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comparison doc/disas_examples/x86.plan9call.disas @ 447:97fff5d9cea1

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- plan9/x86 struct by value passing disas example
author Tassilo Philipp
date Thu, 27 Jan 2022 11:14:11 +0100
parents c0390dc85a07
children e5820b7a3fbc
comparison
equal deleted inserted replaced
446:54c1dc2e6ea5 447:97fff5d9cea1
1 ; void leaf_call(int a, int b, int c, int d, int e, int f) 1 ; void leaf_call(int a, int b, int c, int d, int e, int f)
2 ; { 2 ; {
3 ; } 3 ; }
4 ; 4 ;
5 ; int nonleaf_call(int a, int b, int c, int d, int e, int f, int g) 5 ; int nonleaf_call(int a, int b, int c, int d, int e, int f, int g)
6 ; { 6 ; {
7 ; leaf_call(b,c,d,e,f,g); 7 ; leaf_call(b,c,d,e,f,g);
8 ; return 'x'; 8 ; return 'x';
9 ; } 9 ; }
10 ; 10 ;
11 ; int main() 11 ; int main()
12 ; { 12 ; {
13 ; nonleaf_call(0,1,2,3,4,5,6); 13 ; nonleaf_call(0,1,2,3,4,5,6);
14 ; return 0; 14 ; return 0;
15 ; } 15 ; }
33 00103f 8944240c (7) MOVL AX,12(SP) ; | 33 00103f 8944240c (7) MOVL AX,12(SP) ; |
34 001043 8b442434 (7) MOVL f+52(FP),AX ; | 34 001043 8b442434 (7) MOVL f+52(FP),AX ; |
35 001047 89442410 (7) MOVL AX,16(SP) ; | 35 001047 89442410 (7) MOVL AX,16(SP) ; |
36 00104b 8b442438 (7) MOVL g+56(FP),AX ; | 36 00104b 8b442438 (7) MOVL g+56(FP),AX ; |
37 00104f 89442414 (7) MOVL AX,20(SP) ; | 37 00104f 89442414 (7) MOVL AX,20(SP) ; |
38 001053 e8c8ffffff (7) CALL ,1020+leaf_call ; push return addrss and call 38 001053 e8c8ffffff (7) CALL ,1020+leaf_call ; push return address and call
39 001058 b878000000 (8) MOVL $120,AX ; return value: 'x' -> eax 39 001058 b878000000 (8) MOVL $120,AX ; return value: 'x' -> eax
40 00105d 83c41c (8) ADDL $28,SP ; | 40 00105d 83c41c (8) ADDL $28,SP ; |
41 001060 c3 (8) RET , ; | epilog 41 001060 c3 (8) RET , ; | epilog
42 42
43 001061 (11) TEXT main+0(SB),$32 43 001061 (11) TEXT main+0(SB),$32
53 00108b 89442410 (13) MOVL AX,16(SP) ; . 53 00108b 89442410 (13) MOVL AX,16(SP) ; .
54 00108f b805000000 (13) MOVL $5,AX ; . 54 00108f b805000000 (13) MOVL $5,AX ; .
55 001094 89442414 (13) MOVL AX,20(SP) ; . 55 001094 89442414 (13) MOVL AX,20(SP) ; .
56 001098 b806000000 (13) MOVL $6,AX ; arg 6 -> eax, then ... 56 001098 b806000000 (13) MOVL $6,AX ; arg 6 -> eax, then ...
