
];

## What register should be used as the B source?
word d_srcB = [
    D_icode in { IOPQ, IRMMOVQ, IMRMOVQ  } : D_rB;
    D_icode in { IPUSHQ, IPOPQ, ICALL, IRET } : RRSP;
    1 : RNONE;  # Don‘t need register
];

## What register should be used as the E destination?
word d_dstE = [
    D_icode in { IRRMOVQ, IIRMOVQ, IOPQ} : D_rB;
    D_icode in { IPUSHQ, IPOPQ, ICALL, IRET } : RRSP;
    1 : RNONE;  # Don‘t write any register
];

## What register should be used as the M destination?
word d_dstM = [
    D_icode in { IMRMOVQ, IPOPQ } : D_rA;
    1 : RNONE;  # Don‘t write any register
];

## What should be the A value?
## Forward into decode stage for valA
word d_valA = [
    D_icode in { ICALL, IJXX } : D_valP; # Use incremented PC
    d_srcA == e_dstE : e_valE;    # Forward valE from execute
    d_srcA == M_dstM : m_valM;    # Forward valM from memory
    d_srcA == M_dstE : M_valE;    # Forward valE from memory
    d_srcA == W_dstM : W_valM;    # Forward valM from write back
    d_srcA == W_dstE : W_valE;    # Forward valE from write back
    1 : d_rvalA;  # Use value read from register file
];

word d_valB = [
    d_srcB == e_dstE : e_valE;    # Forward valE from execute
    d_srcB == M_dstM : m_valM;    # Forward valM from memory
    d_srcB == M_dstE : M_valE;    # Forward valE from memory
    d_srcB == W_dstM : W_valM;    # Forward valM from write back
    d_srcB == W_dstE : W_valE;    # Forward valE from write back
    1 : d_rvalB;  # Use value read from register file
];

################ Execute Stage #####################################

# BBTFNT: When some branches are predicted as not-taken, you need some
# way to get valC into pipeline register M, so that
# you can correct for a mispredicted branch.

## Select input A to ALU
word aluA = [
    E_icode in { IRRMOVQ, IOPQ } : E_valA;
    E_icode in { IIRMOVQ, IRMMOVQ, IMRMOVQ, IJXX } : E_valC;
    E_icode in { ICALL, IPUSHQ } : -8;
    E_icode in { IRET, IPOPQ } : 8;
    # Other instructions don‘t need ALU
];

## Select input B to ALU
word aluB = [
    E_icode in { IRMMOVQ, IMRMOVQ, IOPQ, ICALL, 
             IPUSHQ, IRET, IPOPQ } : E_valB;
    E_icode in { IRRMOVQ, IIRMOVQ, IJXX } : 0;
    # Other instructions don‘t need ALU
];

## Set the ALU function
word alufun = [
    E_icode == IOPQ : E_ifun;
    1 : ALUADD;
];

## Should the condition codes be updated?
bool set_cc = E_icode == IOPQ &&
    # State changes only during normal operation
    !m_stat in { SADR, SINS, SHLT } && !W_stat in { SADR, SINS, SHLT };

## Generate valA in execute stage
word e_valA = E_valA;    # Pass valA through stage

## Set dstE to RNONE in event of not-taken conditional move
word e_dstE = [
    E_icode == IRRMOVQ && !e_Cnd : RNONE;
    1 : E_dstE;
];

################ Memory Stage ######################################

## Select memory address
word mem_addr = [
    M_icode in { IRMMOVQ, IPUSHQ, ICALL, IMRMOVQ } : M_valE;
    M_icode in { IPOPQ, IRET } : M_valA;
    # Other instructions don‘t need address
];

## Set read control signal
bool mem_read = M_icode in { IMRMOVQ, IPOPQ, IRET };

## Set write control signal
bool mem_write = M_icode in { IRMMOVQ, IPUSHQ, ICALL };

#/* $begin pipe-m_stat-hcl */
## Update the status
word m_stat = [
    dmem_error : SADR;
    1 : M_stat;
];
#/* $end pipe-m_stat-hcl */

