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comparison doc/disas_examples/x86.cdecl.disas @ 497:cb19b2fe2422
- more disas examples to check behaviour of passing C++ non-trivial aggregates by value; they all behave the same, calling the copy ctor first, passing a pointer then
| author | Tassilo Philipp |
|---|---|
| date | Wed, 23 Mar 2022 15:24:31 +0100 |
| parents | 4e84d6faed54 |
| children | fc614cb865c6 |
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| 496:da5232da6270 | 497:cb19b2fe2422 |
|---|---|
| 631 ret 0 ; | | 631 ret 0 ; | |
| 632 _main ENDP | 632 _main ENDP |
| 633 | 633 |
| 634 | 634 |
| 635 | 635 |
| 636 ; ---------- C++ trivial and non-trivial aggrs passed to C funcs ----------> | |
| 637 ; | |
| 638 ; struct Trivial { int a; }; | |
| 639 ; struct NonTrivial { int a; NonTrivial() : a(0) {} NonTrivial(const NonTrivial& rhs) : a(rhs.a) { } }; | |
| 640 ; | |
| 641 ; extern "C" { | |
| 642 ; | |
| 643 ; void f1(struct Trivial s) { } | |
| 644 ; void f2(struct NonTrivial s) { } | |
| 645 ; | |
| 646 ; void f() | |
| 647 ; { | |
| 648 ; struct Trivial t; | |
| 649 ; struct NonTrivial n; | |
| 650 ; int a=1; | |
| 651 ; a += 123; | |
| 652 ; f1(t); | |
| 653 ; a -= 123; | |
| 654 ; f2(n); | |
| 655 ; a -= 12; | |
| 656 ; } | |
| 657 ; } | |
| 658 | |
| 659 | |
| 660 | |
| 661 ; output from openbsd-4.0-x86 w/ gcc 3.3.5 (propolice) | |
| 662 | |
| 663 1c0005a0 <f1>: | |
| 664 1c0005a0: 55 push %ebp | |
| 665 1c0005a1: 89 e5 mov %esp,%ebp | |
| 666 1c0005a3: c9 leave | |
| 667 1c0005a4: c3 ret | |
| 668 1c0005a5: 90 nop | |
| 669 | |
| 670 1c0005a6 <f2>: | |
| 671 1c0005a6: 55 push %ebp | |
| 672 1c0005a7: 89 e5 mov %esp,%ebp | |
| 673 1c0005a9: c9 leave | |
| 674 1c0005aa: c3 ret | |
| 675 1c0005ab: 90 nop | |
| 676 | |
| 677 1c0005ac <f>: | |
| 678 1c0005ac: 55 push %ebp ; | |
| 679 1c0005ad: 89 e5 mov %esp,%ebp ; | |
| 680 1c0005af: 83 ec 48 sub $0x48,%esp ; | |
| 681 1c0005b2: 83 ec 0c sub $0xc,%esp ; | |
| 682 1c0005b5: 8d 45 d8 lea 0xffffffd8(%ebp),%eax ; | |
| 683 1c0005b8: 50 push %eax ; | |
| 684 1c0005b9: e8 8e 00 00 00 call 1c00064c <_ZN10NonTrivialC1Ev> ; NonTrivial::NonTrivial() / ctor | |
| 685 1c0005be: 83 c4 10 add $0x10,%esp ; | |
| 686 1c0005c1: c7 45 d4 01 00 00 00 movl $0x1,0xffffffd4(%ebp) ; | |
| 687 1c0005c8: 8d 45 d4 lea 0xffffffd4(%ebp),%eax ; | |
| 688 1c0005cb: 83 00 7b addl $0x7b,(%eax) ; | |
| 689 1c0005ce: 83 ec 0c sub $0xc,%esp ; | |
| 690 1c0005d1: 8b 45 f4 mov 0xfffffff4(%ebp),%eax ; | |
| 691 1c0005d4: 50 push %eax ; | |
| 692 1c0005d5: e8 c6 ff ff ff call 1c0005a0 <f1> ; call f1(struct Trivial) | |
| 693 1c0005da: 83 c4 10 add $0x10,%esp ; | |
| 694 1c0005dd: 8d 45 d4 lea 0xffffffd4(%ebp),%eax ; | |
| 695 1c0005e0: 83 28 7b subl $0x7b,(%eax) ; | |
| 696 1c0005e3: 83 ec 0c sub $0xc,%esp ; | |
| 697 1c0005e6: 83 ec 0c sub $0xc,%esp ; | |
| 698 1c0005e9: 8d 45 d8 lea 0xffffffd8(%ebp),%eax ; | | | |
| 699 1c0005ec: 50 push %eax ; | / ptr to n | |
| 700 1c0005ed: 8d 45 b8 lea 0xffffffb8(%ebp),%eax ; | \ | |
| 701 1c0005f0: 50 push %eax ; | copy n | ptr to dest of copy of n | |
| 702 1c0005f1: e8 64 00 00 00 call 1c00065a <_ZN10NonTrivialC1ERKS_> ; | NonTrivial::NonTrivial(const NonTrivial&) / copy ctor | |
| 703 1c0005f6: 83 c4 14 add $0x14,%esp ; | |
| 704 1c0005f9: 8d 45 b8 lea 0xffffffb8(%ebp),%eax ; | | |
| 705 1c0005fc: 50 push %eax ; | f2 arg 0 (ptr to copy of struct NonTrivial), via ptr as non-trivial | |
| 706 1c0005fd: e8 a4 ff ff ff call 1c0005a6 <f2> ; call f2(struct NonTrivial) | |
| 707 1c000602: 83 c4 10 add $0x10,%esp ; | |
| 708 1c000605: 8d 45 d4 lea 0xffffffd4(%ebp),%eax ; | |
| 709 1c000608: 83 28 0c subl $0xc,(%eax) ; | |
| 710 1c00060b: c9 leave ; | |
| 711 1c00060c: c3 ret ; | |
| 712 1c00060d: 90 nop ; | |
| 713 | |
| 714 ; ... snip, removed code of ctor and copy ctor ... | |
| 715 | |
| 716 | |
| 717 | |
| 636 ; vim: ft=asm | 718 ; vim: ft=asm |
| 637 | 719 |