57 00109d 89442418 (13) MOVL AX,24(SP) ; ... "pushed" onto stack 57 00109d 89442418 (13) MOVL AX,24(SP) ; ... "pushed" onto stack
58 0010a1 e87bffffff (13) CALL ,1021+nonleaf_call ; push return addrss and call 58 0010a1 e87bffffff (13) CALL ,1021+nonleaf_call ; push return address and call
59 0010a6 31c0 (14) MOVL $0,AX ; return value 59 0010a6 31c0 (14) MOVL $0,AX ; return value
60 0010a8 83c420 (14) ADDL $32,SP ; | 60 0010a8 83c420 (14) ADDL $32,SP ; |
61 0010ab c3 (14) RET , ; | epilog 61 0010ab c3 (14) RET , ; | epilog
62 62
63
64
65 ; ---------- structs by value ---------->
66 ;
67 ; struct A { int i, j; long long l; };
68 ;
69 ; void leaf_call(int b, int c, int d, int e, struct A f, int g, int h)
70 ; {
71 ; }
72 ;
73 ; void nonleaf_call(int a, int b, int c, int d, int e, struct A f, int g, int h)
74 ; {
75 ; /* use some local data */
76 ; char l[100] = 'L';
77 ; leaf_call(b, c, d, e, f, g, h);
78 ; }
79 ;
80 ; int main()
81 ; {
82 ; nonleaf_call(0, 1, 2, 3, 4, (struct A){5, 6, 7ll}, 8, 9);
83 ; return 0;
84 ; }
85
86
87
88 ; output from plan9-4th_edition-x86 w/ 8c x.c && 8l -a x.8
89
90 001020 (3) TEXT leaf_call+0(SB),$0
91 001020 c3 (5) RET ,
92
93 001021 (7) TEXT nonleaf_call+0(SB),$148
94 001021 81ec94000000 (7) SUBL $148,SP ; prolog (note, there is no register save area at all)
95 001027 8d842494000000 (10) LEAL l+148(SP),AX ; |
96 00102e 89442430 (10) MOVL AX,l+48(SP) ; | loop's write ptr (stored at beginning of char[100] space)
97 001032 83442430fc (10) ADDL $-4,l+48(SP) ; | decr loop ptr in memory
98 001037 8b442430 (10) MOVL l+48(SP),AX ; | ptr -> eax
99 00103b c70000000000 (10) MOVL $0,(AX) ; | zero-init char[100] space write a 0
100 001041 837c243000 (10) CMPL l+48(SP),$0 ; | cmp if done
101 001046 75ea (10) JNE ,1032 ; | loop
102 001048 c64424304c (10) MOVB $76,l+48(SP) ; 'L' -> local area (beginning of char[100] space)
103 00104d 8b84249c000000 (11) MOVL b+156(FP),AX ; |
104 001054 890424 (11) MOVL AX,(SP) ; |
105 001057 8b8424a0000000 (11) MOVL c+160(FP),AX ; |
106 00105e 89442404 (11) MOVL AX,4(SP) ; | fetch in args (ints before struct) from prev frame's param area ...
107 001062 8b8424a4000000 (11) MOVL d+164(FP),AX ; | ... and "push" onto stack
108 001069 89442408 (11) MOVL AX,8(SP) ; |
109 00106d 8b8424a8000000 (11) MOVL e+168(FP),AX ; |
110 001074 8944240c (11) MOVL AX,12(SP) ; /
111 001078 8d7c2410 (11) LEAL 16(SP),DI ; \ dst ptr
112 00107c 8db424ac000000 (11) LEAL f+172(FP),SI ; | src ptr
113 001083 b904000000 (11) MOVL $4,CX ; | rep counter (4, for dwords = 16b = sizeof(struct A))
114 001088 fc (11) CLD , ; | copy struct to next call's stack
115 001089 f3 (11) REP , ; |
116 00108a a5 (11) MOVSL , ; /
117 00108b 8b8424bc000000 (11) MOVL g+188(FP),AX ; \
118 001092 89442420 (11) MOVL AX,32(SP) ; | fetch remaining in args (ints after struct) from prev frame's param area ...
119 001096 8b8424c0000000 (11) MOVL h+192(FP),AX ; | ... and "push" onto stack
120 00109d 89442424 (11) MOVL AX,36(SP) ; |
121 0010a1 e87affffff (11) CALL ,1020+leaf_call ; push return address and call
122 0010a6 81c494000000 (11) ADDL $148,SP ; |
123 0010ac c3 (11) RET , ; | epilog
124
125 0010ad (14) TEXT main+0(SB),$52
126 0010ad 83ec34 (14) SUBL $52,SP ; prolog (note, there is no register save area at all)
127 0010b0 c7042400000000 (16) MOVL $0,(SP) ; arg 0 -> "push" onto stack
128 0010b7 b801000000 (16) MOVL $1,AX ; arg 1 -> eax, then ...
129 0010bc 89442404 (16) MOVL AX,4(SP) ; ... "pushed" onto stack
130 0010c0 b802000000 (16) MOVL $2,AX ; arg 2 -> eax, then ...
131 0010c5 89442408 (16) MOVL AX,8(SP) ; ... "pushed" onto stack
132 0010c9 b803000000 (16) MOVL $3,AX ; .
133 0010ce 8944240c (16) MOVL AX,12(SP) ; .
134 0010d2 b804000000 (16) MOVL $4,AX ; .
135 0010d7 89442410 (16) MOVL AX,16(SP) ; .
136 0010db 8d442414 (16) LEAL 20(SP),AX ; get ptr to next (unused) stack bytes -> eax ...