## Set E port register ID
word w_dstE = W_dstE;

## Set E port value
word w_valE = W_valE;

## Set M port register ID
word w_dstM = W_dstM;

## Set M port value
word w_valM = W_valM;

## Update processor status
word Stat = [
    W_stat == SBUB : SAOK;
    1 : W_stat;
];

################ Pipeline Register Control #########################

# Should I stall or inject a bubble into Pipeline Register F?
# At most one of these can be true.
bool F_bubble = 0;
bool F_stall =
    # Conditions for a load/use hazard
    E_icode in { IMRMOVQ, IPOPQ } &&
     E_dstM in { d_srcA, d_srcB } ||
    # Stalling at fetch while ret passes through pipeline
    IRET in { D_icode, E_icode, M_icode };

# Should I stall or inject a bubble into Pipeline Register D?
# At most one of these can be true.
bool D_stall = 
    # Conditions for a load/use hazard
    E_icode in { IMRMOVQ, IPOPQ } &&
     E_dstM in { d_srcA, d_srcB };

bool D_bubble =
    # Mispredicted branch: backward taken error or forward not-taken error
    (
    (E_icode == IJXX && E_ifun != UNCOND && E_valC < E_valA && !e_Cnd) ||
    (E_icode == IJXX && E_ifun != UNCOND && E_valC >= E_valA && e_Cnd)
    ) ||
    # BBTFNT: This condition will change
    # Stalling at fetch while ret passes through pipeline
    # but not condition for a load/use hazard
    !(E_icode in { IMRMOVQ, IPOPQ } && E_dstM in { d_srcA, d_srcB }) &&
      IRET in { D_icode, E_icode, M_icode };

# Should I stall or inject a bubble into Pipeline Register E?
# At most one of these can be true.
bool E_stall = 0;
bool E_bubble =
    # Mispredicted branch: backward taken error or forward not-taken error
    (
    (E_icode == IJXX && E_ifun != UNCOND && E_valC < E_valA && !e_Cnd) ||
    (E_icode == IJXX && E_ifun != UNCOND && E_valC >= E_valA && e_Cnd)
    ) ||
    # BBTFNT: This condition will change
    # Conditions for a load/use hazard
    E_icode in { IMRMOVQ, IPOPQ } &&
     E_dstM in { d_srcA, d_srcB};

# Should I stall or inject a bubble into Pipeline Register M?
# At most one of these can be true.
bool M_stall = 0;
# Start injecting bubbles as soon as exception passes through memory stage
bool M_bubble = m_stat in { SADR, SINS, SHLT } || W_stat in { SADR, SINS, SHLT };

# Should I stall or inject a bubble into Pipeline Register W?
bool W_stall = W_stat in { SADR, SINS, SHLT };
bool W_bubble = 0;
#/* $end pipe-all-hcl */

运行结果如下：

4.58

这个题巴拉巴拉说了一大堆就是要处理popq的情况。其中有一个方法就是使用4.46里面的替换策略，将popq动态替换为（这里我们先实现为iaddq ）：

iaddq $8, %rsp
mrmovq 8(%rsp), REG

处理iaddq后，在第二次fetch的时候PC不变，但是icode变为一个特殊的编码（书上说的是IPOP2），以此来识别进行mrmovq 8(%rsp), REG的操作。书上把要改变的地方用“1W”标出来了。

pipi-1w.hcl:

#/* $begin pipe-all-hcl */
####################################################################
#    HCL Description of Control for Pipelined Y86-64 Processor     #
#    Copyright (C) Randal E. Bryant, David R. O‘Hallaron, 2014     #
####################################################################

## Your task is to modify the design so that on any cycle, only
## one of the two possible (valE and valM) register writes will occur.
## This requires special handling of the popq instruction.
## Overall strategy:  IPOPQ passes through pipe, 
## treated as stack pointer increment, but not incrementing the PC
## On refetch, modify fetched icode to indicate an instruction "IPOP2",
## which reads from memory.
## This requires modifying the definition of f_icode
## and lots of other changes.  Relevant positions to change
## are indicated by comments starting with keyword "1W".

