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
|
; RUN: llc < %s | FileCheck %s --check-prefix=ASM
; RUN: llc -filetype=obj < %s | llvm-readobj --codeview - | FileCheck %s --check-prefix=OBJ
; PR38857
; When stack realignment is required by dynamic allocas are not used, the
; compiler will address locals with the ESP register. However, if call argument
; set up uses PUSH instructions, ESP may vary over the course of the function.
; This means it's not useful as a base register for describing the locations of
; variables. Instead, our CodeView output prefers to use the VFRAME virtual
; register, which is defined in the FPO data as $T0. Make sure we define it.
; Original C++ test case, which uses __thiscall to encourage PUSH conversion:
; struct Foo {
; int x = 42;
; int __declspec(noinline) foo();
; void __declspec(noinline) bar(int *a, int *b, double *c);
; };
; int Foo::foo() {
; int a = 1;
; int b = 2;
; double __declspec(align(8)) force_alignment = 0.42;
; bar(&a, &b, &force_alignment);
; x += (int)force_alignment;
; return x;
; }
; void Foo::bar(int *a, int *b, double *c) {
; __debugbreak();
; *c += *a + *b;
; }
; int main() {
; Foo o;
; o.foo();
; }
; This stops the debugger in bar, and locals in Foo::foo would be corrupt.
; More reduced C code to generate this IR:
; int getval(void);
; void usevals(int *, int *, double *);
; int realign_with_csrs(int x) {
; int a = getval();
; double __declspec(align(8)) force_alignment = 0.42;
; usevals(&a, &x, &force_alignment);
; return x;
; }
; Match the prologue for the .cv_fpo* directives.
; ASM-LABEL: _realign_with_csrs:
; ASM: .cv_fpo_proc _realign_with_csrs 4
; ASM: # %bb.0: # %entry
; ASM: pushl %ebp
; ASM: .cv_fpo_pushreg %ebp
; ASM: movl %esp, %ebp
; ASM: .cv_fpo_setframe %ebp
; ASM: andl $-8, %esp
; ASM: .cv_fpo_stackalign 8
; ASM: subl $16, %esp
; ASM: .cv_fpo_stackalloc 16
; ASM: .cv_fpo_endprologue
; 'x' should be EBP-relative, 'a' and 'force_alignment' ESP relative.
; ASM: calll _getval
; ASM-DAG: leal 8(%esp), %[[LEA_DBL:[^ ]*]]
; ASM-DAG: leal 8(%ebp), %[[LEA_X:[^ ]*]]
; ASM-DAG: leal 4(%esp), %[[LEA_A:[^ ]*]]
; ASM: pushl %[[LEA_DBL]]
; ASM: pushl %[[LEA_X]]
; ASM: pushl %[[LEA_A]]
; ASM: calll _usevals
; ASM: addl $12, %esp
; OBJ: Subsection [
; OBJ: SubSectionType: Symbols (0xF1)
; OBJ: ]
; OBJ: Subsection [
; OBJ: SubSectionType: FrameData (0xF5)
; Really, the only important FrameFunc is the last one.
; OBJ: FrameData {
; OBJ: }
; OBJ: FrameData {
; OBJ: }
; OBJ: FrameData {
; OBJ: }
; OBJ: FrameData {
; OBJ: FrameFunc [
; OBJ-NEXT: $T1 $ebp 4 + =
; OBJ-NEXT: $T0 $T1 4 - 8 @ =
; OBJ-NEXT: $eip $T1 ^ =
; OBJ-NEXT: $esp $T1 4 + =
; OBJ-NEXT: $ebp $T1 4 - ^ =
; OBJ-NEXT: ]
; OBJ: }
; OBJ: ]
; OBJ: Subsection [
; OBJ: SubSectionType: Symbols (0xF1)
; OBJ: GlobalProcIdSym {
; OBJ: Kind: S_GPROC32_ID (0x1147)
; OBJ: DisplayName: realign_with_csrs
; OBJ: LinkageName: _realign_with_csrs
; OBJ: }
; The frame register for locals should be VFRAME, and EBP for parameters.
; OBJ: FrameProcSym {
; OBJ: Kind: S_FRAMEPROC (0x1012)
; OBJ: TotalFrameBytes: 0x14
; OBJ: LocalFramePtrReg: VFRAME (0x7536)
; OBJ: ParamFramePtrReg: EBP (0x16)
; OBJ: }
; As seen in ASM, offset of x is 8.
; OBJ: LocalSym {
; OBJ: Kind: S_LOCAL (0x113E)
; OBJ: Type: int (0x74)
; OBJ: Flags [ (0x1)
; OBJ: IsParameter (0x1)
; OBJ: ]
; OBJ: VarName: x
; OBJ: }
; OBJ: DefRangeFramePointerRelSym {
; OBJ: Kind: S_DEFRANGE_FRAMEPOINTER_REL (0x1142)
; OBJ: Offset: 8
; OBJ: }
; ESP is VFRAME - 16, ESP offset of 'a' is 4, so -12.
; OBJ: LocalSym {
; OBJ: Kind: S_LOCAL (0x113E)
; OBJ: Type: int (0x74)
; OBJ: Flags [ (0x0)
; OBJ: ]
; OBJ: VarName: a
; OBJ: }
; OBJ: DefRangeFramePointerRelSym {
; OBJ: Kind: S_DEFRANGE_FRAMEPOINTER_REL (0x1142)
; OBJ: Offset: -12
; OBJ: }
; ESP is VFRAME - 16, ESP offset of 'force_alignment' is 8, so -8.
