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[section Object Code]
The object code generated by modern template metaprogramming can be quite
good, in large part due to the drastic reduction in the amount of
metaprogramming necessary to determine the result type -- you can just write
`auto` in front of nearly every function template.
For example, here is a function using code from the Map Assign example:
std::map<std::string, int> make_map_with_boost_yap ()
{
return map_list_of
("<", 1)
("<=",2)
(">", 3)
(">=",4)
("=", 5)
("<>",6)
;
}
and here is the x86-64 assembly it produces with Clang 4.0 with `-O3` on Linux
(all the assembly below was produced with the same compiler and build
settings):
0x00000000004012e0 <+0>: push %rbx
0x00000000004012e1 <+1>: sub $0x70,%rsp
0x00000000004012e5 <+5>: mov %rdi,%rbx
0x00000000004012e8 <+8>: mov $0x405f60,%eax
0x00000000004012ed <+13>: movq %rax,%xmm0
0x00000000004012f2 <+18>: mov $0x608251,%eax
0x00000000004012f7 <+23>: movq %rax,%xmm1
0x00000000004012fc <+28>: punpcklqdq %xmm0,%xmm1
0x0000000000401300 <+32>: movdqa %xmm1,(%rsp)
0x0000000000401305 <+37>: movl $0x1,0x10(%rsp)
0x000000000040130d <+45>: movq $0x405f62,0x18(%rsp)
0x0000000000401316 <+54>: movl $0x2,0x20(%rsp)
0x000000000040131e <+62>: movq $0x405f69,0x28(%rsp)
0x0000000000401327 <+71>: movl $0x3,0x30(%rsp)
0x000000000040132f <+79>: movq $0x405f65,0x38(%rsp)
0x0000000000401338 <+88>: movl $0x4,0x40(%rsp)
0x0000000000401340 <+96>: movq $0x405f63,0x48(%rsp)
0x0000000000401349 <+105>: movl $0x5,0x50(%rsp)
0x0000000000401351 <+113>: movq $0x405f68,0x58(%rsp)
0x000000000040135a <+122>: movl $0x6,0x60(%rsp)
0x0000000000401362 <+130>: mov %rsp,%rsi
0x0000000000401365 <+133>: callq 0x4029f0 <_ZNK16map_list_of_exprILN5boost3yap9expr_kindE46ENS0_4hana5tupleIJS_ILS2_46ENS4_IJS_ILS2_46ENS4_IJS_ILS2_46ENS4_IJS_ILS2_46ENS4_IJS_ILS2_46ENS4_IJS_ILS2_0ENS4_IJPS_ILS2_1ENS4_IJ15map_list_of_tagEEEEEEEES_ILS2_1ENS4_IJPKcEEEES_ILS2_1ENS4_IJiEEEEEEEESE_SG_EEEESE_SG_EEEESE_SG_EEEESE_SG_EEEESE_SG_EEEEcvNSt3__13mapIT_T0_T1_NST_9allocatorINST_4pairIKSV_SW_EEEEEEINST_12basic_stringIcNST_11char_traitsIcEENSY_IcEEEEiNST_4lessIS19_EEEEv>
0x000000000040136a <+138>: mov %rbx,%rax
0x000000000040136d <+141>: add $0x70,%rsp
0x0000000000401371 <+145>: pop %rbx
0x0000000000401372 <+146>: retq
Not bad. By contrast, here is the Boost.Assign version of the same function:
std::map<std::string, int> make_map_with_boost_assign ()
{
return boost::assign::map_list_of
("<", 1)
("<=",2)
(">", 3)
(">=",4)
("=", 5)
("<>",6)
;
}
and the assembly:
0x0000000000401380 <+0>: push %r15
0x0000000000401382 <+2>: push %r14
0x0000000000401384 <+4>: push %r13
0x0000000000401386 <+6>: push %r12
0x0000000000401388 <+8>: push %rbx
0x0000000000401389 <+9>: sub $0x40,%rsp
0x000000000040138d <+13>: mov %rdi,%r14
0x0000000000401390 <+16>: movl $0x1,0x3c(%rsp)
0x0000000000401398 <+24>: lea 0x8(%rsp),%rdi
0x000000000040139d <+29>: lea 0x3c(%rsp),%rdx
0x00000000004013a2 <+34>: mov $0x405f60,%esi
0x00000000004013a7 <+39>: callq 0x402ae0 <boost::assign::map_list_of<char [2], int>(char const (&) [2], int const&)>
0x00000000004013ac <+44>: mov 0x10(%rsp),%rax
0x00000000004013b1 <+49>: mov 0x18(%rsp),%rcx
0x00000000004013b6 <+54>: mov %rcx,%rdx
0x00000000004013b9 <+57>: sub %rax,%rdx
0x00000000004013bc <+60>: shl $0x5,%rdx
0x00000000004013c0 <+64>: dec %rdx
0x00000000004013c3 <+67>: xor %edi,%edi
0x00000000004013c5 <+69>: cmp %rax,%rcx
0x00000000004013c8 <+72>: cmovne %rdx,%rdi
0x00000000004013cc <+76>: mov 0x28(%rsp),%rsi
0x00000000004013d1 <+81>: mov 0x30(%rsp),%rdx
0x00000000004013d6 <+86>: lea (%rdx,%rsi,1),%rbx
0x00000000004013da <+90>: cmp %rbx,%rdi