137 0010df 89442430 (16) MOVL AX,.safe+48(SP) ; ... and write it to very top of stack (seems aligned and not adjacent to last arg) | looks like callconv keeps a ptr to
138 0010e3 8b442430 (16) MOVL .safe+48(SP),AX ; regetting of same ptr into eax (pointless as same as in eax) | each struct params in local area
139 0010e7 c70005000000 (16) MOVL $5,(AX) ; |
140 0010ed 8b442430 (16) MOVL .safe+48(SP),AX ; |
141 0010f1 c7400406000000 (16) MOVL $6,4(AX) ; | copy struct linearly to stack, adjacent to other args
142 0010f8 8b442430 (16) MOVL .safe+48(SP),AX ; |
143 0010fc c7400807000000 (16) MOVL $7,8(AX) ; |
144 001103 c7400c00000000 (16) MOVL $0,12(AX) ; | msbytes of long long
145 00110a b808000000 (16) MOVL $8,AX ; arg 6 -> eax, then ...
146 00110f 89442424 (16) MOVL AX,36(SP) ; ... "pushed" onto stack
147 001113 b809000000 (16) MOVL $9,AX ; arg 7 -> eax, then ...
148 001118 89442428 (16) MOVL AX,40(SP) ; ... "pushed" onto stack
149 00111c e800ffffff (16) CALL ,1021+nonleaf_call ; push return address and call
150 001121 31c0 (17) MOVL $0,AX ; return value
151 001123 83c434 (17) ADDL $52,SP ; |
152 001126 c3 (17) RET , ; | epilog
153
154
155
156 ; ---------- structs by value, complex example (multiple structs) ---------->
157 ;
158 ; struct A { int i, j; float f; };
159 ; struct B { double d; long long l; };
160 ;
161 ; void leaf_call(int b, struct A c, struct B d, int e, int f, struct A g, struct B h, int i, int j)
162 ; {
163 ; }
164 ;
165 ; void nonleaf_call(int a, int b, struct A c, struct B d, int e, int f, struct A g, struct B h, int i, int j)
166 ; {
167 ; /* use some local data */
168 ; char l[100] = 'L';
169 ; leaf_call(b, c, d, e, f, g, h, i, j);
170 ; }
171 ;
172 ; int main()
173 ; {
174 ; nonleaf_call(0, 1, (struct A){2, 3, 4.f}, (struct B){5., 6ll}, 7, 8, (struct A){9, 10, 11.f}, (struct B){12., 13ll}, 14, 15);
175 ; return 0;
176 ; }
177
178
179
180 ; output from plan9-4th_edition-x86 w/ 8c x.c && 8l -a x.8
181
182 001020 (4) TEXT leaf_call+0(SB),$0
183 001020 c3 (6) RET ,
184
185 001021 (8) TEXT nonleaf_call+0(SB),$184
186 001021 81ecb8000000 (8) SUBL $184,SP
187 001027 8d8424b8000000 (11) LEAL l+184(SP),AX
188 00102e 89442454 (11) MOVL AX,l+84(SP)
189 001032 83442454fc (11) ADDL $-4,l+84(SP)
190 001037 8b442454 (11) MOVL l+84(SP),AX
191 00103b c70000000000 (11) MOVL $0,(AX)
192 001041 837c245400 (11) CMPL l+84(SP),$0
193 001046 75ea (11) JNE ,1032
194 001048 c64424544c (11) MOVB $76,l+84(SP)
195 00104d 8b8424c0000000 (12) MOVL b+192(FP),AX
196 001054 890424 (12) MOVL AX,(SP)
197 001057 8d7c2404 (12) LEAL 4(SP),DI
198 00105b 8db424c4000000 (12) LEAL c+196(FP),SI
199 001062 b903000000 (12) MOVL $3,CX
200 001067 fc (12) CLD ,
201 001068 f3 (12) REP ,
202 001069 a5 (12) MOVSL ,
203 00106a 8d7c2410 (12) LEAL 16(SP),DI
204 00106e 8db424d0000000 (12) LEAL d+208(FP),SI
205 001075 b904000000 (12) MOVL $4,CX
206 00107a fc (12) CLD ,
207 00107b f3 (12) REP ,
208 00107c a5 (12) MOVSL ,
209 00107d 8b8424e0000000 (12) MOVL e+224(FP),AX
210 001084 89442420 (12) MOVL AX,32(SP)
211 001088 8b8424e4000000 (12) MOVL f+228(FP),AX
212 00108f 89442424 (12) MOVL AX,36(SP)
213 001093 8d7c2428 (12) LEAL 40(SP),DI
214 001097 8db424e8000000 (12) LEAL g+232(FP),SI
