一个函数返回临时对象引起的编译器优化问题

我们都知道，如果在一个函数调用另一个函数，假设是 main 函数调用 fun 函数，这个 fun 函数返回一个临时类类型变量，那么这个时候编译器就会在 main 函数申请一个空间并生成一个临时对象，通过拷贝构造函数将 fun 返回的临时变量的值拷贝到这个临时对象。我们看如下的代码：

#include <iostream>
#include <cstring>

using namespace std;

class Matrix
{
public:
explicit Matrix(double d = 1.0)
{
cout << "Matrix::Matrix()" << endl;

for(int i = 0; i < 10; i++)
for(int j = 0; j < 10; j++)
m[i][j] = d;
}

Matrix(const Matrix& mt)
{
cout << "Matrix::Matrix(const Matrix&)" << endl;
memcpy(this, &mt, sizeof(Matrix));
}

Matrix& operator=(const Matrix& mt)
{
if(this == &mt)
return *this;

cout << "Matrix::operator=(const Matrix&)" << endl;
memcpy(this, &mt, sizeof(Matrix));

return *this;
}

friend const Matrix operator+(const Matrix&, const Matrix&);
//...

private:
double m[10][10];
};

const Matrix operator+(const Matrix& arg1, const Matrix& arg2)
{
Matrix sum;
for(int i = 0; i < 10; i++)
for(int j = 0; j < 10; j++)
sum.m[i][j] = arg1.m[i][j] + arg2.m[i][j];  return sum;
}

int main()
{
Matrix a(2.0),  b(3.0);
Matrix c = (a + b);  return 0;
}

按照我们的预期，输出结果应该是这样的：



这也正是 vs2012 的执行结果，但是在 GCC4.2.1 中的执行结果却是这样的：



这样看来，在构造 c 的时候根本就没有调用拷贝构造函数，同时也没用调用赋值操作符和构造函数。这样就会有一个问题，c 到底是怎么构造的？我们把代码改成这样：

#include <iostream>
#include <cstring>

using namespace std;

class Matrix
{
public:
explicit Matrix(double d = 1.0)
{
cout << "Matrix::Matrix()" << endl;

for(int i = 0; i < 10; i++)
for(int j = 0; j < 10; j++)
m[i][j] = d;
}

Matrix(const Matrix& mt)
{
cout << "Matrix::Matrix(const Matrix&)" << endl;
memcpy(this, &mt, sizeof(Matrix));
}

Matrix& operator=(const Matrix& mt)
{
if(this == &mt)
return *this;

cout << "Matrix::operator=(const Matrix&)" << endl;
memcpy(this, &mt, sizeof(Matrix));

return *this;
}

friend const Matrix operator+(const Matrix&, const Matrix&);
//...

private:
double m[10][10];
};

const Matrix operator+(const Matrix& arg1, const Matrix& arg2)
{
Matrix sum;
for(int i = 0; i < 10; i++)
for(int j = 0; j < 10; j++)
sum.m[i][j] = arg1.m[i][j] + arg2.m[i][j];
cout << "Address of sum: " << &sum << endl;
return sum;
}

int main()
{
Matrix a(2.0),  b(3.0);
Matrix c = (a + b);
cout << "Address of c:   " << &c << endl;

return 0;
}

其实就是把 sum 和 c 的地址打了出来，我们会发现在 gcc 的结果如下：



从这里可以看出，gcc 编译器对 c 的初始化做了优化，它没有再调用拷贝构造函数来构造 c，而是直接让 c 指向了 + 函数里的临时变量。当然这里也让 sum 的空间所有权交给了 main 作用域的 c, 否则在推出 sum 的时候 sum 的空间就应该被释放了。

这只是我从其执行结果推测的结果，而 gcc 产生的目标文件的汇编代码简直没法看，所以没有研究其汇编代码来验证我的想法，有人看得懂 gcc 的汇编代码的看完结果望告知！下面是代码的gcc汇编代码：

.section    __TEXT,__text,regular,pure_instructions
.globl    __ZplRK6MatrixS1_
.align    4, 0x90
__ZplRK6MatrixS1_:                      ## @_ZplRK6MatrixS1_
.cfi_startproc
## BB#0:
pushq    %rbp
Ltmp2:
.cfi_def_cfa_offset 16
Ltmp3:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp4:
.cfi_def_cfa_register %rbp
subq    $64, %rsp
movq    %rdi, %rax
movabsq    $1, %rcx
cvtsi2sdq    %rcx, %xmm0
movq    %rsi, -24(%rbp)
movq    %rdx, -32(%rbp)
movq    %rdi, -48(%rbp)         ## 8-byte Spill
movq    %rax, -56(%rbp)         ## 8-byte Spill
callq    __ZN6MatrixC1Ed
movl    $0, -36(%rbp)
LBB0_1:                                 ## =>This Loop Header: Depth=1
##     Child Loop BB0_3 Depth 2
cmpl    $10, -36(%rbp)
jge    LBB0_8
## BB#2:                                ##   in Loop: Header=BB0_1 Depth=1
movl    $0, -40(%rbp)
LBB0_3:                                 ##   Parent Loop BB0_1 Depth=1
## =>  This Inner Loop Header: Depth=2
cmpl    $10, -40(%rbp)
jge    LBB0_6
## BB#4:                                ##   in Loop: Header=BB0_3 Depth=2
movslq    -40(%rbp), %rax
movslq    -36(%rbp), %rcx
movq    -24(%rbp), %rdx
imulq    $80, %rcx, %rcx
addq    %rcx, %rdx
movsd    (%rdx,%rax,8), %xmm0
movslq    -40(%rbp), %rax
movslq    -36(%rbp), %rcx
movq    -32(%rbp), %rdx
imulq    $80, %rcx, %rcx
addq    %rcx, %rdx
addsd    (%rdx,%rax,8), %xmm0
movslq    -40(%rbp), %rax
movslq    -36(%rbp), %rcx
imulq    $80, %rcx, %rcx
movq    -48(%rbp), %rdx         ## 8-byte Reload
addq    %rcx, %rdx
movsd    %xmm0, (%rdx,%rax,8)
## BB#5:                                ##   in Loop: Header=BB0_3 Depth=2
movl    -40(%rbp), %eax
addl    $1, %eax
movl    %eax, -40(%rbp)
jmp    LBB0_3
LBB0_6:                                 ##   in Loop: Header=BB0_1 Depth=1
jmp    LBB0_7
LBB0_7:                                 ##   in Loop: Header=BB0_1 Depth=1
movl    -36(%rbp), %eax
addl    $1, %eax
movl    %eax, -36(%rbp)
jmp    LBB0_1
LBB0_8:
movq    __ZNSt3__14coutE@GOTPCREL(%rip), %rdi
leaq    L_.str(%rip), %rsi
callq    __ZNSt3__1lsINS_11char_traitsIcEEEERNS_13basic_ostreamIcT_EES6_PKc
movq    -48(%rbp), %rsi         ## 8-byte Reload
movq    %rax, %rdi
callq    __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEPKv
leaq    __ZNSt3__14endlIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_(%rip), %rsi
movq    %rax, -8(%rbp)
movq    %rsi, -16(%rbp)
movq    -8(%rbp), %rdi
callq    *-16(%rbp)
movq    -56(%rbp), %rsi         ## 8-byte Reload
movq    %rax, -64(%rbp)         ## 8-byte Spill
movq    %rsi, %rax
addq    $64, %rsp
popq    %rbp
retq
.cfi_endproc