0x00000000004013dd <+93>: jne 0x4013fd <make_map_with_boost_assign()+125>
0x00000000004013df <+95>: lea 0x8(%rsp),%rdi
0x00000000004013e4 <+100>: callq 0x404f30 <std::__1::deque<std::__1::pair<char const*, int>, std::__1::allocator<std::__1::pair<char const*, int> > >::__add_back_capacity()>
0x00000000004013e9 <+105>: mov 0x30(%rsp),%rdx
0x00000000004013ee <+110>: mov 0x28(%rsp),%rsi
0x00000000004013f3 <+115>: mov 0x10(%rsp),%rax
0x00000000004013f8 <+120>: mov 0x18(%rsp),%rcx
0x00000000004013fd <+125>: cmp %rax,%rcx
0x0000000000401400 <+128>: je 0x401419 <make_map_with_boost_assign()+153>
0x0000000000401402 <+130>: add %rsi,%rdx
0x0000000000401405 <+133>: mov %rdx,%rsi
0x0000000000401408 <+136>: shr $0x8,%rsi
0x000000000040140c <+140>: movzbl %dl,%ecx
0x000000000040140f <+143>: shl $0x4,%rcx
0x0000000000401413 <+147>: add (%rax,%rsi,8),%rcx
0x0000000000401417 <+151>: jmp 0x40141b <make_map_with_boost_assign()+155>
0x0000000000401419 <+153>: xor %ecx,%ecx
0x000000000040141b <+155>: movq $0x405f62,(%rcx)
0x0000000000401422 <+162>: movl $0x2,0x8(%rcx)
0x0000000000401429 <+169>: mov 0x30(%rsp),%rdi
0x000000000040142e <+174>: lea 0x1(%rdi),%rcx
0x0000000000401432 <+178>: mov %rcx,0x30(%rsp)
0x0000000000401437 <+183>: mov 0x10(%rsp),%rax
0x000000000040143c <+188>: mov 0x18(%rsp),%rdx
0x0000000000401441 <+193>: mov %rdx,%rsi
0x0000000000401444 <+196>: sub %rax,%rsi
0x0000000000401447 <+199>: shl $0x5,%rsi
0x000000000040144b <+203>: dec %rsi
0x000000000040144e <+206>: xor %ebx,%ebx
0x0000000000401450 <+208>: cmp %rax,%rdx
0x0000000000401453 <+211>: cmovne %rsi,%rbx
0x0000000000401457 <+215>: mov 0x28(%rsp),%rsi
0x000000000040145c <+220>: lea 0x1(%rsi,%rdi,1),%rdi
0x0000000000401461 <+225>: cmp %rdi,%rbx
0x0000000000401464 <+228>: jne 0x401484 <make_map_with_boost_assign()+260>
0x0000000000401466 <+230>: lea 0x8(%rsp),%rdi
0x000000000040146b <+235>: callq 0x404f30 <std::__1::deque<std::__1::pair<char const*, int>, std::__1::allocator<std::__1::pair<char const*, int> > >::__add_back_capacity()>
0x0000000000401470 <+240>: mov 0x30(%rsp),%rcx
0x0000000000401475 <+245>: mov 0x28(%rsp),%rsi
0x000000000040147a <+250>: mov 0x10(%rsp),%rax
0x000000000040147f <+255>: mov 0x18(%rsp),%rdx
0x0000000000401484 <+260>: cmp %rax,%rdx
0x0000000000401487 <+263>: je 0x4014a0 <make_map_with_boost_assign()+288>
0x0000000000401489 <+265>: add %rsi,%rcx
0x000000000040148c <+268>: mov %rcx,%rdx
0x000000000040148f <+271>: shr $0x8,%rdx
0x0000000000401493 <+275>: movzbl %cl,%ecx
0x0000000000401496 <+278>: shl $0x4,%rcx
0x000000000040149a <+282>: add (%rax,%rdx,8),%rcx
0x000000000040149e <+286>: jmp 0x4014a2 <make_map_with_boost_assign()+290>
0x00000000004014a0 <+288>: xor %ecx,%ecx
0x00000000004014a2 <+290>: movq $0x405f69,(%rcx)
0x00000000004014a9 <+297>: movl $0x3,0x8(%rcx)
0x00000000004014b0 <+304>: mov 0x30(%rsp),%rdi
0x00000000004014b5 <+309>: lea 0x1(%rdi),%rcx
0x00000000004014b9 <+313>: mov %rcx,0x30(%rsp)
0x00000000004014be <+318>: mov 0x10(%rsp),%rax
0x00000000004014c3 <+323>: mov 0x18(%rsp),%rdx
0x00000000004014c8 <+328>: mov %rdx,%rsi
0x00000000004014cb <+331>: sub %rax,%rsi
0x00000000004014ce <+334>: shl $0x5,%rsi
0x00000000004014d2 <+338>: dec %rsi
0x00000000004014d5 <+341>: xor %ebx,%ebx
0x00000000004014d7 <+343>: cmp %rax,%rdx
0x00000000004014da <+346>: cmovne %rsi,%rbx
0x00000000004014de <+350>: mov 0x28(%rsp),%rsi
0x00000000004014e3 <+355>: lea 0x1(%rsi,%rdi,1),%rdi
0x00000000004014e8 <+360>: cmp %rdi,%rbx
0x00000000004014eb <+363>: jne 0x40150b <make_map_with_boost_assign()+395>
0x00000000004014ed <+365>: lea 0x8(%rsp),%rdi
0x00000000004014f2 <+370>: callq 0x404f30 <std::__1::deque<std::__1::pair<char const*, int>, std::__1::allocator<std::__1::pair<char const*, int> > >::__add_back_capacity()>
