1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
|
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
; RUN: llc -mtriple=armv7a-none-eabi %s -o - | FileCheck %s
declare i32 @many_args_callee(i32 %0, i32 %1, i32 %2, i32 %3, i32 %4, i32 %5)
define i32 @many_args_tail(i32 %0, i32 %1, i32 %2, i32 %3, i32 %4, i32 %5) {
; CHECK-LABEL: many_args_tail:
; CHECK: @ %bb.0:
; CHECK-NEXT: mov r0, #5
; CHECK-NEXT: mov r1, #2
; CHECK-NEXT: str r0, [sp]
; CHECK-NEXT: mov r0, #6
; CHECK-NEXT: str r0, [sp, #4]
; CHECK-NEXT: mov r0, #1
; CHECK-NEXT: mov r2, #3
; CHECK-NEXT: mov r3, #4
; CHECK-NEXT: b many_args_callee
%ret = tail call i32 @many_args_callee(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6)
ret i32 %ret
}
define i32 @many_args_musttail(i32 %0, i32 %1, i32 %2, i32 %3, i32 %4, i32 %5) {
; CHECK-LABEL: many_args_musttail:
; CHECK: @ %bb.0:
; CHECK-NEXT: mov r0, #5
; CHECK-NEXT: mov r1, #2
; CHECK-NEXT: str r0, [sp]
; CHECK-NEXT: mov r0, #6
; CHECK-NEXT: str r0, [sp, #4]
; CHECK-NEXT: mov r0, #1
; CHECK-NEXT: mov r2, #3
; CHECK-NEXT: mov r3, #4
; CHECK-NEXT: b many_args_callee
%ret = musttail call i32 @many_args_callee(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6)
ret i32 %ret
}
; This function has more arguments than it's tail-callee. This isn't valid for
; the musttail attribute, but can still be tail-called as a non-guaranteed
; optimisation, because the outgoing arguments to @many_args_callee fit in the
; stack space allocated by the caller of @more_args_tail.
define i32 @more_args_tail(i32 %0, i32 %1, i32 %2, i32 %3, i32 %4, i32 %5, i32 %6) {
; CHECK-LABEL: more_args_tail:
; CHECK: @ %bb.0:
; CHECK-NEXT: mov r0, #5
; CHECK-NEXT: mov r1, #2
; CHECK-NEXT: str r0, [sp]
; CHECK-NEXT: mov r0, #6
; CHECK-NEXT: str r0, [sp, #4]
; CHECK-NEXT: mov r0, #1
; CHECK-NEXT: mov r2, #3
; CHECK-NEXT: mov r3, #4
; CHECK-NEXT: b many_args_callee
%ret = tail call i32 @many_args_callee(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6)
ret i32 %ret
}
; Again, this isn't valid for musttail, but can be tail-called in practice
; because the stack size if the same.
define i32 @different_args_tail(i64 %0, i64 %1, i64 %2) {
; CHECK-LABEL: different_args_tail:
; CHECK: @ %bb.0:
; CHECK-NEXT: mov r0, #5
; CHECK-NEXT: mov r1, #2
; CHECK-NEXT: str r0, [sp]
; CHECK-NEXT: mov r0, #6
; CHECK-NEXT: str r0, [sp, #4]
; CHECK-NEXT: mov r0, #1
; CHECK-NEXT: mov r2, #3
; CHECK-NEXT: mov r3, #4
; CHECK-NEXT: b many_args_callee
%ret = tail call i32 @many_args_callee(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6)
ret i32 %ret
}
; Here, the caller requires less stack space for it's arguments than the
; callee, so it would not ba valid to do a tail-call.
define i32 @fewer_args_tail(i32 %0, i32 %1, i32 %2, i32 %3, i32 %4) {
; CHECK-LABEL: fewer_args_tail:
; CHECK: @ %bb.0:
; CHECK-NEXT: .save {r11, lr}
; CHECK-NEXT: push {r11, lr}
; CHECK-NEXT: .pad #8
; CHECK-NEXT: sub sp, sp, #8
; CHECK-NEXT: mov r1, #6
; CHECK-NEXT: mov r0, #5
; CHECK-NEXT: strd r0, r1, [sp]
; CHECK-NEXT: mov r0, #1
; CHECK-NEXT: mov r1, #2
; CHECK-NEXT: mov r2, #3
; CHECK-NEXT: mov r3, #4
; CHECK-NEXT: bl many_args_callee
; CHECK-NEXT: add sp, sp, #8
; CHECK-NEXT: pop {r11, pc}
%ret = tail call i32 @many_args_callee(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6)
ret i32 %ret
}
declare void @sret_callee(ptr sret({ double, double }) align 8)
; Functions which return by sret can be tail-called because the incoming sret
; pointer gets passed through to the callee.