.section    __TEXT,__textcoal_nt,coalesced,pure_instructions
.globl    __ZN6MatrixC1Ed
.weak_def_can_be_hidden    __ZN6MatrixC1Ed
.align    4, 0x90
__ZN6MatrixC1Ed:                        ## @_ZN6MatrixC1Ed
.cfi_startproc
## BB#0:
pushq    %rbp
Ltmp7:
.cfi_def_cfa_offset 16
Ltmp8:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp9:
.cfi_def_cfa_register %rbp
subq    $16, %rsp
movq    %rdi, -8(%rbp)
movsd    %xmm0, -16(%rbp)
movq    -8(%rbp), %rdi
movsd    -16(%rbp), %xmm0
callq    __ZN6MatrixC2Ed
addq    $16, %rsp
popq    %rbp
retq
.cfi_endproc

.globl    __ZNSt3__1lsINS_11char_traitsIcEEEERNS_13basic_ostreamIcT_EES6_PKc
.weak_def_can_be_hidden    __ZNSt3__1lsINS_11char_traitsIcEEEERNS_13basic_ostreamIcT_EES6_PKc
.align    4, 0x90
__ZNSt3__1lsINS_11char_traitsIcEEEERNS_13basic_ostreamIcT_EES6_PKc: ## @_ZNSt3__1lsINS_11char_traitsIcEEEERNS_13basic_ostreamIcT_EES6_PKc
.cfi_startproc
## BB#0:
pushq    %rbp
Ltmp12:
.cfi_def_cfa_offset 16
Ltmp13:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp14:
.cfi_def_cfa_register %rbp
subq    $48, %rsp
movq    %rdi, -16(%rbp)
movq    %rsi, -24(%rbp)
movq    -16(%rbp), %rdi
movq    -24(%rbp), %rsi
movq    -24(%rbp), %rax
movq    %rax, -8(%rbp)
movq    -8(%rbp), %rax
movq    %rdi, -32(%rbp)         ## 8-byte Spill
movq    %rax, %rdi
movq    %rsi, -40(%rbp)         ## 8-byte Spill
callq    _strlen
movq    -32(%rbp), %rdi         ## 8-byte Reload
movq    -40(%rbp), %rsi         ## 8-byte Reload
movq    %rax, %rdx
callq    __ZNSt3__124__put_character_sequenceIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_PKS4_m
addq    $48, %rsp
popq    %rbp
retq
.cfi_endproc

.private_extern    __ZNSt3__14endlIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_
.globl    __ZNSt3__14endlIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_
.weak_definition    __ZNSt3__14endlIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_
.align    4, 0x90
__ZNSt3__14endlIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_: ## @_ZNSt3__14endlIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_
.cfi_startproc
.cfi_personality 155, ___gxx_personality_v0
Leh_func_begin3:
.cfi_lsda 16, Lexception3
## BB#0:
pushq    %rbp
Ltmp25:
.cfi_def_cfa_offset 16
Ltmp26:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp27:
.cfi_def_cfa_register %rbp
subq    $144, %rsp
movq    %rdi, -72(%rbp)
movq    %rdi, %rax
movq    (%rdi), %rcx
movq    -24(%rcx), %rcx
addq    %rcx, %rdi
movq    %rdi, -32(%rbp)
movb    $10, -33(%rbp)
movq    -32(%rbp), %rsi
leaq    -48(%rbp), %rcx
movq    %rcx, %rdi
movq    %rax, -80(%rbp)         ## 8-byte Spill
movq    %rcx, -88(%rbp)         ## 8-byte Spill
callq    __ZNKSt3__18ios_base6getlocEv
movq    -88(%rbp), %rax         ## 8-byte Reload
movq    %rax, -24(%rbp)
Ltmp15:
movq    __ZNSt3__15ctypeIcE2idE@GOTPCREL(%rip), %rsi
movq    %rax, %rdi
callq    __ZNKSt3__16locale9use_facetERNS0_2idE
Ltmp16:
movq    %rax, -96(%rbp)         ## 8-byte Spill
jmp    LBB3_1
LBB3_1:                                 ## %_ZNSt3__19use_facetINS_5ctypeIcEEEERKT_RKNS_6localeE.exit.i
movb    -33(%rbp), %al
movq    -96(%rbp), %rcx         ## 8-byte Reload
movq    %rcx, -8(%rbp)
movb    %al, -9(%rbp)
movq    -8(%rbp), %rdx
movq    (%rdx), %rsi
movq    56(%rsi), %rsi
movsbl    -9(%rbp), %edi
Ltmp17:
movl    %edi, -100(%rbp)        ## 4-byte Spill
movq    %rdx, %rdi
movl    -100(%rbp), %r8d        ## 4-byte Reload
movq    %rsi, -112(%rbp)        ## 8-byte Spill
movl    %r8d, %esi
movq    -112(%rbp), %rdx        ## 8-byte Reload
callq    *%rdx
Ltmp18:
movb    %al, -113(%rbp)         ## 1-byte Spill
jmp    LBB3_5
LBB3_2:
Ltmp19:
movl    %edx, %ecx
movq    %rax, -56(%rbp)
movl    %ecx, -60(%rbp)
Ltmp20:
leaq    -48(%rbp), %rdi
callq    __ZNSt3__16localeD1Ev
Ltmp21:
jmp    LBB3_3
LBB3_3:
movq    -56(%rbp), %rdi
callq    __Unwind_Resume
LBB3_4:
Ltmp22:
movl    %edx, %ecx
movq    %rax, %rdi
movl    %ecx, -120(%rbp)        ## 4-byte Spill
callq    ___clang_call_terminate
LBB3_5:                                 ## %_ZNKSt3__19basic_iosIcNS_11char_traitsIcEEE5widenEc.exit
leaq    -48(%rbp), %rdi
callq    __ZNSt3__16localeD1Ev
movq    -80(%rbp), %rdi         ## 8-byte Reload
movb    -113(%rbp), %al         ## 1-byte Reload
movsbl    %al, %esi
callq    __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE3putEc
movq    -72(%rbp), %rdi
movq    %rax, -128(%rbp)        ## 8-byte Spill
callq    __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE5flushEv
movq    -72(%rbp), %rdi
movq    %rax, -136(%rbp)        ## 8-byte Spill
movq    %rdi, %rax
addq    $144, %rsp
popq    %rbp
retq
.cfi_endproc
Leh_func_end3:
.section    __TEXT,__gcc_except_tab
.align    2
GCC_except_table3:
Lexception3:
.byte    255                     ## @LPStart Encoding = omit
.byte    155                     ## @TType Encoding = indirect pcrel sdata4
.asciz    "\274"                  ## @TType base offset
.byte    3                       ## Call site Encoding = udata4
.byte    52                      ## Call site table length
Lset0 = Leh_func_begin3-Leh_func_begin3 ## >> Call Site 1 <<
.long    Lset0
Lset1 = Ltmp15-Leh_func_begin3          ##   Call between Leh_func_begin3 and Ltmp15
.long    Lset1
.long    0                       ##     has no landing pad
.byte    0                       ##   On action: cleanup
Lset2 = Ltmp15-Leh_func_begin3          ## >> Call Site 2 <<
.long    Lset2
Lset3 = Ltmp18-Ltmp15                   ##   Call between Ltmp15 and Ltmp18
.long    Lset3
Lset4 = Ltmp19-Leh_func_begin3          ##     jumps to Ltmp19
.long    Lset4
.byte    0                       ##   On action: cleanup
Lset5 = Ltmp20-Leh_func_begin3          ## >> Call Site 3 <<
.long    Lset5
Lset6 = Ltmp21-Ltmp20                   ##   Call between Ltmp20 and Ltmp21
.long    Lset6
Lset7 = Ltmp22-Leh_func_begin3          ##     jumps to Ltmp22
.long    Lset7
.byte    1                       ##   On action: 1
Lset8 = Ltmp21-Leh_func_begin3          ## >> Call Site 4 <<
.long    Lset8
Lset9 = Leh_func_end3-Ltmp21            ##   Call between Ltmp21 and Leh_func_end3
.long    Lset9
.long    0                       ##     has no landing pad
.byte    0                       ##   On action: cleanup
.byte    1                       ## >> Action Record 1 <<
##   Catch TypeInfo 1
.byte    0                       ##   No further actions
## >> Catch TypeInfos <<
.long    0                       ## TypeInfo 1
.align    2