0x00000000004014f7 <+375>: mov 0x30(%rsp),%rcx
0x00000000004014fc <+380>: mov 0x28(%rsp),%rsi
0x0000000000401501 <+385>: mov 0x10(%rsp),%rax
0x0000000000401506 <+390>: mov 0x18(%rsp),%rdx
0x000000000040150b <+395>: cmp %rax,%rdx
0x000000000040150e <+398>: je 0x401527 <make_map_with_boost_assign()+423>
0x0000000000401510 <+400>: add %rsi,%rcx
0x0000000000401513 <+403>: mov %rcx,%rdx
0x0000000000401516 <+406>: shr $0x8,%rdx
0x000000000040151a <+410>: movzbl %cl,%ecx
0x000000000040151d <+413>: shl $0x4,%rcx
0x0000000000401521 <+417>: add (%rax,%rdx,8),%rcx
0x0000000000401525 <+421>: jmp 0x401529 <make_map_with_boost_assign()+425>
0x0000000000401527 <+423>: xor %ecx,%ecx
0x0000000000401529 <+425>: movq $0x405f65,(%rcx)
0x0000000000401530 <+432>: movl $0x4,0x8(%rcx)
0x0000000000401537 <+439>: mov 0x30(%rsp),%rdi
0x000000000040153c <+444>: lea 0x1(%rdi),%rcx
0x0000000000401540 <+448>: mov %rcx,0x30(%rsp)
0x0000000000401545 <+453>: mov 0x10(%rsp),%rax
0x000000000040154a <+458>: mov 0x18(%rsp),%rdx
0x000000000040154f <+463>: mov %rdx,%rsi
0x0000000000401552 <+466>: sub %rax,%rsi
0x0000000000401555 <+469>: shl $0x5,%rsi
0x0000000000401559 <+473>: dec %rsi
0x000000000040155c <+476>: xor %ebx,%ebx
0x000000000040155e <+478>: cmp %rax,%rdx
0x0000000000401561 <+481>: cmovne %rsi,%rbx
0x0000000000401565 <+485>: mov 0x28(%rsp),%rsi
0x000000000040156a <+490>: lea 0x1(%rsi,%rdi,1),%rdi
0x000000000040156f <+495>: cmp %rdi,%rbx
0x0000000000401572 <+498>: jne 0x401592 <make_map_with_boost_assign()+530>
0x0000000000401574 <+500>: lea 0x8(%rsp),%rdi
0x0000000000401579 <+505>: callq 0x404f30 <std::__1::deque<std::__1::pair<char const*, int>, std::__1::allocator<std::__1::pair<char const*, int> > >::__add_back_capacity()>
0x000000000040157e <+510>: mov 0x30(%rsp),%rcx
0x0000000000401583 <+515>: mov 0x28(%rsp),%rsi
0x0000000000401588 <+520>: mov 0x10(%rsp),%rax
0x000000000040158d <+525>: mov 0x18(%rsp),%rdx
0x0000000000401592 <+530>: cmp %rax,%rdx
0x0000000000401595 <+533>: je 0x4015ae <make_map_with_boost_assign()+558>
0x0000000000401597 <+535>: add %rsi,%rcx
0x000000000040159a <+538>: mov %rcx,%rdx
0x000000000040159d <+541>: shr $0x8,%rdx
0x00000000004015a1 <+545>: movzbl %cl,%ecx
0x00000000004015a4 <+548>: shl $0x4,%rcx
0x00000000004015a8 <+552>: add (%rax,%rdx,8),%rcx
0x00000000004015ac <+556>: jmp 0x4015b0 <make_map_with_boost_assign()+560>
0x00000000004015ae <+558>: xor %ecx,%ecx
0x00000000004015b0 <+560>: movq $0x405f63,(%rcx)
0x00000000004015b7 <+567>: movl $0x5,0x8(%rcx)
0x00000000004015be <+574>: mov 0x30(%rsp),%rdi
0x00000000004015c3 <+579>: lea 0x1(%rdi),%rcx
0x00000000004015c7 <+583>: mov %rcx,0x30(%rsp)
0x00000000004015cc <+588>: mov 0x10(%rsp),%rax
0x00000000004015d1 <+593>: mov 0x18(%rsp),%rdx
0x00000000004015d6 <+598>: mov %rdx,%rsi
0x00000000004015d9 <+601>: sub %rax,%rsi
0x00000000004015dc <+604>: shl $0x5,%rsi
0x00000000004015e0 <+608>: dec %rsi
0x00000000004015e3 <+611>: xor %ebx,%ebx
0x00000000004015e5 <+613>: cmp %rax,%rdx
0x00000000004015e8 <+616>: cmovne %rsi,%rbx
0x00000000004015ec <+620>: mov 0x28(%rsp),%rsi
0x00000000004015f1 <+625>: lea 0x1(%rsi,%rdi,1),%rdi
0x00000000004015f6 <+630>: cmp %rdi,%rbx
0x00000000004015f9 <+633>: jne 0x401619 <make_map_with_boost_assign()+665>
0x00000000004015fb <+635>: lea 0x8(%rsp),%rdi
0x0000000000401600 <+640>: callq 0x404f30 <std::__1::deque<std::__1::pair<char const*, int>, std::__1::allocator<std::__1::pair<char const*, int> > >::__add_back_capacity()>
0x0000000000401605 <+645>: mov 0x30(%rsp),%rcx
0x000000000040160a <+650>: mov 0x28(%rsp),%rsi
0x000000000040160f <+655>: mov 0x10(%rsp),%rax
0x0000000000401614 <+660>: mov 0x18(%rsp),%rdx