; OBJ: LocalSym {
; OBJ: Kind: S_LOCAL (0x113E)
; OBJ: Type: double (0x41)
; OBJ: Flags [ (0x0)
; OBJ: ]
; OBJ: VarName: force_alignment
; OBJ: }
; OBJ: DefRangeFramePointerRelSym {
; OBJ: Kind: S_DEFRANGE_FRAMEPOINTER_REL (0x1142)
; OBJ: Offset: -8
; OBJ: }
; OBJ: ProcEnd {
; OBJ: Kind: S_PROC_ID_END (0x114F)
; OBJ: }
; OBJ: ]
; ModuleID = 't.c'
source_filename = "t.c"
target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
target triple = "i386-pc-windows-msvc19.14.26433"
; Function Attrs: nounwind
define dso_local i32 @realign_with_csrs(i32 %x) local_unnamed_addr #0 !dbg !8 {
entry:
%x.addr = alloca i32, align 4
%a = alloca i32, align 4
%force_alignment = alloca double, align 8
store i32 %x, i32* %x.addr, align 4, !tbaa !17
call void @llvm.dbg.declare(metadata i32* %x.addr, metadata !13, metadata !DIExpression()), !dbg !21
%0 = bitcast i32* %a to i8*, !dbg !22
call void @llvm.lifetime.start.p0i8(i64 4, i8* nonnull %0) #4, !dbg !22
call void @llvm.dbg.declare(metadata i32* %a, metadata !14, metadata !DIExpression()), !dbg !22
%call = tail call i32 @getval() #4, !dbg !22
store i32 %call, i32* %a, align 4, !dbg !22, !tbaa !17
%1 = bitcast double* %force_alignment to i8*, !dbg !23
call void @llvm.lifetime.start.p0i8(i64 8, i8* nonnull %1) #4, !dbg !23
call void @llvm.dbg.declare(metadata double* %force_alignment, metadata !15, metadata !DIExpression()), !dbg !23
store double 4.200000e-01, double* %force_alignment, align 8, !dbg !23, !tbaa !24
call void @usevals(i32* nonnull %a, i32* nonnull %x.addr, double* nonnull %force_alignment) #4, !dbg !26
%2 = load i32, i32* %x.addr, align 4, !dbg !27, !tbaa !17
call void @llvm.lifetime.end.p0i8(i64 8, i8* nonnull %1) #4, !dbg !28
call void @llvm.lifetime.end.p0i8(i64 4, i8* nonnull %0) #4, !dbg !28
ret i32 %2, !dbg !27
}
; Function Attrs: nounwind readnone speculatable
declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
; Function Attrs: argmemonly nounwind
declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #2
declare dso_local i32 @getval() local_unnamed_addr #3
declare dso_local void @usevals(i32*, i32*, double*) local_unnamed_addr #3
; Function Attrs: argmemonly nounwind
declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) #2
attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "frame-pointer"="none" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="pentium4" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { nounwind readnone speculatable }
attributes #2 = { argmemonly nounwind }
attributes #3 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "frame-pointer"="none" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="pentium4" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #4 = { nounwind }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5, !6}
!llvm.ident = !{!7}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 8.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
!1 = !DIFile(filename: "t.c", directory: "C:\5Csrc\5Cllvm-project\5Cbuild", checksumkind: CSK_MD5, checksum: "a646950309d5d01d8087fc10fea33941")
!2 = !{}
!3 = !{i32 1, !"NumRegisterParameters", i32 0}
!4 = !{i32 2, !"CodeView", i32 1}
!5 = !{i32 2, !"Debug Info Version", i32 3}
!6 = !{i32 1, !"wchar_size", i32 2}
!7 = !{!"clang version 8.0.0 "}
!8 = distinct !DISubprogram(name: "realign_with_csrs", scope: !1, file: !1, line: 3, type: !9, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !12)
!9 = !DISubroutineType(types: !10)
!10 = !{!11, !11}
!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!12 = !{!13, !14, !15}
!13 = !DILocalVariable(name: "x", arg: 1, scope: !8, file: !1, line: 3, type: !11)
!14 = !DILocalVariable(name: "a", scope: !8, file: !1, line: 4, type: !11)
!15 = !DILocalVariable(name: "force_alignment", scope: !8, file: !1, line: 5, type: !16, align: 64)
!16 = !DIBasicType(name: "double", size: 64, encoding: DW_ATE_float)
!17 = !{!18, !18, i64 0}
!18 = !{!"int", !19, i64 0}
!19 = !{!"omnipotent char", !20, i64 0}
!20 = !{!"Simple C/C++ TBAA"}
!21 = !DILocation(line: 3, scope: !8)
!22 = !DILocation(line: 4, scope: !8)
!23 = !DILocation(line: 5, scope: !8)
!24 = !{!25, !25, i64 0}
!25 = !{!"double", !19, i64 0}
!26 = !DILocation(line: 6, scope: !8)
!27 = !DILocation(line: 7, scope: !8)
!28 = !DILocation(line: 8, scope: !8)
|