define void @sret_caller_tail(ptr sret({ double, double }) align 8 %result) {
; CHECK-LABEL: sret_caller_tail:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: b sret_callee
entry:
tail call void @sret_callee(ptr sret({ double, double }) align 8 %result)
ret void
}
define void @sret_caller_musttail(ptr sret({ double, double }) align 8 %result) {
; CHECK-LABEL: sret_caller_musttail:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: b sret_callee
entry:
musttail call void @sret_callee(ptr sret({ double, double }) align 8 %result)
ret void
}
; Clang only uses byval for arguments of 65 bytes or larger, but we test with a
; 20 byte struct to keep the tests more readable. This size was chosen to still
; make sure that it will be split between registers and the stack, to test all
; of the interesting code paths in the backend.
%twenty_bytes = type { [5 x i32] }
declare void @large_callee(%twenty_bytes* byval(%twenty_bytes) align 4)
; Functions with byval parameters can be tail-called, because the value is
; actually passed in registers and the stack in the same way for the caller and
; callee. Within @large_caller the first 16 bytes of the argument are spilled
; to the local stack frame, but for the tail-call they are passed in r0-r3, so
; it's safe to de-allocate that memory before the call.
; TODO: The SUB and STM instructions are unnecessary and could be optimised
; out, but the behaviour of this is still correct.
define void @large_caller(%twenty_bytes* byval(%twenty_bytes) align 4 %a) {
; CHECK-LABEL: large_caller:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: .pad #16
; CHECK-NEXT: sub sp, sp, #16
; CHECK-NEXT: stm sp!, {r0, r1, r2, r3}
; CHECK-NEXT: b large_callee
entry:
musttail call void @large_callee(%twenty_bytes* byval(%twenty_bytes) align 4 %a)
ret void
}
; As above, but with some inline asm to test that the arguments in r0-r3 are
; re-loaded before the call.
define void @large_caller_check_regs(%twenty_bytes* byval(%twenty_bytes) align 4 %a) {
; CHECK-LABEL: large_caller_check_regs:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: .pad #16
; CHECK-NEXT: sub sp, sp, #16
; CHECK-NEXT: stm sp, {r0, r1, r2, r3}
; CHECK-NEXT: @APP
; CHECK-NEXT: @NO_APP
; CHECK-NEXT: pop {r0, r1, r2, r3}
; CHECK-NEXT: b large_callee
entry:
tail call void asm sideeffect "", "~{r0},~{r1},~{r2},~{r3}"()
musttail call void @large_callee(%twenty_bytes* byval(%twenty_bytes) align 4 %a)
ret void
}
; The IR for this one looks dodgy, because it has an alloca passed to a
; musttail function, but it is passed as a byval argument, so will be copied
; into the stack space allocated by @large_caller_new_value's caller, so is
; valid.