0x0000000000401619 <+665>: cmp %rax,%rdx
0x000000000040161c <+668>: je 0x401635 <make_map_with_boost_assign()+693>
0x000000000040161e <+670>: add %rsi,%rcx
0x0000000000401621 <+673>: mov %rcx,%rdx
0x0000000000401624 <+676>: shr $0x8,%rdx
0x0000000000401628 <+680>: movzbl %cl,%ecx
0x000000000040162b <+683>: shl $0x4,%rcx
0x000000000040162f <+687>: add (%rax,%rdx,8),%rcx
0x0000000000401633 <+691>: jmp 0x401637 <make_map_with_boost_assign()+695>
0x0000000000401635 <+693>: xor %ecx,%ecx
0x0000000000401637 <+695>: movq $0x405f68,(%rcx)
0x000000000040163e <+702>: movl $0x6,0x8(%rcx)
0x0000000000401645 <+709>: mov 0x30(%rsp),%rcx
0x000000000040164a <+714>: inc %rcx
0x000000000040164d <+717>: mov %rcx,0x30(%rsp)
0x0000000000401652 <+722>: mov 0x10(%rsp),%rax
0x0000000000401657 <+727>: mov 0x28(%rsp),%rdx
0x000000000040165c <+732>: mov %rdx,%rsi
0x000000000040165f <+735>: shr $0x8,%rsi
0x0000000000401663 <+739>: lea (%rax,%rsi,8),%r12
0x0000000000401667 <+743>: cmp %rax,0x18(%rsp)
0x000000000040166c <+748>: je 0x401691 <make_map_with_boost_assign()+785>
0x000000000040166e <+750>: movzbl %dl,%ebx
0x0000000000401671 <+753>: shl $0x4,%rbx
0x0000000000401675 <+757>: add (%r12),%rbx
0x0000000000401679 <+761>: add %rdx,%rcx
0x000000000040167c <+764>: mov %rcx,%rdx
0x000000000040167f <+767>: shr $0x8,%rdx
0x0000000000401683 <+771>: movzbl %cl,%r13d
0x0000000000401687 <+775>: shl $0x4,%r13
0x000000000040168b <+779>: add (%rax,%rdx,8),%r13
0x000000000040168f <+783>: jmp 0x401696 <make_map_with_boost_assign()+790>
0x0000000000401691 <+785>: xor %ebx,%ebx
0x0000000000401693 <+787>: xor %r13d,%r13d
0x0000000000401696 <+790>: lea 0x8(%r14),%r15
0x000000000040169a <+794>: xorps %xmm0,%xmm0
0x000000000040169d <+797>: movups %xmm0,0x8(%r14)
0x00000000004016a2 <+802>: mov %r15,(%r14)
0x00000000004016a5 <+805>: cmp %r13,%rbx
0x00000000004016a8 <+808>: jne 0x4016c5 <make_map_with_boost_assign()+837>
0x00000000004016aa <+810>: jmp 0x4016e8 <make_map_with_boost_assign()+872>
0x00000000004016ac <+812>: mov 0x8(%r12),%rbx
0x00000000004016b1 <+817>: add $0x8,%r12
0x00000000004016b5 <+821>: data32 nopw %cs:0x0(%rax,%rax,1)
0x00000000004016c0 <+832>: cmp %r13,%rbx
0x00000000004016c3 <+835>: je 0x4016e8 <make_map_with_boost_assign()+872>
0x00000000004016c5 <+837>: mov %r14,%rdi
0x00000000004016c8 <+840>: mov %r15,%rsi
0x00000000004016cb <+843>: mov %rbx,%rdx
0x00000000004016ce <+846>: callq 0x405470 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_hint_unique_impl<std::__1::pair<char const*, int>&>(std::__1::__tree_const_iterator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__tree_node<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, void*>*, long>, std::__1::pair<char const*, int>&)>
0x00000000004016d3 <+851>: add $0x10,%rbx
0x00000000004016d7 <+855>: mov %rbx,%rax
0x00000000004016da <+858>: sub (%r12),%rax
0x00000000004016de <+862>: cmp $0x1000,%rax
0x00000000004016e4 <+868>: jne 0x4016c0 <make_map_with_boost_assign()+832>
0x00000000004016e6 <+870>: jmp 0x4016ac <make_map_with_boost_assign()+812>
0x00000000004016e8 <+872>: lea 0x8(%rsp),%rdi
0x00000000004016ed <+877>: callq 0x402bf0 <std::__1::__deque_base<std::__1::pair<char const*, int>, std::__1::allocator<std::__1::pair<char const*, int> > >::~__deque_base()>
0x00000000004016f2 <+882>: mov %r14,%rax
0x00000000004016f5 <+885>: add $0x40,%rsp
0x00000000004016f9 <+889>: pop %rbx
0x00000000004016fa <+890>: pop %r12
0x00000000004016fc <+892>: pop %r13
0x00000000004016fe <+894>: pop %r14
0x0000000000401700 <+896>: pop %r15
0x0000000000401702 <+898>: retq
0x0000000000401703 <+899>: jmp 0x40170b <make_map_with_boost_assign()+907>
0x0000000000401705 <+901>: jmp 0x40170b <make_map_with_boost_assign()+907>