####################################################################
#    C Include‘s.  Don‘t alter these                               #
####################################################################

quote ‘#include <stdio.h>‘
quote ‘#include "isa.h"‘
quote ‘#include "pipeline.h"‘
quote ‘#include "stages.h"‘
quote ‘#include "sim.h"‘
quote ‘int sim_main(int argc, char *argv[]);‘
quote ‘int main(int argc, char *argv[]){return sim_main(argc,argv);}‘

####################################################################
#    Declarations.  Do not change/remove/delete any of these       #
####################################################################

##### Symbolic representation of Y86-64 Instruction Codes #############
wordsig INOP    ‘I_NOP‘
wordsig IHALT   ‘I_HALT‘
wordsig IRRMOVQ ‘I_RRMOVQ‘
wordsig IIRMOVQ ‘I_IRMOVQ‘
wordsig IRMMOVQ ‘I_RMMOVQ‘
wordsig IMRMOVQ ‘I_MRMOVQ‘
wordsig IOPQ    ‘I_ALU‘
wordsig IJXX    ‘I_JMP‘
wordsig ICALL   ‘I_CALL‘
wordsig IRET    ‘I_RET‘
wordsig IPUSHQ  ‘I_PUSHQ‘
wordsig IPOPQ   ‘I_POPQ‘
# 1W: Special instruction code for second try of popq
wordsig IPOP2   ‘I_POP2‘

##### Symbolic represenations of Y86-64 function codes            #####
wordsig FNONE    ‘F_NONE‘        # Default function code

##### Symbolic representation of Y86-64 Registers referenced      #####
wordsig RRSP     ‘REG_RSP‘           # Stack Pointer
wordsig RNONE    ‘REG_NONE‘          # Special value indicating "no register"

##### ALU Functions referenced explicitly ##########################
wordsig ALUADD  ‘A_ADD‘          # ALU should add its arguments

##### Possible instruction status values                       #####
wordsig SBUB    ‘STAT_BUB‘  # Bubble in stage
wordsig SAOK    ‘STAT_AOK‘  # Normal execution
wordsig SADR    ‘STAT_ADR‘  # Invalid memory address
wordsig SINS    ‘STAT_INS‘  # Invalid instruction
wordsig SHLT    ‘STAT_HLT‘  # Halt instruction encountered

##### Signals that can be referenced by control logic ##############

##### Pipeline Register F ##########################################

wordsig F_predPC ‘pc_curr->pc‘       # Predicted value of PC

##### Intermediate Values in Fetch Stage ###########################

wordsig imem_icode  ‘imem_icode‘      # icode field from instruction memory
wordsig imem_ifun   ‘imem_ifun‘       # ifun  field from instruction memory
wordsig f_icode ‘if_id_next->icode‘  # (Possibly modified) instruction code
wordsig f_ifun  ‘if_id_next->ifun‘   # Fetched instruction function
wordsig f_valC  ‘if_id_next->valc‘   # Constant data of fetched instruction
wordsig f_valP  ‘if_id_next->valp‘   # Address of following instruction
## 1W: Provide access to the PC value for the current instruction
wordsig f_pc    ‘f_pc‘               # Address of fetched instruction
boolsig imem_error ‘imem_error‘      # Error signal from instruction memory
boolsig instr_valid ‘instr_valid‘    # Is fetched instruction valid?