.section    __TEXT,__text,regular,pure_instructions
.globl    _main
.align    4, 0x90
_main:                                  ## @main
.cfi_startproc
## BB#0:
pushq    %rbp
Ltmp30:
.cfi_def_cfa_offset 16
Ltmp31:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp32:
.cfi_def_cfa_register %rbp
subq    $2448, %rsp             ## imm = 0x990
leaq    -824(%rbp), %rdi
movabsq    $2, %rax
cvtsi2sdq    %rax, %xmm0
movl    $0, -20(%rbp)
callq    __ZN6MatrixC1Ed
leaq    -1624(%rbp), %rdi
movabsq    $3, %rax
cvtsi2sdq    %rax, %xmm0
callq    __ZN6MatrixC1Ed
leaq    -2424(%rbp), %rdi
leaq    -824(%rbp), %rsi
leaq    -1624(%rbp), %rdx
callq    __ZplRK6MatrixS1_
movq    __ZNSt3__14coutE@GOTPCREL(%rip), %rdi
leaq    L_.str1(%rip), %rsi
callq    __ZNSt3__1lsINS_11char_traitsIcEEEERNS_13basic_ostreamIcT_EES6_PKc
leaq    -2424(%rbp), %rdx
movq    %rax, %rdi
movq    %rdx, %rsi
callq    __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEPKv
movl    $0, %ecx
leaq    __ZNSt3__14endlIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_(%rip), %rdx
movq    %rax, -8(%rbp)
movq    %rdx, -16(%rbp)
movq    -8(%rbp), %rdi
movl    %ecx, -2428(%rbp)       ## 4-byte Spill
callq    *-16(%rbp)
movl    -2428(%rbp), %ecx       ## 4-byte Reload
movq    %rax, -2440(%rbp)       ## 8-byte Spill
movl    %ecx, %eax
addq    $2448, %rsp             ## imm = 0x990
popq    %rbp
retq
.cfi_endproc

.section    __TEXT,__textcoal_nt,coalesced,pure_instructions
.private_extern    ___clang_call_terminate
.globl    ___clang_call_terminate
.weak_def_can_be_hidden    ___clang_call_terminate
.align    4, 0x90
___clang_call_terminate:                ## @__clang_call_terminate
## BB#0:
pushq    %rbp
movq    %rsp, %rbp
subq    $16, %rsp
callq    ___cxa_begin_catch
movq    %rax, -8(%rbp)          ## 8-byte Spill
callq    __ZSt9terminatev

