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comparison doc/disas_examples/arm.armhf.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 | 0fc22b5feac7 |
| children | fc614cb865c6 |
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| 496:da5232da6270 | 497:cb19b2fe2422 |
|---|---|
| 611 5c: e24bd004 sub sp, fp, #4 | 611 5c: e24bd004 sub sp, fp, #4 |
| 612 60: e8bd8800 pop {fp, pc} | 612 60: e8bd8800 pop {fp, pc} |
| 613 | 613 |
| 614 | 614 |
| 615 | 615 |
| 616 ; ---------- C++ trivial and non-trivial aggrs passed to C funcs ----------> | |
| 617 ; | |
| 618 ; struct Trivial { int a; }; | |
| 619 ; struct NonTrivial { int a; NonTrivial() : a(0) {} NonTrivial(const NonTrivial& rhs) : a(rhs.a) { } }; | |
| 620 ; | |
| 621 ; extern "C" { | |
| 622 ; | |
| 623 ; void f1(struct Trivial s) { } | |
| 624 ; void f2(struct NonTrivial s) { } | |
| 625 ; | |
| 626 ; void f() | |
| 627 ; { | |
| 628 ; struct Trivial t; | |
| 629 ; struct NonTrivial n; | |
| 630 ; int a=1; | |
| 631 ; a += 123; | |
| 632 ; f1(t); | |
| 633 ; a -= 123; | |
| 634 ; f2(n); | |
| 635 ; a -= 12; | |
| 636 ; } | |
| 637 ; } | |
| 638 | |
| 639 | |
| 640 | |
| 641 ; output from raspbian-11-armelhf w/ gcc 10.2.1 | |
| 642 | |
| 643 00000000 <f1>: | |
| 644 0: e52db004 push {fp} | |
| 645 4: e28db000 add fp, sp, #0 | |
| 646 8: e24dd00c sub sp, sp, #12 | |
| 647 c: e50b0008 str r0, [fp, #-8] | |
| 648 10: e1a00000 nop | |
| 649 14: e28bd000 add sp, fp, #0 | |
| 650 18: e49db004 pop {fp} | |
| 651 1c: e12fff1e bx lr | |
| 652 | |
| 653 00000020 <f2>: | |
| 654 20: e52db004 push {fp} | |
| 655 24: e28db000 add fp, sp, #0 | |
| 656 28: e24dd00c sub sp, sp, #12 | |
| 657 2c: e50b0008 str r0, [fp, #-8] | |
| 658 30: e1a00000 nop | |
| 659 34: e28bd000 add sp, fp, #0 | |
| 660 38: e49db004 pop {fp} | |
| 661 3c: e12fff1e bx lr | |
| 662 | |
| 663 00000040 <f>: | |
| 664 40: e92d4800 push {fp, lr} ; | | |
| 665 44: e28db004 add fp, sp, #4 ; | prolog | |
| 666 48: e24dd010 sub sp, sp, #16 ; / | |
| 667 4c: e24b3014 sub r3, fp, #20 ; \ | |
| 668 50: e1a00003 mov r0, r3 ; | this ptr (ptr to n's (NonTrivial) space) | |
| 669 54: ebfffffe bl 0 <_ZN10NonTrivialC1Ev> ; | NonTrivial::NonTrivial() / ctor | |
| 670 58: e3a03001 mov r3, #1 ; a = 1 | |
| 671 5c: e50b3008 str r3, [fp, #-8] ; | | |
| 672 60: e51b3008 ldr r3, [fp, #-8] ; | a += 123 | |
| 673 64: e283307b add r3, r3, #123 ; | | |
| 674 68: e50b3008 str r3, [fp, #-8] ; | | |
| 675 6c: e51b0010 ldr r0, [fp, #-16] ; f1 arg 0 (struct Trivial), via reg as small struct | |
| 676 70: ebfffffe bl 0 <f1> ; call f1(struct Trivial) | |
| 677 74: e51b3008 ldr r3, [fp, #-8] ; | | |
| 678 78: e243307b sub r3, r3, #123 ; | a -= 123 | |
| 679 7c: e50b3008 str r3, [fp, #-8] ; / | |
| 680 80: e24b2014 sub r2, fp, #20 ; \ | |
| 681 84: e24b300c sub r3, fp, #12 ; | | |
| 682 88: e1a01002 mov r1, r2 ; | ptr to n | |
| 683 8c: e1a00003 mov r0, r3 ; | copy n ptr to dest of copy of n | |
| 684 90: ebfffffe bl 0 <_ZN10NonTrivialC1ERKS_> ; / NonTrivial::NonTrivial(const NonTrivial&) / copy ctor | |
| 685 94: e24b300c sub r3, fp, #12 ; \ | |
| 686 98: e1a00003 mov r0, r3 ; | f2 arg 0 (ptr to copy of struct NonTrivial), via ptr as non-trivial | |
| 687 9c: ebfffffe bl 20 <f2> ; call f2(struct NonTrivial) | |
| 688 a0: e51b3008 ldr r3, [fp, #-8] ; | | |
| 689 a4: e243300c sub r3, r3, #12 ; | a -= 12 | |
| 690 a8: e50b3008 str r3, [fp, #-8] ; / | |
| 691 ac: e1a00000 nop ; \ | |
| 692 b0: e24bd004 sub sp, fp, #4 ; | epilog | |
| 693 b4: e8bd8800 pop {fp, pc} ; | | |
| 694 | |
| 695 ; ... snip, removed code of ctor and copy ctor ... | |
| 696 | |
| 697 | |
| 698 | |
| 616 ; vim: ft=asm68k | 699 ; vim: ft=asm68k |
| 617 | 700 |