##### Pipeline Register D ##########################################
wordsig D_icode ‘if_id_curr->icode‘   # Instruction code
wordsig D_rA ‘if_id_curr->ra‘        # rA field from instruction
wordsig D_rB ‘if_id_curr->rb‘        # rB field from instruction
wordsig D_valP ‘if_id_curr->valp‘     # Incremented PC

##### Intermediate Values in Decode Stage  #########################

wordsig d_srcA   ‘id_ex_next->srca‘  # srcA from decoded instruction
wordsig d_srcB   ‘id_ex_next->srcb‘  # srcB from decoded instruction
wordsig d_rvalA ‘d_regvala‘      # valA read from register file
wordsig d_rvalB ‘d_regvalb‘      # valB read from register file

##### Pipeline Register E ##########################################
wordsig E_icode ‘id_ex_curr->icode‘   # Instruction code
wordsig E_ifun  ‘id_ex_curr->ifun‘    # Instruction function
wordsig E_valC  ‘id_ex_curr->valc‘    # Constant data
wordsig E_srcA  ‘id_ex_curr->srca‘    # Source A register ID
wordsig E_valA  ‘id_ex_curr->vala‘    # Source A value
wordsig E_srcB  ‘id_ex_curr->srcb‘    # Source B register ID
wordsig E_valB  ‘id_ex_curr->valb‘    # Source B value
wordsig E_dstE ‘id_ex_curr->deste‘    # Destination E register ID
wordsig E_dstM ‘id_ex_curr->destm‘    # Destination M register ID

##### Intermediate Values in Execute Stage #########################
wordsig e_valE ‘ex_mem_next->vale‘  # valE generated by ALU
boolsig e_Cnd ‘ex_mem_next->takebranch‘ # Does condition hold?
wordsig e_dstE ‘ex_mem_next->deste‘      # dstE (possibly modified to be RNONE)

##### Pipeline Register M                  #########################
wordsig M_stat ‘ex_mem_curr->status‘     # Instruction status
wordsig M_icode ‘ex_mem_curr->icode‘    # Instruction code
wordsig M_ifun  ‘ex_mem_curr->ifun‘ # Instruction function
wordsig M_valA  ‘ex_mem_curr->vala‘      # Source A value
wordsig M_dstE ‘ex_mem_curr->deste‘ # Destination E register ID
wordsig M_valE  ‘ex_mem_curr->vale‘      # ALU E value
wordsig M_dstM ‘ex_mem_curr->destm‘ # Destination M register ID
boolsig M_Cnd ‘ex_mem_curr->takebranch‘ # Condition flag
boolsig dmem_error ‘dmem_error‘         # Error signal from instruction memory

##### Intermediate Values in Memory Stage ##########################
wordsig m_valM ‘mem_wb_next->valm‘  # valM generated by memory
wordsig m_stat ‘mem_wb_next->status‘    # stat (possibly modified to be SADR)

##### Pipeline Register W ##########################################
wordsig W_stat ‘mem_wb_curr->status‘     # Instruction status
wordsig W_icode ‘mem_wb_curr->icode‘    # Instruction code
wordsig W_dstE ‘mem_wb_curr->deste‘ # Destination E register ID
wordsig W_valE  ‘mem_wb_curr->vale‘      # ALU E value
wordsig W_dstM ‘mem_wb_curr->destm‘ # Destination M register ID
wordsig W_valM  ‘mem_wb_curr->valm‘ # Memory M value

####################################################################
#    Control Signal Definitions.                                   #
####################################################################

################ Fetch Stage     ###################################

## What address should instruction be fetched at
word f_pc = [
    # Mispredicted branch.  Fetch at incremented PC
    M_icode == IJXX && !M_Cnd : M_valA;
    # Completion of RET instruction
    W_icode == IRET : W_valM;
    # Default: Use predicted value of PC
    1 : F_predPC;
];

## Determine icode of fetched instruction
## 1W: To split ipopq into two cycles, need to be able to 
## modify value of icode,
## so that it will be IPOP2 when fetched for second time.
word f_icode = [
    imem_error : INOP;
    D_icode == IPOPQ : IPOP2;
    1: imem_icode;
];

# Determine ifun
word f_ifun = [
    imem_error : FNONE;
    1: imem_ifun;
];

# Is instruction valid?
bool instr_valid = f_icode in 
    { INOP, IHALT, IRRMOVQ, IIRMOVQ, IRMMOVQ, IMRMOVQ,
      IOPQ, IJXX, ICALL, IRET, IPUSHQ, IPOPQ, IPOP2 };

