1 From 783006ec19853403b8fe799e4c1b9496cb03504a Mon Sep 17 00:00:00 2001
2 From: Bjorn Pettersson <bjorn.a.pettersson@ericsson.com>
3 Date: Tue, 6 Mar 2018 08:47:07 +0000
4 Subject: [PATCH] [DebugInfo] Discard invalid DBG_VALUE instructions in
5 LiveDebugVariables
6
7 Summary:
8 This is a workaround for pr36417
9 https://bugs.llvm.org/show_bug.cgi?id=36417
10
11 LiveDebugVariables will now verify that the DBG_VALUE instructions
12 are sane (prior to register allocation) by asking LIS if a virtual
13 register used in the DBG_VALUE is live (or dead def) in the slot
14 index before the DBG_VALUE. If it isn't sane the DBG_VALUE is
15 discarded.
16
17 One pass that was identified as introducing non-sane DBG_VALUE
18 instructtons, when analysing pr36417, was the DAG->DAG Instruction
19 Selection. It sometimes inserts DBG_VALUE instructions referring to
20 a virtual register that is defined later in the same basic block.
21 So it is a use before def kind of problem. The DBG_VALUE is
22 typically inserted in the beginning of a basic block when this
23 happens. The problem can be seen in the test case
24 test/DebugInfo/X86/dbg-value-inlined-parameter.ll
25
26 Reviewers: aprantl, rnk, probinson
27
28 Reviewed By: aprantl
29
30 Subscribers: vsk, davide, alexcrichton, Ka-Ka, eraman, llvm-commits, JDevlieghere
31
32 Differential Revision: https://reviews.llvm.org/D43956
33
34 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326769 91177308-0d34-0410-b5e6-96231b3b80d8
35 ---
36 lib/CodeGen/LiveDebugVariables.cpp | 38 +++++-
37 test/DebugInfo/X86/dbg-value-inlined-parameter.ll | 6 +-
38 .../X86/live-debug-vars-discard-invalid.mir | 141 +++++++++++++++++++++
39 3 files changed, 181 insertions(+), 4 deletions(-)
40 create mode 100644 test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
41
42 diff --git a/lib/CodeGen/LiveDebugVariables.cpp b/lib/CodeGen/LiveDebugVariables.cpp
43 index 09168b6b9309..f3fcd004defd 100644
44 --- a/lib/CodeGen/LiveDebugVariables.cpp
45 +++ b/lib/CodeGen/LiveDebugVariables.cpp
46 @@ -514,6 +514,39 @@ bool LDVImpl::handleDebugValue(MachineInstr &MI, SlotIndex Idx) {
47 return false;
48 }
49
50 + // Detect invalid DBG_VALUE instructions, with a debug-use of a virtual
51 + // register that hasn't been defined yet. If we do not remove those here, then
52 + // the re-insertion of the DBG_VALUE instruction after register allocation
53 + // will be incorrect.
54 + // TODO: If earlier passes are corrected to generate sane debug information
55 + // (and if the machine verifier is improved to catch this), then these checks
56 + // could be removed or replaced by asserts.
57 + bool Discard = false;
58 + if (MI.getOperand(0).isReg() &&
59 + TargetRegisterInfo::isVirtualRegister(MI.getOperand(0).getReg())) {
60 + const unsigned Reg = MI.getOperand(0).getReg();
61 + if (!LIS->hasInterval(Reg)) {
62 + // The DBG_VALUE is described by a virtual register that does not have a
63 + // live interval. Discard the DBG_VALUE.
64 + Discard = true;
65 + DEBUG(dbgs() << "Discarding debug info (no LIS interval): "
66 + << Idx << " " << MI);
67 + } else {
68 + // The DBG_VALUE is only valid if either Reg is live out from Idx, or Reg
69 + // is defined dead at Idx (where Idx is the slot index for the instruction
70 + // preceeding the DBG_VALUE).