.globl    __ZNSt3__124__put_character_sequenceIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_PKS4_m
.weak_def_can_be_hidden    __ZNSt3__124__put_character_sequenceIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_PKS4_m
.align    4, 0x90
__ZNSt3__124__put_character_sequenceIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_PKS4_m: ## @_ZNSt3__124__put_character_sequenceIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_PKS4_m
.cfi_startproc
.cfi_personality 155, ___gxx_personality_v0
Leh_func_begin6:
.cfi_lsda 16, Lexception6
## BB#0:
pushq    %rbp
Ltmp65:
.cfi_def_cfa_offset 16
Ltmp66:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp67:
.cfi_def_cfa_register %rbp
subq    $416, %rsp              ## imm = 0x1A0
movq    %rdi, -208(%rbp)
movq    %rsi, -216(%rbp)
movq    %rdx, -224(%rbp)
movq    -208(%rbp), %rsi
Ltmp33:
leaq    -240(%rbp), %rdi
callq    __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE6sentryC1ERS3_
Ltmp34:
jmp    LBB6_1
LBB6_1:
leaq    -240(%rbp), %rax
movq    %rax, -200(%rbp)
movq    -200(%rbp), %rax
movb    (%rax), %cl
movb    %cl, -273(%rbp)         ## 1-byte Spill
## BB#2:
movb    -273(%rbp), %al         ## 1-byte Reload
testb    $1, %al
jne    LBB6_3
jmp    LBB6_26
LBB6_3:
leaq    -264(%rbp), %rax
movq    -208(%rbp), %rcx
movq    %rax, -184(%rbp)
movq    %rcx, -192(%rbp)
movq    -184(%rbp), %rax
movq    -192(%rbp), %rcx
movq    %rax, -152(%rbp)
movq    %rcx, -160(%rbp)
movq    -152(%rbp), %rax
movq    -160(%rbp), %rcx
movq    (%rcx), %rdx
movq    -24(%rdx), %rdx
addq    %rdx, %rcx
movq    %rcx, -144(%rbp)
movq    -144(%rbp), %rcx
movq    %rcx, -136(%rbp)
movq    -136(%rbp), %rcx
movq    40(%rcx), %rcx
movq    %rcx, (%rax)
movq    -216(%rbp), %rsi
movq    -208(%rbp), %rax
movq    (%rax), %rcx
movq    -24(%rcx), %rcx
addq    %rcx, %rax
movq    %rax, -96(%rbp)
movq    -96(%rbp), %rax
movl    8(%rax), %edi
movq    %rsi, -288(%rbp)        ## 8-byte Spill
movl    %edi, -292(%rbp)        ## 4-byte Spill
## BB#4:
movl    -292(%rbp), %eax        ## 4-byte Reload
andl    $176, %eax
cmpl    $32, %eax
jne    LBB6_6
## BB#5:
movq    -216(%rbp), %rax
addq    -224(%rbp), %rax
movq    %rax, -304(%rbp)        ## 8-byte Spill
jmp    LBB6_7
LBB6_6:
movq    -216(%rbp), %rax
movq    %rax, -304(%rbp)        ## 8-byte Spill
LBB6_7:
movq    -304(%rbp), %rax        ## 8-byte Reload
movq    -216(%rbp), %rcx
addq    -224(%rbp), %rcx
movq    -208(%rbp), %rdx
movq    (%rdx), %rsi
movq    -24(%rsi), %rsi
addq    %rsi, %rdx
movq    -208(%rbp), %rsi
movq    (%rsi), %rdi
movq    -24(%rdi), %rdi
addq    %rdi, %rsi
movq    %rsi, -80(%rbp)
movq    -80(%rbp), %rsi
movl    144(%rsi), %r8d
movl    $-1, -4(%rbp)
movl    %r8d, -8(%rbp)
movl    -4(%rbp), %r8d
cmpl    -8(%rbp), %r8d
movq    %rax, -312(%rbp)        ## 8-byte Spill
movq    %rcx, -320(%rbp)        ## 8-byte Spill
movq    %rdx, -328(%rbp)        ## 8-byte Spill
movq    %rsi, -336(%rbp)        ## 8-byte Spill
jne    LBB6_16
## BB#8:
movq    -336(%rbp), %rax        ## 8-byte Reload
movq    %rax, -40(%rbp)
movb    $32, -41(%rbp)
movq    -40(%rbp), %rsi
Ltmp35:
leaq    -56(%rbp), %rdi
callq    __ZNKSt3__18ios_base6getlocEv
Ltmp36:
jmp    LBB6_9
LBB6_9:                                 ## %.noexc
leaq    -56(%rbp), %rax
movq    %rax, -32(%rbp)
Ltmp37:
movq    __ZNSt3__15ctypeIcE2idE@GOTPCREL(%rip), %rsi
movq    %rax, %rdi
callq    __ZNKSt3__16locale9use_facetERNS0_2idE
Ltmp38:
movq    %rax, -344(%rbp)        ## 8-byte Spill
jmp    LBB6_10
LBB6_10:                                ## %_ZNSt3__19use_facetINS_5ctypeIcEEEERKT_RKNS_6localeE.exit.i.i
movb    -41(%rbp), %al
movq    -344(%rbp), %rcx        ## 8-byte Reload
movq    %rcx, -16(%rbp)
movb    %al, -17(%rbp)
movq    -16(%rbp), %rdx
movq    (%rdx), %rsi
movq    56(%rsi), %rsi
movsbl    -17(%rbp), %edi
Ltmp39:
movl    %edi, -348(%rbp)        ## 4-byte Spill
movq    %rdx, %rdi
movl    -348(%rbp), %r8d        ## 4-byte Reload
movq    %rsi, -360(%rbp)        ## 8-byte Spill
movl    %r8d, %esi
movq    -360(%rbp), %rdx        ## 8-byte Reload
callq    *%rdx
Ltmp40:
movb    %al, -361(%rbp)         ## 1-byte Spill
jmp    LBB6_14
LBB6_11:
Ltmp41:
movl    %edx, %ecx
movq    %rax, -64(%rbp)
movl    %ecx, -68(%rbp)
Ltmp42:
leaq    -56(%rbp), %rdi
callq    __ZNSt3__16localeD1Ev
Ltmp43:
jmp    LBB6_12
LBB6_12:
movq    -64(%rbp), %rax
movl    -68(%rbp), %ecx
movq    %rax, -376(%rbp)        ## 8-byte Spill
movl    %ecx, -380(%rbp)        ## 4-byte Spill
jmp    LBB6_24
LBB6_13:
Ltmp44:
movl    %edx, %ecx
movq    %rax, %rdi
movl    %ecx, -384(%rbp)        ## 4-byte Spill
callq    ___clang_call_terminate
LBB6_14:                                ## %_ZNKSt3__19basic_iosIcNS_11char_traitsIcEEE5widenEc.exit.i
Ltmp45:
leaq    -56(%rbp), %rdi
callq    __ZNSt3__16localeD1Ev
Ltmp46:
jmp    LBB6_15
LBB6_15:                                ## %.noexc1
movb    -361(%rbp), %al         ## 1-byte Reload
movsbl    %al, %ecx
movq    -336(%rbp), %rdx        ## 8-byte Reload
movl    %ecx, 144(%rdx)
LBB6_16:                                ## %_ZNKSt3__19basic_iosIcNS_11char_traitsIcEEE4fillEv.exit
movq    -336(%rbp), %rax        ## 8-byte Reload
movl    144(%rax), %ecx
movb    %cl, %dl
movb    %dl, -385(%rbp)         ## 1-byte Spill
## BB#17:
movq    -264(%rbp), %rdi
Ltmp47:
movb    -385(%rbp), %al         ## 1-byte Reload
movsbl    %al, %r9d
movq    -288(%rbp), %rsi        ## 8-byte Reload
movq    -312(%rbp), %rdx        ## 8-byte Reload
movq    -320(%rbp), %rcx        ## 8-byte Reload
movq    -328(%rbp), %r8         ## 8-byte Reload
callq    __ZNSt3__116__pad_and_outputIcNS_11char_traitsIcEEEENS_19ostreambuf_iteratorIT_T0_EES6_PKS4_S8_S8_RNS_8ios_baseES4_
Ltmp48:
movq    %rax, -400(%rbp)        ## 8-byte Spill
jmp    LBB6_18
LBB6_18:
leaq    -272(%rbp), %rax
movq    -400(%rbp), %rcx        ## 8-byte Reload
movq    %rcx, -272(%rbp)
movq    %rax, -88(%rbp)
movq    -88(%rbp), %rax
cmpq    $0, (%rax)
jne    LBB6_25
## BB#19:
movq    -208(%rbp), %rax
movq    (%rax), %rcx
movq    -24(%rcx), %rcx
addq    %rcx, %rax
movq    %rax, -120(%rbp)
movl    $5, -124(%rbp)
movq    -120(%rbp), %rax
movq    %rax, -104(%rbp)
movl    $5, -108(%rbp)
movq    -104(%rbp), %rax
movl    32(%rax), %edx
orl    $5, %edx
Ltmp49:
movq    %rax, %rdi
movl    %edx, %esi
callq    __ZNSt3__18ios_base5clearEj
Ltmp50:
jmp    LBB6_20