0x0000000000401707 <+903>: jmp 0x40170b <make_map_with_boost_assign()+907>
0x0000000000401709 <+905>: jmp 0x40170b <make_map_with_boost_assign()+907>
0x000000000040170b <+907>: mov %rax,%rbx
0x000000000040170e <+910>: jmp 0x40171f <make_map_with_boost_assign()+927>
0x0000000000401710 <+912>: mov %rax,%rbx
0x0000000000401713 <+915>: mov 0x8(%r14),%rsi
0x0000000000401717 <+919>: mov %r14,%rdi
0x000000000040171a <+922>: callq 0x402d40 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::destroy(std::__1::__tree_node<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, void*>*)>
0x000000000040171f <+927>: lea 0x8(%rsp),%rdi
0x0000000000401724 <+932>: callq 0x402bf0 <std::__1::__deque_base<std::__1::pair<char const*, int>, std::__1::allocator<std::__1::pair<char const*, int> > >::~__deque_base()>
0x0000000000401729 <+937>: mov %rbx,%rdi
0x000000000040172c <+940>: callq 0x4011c0 <_Unwind_Resume@plt>
Heh.
For reference, here is how you might do it "manually":
std::map<std::string, int> make_map_manually ()
{
std::map<std::string, int> retval;
retval.emplace("<", 1);
retval.emplace("<=",2);
retval.emplace(">", 3);
retval.emplace(">=",4);
retval.emplace("=", 5);
retval.emplace("<>",6);
return retval;
}
and the assembly:
0x0000000000401740 <+0>: push %r14
0x0000000000401742 <+2>: push %rbx
0x0000000000401743 <+3>: push %rax
0x0000000000401744 <+4>: mov %rdi,%rbx
0x0000000000401747 <+7>: lea 0x8(%rbx),%rax
0x000000000040174b <+11>: xorps %xmm0,%xmm0
0x000000000040174e <+14>: movups %xmm0,0x8(%rbx)
0x0000000000401752 <+18>: mov %rax,(%rbx)
0x0000000000401755 <+21>: movl $0x1,0x4(%rsp)
0x000000000040175d <+29>: lea 0x4(%rsp),%rdx
0x0000000000401762 <+34>: mov $0x406d40,%esi
0x0000000000401767 <+39>: callq 0x4065e0 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_unique_impl<char const (&) [2], int>(char const (&) [2], int&&)>
0x000000000040176c <+44>: movl $0x2,0x4(%rsp)
0x0000000000401774 <+52>: lea 0x4(%rsp),%rdx
0x0000000000401779 <+57>: mov $0x406d42,%esi
0x000000000040177e <+62>: mov %rbx,%rdi
0x0000000000401781 <+65>: callq 0x4067d0 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_unique_impl<char const (&) [3], int>(char const (&) [3], int&&)>
0x0000000000401786 <+70>: movl $0x3,0x4(%rsp)
0x000000000040178e <+78>: lea 0x4(%rsp),%rdx
0x0000000000401793 <+83>: mov $0x406d49,%esi
0x0000000000401798 <+88>: mov %rbx,%rdi
0x000000000040179b <+91>: callq 0x4065e0 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_unique_impl<char const (&) [2], int>(char const (&) [2], int&&)>
0x00000000004017a0 <+96>: movl $0x4,0x4(%rsp)
0x00000000004017a8 <+104>: lea 0x4(%rsp),%rdx
0x00000000004017ad <+109>: mov $0x406d45,%esi
0x00000000004017b2 <+114>: mov %rbx,%rdi
0x00000000004017b5 <+117>: callq 0x4067d0 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_unique_impl<char const (&) [3], int>(char const (&) [3], int&&)>
0x00000000004017ba <+122>: movl $0x5,0x4(%rsp)
0x00000000004017c2 <+130>: lea 0x4(%rsp),%rdx
0x00000000004017c7 <+135>: mov $0x406d43,%esi
0x00000000004017cc <+140>: mov %rbx,%rdi
0x00000000004017cf <+143>: callq 0x4065e0 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_unique_impl<char const (&) [2], int>(char const (&) [2], int&&)>
0x00000000004017d4 <+148>: movl $0x6,0x4(%rsp)
0x00000000004017dc <+156>: lea 0x4(%rsp),%rdx
0x00000000004017e1 <+161>: mov $0x406d48,%esi
0x00000000004017e6 <+166>: mov %rbx,%rdi
0x00000000004017e9 <+169>: callq 0x4067d0 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_unique_impl<char const (&) [3], int>(char const (&) [3], int&&)>
0x00000000004017ee <+174>: mov %rbx,%rax
0x00000000004017f1 <+177>: add $0x8,%rsp
0x00000000004017f5 <+181>: pop %rbx