define void @large_caller_new_value(%twenty_bytes* byval(%twenty_bytes) align 4 %a) {
; CHECK-LABEL: large_caller_new_value:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: .pad #36
; CHECK-NEXT: sub sp, sp, #36
; CHECK-NEXT: add r12, sp, #20
; CHECK-NEXT: stm r12, {r0, r1, r2, r3}
; CHECK-NEXT: mov r0, #4
; CHECK-NEXT: add r1, sp, #36
; CHECK-NEXT: str r0, [sp, #16]
; CHECK-NEXT: mov r0, #3
; CHECK-NEXT: str r0, [sp, #12]
; CHECK-NEXT: mov r0, #2
; CHECK-NEXT: str r0, [sp, #8]
; CHECK-NEXT: mov r0, #1
; CHECK-NEXT: str r0, [sp, #4]
; CHECK-NEXT: mov r0, #0
; CHECK-NEXT: str r0, [sp]
; CHECK-NEXT: mov r0, sp
; CHECK-NEXT: add r0, r0, #16
; CHECK-NEXT: mov r3, #3
; CHECK-NEXT: ldr r2, [r0], #4
; CHECK-NEXT: str r2, [r1], #4
; CHECK-NEXT: mov r0, #0
; CHECK-NEXT: mov r1, #1
; CHECK-NEXT: mov r2, #2
; CHECK-NEXT: add sp, sp, #36
; CHECK-NEXT: b large_callee
entry:
%y = alloca %twenty_bytes, align 4
store i32 0, ptr %y, align 4
%0 = getelementptr inbounds i8, ptr %y, i32 4
store i32 1, ptr %0, align 4
%1 = getelementptr inbounds i8, ptr %y, i32 8
store i32 2, ptr %1, align 4
%2 = getelementptr inbounds i8, ptr %y, i32 12
store i32 3, ptr %2, align 4
%3 = getelementptr inbounds i8, ptr %y, i32 16
store i32 4, ptr %3, align 4
musttail call void @large_callee(%twenty_bytes* byval(%twenty_bytes) align 4 %y)
ret void
}
declare void @two_byvals_callee(%twenty_bytes* byval(%twenty_bytes) align 4, %twenty_bytes* byval(%twenty_bytes) align 4)
define void @swap_byvals(%twenty_bytes* byval(%twenty_bytes) align 4 %a, %twenty_bytes* byval(%twenty_bytes) align 4 %b) {
; CHECK-LABEL: swap_byvals:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: .pad #16
; CHECK-NEXT: sub sp, sp, #16
; CHECK-NEXT: .save {r4, r5, r11, lr}
; CHECK-NEXT: push {r4, r5, r11, lr}
; CHECK-NEXT: .pad #40
; CHECK-NEXT: sub sp, sp, #40
; CHECK-NEXT: add r12, sp, #56
; CHECK-NEXT: add lr, sp, #20
; CHECK-NEXT: stm r12, {r0, r1, r2, r3}
; CHECK-NEXT: add r0, sp, #56
; CHECK-NEXT: mov r12, sp
; CHECK-NEXT: ldr r1, [r0], #4
; CHECK-NEXT: mov r2, r12
; CHECK-NEXT: str r1, [r2], #4
; CHECK-NEXT: add r3, sp, #20
; CHECK-NEXT: ldr r1, [r0], #4
; CHECK-NEXT: add r4, sp, #76
; CHECK-NEXT: str r1, [r2], #4
; CHECK-NEXT: ldr r1, [r0], #4
; CHECK-NEXT: str r1, [r2], #4
; CHECK-NEXT: ldr r1, [r0], #4
; CHECK-NEXT: str r1, [r2], #4
; CHECK-NEXT: ldr r1, [r0], #4
; CHECK-NEXT: add r0, sp, #76
; CHECK-NEXT: str r1, [r2], #4
; CHECK-NEXT: mov r2, lr
; CHECK-NEXT: ldr r1, [r0], #4
; CHECK-NEXT: str r1, [r2], #4
; CHECK-NEXT: ldr r1, [r0], #4
; CHECK-NEXT: str r1, [r2], #4
; CHECK-NEXT: ldr r1, [r0], #4
; CHECK-NEXT: str r1, [r2], #4
; CHECK-NEXT: ldr r1, [r0], #4
; CHECK-NEXT: str r1, [r2], #4
; CHECK-NEXT: ldr r1, [r0], #4
; CHECK-NEXT: str r1, [r2], #4
; CHECK-NEXT: ldm r3, {r0, r1, r2, r3}
; CHECK-NEXT: ldr r5, [r12], #4
; CHECK-NEXT: str r5, [r4], #4
; CHECK-NEXT: ldr r5, [r12], #4
; CHECK-NEXT: str r5, [r4], #4
; CHECK-NEXT: ldr r5, [r12], #4
; CHECK-NEXT: str r5, [r4], #4
; CHECK-NEXT: ldr r5, [r12], #4
; CHECK-NEXT: str r5, [r4], #4
; CHECK-NEXT: ldr r5, [r12], #4
; CHECK-NEXT: str r5, [r4], #4
; CHECK-NEXT: add r5, lr, #16
; CHECK-NEXT: add r12, sp, #72
; CHECK-NEXT: ldr r4, [r5], #4
; CHECK-NEXT: str r4, [r12], #4
; CHECK-NEXT: add sp, sp, #40
; CHECK-NEXT: pop {r4, r5, r11, lr}
; CHECK-NEXT: add sp, sp, #16
; CHECK-NEXT: b two_byvals_callee
entry:
musttail call void @two_byvals_callee(%twenty_bytes* byval(%twenty_bytes) align 4 %b, %twenty_bytes* byval(%twenty_bytes) align 4 %a)
ret void
}
; A forwarded byval arg, but at a different offset on the stack, so it needs to
; be copied to the local stack frame first. This can't be musttail because of
; the different signatures, but is still tail-called as an optimisation.