LBB6_20:                                ## %_ZNSt3__19basic_iosIcNS_11char_traitsIcEEE8setstateEj.exit
jmp    LBB6_21
LBB6_21:
jmp    LBB6_25
LBB6_22:
Ltmp56:
movl    %edx, %ecx
movq    %rax, -248(%rbp)
movl    %ecx, -252(%rbp)
jmp    LBB6_29
LBB6_23:
Ltmp51:
movl    %edx, %ecx
movq    %rax, -376(%rbp)        ## 8-byte Spill
movl    %ecx, -380(%rbp)        ## 4-byte Spill
LBB6_24:                                ## %.body
movl    -380(%rbp), %eax        ## 4-byte Reload
movq    -376(%rbp), %rcx        ## 8-byte Reload
movq    %rcx, -248(%rbp)
movl    %eax, -252(%rbp)
Ltmp52:
leaq    -240(%rbp), %rdi
callq    __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE6sentryD1Ev
Ltmp53:
jmp    LBB6_28
LBB6_25:
jmp    LBB6_26
LBB6_26:
Ltmp54:
leaq    -240(%rbp), %rdi
callq    __ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE6sentryD1Ev
Ltmp55:
jmp    LBB6_27
LBB6_27:
jmp    LBB6_31
LBB6_28:
jmp    LBB6_29
LBB6_29:
movq    -248(%rbp), %rdi
callq    ___cxa_begin_catch
movq    -208(%rbp), %rdi
movq    (%rdi), %rcx
movq    -24(%rcx), %rcx
addq    %rcx, %rdi
Ltmp57:
movq    %rax, -408(%rbp)        ## 8-byte Spill
callq    __ZNSt3__18ios_base33__set_badbit_and_consider_rethrowEv
Ltmp58:
jmp    LBB6_30
LBB6_30:
callq    ___cxa_end_catch
LBB6_31:
movq    -208(%rbp), %rax
addq    $416, %rsp              ## imm = 0x1A0
popq    %rbp
retq
LBB6_32:
Ltmp59:
movl    %edx, %ecx
movq    %rax, -248(%rbp)
movl    %ecx, -252(%rbp)
Ltmp60:
callq    ___cxa_end_catch
Ltmp61:
jmp    LBB6_33
LBB6_33:
jmp    LBB6_34
LBB6_34:
movq    -248(%rbp), %rdi
callq    __Unwind_Resume
LBB6_35:
Ltmp62:
movl    %edx, %ecx
movq    %rax, %rdi
movl    %ecx, -412(%rbp)        ## 4-byte Spill
callq    ___clang_call_terminate
.cfi_endproc
Leh_func_end6:
.section    __TEXT,__gcc_except_tab
.align    2
GCC_except_table6:
Lexception6:
.byte    255                     ## @LPStart Encoding = omit
.byte    155                     ## @TType Encoding = indirect pcrel sdata4
.asciz    "\253\201"              ## @TType base offset
.byte    3                       ## Call site Encoding = udata4
.ascii    "\234\001"              ## Call site table length
Lset10 = Ltmp33-Leh_func_begin6         ## >> Call Site 1 <<
.long    Lset10
Lset11 = Ltmp34-Ltmp33                  ##   Call between Ltmp33 and Ltmp34
.long    Lset11
Lset12 = Ltmp56-Leh_func_begin6         ##     jumps to Ltmp56
.long    Lset12
.byte    5                       ##   On action: 3
Lset13 = Ltmp35-Leh_func_begin6         ## >> Call Site 2 <<
.long    Lset13
Lset14 = Ltmp36-Ltmp35                  ##   Call between Ltmp35 and Ltmp36
.long    Lset14
Lset15 = Ltmp51-Leh_func_begin6         ##     jumps to Ltmp51
.long    Lset15
.byte    5                       ##   On action: 3
Lset16 = Ltmp37-Leh_func_begin6         ## >> Call Site 3 <<
.long    Lset16
Lset17 = Ltmp40-Ltmp37                  ##   Call between Ltmp37 and Ltmp40
.long    Lset17
Lset18 = Ltmp41-Leh_func_begin6         ##     jumps to Ltmp41
.long    Lset18
.byte    3                       ##   On action: 2
Lset19 = Ltmp42-Leh_func_begin6         ## >> Call Site 4 <<
.long    Lset19
Lset20 = Ltmp43-Ltmp42                  ##   Call between Ltmp42 and Ltmp43
.long    Lset20
Lset21 = Ltmp44-Leh_func_begin6         ##     jumps to Ltmp44
.long    Lset21
.byte    7                       ##   On action: 4
Lset22 = Ltmp45-Leh_func_begin6         ## >> Call Site 5 <<
.long    Lset22
Lset23 = Ltmp50-Ltmp45                  ##   Call between Ltmp45 and Ltmp50
.long    Lset23
Lset24 = Ltmp51-Leh_func_begin6         ##     jumps to Ltmp51
.long    Lset24
.byte    5                       ##   On action: 3
Lset25 = Ltmp52-Leh_func_begin6         ## >> Call Site 6 <<
.long    Lset25
Lset26 = Ltmp53-Ltmp52                  ##   Call between Ltmp52 and Ltmp53
.long    Lset26
Lset27 = Ltmp62-Leh_func_begin6         ##     jumps to Ltmp62
.long    Lset27
.byte    5                       ##   On action: 3
Lset28 = Ltmp54-Leh_func_begin6         ## >> Call Site 7 <<
.long    Lset28
Lset29 = Ltmp55-Ltmp54                  ##   Call between Ltmp54 and Ltmp55
.long    Lset29
Lset30 = Ltmp56-Leh_func_begin6         ##     jumps to Ltmp56
.long    Lset30
.byte    5                       ##   On action: 3
Lset31 = Ltmp55-Leh_func_begin6         ## >> Call Site 8 <<
.long    Lset31
Lset32 = Ltmp57-Ltmp55                  ##   Call between Ltmp55 and Ltmp57
.long    Lset32
.long    0                       ##     has no landing pad
.byte    0                       ##   On action: cleanup
Lset33 = Ltmp57-Leh_func_begin6         ## >> Call Site 9 <<
.long    Lset33
Lset34 = Ltmp58-Ltmp57                  ##   Call between Ltmp57 and Ltmp58
.long    Lset34
Lset35 = Ltmp59-Leh_func_begin6         ##     jumps to Ltmp59
.long    Lset35
.byte    0                       ##   On action: cleanup
Lset36 = Ltmp58-Leh_func_begin6         ## >> Call Site 10 <<
.long    Lset36
Lset37 = Ltmp60-Ltmp58                  ##   Call between Ltmp58 and Ltmp60
.long    Lset37
.long    0                       ##     has no landing pad
.byte    0                       ##   On action: cleanup
Lset38 = Ltmp60-Leh_func_begin6         ## >> Call Site 11 <<
.long    Lset38
Lset39 = Ltmp61-Ltmp60                  ##   Call between Ltmp60 and Ltmp61
.long    Lset39
Lset40 = Ltmp62-Leh_func_begin6         ##     jumps to Ltmp62
.long    Lset40
.byte    5                       ##   On action: 3
Lset41 = Ltmp61-Leh_func_begin6         ## >> Call Site 12 <<
.long    Lset41
Lset42 = Leh_func_end6-Ltmp61           ##   Call between Ltmp61 and Leh_func_end6
.long    Lset42
.long    0                       ##     has no landing pad
.byte    0                       ##   On action: cleanup
.byte    0                       ## >> Action Record 1 <<
##   Cleanup
.byte    0                       ##   No further actions
.byte    1                       ## >> Action Record 2 <<
##   Catch TypeInfo 1
.byte    125                     ##   Continue to action 1
.byte    1                       ## >> Action Record 3 <<
##   Catch TypeInfo 1
.byte    0                       ##   No further actions
.byte    1                       ## >> Action Record 4 <<
##   Catch TypeInfo 1
.byte    125                     ##   Continue to action 3
## >> Catch TypeInfos <<
.long    0                       ## TypeInfo 1
.align    2

