Mercurial > pub > dyncall > dyncall

comparison doc/disas_examples/x86.stdcall.disas @ 471:4e84d6faed54

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
- "
author Tassilo Philipp
date Mon, 07 Feb 2022 23:29:24 +0100
parents
children cb19b2fe2422
comparison
equal deleted inserted replaced
470:79e76734bb5c 471:4e84d6faed54
1 ; #include <stdlib.h>
2 ;
3 ; void __stdcall leaf_call(int b, int c, int d, int e, int f, int g, int h)
4 ; {
5 ; }
6 ;
7 ; void __stdcall nonleaf_call(int a, int b, int c, int d, int e, int f, int g, int h)
8 ; {
9 ; /* use some local data */
10 ; *(char*)alloca(220) = 'L';
11 ; leaf_call(b, c, d, e, f, g, h);
12 ; }
13 ;
14 ; int main()
15 ; {
16 ; nonleaf_call(0, 1, 2, 3, 4, 5, 6, 7);
17 ; return 0;
18 ; }
19
20
21
22 ; output from godbolt compiler explorer w/ msvc 19.14 (w/ /GS- for simplicity)
23
24 _leaf_call@28 PROC
25 push ebp
26 mov ebp, esp
27 pop ebp
28 ret 28
29 _leaf_call@28 ENDP
30
31 _b$ = 12
32 _c$ = 16
33 _d$ = 20
34 _e$ = 24
35 _f$ = 28
36 _g$ = 32
37 _h$ = 36
38 _nonleaf_call@32 PROC
39 push ebp
40 mov ebp, esp
41 push 220
42 call _alloca
43 add esp, 4
44 mov BYTE PTR [eax], 76
45 mov eax, DWORD PTR _h$[ebp]
46 push eax
47 mov ecx, DWORD PTR _g$[ebp]
48 push ecx
49 mov edx, DWORD PTR _f$[ebp]
50 push edx
51 mov eax, DWORD PTR _e$[ebp]
52 push eax
53 mov ecx, DWORD PTR _d$[ebp]
54 push ecx
55 mov edx, DWORD PTR _c$[ebp]
56 push edx
57 mov eax, DWORD PTR _b$[ebp]
58 push eax
59 call _leaf_call@28
60 pop ebp
61 ret 32
62 _nonleaf_call@32 ENDP
63
64 _main PROC
65 push ebp
66 mov ebp, esp
67 push 7
68 push 6
69 push 5
70 push 4
71 push 3
72 push 2
73 push 1
74 push 0
75 call _nonleaf_call@32
76 xor eax, eax
77 pop ebp
78 ret 0
79 _main ENDP
80
81
82
83 ; ---------- structs by value, struct in first call on reg arg boundary ---------->
84 ;
85 ; struct A { int x; short y; char z; long long t; };
86 ;
87 ; struct A __stdcall leaf_call(struct A a, short b, long long c, char d, int e, int f, int g, long long h)
88 ; {
89 ; a.x += 1;
90 ; return a;
91 ; }
92 ;
93 ; int main()
94 ; {
95 ; struct A a = {9, 99, 23, 12LL};
96 ; leaf_call(a, 1, 2, 3, 4, 5, 6, 7LL);
97 ; return 0;
98 ; }
99
100
101
102 ; output from godbolt compiler explorer w/ msvc 19.14 (w/ /GS- for simplicity)
103
104 $T1 = 8
105 _a$ = 12
106 _leaf_call@52 PROC
107 push ebp ; | prolog
108 mov ebp, esp ; /
109 mov eax, DWORD PTR _a$[ebp] ; \
110 add eax, 1 ; | get struct's x (from stack args), add 1 and write back
111 mov DWORD PTR _a$[ebp], eax ; /
112 mov ecx, DWORD PTR $T1[ebp] ; get ptr to retval struct passed as hidden arg (+8 to skip retval and saved ebp)
113 mov edx, DWORD PTR _a$[ebp] ; |
114 mov DWORD PTR [ecx], edx ; |
115 mov eax, DWORD PTR _a$[ebp+4] ; |
116 mov DWORD PTR [ecx+4], eax ; | copy modified (b/c of x+=1) struct arg to space of retval
117 mov edx, DWORD PTR _a$[ebp+8] ; |
118 mov DWORD PTR [ecx+8], edx ; |
119 mov eax, DWORD PTR _a$[ebp+12] ; |
120 mov DWORD PTR [ecx+12], eax ; |
121 mov eax, DWORD PTR $T1[ebp] ; return value (= ptr to struct that was passed-in as hidden arg)
122 pop ebp ; |
123 ret 56 ; | epilog (56 = stack cleanup of stdcall)
124 _leaf_call@52 ENDP
125
126 $T1 = -32
127 _a$ = -16
128 _main PROC
129 push ebp ; |
130 mov ebp, esp ; | prolog
131 sub esp, 32 ; / 32 = 16b local area for struct + 16b space used for retval struct
132 mov DWORD PTR _a$[ebp], 9 ; \ int x
133 mov eax, 99 ; | |
134 mov WORD PTR _a$[ebp+4], ax ; | struct values (local area) | short y
135 mov BYTE PTR _a$[ebp+6], 23 ; | char z
136 mov DWORD PTR _a$[ebp+8], 12 ; | |
137 mov DWORD PTR _a$[ebp+12], 0 ; / | long long t
138 push 0 ; \
139 push 7 ; | arg 7
140 push 6 ; arg 6
141 push 5 ; arg 5
142 push 4 ; arg 4
143 push 3 ; arg 3
144 push 0 ; |
145 push 2 ; arg 2
146 push 1 ; arg 1
147 sub esp, 16 ; |
148 mov ecx, esp ; |
149 mov edx, DWORD PTR _a$[ebp] ; |
150 mov DWORD PTR [ecx], edx ; |
151 mov eax, DWORD PTR _a$[ebp+4] ; |
152 mov DWORD PTR [ecx+4], eax ; | arg 0 (struct), "pushed" onto stack (fetched from local area)
153 mov edx, DWORD PTR _a$[ebp+8] ; |
154 mov DWORD PTR [ecx+8], edx ; |
155 mov eax, DWORD PTR _a$[ebp+12] ; |
156 mov DWORD PTR [ecx+12], eax ; /
157 lea ecx, DWORD PTR $T1[ebp] ; \ ptr to space used for struct retval (pushed as hidden first arg)
158 push ecx ; |
159 call _leaf_call@52 ; push return address and call
160 ; (note: cdecl would clean up stack, here)
161 xor eax, eax ; return value
162 mov esp, ebp ; |
163 pop ebp ; | epilog
164 ret 0 ; |
165 _main ENDP
166
167
168
169 ; vim: ft=asm
170