# Determine status code for fetched instruction
word f_stat = [
    imem_error: SADR;
    !instr_valid : SINS;
    f_icode == IHALT : SHLT;
    1 : SAOK;
];

# Does fetched instruction require a regid byte?
bool need_regids =
    f_icode in { IRRMOVQ, IOPQ, IPUSHQ, IPOPQ, 
             IIRMOVQ, IRMMOVQ, IMRMOVQ, IPOP2 };

# Does fetched instruction require a constant word?
bool need_valC =
    f_icode in { IIRMOVQ, IRMMOVQ, IMRMOVQ, IJXX, ICALL };

# Predict next value of PC
word f_predPC = [
    f_icode in { IJXX, ICALL } : f_valC;
    ## 1W: Want to refetch popq one time
    f_icode == IPOPQ : f_pc;
    1 : f_valP;
];

################ Decode Stage ######################################

## W1: Strategy.  Decoding of popq rA should be treated the same
## as would iaddq $8, %rsp
## Decoding of pop2 rA treated same as mrmovq -8(%rsp), rA

## What register should be used as the A source?
word d_srcA = [
    D_icode in { IRRMOVQ, IRMMOVQ, IOPQ, IPUSHQ  } : D_rA;
    D_icode in { IRET } : RRSP;
    1 : RNONE; # Don‘t need register
];

## What register should be used as the B source?
word d_srcB = [
    D_icode in { IOPQ, IRMMOVQ, IMRMOVQ  } : D_rB;
    D_icode in { IPUSHQ, IPOPQ, ICALL, IRET, IPOP2 } : RRSP;
    1 : RNONE;  # Don‘t need register
];

## What register should be used as the E destination?
word d_dstE = [
    D_icode in { IRRMOVQ, IIRMOVQ, IOPQ} : D_rB;
    D_icode in { IPUSHQ, IPOPQ, ICALL, IRET } : RRSP;
    1 : RNONE;  # Don‘t write any register
];

## What register should be used as the M destination?
word d_dstM = [
    D_icode in { IMRMOVQ, IPOP2 } : D_rA;
    1 : RNONE;  # Don‘t write any register
];

## What should be the A value?
## Forward into decode stage for valA
word d_valA = [
    D_icode in { ICALL, IJXX } : D_valP; # Use incremented PC
    d_srcA == e_dstE : e_valE;    # Forward valE from execute
    d_srcA == M_dstM : m_valM;    # Forward valM from memory
    d_srcA == M_dstE : M_valE;    # Forward valE from memory
    d_srcA == W_dstM : W_valM;    # Forward valM from write back
    d_srcA == W_dstE : W_valE;    # Forward valE from write back
    1 : d_rvalA;  # Use value read from register file
];

word d_valB = [
    d_srcB == e_dstE : e_valE;    # Forward valE from execute
    d_srcB == M_dstM : m_valM;    # Forward valM from memory
    d_srcB == M_dstE : M_valE;    # Forward valE from memory
    d_srcB == W_dstM : W_valM;    # Forward valM from write back
    d_srcB == W_dstE : W_valE;    # Forward valE from write back
    1 : d_rvalB;  # Use value read from register file
];

################ Execute Stage #####################################

## Select input A to ALU
word aluA = [
    E_icode in { IRRMOVQ, IOPQ } : E_valA;
    E_icode in { IIRMOVQ, IRMMOVQ, IMRMOVQ } : E_valC;
    E_icode in { ICALL, IPUSHQ, IPOP2 } : -8;
    E_icode in { IRET, IPOPQ } : 8;
    # Other instructions don‘t need ALU
];

## Select input B to ALU
word aluB = [
    E_icode in { IRMMOVQ, IMRMOVQ, IOPQ, ICALL, 
             IPUSHQ, IRET, IPOPQ, IPOP2 } : E_valB;
    E_icode in { IRRMOVQ, IIRMOVQ } : 0;
    # Other instructions don‘t need ALU
];