.section    __TEXT,__textcoal_nt,coalesced,pure_instructions
.private_extern    __ZNSt3__116__pad_and_outputIcNS_11char_traitsIcEEEENS_19ostreambuf_iteratorIT_T0_EES6_PKS4_S8_S8_RNS_8ios_baseES4_
.globl    __ZNSt3__116__pad_and_outputIcNS_11char_traitsIcEEEENS_19ostreambuf_iteratorIT_T0_EES6_PKS4_S8_S8_RNS_8ios_baseES4_
.weak_def_can_be_hidden    __ZNSt3__116__pad_and_outputIcNS_11char_traitsIcEEEENS_19ostreambuf_iteratorIT_T0_EES6_PKS4_S8_S8_RNS_8ios_baseES4_
.align    4, 0x90
__ZNSt3__116__pad_and_outputIcNS_11char_traitsIcEEEENS_19ostreambuf_iteratorIT_T0_EES6_PKS4_S8_S8_RNS_8ios_baseES4_: ## @_ZNSt3__116__pad_and_outputIcNS_11char_traitsIcEEEENS_19ostreambuf_iteratorIT_T0_EES6_PKS4_S8_S8_RNS_8ios_baseES4_
.cfi_startproc
.cfi_personality 155, ___gxx_personality_v0
Leh_func_begin7:
.cfi_lsda 16, Lexception7
## BB#0:
pushq    %rbp
Ltmp76:
.cfi_def_cfa_offset 16
Ltmp77:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp78:
.cfi_def_cfa_register %rbp
subq    $720, %rsp              ## imm = 0x2D0
movb    %r9b, %al
leaq    -552(%rbp), %r10
leaq    -488(%rbp), %r11
movq    %rdi, -504(%rbp)
movq    %rsi, -512(%rbp)
movq    %rdx, -520(%rbp)
movq    %rcx, -528(%rbp)
movq    %r8, -536(%rbp)
movb    %al, -537(%rbp)
movq    -504(%rbp), %rcx
movq    %r11, -472(%rbp)
movq    $-1, -480(%rbp)
movq    -472(%rbp), %rdx
movq    -480(%rbp), %rsi
movq    %rdx, -456(%rbp)
movq    %rsi, -464(%rbp)
movq    -456(%rbp), %rdx
movq    $0, (%rdx)
movq    -488(%rbp), %rdx
movq    %rdx, -552(%rbp)
movq    %r10, -448(%rbp)
cmpq    $0, %rcx
jne    LBB7_2
## BB#1:
movq    -504(%rbp), %rax
movq    %rax, -496(%rbp)
jmp    LBB7_29
LBB7_2:
movq    -528(%rbp), %rax
movq    -512(%rbp), %rcx
subq    %rcx, %rax
movq    %rax, -560(%rbp)
movq    -536(%rbp), %rax
movq    %rax, -344(%rbp)
movq    -344(%rbp), %rax
movq    24(%rax), %rax
movq    %rax, -568(%rbp)
movq    -568(%rbp), %rax
cmpq    -560(%rbp), %rax
jle    LBB7_4
## BB#3:
movq    -560(%rbp), %rax
movq    -568(%rbp), %rcx
subq    %rax, %rcx
movq    %rcx, -568(%rbp)
jmp    LBB7_5
LBB7_4:
movq    $0, -568(%rbp)
LBB7_5:
movq    -520(%rbp), %rax
movq    -512(%rbp), %rcx
subq    %rcx, %rax
movq    %rax, -576(%rbp)
cmpq    $0, -576(%rbp)
jle    LBB7_9
## BB#6:
movq    -504(%rbp), %rax
movq    -512(%rbp), %rcx
movq    -576(%rbp), %rdx
movq    %rax, -248(%rbp)
movq    %rcx, -256(%rbp)
movq    %rdx, -264(%rbp)
movq    -248(%rbp), %rax
movq    (%rax), %rcx
movq    96(%rcx), %rcx
movq    -256(%rbp), %rsi
movq    -264(%rbp), %rdx
movq    %rax, %rdi
callq    *%rcx
cmpq    -576(%rbp), %rax
je    LBB7_8
## BB#7:
leaq    -584(%rbp), %rax
leaq    -240(%rbp), %rcx
movq    %rcx, -224(%rbp)
movq    $-1, -232(%rbp)
movq    -224(%rbp), %rcx
movq    -232(%rbp), %rdx
movq    %rcx, -208(%rbp)
movq    %rdx, -216(%rbp)
movq    -208(%rbp), %rcx
movq    $0, (%rcx)
movq    -240(%rbp), %rcx
movq    %rcx, -584(%rbp)
movq    %rax, -8(%rbp)
movq    $0, -504(%rbp)
movq    -504(%rbp), %rax
movq    %rax, -496(%rbp)
jmp    LBB7_29
LBB7_8:
jmp    LBB7_9
LBB7_9:
cmpq    $0, -568(%rbp)
jle    LBB7_24
## BB#10:
leaq    -608(%rbp), %rax
movq    -568(%rbp), %rcx
movb    -537(%rbp), %dl
movq    %rax, -72(%rbp)
movq    %rcx, -80(%rbp)
movb    %dl, -81(%rbp)
movq    -72(%rbp), %rax
movq    -80(%rbp), %rcx
movb    -81(%rbp), %dl
movq    %rax, -48(%rbp)
movq    %rcx, -56(%rbp)
movb    %dl, -57(%rbp)
movq    -48(%rbp), %rax
movq    %rax, -40(%rbp)
movq    -40(%rbp), %rcx
movq    %rcx, -32(%rbp)
movq    -32(%rbp), %rcx
movq    %rcx, -24(%rbp)
movq    -24(%rbp), %rcx
movq    %rcx, -16(%rbp)
movq    -56(%rbp), %rsi
movq    %rax, %rdi
movsbl    -57(%rbp), %edx
callq    __ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEmc
leaq    -608(%rbp), %rax
movq    -504(%rbp), %rcx
movq    %rax, -200(%rbp)
movq    -200(%rbp), %rax
movq    %rax, -192(%rbp)
movq    -192(%rbp), %rax
movq    %rax, -184(%rbp)
movq    -184(%rbp), %rsi
movq    %rsi, -176(%rbp)
movq    -176(%rbp), %rsi
movq    %rsi, -168(%rbp)
movq    -168(%rbp), %rsi
movzbl    (%rsi), %edx
andl    $1, %edx
cmpl    $0, %edx
movq    %rcx, -656(%rbp)        ## 8-byte Spill
movq    %rax, -664(%rbp)        ## 8-byte Spill
je    LBB7_12
## BB#11:
movq    -664(%rbp), %rax        ## 8-byte Reload
movq    %rax, -120(%rbp)
movq    -120(%rbp), %rcx
movq    %rcx, -112(%rbp)
movq    -112(%rbp), %rcx
movq    %rcx, -104(%rbp)
movq    -104(%rbp), %rcx
movq    16(%rcx), %rcx
movq    %rcx, -672(%rbp)        ## 8-byte Spill
jmp    LBB7_13
LBB7_12:
movq    -664(%rbp), %rax        ## 8-byte Reload
movq    %rax, -160(%rbp)
movq    -160(%rbp), %rcx
movq    %rcx, -152(%rbp)
movq    -152(%rbp), %rcx
movq    %rcx, -144(%rbp)
movq    -144(%rbp), %rcx
addq    $1, %rcx
movq    %rcx, -136(%rbp)
movq    -136(%rbp), %rcx
movq    %rcx, -128(%rbp)
movq    -128(%rbp), %rcx
movq    %rcx, -672(%rbp)        ## 8-byte Spill
LBB7_13:                                ## %_ZNKSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE4dataEv.exit
movq    -672(%rbp), %rax        ## 8-byte Reload
movq    %rax, -96(%rbp)
movq    -568(%rbp), %rcx
movq    -656(%rbp), %rdx        ## 8-byte Reload
movq    %rdx, -272(%rbp)
movq    %rax, -280(%rbp)
movq    %rcx, -288(%rbp)
movq    -272(%rbp), %rax
movq    (%rax), %rsi
movq    96(%rsi), %rsi
movq    -280(%rbp), %rdi
Ltmp68:
movq    %rdi, -680(%rbp)        ## 8-byte Spill
movq    %rax, %rdi
movq    -680(%rbp), %rax        ## 8-byte Reload
movq    %rsi, -688(%rbp)        ## 8-byte Spill
movq    %rax, %rsi
movq    %rcx, %rdx
movq    -688(%rbp), %rcx        ## 8-byte Reload
callq    *%rcx
Ltmp69:
movq    %rax, -696(%rbp)        ## 8-byte Spill
jmp    LBB7_14
LBB7_14:                                ## %_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5sputnEPKcl.exit
jmp    LBB7_15
LBB7_15:
movq    -696(%rbp), %rax        ## 8-byte Reload
cmpq    -568(%rbp), %rax
je    LBB7_20
## BB#16:
leaq    -328(%rbp), %rax
movq    %rax, -312(%rbp)
movq    $-1, -320(%rbp)
movq    -312(%rbp), %rax
movq    -320(%rbp), %rcx
movq    %rax, -296(%rbp)
movq    %rcx, -304(%rbp)
movq    -296(%rbp), %rax
movq    $0, (%rax)
movq    -328(%rbp), %rax
movq    %rax, -704(%rbp)        ## 8-byte Spill
## BB#17:
leaq    -632(%rbp), %rax
movq    -704(%rbp), %rcx        ## 8-byte Reload
movq    %rcx, -632(%rbp)
movq    %rax, -336(%rbp)
## BB#18:
movq    $0, -504(%rbp)
movq    -504(%rbp), %rax
movq    %rax, -496(%rbp)
movl    $1, -636(%rbp)
jmp    LBB7_21
LBB7_19:
Ltmp70:
movl    %edx, %ecx
movq    %rax, -616(%rbp)
movl    %ecx, -620(%rbp)
Ltmp71:
leaq    -608(%rbp), %rdi
callq    __ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEED1Ev
Ltmp72:
jmp    LBB7_23
LBB7_20:
movl    $0, -636(%rbp)
LBB7_21:
leaq    -608(%rbp), %rdi
callq    __ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEED1Ev
movl    -636(%rbp), %eax
movl    %eax, %ecx
subl    $1, %ecx
movl    %eax, -708(%rbp)        ## 4-byte Spill
movl    %ecx, -712(%rbp)        ## 4-byte Spill
je    LBB7_29
jmp    LBB7_33
LBB7_33:
movl    -708(%rbp), %eax        ## 4-byte Reload
testl    %eax, %eax
jne    LBB7_32
jmp    LBB7_22
LBB7_22:
jmp    LBB7_24
LBB7_23:
jmp    LBB7_30
LBB7_24:
movq    -528(%rbp), %rax
movq    -520(%rbp), %rcx
subq    %rcx, %rax
movq    %rax, -576(%rbp)
cmpq    $0, -576(%rbp)
jle    LBB7_28
## BB#25:
movq    -504(%rbp), %rax
movq    -520(%rbp), %rcx
movq    -576(%rbp), %rdx
movq    %rax, -352(%rbp)
movq    %rcx, -360(%rbp)
movq    %rdx, -368(%rbp)
movq    -352(%rbp), %rax
movq    (%rax), %rcx
movq    96(%rcx), %rcx
movq    -360(%rbp), %rsi
movq    -368(%rbp), %rdx
movq    %rax, %rdi
callq    *%rcx
cmpq    -576(%rbp), %rax
je    LBB7_27
## BB#26:
leaq    -648(%rbp), %rax
leaq    -408(%rbp), %rcx
movq    %rcx, -392(%rbp)
movq    $-1, -400(%rbp)
movq    -392(%rbp), %rcx
movq    -400(%rbp), %rdx
movq    %rcx, -376(%rbp)
movq    %rdx, -384(%rbp)
movq    -376(%rbp), %rcx
movq    $0, (%rcx)
movq    -408(%rbp), %rcx
movq    %rcx, -648(%rbp)
movq    %rax, -416(%rbp)
movq    $0, -504(%rbp)
movq    -504(%rbp), %rax
movq    %rax, -496(%rbp)
jmp    LBB7_29
LBB7_27:
jmp    LBB7_28
LBB7_28:
movq    -536(%rbp), %rax
movq    %rax, -424(%rbp)
movq    $0, -432(%rbp)
movq    -424(%rbp), %rax
movq    24(%rax), %rcx
movq    %rcx, -440(%rbp)
movq    -432(%rbp), %rcx
movq    %rcx, 24(%rax)
movq    -504(%rbp), %rax
movq    %rax, -496(%rbp)
LBB7_29:
movq    -496(%rbp), %rax
addq    $720, %rsp              ## imm = 0x2D0
popq    %rbp
retq
LBB7_30:
movq    -616(%rbp), %rdi
callq    __Unwind_Resume
LBB7_31:
Ltmp73:
movl    %edx, %ecx
movq    %rax, %rdi
movl    %ecx, -716(%rbp)        ## 4-byte Spill
callq    ___clang_call_terminate
LBB7_32:
.cfi_endproc
Leh_func_end7:
.section    __TEXT,__gcc_except_tab
.align    2
GCC_except_table7:
Lexception7:
.byte    255                     ## @LPStart Encoding = omit
.byte    155                     ## @TType Encoding = indirect pcrel sdata4
.asciz    "\274"                  ## @TType base offset
.byte    3                       ## Call site Encoding = udata4
.byte    52                      ## Call site table length
Lset43 = Leh_func_begin7-Leh_func_begin7 ## >> Call Site 1 <<
.long    Lset43
Lset44 = Ltmp68-Leh_func_begin7         ##   Call between Leh_func_begin7 and Ltmp68
.long    Lset44
.long    0                       ##     has no landing pad
.byte    0                       ##   On action: cleanup
Lset45 = Ltmp68-Leh_func_begin7         ## >> Call Site 2 <<
.long    Lset45
Lset46 = Ltmp69-Ltmp68                  ##   Call between Ltmp68 and Ltmp69
.long    Lset46
Lset47 = Ltmp70-Leh_func_begin7         ##     jumps to Ltmp70
.long    Lset47
.byte    0                       ##   On action: cleanup
Lset48 = Ltmp71-Leh_func_begin7         ## >> Call Site 3 <<
.long    Lset48
Lset49 = Ltmp72-Ltmp71                  ##   Call between Ltmp71 and Ltmp72
.long    Lset49
Lset50 = Ltmp73-Leh_func_begin7         ##     jumps to Ltmp73
.long    Lset50
.byte    1                       ##   On action: 1
Lset51 = Ltmp72-Leh_func_begin7         ## >> Call Site 4 <<
.long    Lset51
Lset52 = Leh_func_end7-Ltmp72           ##   Call between Ltmp72 and Leh_func_end7
.long    Lset52
.long    0                       ##     has no landing pad
.byte    0                       ##   On action: cleanup
.byte    1                       ## >> Action Record 1 <<
##   Catch TypeInfo 1
.byte    0                       ##   No further actions
## >> Catch TypeInfos <<
.long    0                       ## TypeInfo 1
.align    2