declare void @shift_byval_callee(%twenty_bytes* byval(%twenty_bytes) align 4)
define void @shift_byval(i32 %a, %twenty_bytes* byval(%twenty_bytes) align 4 %b) {
; CHECK-LABEL: shift_byval:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: .pad #12
; CHECK-NEXT: sub sp, sp, #12
; CHECK-NEXT: .save {r4, lr}
; CHECK-NEXT: push {r4, lr}
; CHECK-NEXT: .pad #20
; CHECK-NEXT: sub sp, sp, #20
; CHECK-NEXT: add r0, sp, #28
; CHECK-NEXT: add lr, sp, #40
; CHECK-NEXT: stm r0, {r1, r2, r3}
; CHECK-NEXT: add r0, sp, #28
; CHECK-NEXT: mov r1, sp
; CHECK-NEXT: ldr r2, [r0], #4
; CHECK-NEXT: add r12, r1, #16
; CHECK-NEXT: str r2, [r1], #4
; CHECK-NEXT: ldr r2, [r0], #4
; CHECK-NEXT: str r2, [r1], #4
; CHECK-NEXT: ldr r2, [r0], #4
; CHECK-NEXT: str r2, [r1], #4
; CHECK-NEXT: ldr r2, [r0], #4
; CHECK-NEXT: str r2, [r1], #4
; CHECK-NEXT: ldr r2, [r0], #4
; CHECK-NEXT: str r2, [r1], #4
; CHECK-NEXT: ldm sp, {r0, r1, r2, r3}
; CHECK-NEXT: ldr r4, [r12], #4
; CHECK-NEXT: str r4, [lr], #4
; CHECK-NEXT: add sp, sp, #20
; CHECK-NEXT: pop {r4, lr}
; CHECK-NEXT: add sp, sp, #12
; CHECK-NEXT: b shift_byval_callee
entry:
tail call void @shift_byval_callee(%twenty_bytes* byval(%twenty_bytes) align 4 %b)
ret void
}
; A global object passed to a byval argument, so it must be copied, but doesn't
; need a stack temporary.
@large_global = external global %twenty_bytes
define void @large_caller_from_global(%twenty_bytes* byval(%twenty_bytes) align 4 %a) {
; CHECK-LABEL: large_caller_from_global:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: .pad #16
; CHECK-NEXT: sub sp, sp, #16
; CHECK-NEXT: .save {r4, lr}
; CHECK-NEXT: push {r4, lr}
; CHECK-NEXT: add r12, sp, #8
; CHECK-NEXT: add lr, sp, #24
; CHECK-NEXT: stm r12, {r0, r1, r2, r3}
; CHECK-NEXT: movw r3, :lower16:large_global
; CHECK-NEXT: movt r3, :upper16:large_global
; CHECK-NEXT: add r12, r3, #16
; CHECK-NEXT: ldm r3, {r0, r1, r2, r3}
; CHECK-NEXT: ldr r4, [r12], #4
; CHECK-NEXT: str r4, [lr], #4
; CHECK-NEXT: pop {r4, lr}
; CHECK-NEXT: add sp, sp, #16
; CHECK-NEXT: b large_callee
entry:
musttail call void @large_callee(%twenty_bytes* byval(%twenty_bytes) align 4 @large_global)
ret void
}
|