71 + const LiveInterval &LI = LIS->getInterval(Reg);
72 + LiveQueryResult LRQ = LI.Query(Idx);
73 + if (!LRQ.valueOutOrDead()) {
74 + // We have found a DBG_VALUE with the value in a virtual register that
75 + // is not live. Discard the DBG_VALUE.
76 + Discard = true;
77 + DEBUG(dbgs() << "Discarding debug info (reg not live): "
78 + << Idx << " " << MI);
79 + }
80 + }
81 + }
82 +
83 // Get or create the UserValue for (variable,offset) here.
84 bool IsIndirect = MI.getOperand(1).isImm();
85 if (IsIndirect)
86 @@ -522,7 +555,10 @@ bool LDVImpl::handleDebugValue(MachineInstr &MI, SlotIndex Idx) {
87 const DIExpression *Expr = MI.getDebugExpression();
88 UserValue *UV =
89 getUserValue(Var, Expr, MI.getDebugLoc());
90 - UV->addDef(Idx, MI.getOperand(0), IsIndirect);
91 + if (!Discard)
92 + UV->addDef(Idx, MI.getOperand(0), IsIndirect);
93 + else
94 + UV->addDef(Idx, MachineOperand::CreateReg(0U, RegState::Debug), false);
95 return true;
96 }
97
98 diff --git a/test/DebugInfo/X86/dbg-value-inlined-parameter.ll b/test/DebugInfo/X86/dbg-value-inlined-parameter.ll
99 index 9954039654bb..e83cf0aa7ffd 100644
100 --- a/test/DebugInfo/X86/dbg-value-inlined-parameter.ll
101 +++ b/test/DebugInfo/X86/dbg-value-inlined-parameter.ll
102 @@ -32,10 +32,10 @@
103 ;CHECK-NEXT: DW_AT_call_line
104
105 ;CHECK: DW_TAG_formal_parameter
106 -;FIXME: Linux shouldn't drop this parameter either...
107 ;CHECK-NOT: DW_TAG
108 -;DARWIN: DW_AT_abstract_origin {{.*}} "sp"
109 -;DARWIN: DW_TAG_formal_parameter
110 +;FIXME: Shouldn't drop this parameter...
111 +;XCHECK: DW_AT_abstract_origin {{.*}} "sp"
112 +;XCHECK: DW_TAG_formal_parameter
113 ;CHECK: DW_AT_abstract_origin {{.*}} "nums"
114 ;CHECK-NOT: DW_TAG_formal_parameter
115
116 diff --git a/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir b/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
117 new file mode 100644
118 index 000000000000..abc21bc6ac90
119 --- /dev/null
120 +++ b/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
121 @@ -0,0 +1,141 @@
122 +# RUN: llc -mtriple=x86_64-linux-gnu -start-before greedy -stop-after virtregrewriter -o - %s | FileCheck %s
123 +
124 +--- |
125 + ; ModuleID = '<stdin>'
126 + source_filename = "test/DebugInfo/X86/dbg-value-inlined-parameter.ll"
127 + target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
128 + target triple = "x86_64-apple-darwin"
129 +
130 + %struct.S1 = type { float*, i32 }
131 +
132 + @p = common global %struct.S1 zeroinitializer, align 8, !dbg !0
133 +
134 + ; Function Attrs: nounwind optsize ssp
135 + define void @foobar() !dbg !15 {
136 + entry:
137 + tail call void @llvm.dbg.value(metadata %struct.S1* @p, metadata !18, metadata !DIExpression()) , !dbg !25
138 + ret void, !dbg !32
139 + }
140 +
141 + ; Function Attrs: nounwind readnone speculatable
142 + declare void @llvm.dbg.value(metadata, metadata, metadata) #2
143 +
144 + !llvm.dbg.cu = !{!2}
145 + !llvm.module.flags = !{!14}
146 +