215 00109e b903000000 (12) MOVL $3,CX
216 0010a3 fc (12) CLD ,
217 0010a4 f3 (12) REP ,
218 0010a5 a5 (12) MOVSL ,
219 0010a6 8d7c2434 (12) LEAL 52(SP),DI
220 0010aa 8db424f4000000 (12) LEAL h+244(FP),SI
221 0010b1 b904000000 (12) MOVL $4,CX
222 0010b6 fc (12) CLD ,
223 0010b7 f3 (12) REP ,
224 0010b8 a5 (12) MOVSL ,
225 0010b9 8b842404010000 (12) MOVL i+260(FP),AX
226 0010c0 89442444 (12) MOVL AX,68(SP)
227 0010c4 8b842408010000 (12) MOVL j+264(FP),AX
228 0010cb 89442448 (12) MOVL AX,72(SP)
229 0010cf e84cffffff (12) CALL ,1020+leaf_call
230 0010d4 81c4b8000000 (12) ADDL $184,SP
231 0010da c3 (12) RET ,
232
233 0010db (15) TEXT main+0(SB),$100
234 0010db 83ec64 (15) SUBL $100,SP
235 0010de c7042400000000 (17) MOVL $0,(SP)
236 0010e5 b801000000 (17) MOVL $1,AX
237 0010ea 89442404 (17) MOVL AX,4(SP)
238 0010ee 8d442408 (17) LEAL 8(SP),AX
239 0010f2 89442460 (17) MOVL AX,.safe+96(SP)
240 0010f6 8b442460 (17) MOVL .safe+96(SP),AX
241 0010fa c70002000000 (17) MOVL $2,(AX)
242 001100 8b442460 (17) MOVL .safe+96(SP),AX
243 001104 c7400403000000 (17) MOVL $3,4(AX)
244 00110b dd0500200000 (17) FMOVD $0.40100000+0(SB),F0
245 001111 8b442460 (17) MOVL .safe+96(SP),AX
246 001115 d95808 (17) FMOVFP F0,8(AX)
247 001118 8d442414 (17) LEAL 20(SP),AX
248 00111c 8944245c (17) MOVL AX,.safe+92(SP)
249 001120 dd0508200000 (17) FMOVD $0.40140000+0(SB),F0
250 001126 8b44245c (17) MOVL .safe+92(SP),AX
251 00112a dd18 (17) FMOVDP F0,(AX)
252 00112c 8b44245c (17) MOVL .safe+92(SP),AX
253 001130 c7400806000000 (17) MOVL $6,8(AX)
254 001137 c7400c00000000 (17) MOVL $0,12(AX)
255 00113e b807000000 (17) MOVL $7,AX
256 001143 89442424 (17) MOVL AX,36(SP)
257 001147 b808000000 (17) MOVL $8,AX
258 00114c 89442428 (17) MOVL AX,40(SP)
259 001150 8d44242c (17) LEAL 44(SP),AX
260 001154 89442458 (17) MOVL AX,.safe+88(SP)
261 001158 8b442458 (17) MOVL .safe+88(SP),AX
262 00115c c70009000000 (17) MOVL $9,(AX)
263 001162 8b442458 (17) MOVL .safe+88(SP),AX
264 001166 c740040a000000 (17) MOVL $10,4(AX)
265 00116d dd0510200000 (17) FMOVD $0.40260000+0(SB),F0
266 001173 8b442458 (17) MOVL .safe+88(SP),AX
267 001177 d95808 (17) FMOVFP F0,8(AX)
268 00117a 8d442438 (17) LEAL 56(SP),AX
269 00117e 89442454 (17) MOVL AX,.safe+84(SP)
270 001182 dd0518200000 (17) FMOVD $0.40280000+0(SB),F0
271 001188 8b442454 (17) MOVL .safe+84(SP),AX
272 00118c dd18 (17) FMOVDP F0,(AX)
273 00118e 8b442454 (17) MOVL .safe+84(SP),AX
274 001192 c740080d000000 (17) MOVL $13,8(AX)
275 001199 c7400c00000000 (17) MOVL $0,12(AX)
276 0011a0 b80e000000 (17) MOVL $14,AX
277 0011a5 89442448 (17) MOVL AX,72(SP)
278 0011a9 b80f000000 (17) MOVL $15,AX
279 0011ae 8944244c (17) MOVL AX,76(SP)
280 0011b2 e86afeffff (17) CALL ,1021+nonleaf_call
281 0011b7 31c0 (18) MOVL $0,AX
282 0011b9 83c464 (18) ADDL $100,SP
283 0011bc c3 (18) RET ,
284
285 002000 0000000000001040 (17) DATA $0.40100000+0(SB)/8,$(40100000,00000000)
286 002008 0000000000001440 (17) DATA $0.40140000+0(SB)/8,$(40140000,00000000)
287 002010 0000000000002640 (17) DATA $0.40260000+0(SB)/8,$(40260000,00000000)
288 002018 0000000000002840 (17) DATA $0.40280000+0(SB)/8,$(40280000,00000000)
289
290
291
63 ; vim: ft=asm 292 ; vim: ft=asm
64 293