## Set the ALU function
word alufun = [
    E_icode == IOPQ : E_ifun;
    1 : ALUADD;
];

## Should the condition codes be updated?
bool set_cc = E_icode == IOPQ &&
    # State changes only during normal operation
    !m_stat in { SADR, SINS, SHLT } && !W_stat in { SADR, SINS, SHLT };

## Generate valA in execute stage
word e_valA = E_valA;    # Pass valA through stage

## Set dstE to RNONE in event of not-taken conditional move
word e_dstE = [
    E_icode == IRRMOVQ && !e_Cnd : RNONE;
    1 : E_dstE;
];

################ Memory Stage ######################################

## Select memory address
word mem_addr = [
    M_icode in { IRMMOVQ, IPUSHQ, ICALL, IMRMOVQ, IPOP2 } : M_valE;
    M_icode in { IRET } : M_valA;
    # Other instructions don‘t need address
];

## Set read control signal
bool mem_read = M_icode in { IMRMOVQ, IPOP2, IRET };

## Set write control signal
bool mem_write = M_icode in { IRMMOVQ, IPUSHQ, ICALL };

#/* $begin pipe-m_stat-hcl */
## Update the status
word m_stat = [
    dmem_error : SADR;
    1 : M_stat;
];
#/* $end pipe-m_stat-hcl */

################ Write back stage ##################################

## 1W: For this problem, we introduce a multiplexor that merges
## valE and valM into a single value for writing to register port E.
## DO NOT CHANGE THIS LOGIC
## Merge both write back sources onto register port E 
## Set E port register ID
word w_dstE = [
    ## writing from valM
    W_dstM != RNONE : W_dstM;
    1: W_dstE;
];

## Set E port value
word w_valE = [
    W_dstM != RNONE : W_valM;
    1: W_valE;
];

## Disable register port M
## Set M port register ID
word w_dstM = RNONE;

## Set M port value
word w_valM = 0;

## Update processor status
word Stat = [
    W_stat == SBUB : SAOK;
    1 : W_stat;
];

################ Pipeline Register Control #########################

# Should I stall or inject a bubble into Pipeline Register F?
# At most one of these can be true.
bool F_bubble = 0;
bool F_stall =
    # Conditions for a load/use hazard
    E_icode in { IMRMOVQ, IPOP2 } &&
     E_dstM in { d_srcA, d_srcB } ||
    # Stalling at fetch while ret passes through pipeline
    IRET in { D_icode, E_icode, M_icode };

# Should I stall or inject a bubble into Pipeline Register D?
# At most one of these can be true.
bool D_stall = 
    # Conditions for a load/use hazard
    E_icode in { IMRMOVQ, IPOP2 } &&
     E_dstM in { d_srcA, d_srcB };

bool D_bubble =
    # Mispredicted branch
    (E_icode == IJXX && !e_Cnd) ||
    # Stalling at fetch while ret passes through pipeline
    # but not condition for a load/use hazard
    !(E_icode in { IMRMOVQ, IPOP2 } && E_dstM in { d_srcA, d_srcB }) &&
    # 1W: This condition will change
      IRET in { D_icode, E_icode, M_icode };

# Should I stall or inject a bubble into Pipeline Register E?
# At most one of these can be true.
bool E_stall = 0;
bool E_bubble =
    # Mispredicted branch
    (E_icode == IJXX && !e_Cnd) ||
    # Conditions for a load/use hazard
    E_icode in { IMRMOVQ, IPOP2 } &&
     E_dstM in { d_srcA, d_srcB};

# Should I stall or inject a bubble into Pipeline Register M?
# At most one of these can be true.
bool M_stall = 0;
# Start injecting bubbles as soon as exception passes through memory stage
bool M_bubble = m_stat in { SADR, SINS, SHLT } || W_stat in { SADR, SINS, SHLT };

# Should I stall or inject a bubble into Pipeline Register W?
bool W_stall = W_stat in { SADR, SINS, SHLT };
bool W_bubble = 0;
#/* $end pipe-all-hcl */

运行结果如下：