.section    __TEXT,__textcoal_nt,coalesced,pure_instructions
.globl    __ZN6MatrixC2Ed
.weak_def_can_be_hidden    __ZN6MatrixC2Ed
.align    4, 0x90
__ZN6MatrixC2Ed:                        ## @_ZN6MatrixC2Ed
.cfi_startproc
## BB#0:
pushq    %rbp
Ltmp81:
.cfi_def_cfa_offset 16
Ltmp82:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp83:
.cfi_def_cfa_register %rbp
subq    $64, %rsp
movq    __ZNSt3__14coutE@GOTPCREL(%rip), %rax
leaq    L_.str2(%rip), %rsi
movq    %rdi, -24(%rbp)
movsd    %xmm0, -32(%rbp)
movq    -24(%rbp), %rdi
movq    %rdi, -48(%rbp)         ## 8-byte Spill
movq    %rax, %rdi
callq    __ZNSt3__1lsINS_11char_traitsIcEEEERNS_13basic_ostreamIcT_EES6_PKc
leaq    __ZNSt3__14endlIcNS_11char_traitsIcEEEERNS_13basic_ostreamIT_T0_EES7_(%rip), %rsi
movq    %rax, -8(%rbp)
movq    %rsi, -16(%rbp)
movq    -8(%rbp), %rdi
callq    *-16(%rbp)
movl    $0, -36(%rbp)
movq    %rax, -56(%rbp)         ## 8-byte Spill
LBB8_1:                                 ## =>This Loop Header: Depth=1
##     Child Loop BB8_3 Depth 2
cmpl    $10, -36(%rbp)
jge    LBB8_8
## BB#2:                                ##   in Loop: Header=BB8_1 Depth=1
movl    $0, -40(%rbp)
LBB8_3:                                 ##   Parent Loop BB8_1 Depth=1
## =>  This Inner Loop Header: Depth=2
cmpl    $10, -40(%rbp)
jge    LBB8_6
## BB#4:                                ##   in Loop: Header=BB8_3 Depth=2
movsd    -32(%rbp), %xmm0
movslq    -40(%rbp), %rax
movslq    -36(%rbp), %rcx
imulq    $80, %rcx, %rcx
movq    -48(%rbp), %rdx         ## 8-byte Reload
addq    %rcx, %rdx
movsd    %xmm0, (%rdx,%rax,8)
## BB#5:                                ##   in Loop: Header=BB8_3 Depth=2
movl    -40(%rbp), %eax
addl    $1, %eax
movl    %eax, -40(%rbp)
jmp    LBB8_3
LBB8_6:                                 ##   in Loop: Header=BB8_1 Depth=1
jmp    LBB8_7
LBB8_7:                                 ##   in Loop: Header=BB8_1 Depth=1
movl    -36(%rbp), %eax
addl    $1, %eax
movl    %eax, -36(%rbp)
jmp    LBB8_1
LBB8_8:
addq    $64, %rsp
popq    %rbp
retq
.cfi_endproc