147 + !0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
148 + !1 = !DIGlobalVariable(name: "p", scope: !2, file: !3, line: 14, type: !6, isLocal: false, isDefinition: true)
149 + !2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 2.9 (trunk 125693)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, retainedTypes: !4, globals: !5, imports: !4)
150 + !3 = !DIFile(filename: "nm2.c", directory: "/private/tmp")
151 + !4 = !{}
152 + !5 = !{!0}
153 + !6 = !DIDerivedType(tag: DW_TAG_typedef, name: "S1", scope: !2, file: !3, line: 4, baseType: !7)
154 + !7 = !DICompositeType(tag: DW_TAG_structure_type, name: "S1", scope: !2, file: !3, line: 1, size: 128, align: 64, elements: !8)
155 + !8 = !{!9, !12}
156 + !9 = !DIDerivedType(tag: DW_TAG_member, name: "m", scope: !3, file: !3, line: 2, baseType: !10, size: 64, align: 64)
157 + !10 = !DIDerivedType(tag: DW_TAG_pointer_type, scope: !2, baseType: !11, size: 64, align: 64)
158 + !11 = !DIBasicType(name: "float", size: 32, align: 32, encoding: DW_ATE_float)
159 + !12 = !DIDerivedType(tag: DW_TAG_member, name: "nums", scope: !3, file: !3, line: 3, baseType: !13, size: 32, align: 32, offset: 64)
160 + !13 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
161 + !14 = !{i32 1, !"Debug Info Version", i32 3}
162 + !15 = distinct !DISubprogram(name: "foobar", scope: !3, file: !3, line: 15, type: !16, isLocal: false, isDefinition: true, virtualIndex: 6, isOptimized: true, unit: !2)
163 + !16 = !DISubroutineType(types: !17)
164 + !17 = !{null}
165 + !18 = !DILocalVariable(name: "sp", arg: 1, scope: !19, file: !3, line: 7, type: !24)
166 + !19 = distinct !DISubprogram(name: "foo", scope: !3, file: !3, line: 8, type: !20, isLocal: false, isDefinition: true, scopeLine: 8, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !2, variables: !22)
167 + !20 = !DISubroutineType(types: !21)
168 + !21 = !{!13}
169 + !22 = !{!18, !23}
170 + !23 = !DILocalVariable(name: "nums", arg: 2, scope: !19, file: !3, line: 7, type: !13)
171 + !24 = !DIDerivedType(tag: DW_TAG_pointer_type, scope: !2, baseType: !6, size: 64, align: 64)
172 + !25 = !DILocation(line: 7, column: 13, scope: !19, inlinedAt: !26)
173 + !26 = !DILocation(line: 16, column: 3, scope: !27)
174 + !27 = distinct !DILexicalBlock(scope: !15, file: !3, line: 15, column: 15)
175 + !32 = !DILocation(line: 17, column: 1, scope: !27)
176 +
177 +...
178 +---
179 +name: foobar
180 +tracksRegLiveness: true
181 +body: |
182 + bb.0:
183 + %1:gr64 = IMPLICIT_DEF
184 + %2:gr64 = IMPLICIT_DEF
185 +
186 + bb.1:
187 + ; This DBG_VALUE will be discarded (use before def of %0).
188 + DBG_VALUE debug-use %0, debug-use %noreg, !18, !DIExpression(), debug-location !25
189 + %0:gr64 = IMPLICIT_DEF
190 + %0:gr64 = IMPLICIT_DEF
191 + %0:gr64 = IMPLICIT_DEF
192 + %0:gr64 = IMPLICIT_DEF
193 +
194 + bb.2:
195 + ; This DBG_VALUE will be discarded (%1 is defined earlier, but it is not live in, so we do not know where %1 is stored).