0x00000000004017f6 <+182>: pop %r14
0x00000000004017f8 <+184>: retq
0x00000000004017f9 <+185>: jmp 0x401803 <make_map_manually()+195>
0x00000000004017fb <+187>: jmp 0x401803 <make_map_manually()+195>
0x00000000004017fd <+189>: jmp 0x401803 <make_map_manually()+195>
0x00000000004017ff <+191>: jmp 0x401803 <make_map_manually()+195>
0x0000000000401801 <+193>: jmp 0x401803 <make_map_manually()+195>
0x0000000000401803 <+195>: mov %rax,%r14
0x0000000000401806 <+198>: mov 0x8(%rbx),%rsi
0x000000000040180a <+202>: mov %rbx,%rdi
0x000000000040180d <+205>: callq 0x403740 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::destroy(std::__1::__tree_node<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, void*>*)>
0x0000000000401812 <+210>: mov %r14,%rdi
0x0000000000401815 <+213>: callq 0x4011c0 <_Unwind_Resume@plt>
Finally, here is the same map created from an initializer list:
std::map<std::string, int> make_map_inializer_list ()
{
std::map<std::string, int> retval = {
{"<", 1},
{"<=",2},
{">", 3},
{">=",4},
{"=", 5},
{"<>",6}
};
return retval;
}
and it's assembly is:
0x0000000000401820 <+0>: push %r15
0x0000000000401822 <+2>: push %r14
0x0000000000401824 <+4>: push %rbx
0x0000000000401825 <+5>: sub $0xc0,%rsp
0x000000000040182c <+12>: mov %rdi,%r15
0x000000000040182f <+15>: xorps %xmm0,%xmm0
0x0000000000401832 <+18>: movaps %xmm0,(%rsp)
0x0000000000401836 <+22>: movq $0x0,0x10(%rsp)
0x000000000040183f <+31>: movb $0x2,(%rsp)
0x0000000000401843 <+35>: movb $0x3c,0x1(%rsp)
0x0000000000401848 <+40>: movb $0x0,0x2(%rsp)
0x000000000040184d <+45>: movl $0x1,0x18(%rsp)
0x0000000000401855 <+53>: movaps %xmm0,0x20(%rsp)
0x000000000040185a <+58>: movq $0x0,0x30(%rsp)
0x0000000000401863 <+67>: movb $0x4,0x20(%rsp)
0x0000000000401868 <+72>: movw $0x3d3c,0x21(%rsp)
0x000000000040186f <+79>: movb $0x0,0x23(%rsp)
0x0000000000401874 <+84>: movl $0x2,0x38(%rsp)
0x000000000040187c <+92>: movaps %xmm0,0x40(%rsp)
0x0000000000401881 <+97>: movq $0x0,0x50(%rsp)
0x000000000040188a <+106>: movb $0x2,0x40(%rsp)
0x000000000040188f <+111>: movb $0x3e,0x41(%rsp)
0x0000000000401894 <+116>: movb $0x0,0x42(%rsp)
0x0000000000401899 <+121>: movl $0x3,0x58(%rsp)
0x00000000004018a1 <+129>: movaps %xmm0,0x60(%rsp)
0x00000000004018a6 <+134>: movq $0x0,0x70(%rsp)
0x00000000004018af <+143>: movb $0x4,0x60(%rsp)
0x00000000004018b4 <+148>: movw $0x3d3e,0x61(%rsp)
0x00000000004018bb <+155>: movb $0x0,0x63(%rsp)
0x00000000004018c0 <+160>: movl $0x4,0x78(%rsp)
0x00000000004018c8 <+168>: movaps %xmm0,0x80(%rsp)
0x00000000004018d0 <+176>: movq $0x0,0x90(%rsp)
0x00000000004018dc <+188>: movb $0x2,0x80(%rsp)
0x00000000004018e4 <+196>: movb $0x3d,0x81(%rsp)
0x00000000004018ec <+204>: movb $0x0,0x82(%rsp)
0x00000000004018f4 <+212>: movl $0x5,0x98(%rsp)
0x00000000004018ff <+223>: movaps %xmm0,0xa0(%rsp)
0x0000000000401907 <+231>: movq $0x0,0xb0(%rsp)
0x0000000000401913 <+243>: movb $0x4,0xa0(%rsp)
0x000000000040191b <+251>: movw $0x3e3c,0xa1(%rsp)
0x0000000000401925 <+261>: movb $0x0,0xa3(%rsp)
0x000000000040192d <+269>: movl $0x6,0xb8(%rsp)
0x0000000000401938 <+280>: lea 0x8(%r15),%rbx
0x000000000040193c <+284>: movups %xmm0,0x8(%r15)
0x0000000000401941 <+289>: mov %rbx,(%r15)
0x0000000000401944 <+292>: mov %rsp,%rdx
0x0000000000401947 <+295>: mov %rbx,%rsi
0x000000000040194a <+298>: mov %rdx,%rcx
0x000000000040194d <+301>: callq 0x404e40 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_hint_unique_key_args<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&>(std::__1::__tree_const_iterator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__tree_node<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, void*>*, long>, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&)>
