Mercurial > pub > dyncall > dyncall
diff 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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--- a/doc/disas_examples/x86.cdecl.disas Mon Mar 21 18:11:38 2022 +0100 +++ b/doc/disas_examples/x86.cdecl.disas Wed Mar 23 15:24:31 2022 +0100 @@ -633,5 +633,87 @@ +; ---------- C++ trivial and non-trivial aggrs passed to C funcs ----------> +; +; struct Trivial { int a; }; +; struct NonTrivial { int a; NonTrivial() : a(0) {} NonTrivial(const NonTrivial& rhs) : a(rhs.a) { } }; +; +; extern "C" { +; +; void f1(struct Trivial s) { } +; void f2(struct NonTrivial s) { } +; +; void f() +; { +; struct Trivial t; +; struct NonTrivial n; +; int a=1; +; a += 123; +; f1(t); +; a -= 123; +; f2(n); +; a -= 12; +; } +; } + + + +; output from openbsd-4.0-x86 w/ gcc 3.3.5 (propolice) + +1c0005a0 <f1>: +1c0005a0: 55 push %ebp +1c0005a1: 89 e5 mov %esp,%ebp +1c0005a3: c9 leave +1c0005a4: c3 ret +1c0005a5: 90 nop + +1c0005a6 <f2>: +1c0005a6: 55 push %ebp +1c0005a7: 89 e5 mov %esp,%ebp +1c0005a9: c9 leave +1c0005aa: c3 ret +1c0005ab: 90 nop + +1c0005ac <f>: +1c0005ac: 55 push %ebp ; +1c0005ad: 89 e5 mov %esp,%ebp ; +1c0005af: 83 ec 48 sub $0x48,%esp ; +1c0005b2: 83 ec 0c sub $0xc,%esp ; +1c0005b5: 8d 45 d8 lea 0xffffffd8(%ebp),%eax ; +1c0005b8: 50 push %eax ; +1c0005b9: e8 8e 00 00 00 call 1c00064c <_ZN10NonTrivialC1Ev> ; NonTrivial::NonTrivial() / ctor +1c0005be: 83 c4 10 add $0x10,%esp ; +1c0005c1: c7 45 d4 01 00 00 00 movl $0x1,0xffffffd4(%ebp) ; +1c0005c8: 8d 45 d4 lea 0xffffffd4(%ebp),%eax ; +1c0005cb: 83 00 7b addl $0x7b,(%eax) ; +1c0005ce: 83 ec 0c sub $0xc,%esp ; +1c0005d1: 8b 45 f4 mov 0xfffffff4(%ebp),%eax ; +1c0005d4: 50 push %eax ; +1c0005d5: e8 c6 ff ff ff call 1c0005a0 <f1> ; call f1(struct Trivial) +1c0005da: 83 c4 10 add $0x10,%esp ; +1c0005dd: 8d 45 d4 lea 0xffffffd4(%ebp),%eax ; +1c0005e0: 83 28 7b subl $0x7b,(%eax) ; +1c0005e3: 83 ec 0c sub $0xc,%esp ; +1c0005e6: 83 ec 0c sub $0xc,%esp ; +1c0005e9: 8d 45 d8 lea 0xffffffd8(%ebp),%eax ; | | +1c0005ec: 50 push %eax ; | / ptr to n +1c0005ed: 8d 45 b8 lea 0xffffffb8(%ebp),%eax ; | \ +1c0005f0: 50 push %eax ; | copy n | ptr to dest of copy of n +1c0005f1: e8 64 00 00 00 call 1c00065a <_ZN10NonTrivialC1ERKS_> ; | NonTrivial::NonTrivial(const NonTrivial&) / copy ctor +1c0005f6: 83 c4 14 add $0x14,%esp ; +1c0005f9: 8d 45 b8 lea 0xffffffb8(%ebp),%eax ; | +1c0005fc: 50 push %eax ; | f2 arg 0 (ptr to copy of struct NonTrivial), via ptr as non-trivial +1c0005fd: e8 a4 ff ff ff call 1c0005a6 <f2> ; call f2(struct NonTrivial) +1c000602: 83 c4 10 add $0x10,%esp ; +1c000605: 8d 45 d4 lea 0xffffffd4(%ebp),%eax ; +1c000608: 83 28 0c subl $0xc,(%eax) ; +1c00060b: c9 leave ; +1c00060c: c3 ret ; +1c00060d: 90 nop ; + + ; ... snip, removed code of ctor and copy ctor ... + + + ; vim: ft=asm