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comparison doc/disas_examples/arm.atpcs_arm.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 |
|---|---|
| 747 f0: 40a00000 .word 0x40a00000 | 747 f0: 40a00000 .word 0x40a00000 |
| 748 f4: 00000000 .word 0x00000000 | 748 f4: 00000000 .word 0x00000000 |
| 749 | 749 |
| 750 | 750 |
| 751 | 751 |
| 752 ; ---------- C++ trivial and non-trivial aggrs passed to C funcs ----------> | |
| 753 ; | |
| 754 ; struct Trivial { int a; }; | |
| 755 ; struct NonTrivial { int a; NonTrivial() : a(0) {} NonTrivial(const NonTrivial& rhs) : a(rhs.a) { } }; | |
| 756 ; | |
| 757 ; extern "C" { | |
| 758 ; | |
| 759 ; void f1(struct Trivial s) { } | |
| 760 ; void f2(struct NonTrivial s) { } | |
| 761 ; | |
| 762 ; void f() | |
| 763 ; { | |
| 764 ; struct Trivial t; | |
| 765 ; struct NonTrivial n; | |
| 766 ; int a=1; | |
| 767 ; a += 123; | |
| 768 ; f1(t); | |
| 769 ; a -= 123; | |
| 770 ; f2(n); | |
| 771 ; a -= 12; | |
| 772 ; } | |
| 773 ; } | |
| 774 | |
| 775 | |
| 776 | |
| 777 ; output from debian-6.0.8-armel w/ gcc 4.4.5 | |
| 778 | |
| 779 00000000 <f1>: | |
| 780 0: e52db004 push {fp} | |
| 781 4: e28db000 add fp, sp, #0 | |
| 782 8: e24dd00c sub sp, sp, #12 | |
| 783 c: e50b0008 str r0, [fp, #-8] | |
| 784 10: e28bd000 add sp, fp, #0 | |
| 785 14: e8bd0800 pop {fp} | |
| 786 18: e12fff1e bx lr | |
| 787 | |
| 788 0000001c <f2>: | |
| 789 1c: e52db004 push {fp} | |
| 790 20: e28db000 add fp, sp, #0 | |
| 791 24: e24dd00c sub sp, sp, #12 | |
| 792 28: e50b0008 str r0, [fp, #-8] | |
| 793 2c: e28bd000 add sp, fp, #0 | |
| 794 30: e8bd0800 pop {fp} | |
| 795 34: e12fff1e bx lr | |
| 796 | |
| 797 00000038 <f>: | |
| 798 38: e92d4800 push {fp, lr} ; | | |
| 799 3c: e28db004 add fp, sp, #4 ; | prolog | |
| 800 40: e24dd010 sub sp, sp, #16 ; / | |
| 801 44: e24b3014 sub r3, fp, #20 ; \ | |
| 802 48: e1a00003 mov r0, r3 ; | this ptr (ptr to n's (NonTrivial) space) | |
| 803 4c: ebfffffe bl 0 <_ZN10NonTrivialC1Ev> ; | NonTrivial::NonTrivial() / ctor | |
| 804 50: e3a03001 mov r3, #1 ; a = 1 | |
| 805 54: e50b3008 str r3, [fp, #-8] ; | | |
| 806 58: e51b3008 ldr r3, [fp, #-8] ; | a += 123 | |
| 807 5c: e283307b add r3, r3, #123 ; | | |
| 808 60: e50b3008 str r3, [fp, #-8] ; | | |
| 809 64: e51b0010 ldr r0, [fp, #-16] ; f1 arg 0 (struct Trivial), via reg as small struct | |
| 810 68: ebfffffe bl 0 <f1> ; call f1(struct Trivial) | |
| 811 6c: e51b3008 ldr r3, [fp, #-8] ; | | |
| 812 70: e243307b sub r3, r3, #123 ; | a -= 123 | |
| 813 74: e50b3008 str r3, [fp, #-8] ; / | |
| 814 78: e24b200c sub r2, fp, #12 ; \ | |
| 815 7c: e24b3014 sub r3, fp, #20 ; | | |
| 816 80: e1a00002 mov r0, r2 ; | ptr to dest of copy of n | |
| 817 84: e1a01003 mov r1, r3 ; | copy n ptr to n | |
| 818 88: ebfffffe bl 0 <_ZN10NonTrivialC1ERKS_> ; / NonTrivial::NonTrivial(const NonTrivial&) / copy ctor | |
| 819 8c: e24b300c sub r3, fp, #12 ; \ | |
| 820 90: e1a00003 mov r0, r3 ; | f2 arg 0 (ptr to copy of struct NonTrivial), via ptr as non-trivial | |
| 821 94: ebfffffe bl 1c <f2> ; call f2(struct NonTrivial) | |
| 822 98: e51b3008 ldr r3, [fp, #-8] ; | | |
| 823 9c: e243300c sub r3, r3, #12 ; | a -= 12 | |
| 824 a0: e50b3008 str r3, [fp, #-8] ; / | |
| 825 a4: e24bd004 sub sp, fp, #4 ; \ | |
| 826 a8: e8bd4800 pop {fp, lr} ; | epilog | |
| 827 ac: e12fff1e bx lr ; | | |
| 828 | |
| 829 ; ... snip, removed code of ctor and copy ctor ... | |
| 830 | |
| 831 | |
| 832 | |
| 752 ; vim: ft=asm68k | 833 ; vim: ft=asm68k |
| 753 | 834 |