0x0000000000401952 <+306>: lea 0x20(%rsp),%rdx
0x0000000000401957 <+311>: mov %r15,%rdi
0x000000000040195a <+314>: mov %rbx,%rsi
0x000000000040195d <+317>: mov %rdx,%rcx
0x0000000000401960 <+320>: callq 0x404e40 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_hint_unique_key_args<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&>(std::__1::__tree_const_iterator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__tree_node<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, void*>*, long>, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&)>
0x0000000000401965 <+325>: lea 0x40(%rsp),%rdx
0x000000000040196a <+330>: mov %r15,%rdi
0x000000000040196d <+333>: mov %rbx,%rsi
0x0000000000401970 <+336>: mov %rdx,%rcx
0x0000000000401973 <+339>: callq 0x404e40 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_hint_unique_key_args<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&>(std::__1::__tree_const_iterator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__tree_node<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, void*>*, long>, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&)>
0x0000000000401978 <+344>: lea 0x60(%rsp),%rdx
0x000000000040197d <+349>: mov %r15,%rdi
0x0000000000401980 <+352>: mov %rbx,%rsi
0x0000000000401983 <+355>: mov %rdx,%rcx
0x0000000000401986 <+358>: callq 0x404e40 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_hint_unique_key_args<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&>(std::__1::__tree_const_iterator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__tree_node<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, void*>*, long>, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&)>
0x000000000040198b <+363>: lea 0x80(%rsp),%rdx
0x0000000000401993 <+371>: mov %r15,%rdi
0x0000000000401996 <+374>: mov %rbx,%rsi
0x0000000000401999 <+377>: mov %rdx,%rcx
0x000000000040199c <+380>: callq 0x404e40 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_hint_unique_key_args<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&>(std::__1::__tree_const_iterator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__tree_node<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, void*>*, long>, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&)>
0x00000000004019a1 <+385>: lea 0xa0(%rsp),%rdx
0x00000000004019a9 <+393>: mov %r15,%rdi
0x00000000004019ac <+396>: mov %rbx,%rsi
0x00000000004019af <+399>: mov %rdx,%rcx
0x00000000004019b2 <+402>: callq 0x404e40 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::__emplace_hint_unique_key_args<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&>(std::__1::__tree_const_iterator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__tree_node<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, void*>*, long>, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const, int> const&)>
0x00000000004019b7 <+407>: testb $0x1,0xa0(%rsp)
0x00000000004019bf <+415>: je 0x4019ce <make_map_inializer_list()+430>
0x00000000004019c1 <+417>: mov 0xb0(%rsp),%rdi
0x00000000004019c9 <+425>: callq 0x401070 <_ZdlPv@plt>
0x00000000004019ce <+430>: testb $0x1,0x80(%rsp)
0x00000000004019d6 <+438>: je 0x4019e5 <make_map_inializer_list()+453>
0x00000000004019d8 <+440>: mov 0x90(%rsp),%rdi
0x00000000004019e0 <+448>: callq 0x401070 <_ZdlPv@plt>
0x00000000004019e5 <+453>: testb $0x1,0x60(%rsp)
0x00000000004019ea <+458>: je 0x4019f6 <make_map_inializer_list()+470>
0x00000000004019ec <+460>: mov 0x70(%rsp),%rdi
0x00000000004019f1 <+465>: callq 0x401070 <_ZdlPv@plt>
0x00000000004019f6 <+470>: testb $0x1,0x40(%rsp)
0x00000000004019fb <+475>: je 0x401a07 <make_map_inializer_list()+487>