.section    __TEXT,__cstring,cstring_literals
L_.str:                                 ## @.str
.asciz    "Address of sum: "

L_.str1:                                ## @.str1
.asciz    "Address of c:   "

L_.str2:                                ## @.str2
.asciz    "Matrix::Matrix()"

.section    __TEXT,__eh_frame,coalesced,no_toc+strip_static_syms+live_support

.subsections_via_symbols

而这时简化版的代码（突出返回临时对象）：

#include <iostream>
#include <cstring>

using namespace std;

class Matrix
{
public:
explicit Matrix()  {  }
friend const Matrix operator+(const Matrix&, const Matrix&);
};

const Matrix operator+(const Matrix& arg1, const Matrix& arg2)
{
Matrix sum;
return sum;
}

int main()
{
Matrix a,  b;
Matrix c = (a + b);

return 0;
}

汇编：

.section    __TEXT,__text,regular,pure_instructions
.globl    __ZplRK6MatrixS1_
.align    4, 0x90
__ZplRK6MatrixS1_:                      ## @_ZplRK6MatrixS1_
.cfi_startproc
## BB#0:
pushq    %rbp
Ltmp2:
.cfi_def_cfa_offset 16
Ltmp3:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp4:
.cfi_def_cfa_register %rbp
subq    $32, %rsp
leaq    -8(%rbp), %rax
movq    %rdi, -16(%rbp)
movq    %rsi, -24(%rbp)
movq    %rax, %rdi
callq    __ZN6MatrixC1Ev
addq    $32, %rsp
popq    %rbp
retq
.cfi_endproc

.section    __TEXT,__textcoal_nt,coalesced,pure_instructions
.globl    __ZN6MatrixC1Ev
.weak_def_can_be_hidden    __ZN6MatrixC1Ev
.align    4, 0x90
__ZN6MatrixC1Ev:                        ## @_ZN6MatrixC1Ev
.cfi_startproc
## BB#0:
pushq    %rbp
Ltmp7:
.cfi_def_cfa_offset 16
Ltmp8:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp9:
.cfi_def_cfa_register %rbp
subq    $16, %rsp
movq    %rdi, -8(%rbp)
movq    -8(%rbp), %rdi
callq    __ZN6MatrixC2Ev
addq    $16, %rsp
popq    %rbp
retq
.cfi_endproc

.section    __TEXT,__text,regular,pure_instructions
.globl    _main
.align    4, 0x90
_main:                                  ## @main
.cfi_startproc
## BB#0:
pushq    %rbp
Ltmp12:
.cfi_def_cfa_offset 16
Ltmp13:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp14:
.cfi_def_cfa_register %rbp
subq    $32, %rsp
leaq    -8(%rbp), %rdi
movl    $0, -4(%rbp)
callq    __ZN6MatrixC1Ev
leaq    -16(%rbp), %rdi
callq    __ZN6MatrixC1Ev
leaq    -8(%rbp), %rdi
leaq    -16(%rbp), %rsi
callq    __ZplRK6MatrixS1_
movl    $0, %eax
addq    $32, %rsp
popq    %rbp
retq
.cfi_endproc

.section    __TEXT,__textcoal_nt,coalesced,pure_instructions
.globl    __ZN6MatrixC2Ev
.weak_def_can_be_hidden    __ZN6MatrixC2Ev
.align    4, 0x90
__ZN6MatrixC2Ev:                        ## @_ZN6MatrixC2Ev
.cfi_startproc
## BB#0:
pushq    %rbp
Ltmp17:
.cfi_def_cfa_offset 16
Ltmp18:
.cfi_offset %rbp, -16
movq    %rsp, %rbp
Ltmp19:
.cfi_def_cfa_register %rbp
movq    %rdi, -8(%rbp)
popq    %rbp
retq
.cfi_endproc

.subsections_via_symbols