0x00000000004019fd <+477>: mov 0x50(%rsp),%rdi
0x0000000000401a02 <+482>: callq 0x401070 <_ZdlPv@plt>
0x0000000000401a07 <+487>: testb $0x1,0x20(%rsp)
0x0000000000401a0c <+492>: je 0x401a18 <make_map_inializer_list()+504>
0x0000000000401a0e <+494>: mov 0x30(%rsp),%rdi
0x0000000000401a13 <+499>: callq 0x401070 <_ZdlPv@plt>
0x0000000000401a18 <+504>: testb $0x1,(%rsp)
0x0000000000401a1c <+508>: je 0x401a28 <make_map_inializer_list()+520>
0x0000000000401a1e <+510>: mov 0x10(%rsp),%rdi
0x0000000000401a23 <+515>: callq 0x401070 <_ZdlPv@plt>
0x0000000000401a28 <+520>: mov %r15,%rax
0x0000000000401a2b <+523>: add $0xc0,%rsp
0x0000000000401a32 <+530>: pop %rbx
0x0000000000401a33 <+531>: pop %r14
0x0000000000401a35 <+533>: pop %r15
0x0000000000401a37 <+535>: retq
0x0000000000401a38 <+536>: mov %rax,%r14
0x0000000000401a3b <+539>: mov 0x8(%r15),%rsi
0x0000000000401a3f <+543>: mov %r15,%rdi
0x0000000000401a42 <+546>: callq 0x404300 <std::__1::__tree<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::__map_value_compare<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, true>, std::__1::allocator<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int> > >::destroy(std::__1::__tree_node<std::__1::__value_type<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int>, void*>*)>
0x0000000000401a47 <+551>: testb $0x1,0xa0(%rsp)
0x0000000000401a4f <+559>: je 0x401a5e <make_map_inializer_list()+574>
0x0000000000401a51 <+561>: mov 0xb0(%rsp),%rdi
0x0000000000401a59 <+569>: callq 0x401070 <_ZdlPv@plt>
0x0000000000401a5e <+574>: testb $0x1,0x80(%rsp)
0x0000000000401a66 <+582>: je 0x401a75 <make_map_inializer_list()+597>
0x0000000000401a68 <+584>: mov 0x90(%rsp),%rdi
0x0000000000401a70 <+592>: callq 0x401070 <_ZdlPv@plt>
0x0000000000401a75 <+597>: testb $0x1,0x60(%rsp)
0x0000000000401a7a <+602>: je 0x401a86 <make_map_inializer_list()+614>
0x0000000000401a7c <+604>: mov 0x70(%rsp),%rdi
0x0000000000401a81 <+609>: callq 0x401070 <_ZdlPv@plt>
0x0000000000401a86 <+614>: testb $0x1,0x40(%rsp)
0x0000000000401a8b <+619>: je 0x401a97 <make_map_inializer_list()+631>
0x0000000000401a8d <+621>: mov 0x50(%rsp),%rdi
0x0000000000401a92 <+626>: callq 0x401070 <_ZdlPv@plt>
0x0000000000401a97 <+631>: testb $0x1,0x20(%rsp)
0x0000000000401a9c <+636>: je 0x401aa8 <make_map_inializer_list()+648>
0x0000000000401a9e <+638>: mov 0x30(%rsp),%rdi
0x0000000000401aa3 <+643>: callq 0x401070 <_ZdlPv@plt>
0x0000000000401aa8 <+648>: testb $0x1,(%rsp)
0x0000000000401aac <+652>: je 0x401ab8 <make_map_inializer_list()+664>
0x0000000000401aae <+654>: mov 0x10(%rsp),%rdi
0x0000000000401ab3 <+659>: callq 0x401070 <_ZdlPv@plt>
0x0000000000401ab8 <+664>: mov %r14,%rdi
0x0000000000401abb <+667>: callq 0x4011c0 <_Unwind_Resume@plt>
A bit surprisingly, _yap_'s approach produces the smallest assembly.
However, that is not the whole story. Benchmarking these four functions with
Google Benchmark yields these results:
[table Runtimes of Different Map Constructions
[Function] [Time (ns)]
[[make_map_with_boost_yap()] [1285]]
[[make_map_with_boost_assign()] [1459]]
[[make_map_manually()] [985]]
[[make_map_inializer_list()] [954]]
]
The _yap_-based implementation finishes in the middle of the pack, even though
it has the smallest code size.
In general, the expression trees produced by _yap_ get evaluated down to
something close to the hand-written equivalent. There is an abstraction
penalty, but it is small for reasonably-sized expressions. Somewhere between
35 and 45 terminals in an arithmetic-only expression, Clang 4.0 can no longer
inline the entire expression, and poorer code results (including uninlined
function calls).
[endsect]
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