196 + DBG_VALUE debug-use %1, debug-use %noreg, !18, !DIExpression(), debug-location !25
197 + %1:gr64 = IMPLICIT_DEF
198 + %1:gr64 = IMPLICIT_DEF
199 + %1:gr64 = IMPLICIT_DEF
200 + %1:gr64 = IMPLICIT_DEF
201 + ; This DBG_VALUE is kept, even if %1 is dead, it was defined in the prev instruction,
202 + ; so the value should be available for as long as the register allocated to %1 is live.
203 + DBG_VALUE debug-use %1, debug-use %noreg, !18, !DIExpression(), debug-location !25
204 +
205 + bb.3:
206 + %1:gr64 = IMPLICIT_DEF
207 + DBG_VALUE 0, debug-use %noreg, !23, !DIExpression(), debug-location !25
208 + ; This DBG_VALUE is kept, even if %1 is dead, it was defined in the prev non-dbg instruction,
209 + ; so the value should be available for as long as the register allocated to %1 is live.
210 + DBG_VALUE debug-use %1, debug-use %noreg, !18, !DIExpression(), debug-location !25
211 +
212 + bb.4:
213 + ; All DBG_VALUEs here should survive. %2 is livein as it was defined in bb.0, and it has use/def in the BTS64rr instruction.
214 + DBG_VALUE debug-use %2, debug-use %noreg, !18, !DIExpression(), debug-location !25
215 + %2:gr64 = BTS64rr %2, 0, implicit-def %eflags
216 + DBG_VALUE 0, debug-use %noreg, !23, !DIExpression(), debug-location !25
217 + DBG_VALUE debug-use %2, debug-use %noreg, !18, !DIExpression(), debug-location !25
218 + %2:gr64 = BTS64rr %2, 0, implicit-def %eflags
219 + DBG_VALUE debug-use %2, debug-use %noreg, !18, !DIExpression(), debug-location !25
220 + %2:gr64 = BTS64rr %2, 0, implicit-def %eflags
221 + DBG_VALUE debug-use %2, debug-use %noreg, !18, !DIExpression(), debug-location !25
222 +
223 + bb.5:
224 + RET 0, debug-location !32
225 +...
226 +
227 +# CHECK-LABEL: name: foobar
228 +
229 +# CHECK-LABEL: bb.1:
230 +## After solving https://bugs.llvm.org/show_bug.cgi?id=36579 we expect to get a
231 +## DBG_VALUE debug-use %noreg
232 +## here.
233 +# CHECK-NOT: DBG_VALUE
234 +
235 +# CHECK-LABEL: bb.2:
236 +## After solving https://bugs.llvm.org/show_bug.cgi?id=36579 we expect to get a
237 +## DBG_VALUE debug-use %noreg
238 +## here.
239 +# CHECK-NOT: DBG_VALUE
240 +# CHECK: dead renamable %rcx = IMPLICIT_DEF
241 +# CHECK-NEXT: dead renamable %rcx = IMPLICIT_DEF
242 +# CHECK-NEXT: dead renamable %rcx = IMPLICIT_DEF
243 +# CHECK-NEXT: dead renamable %rcx = IMPLICIT_DEF
244 +# CHECK-NEXT: DBG_VALUE debug-use %rcx, debug-use %noreg, !18, !DIExpression()
245 +
246 +# CHECK-LABEL: bb.3:
247 +# CHECK: dead renamable %rcx = IMPLICIT_DEF
248 +# CHECK-NEXT: DBG_VALUE 0, debug-use %noreg, !23, !DIExpression()
249 +# CHECK-NEXT: DBG_VALUE debug-use %rcx, debug-use %noreg, !18, !DIExpression()
250 +
251 +# CHECK-LABEL: bb.4:
252 +# CHECK: liveins: %rax
253 +# CHECK: DBG_VALUE debug-use %rax, debug-use %noreg, !18, !DIExpression()
254 +# CHECK-NEXT: renamable %rax = BTS64rr killed renamable %rax, 0, implicit-def %eflags
255 +# CHECK-NEXT: DBG_VALUE 0, debug-use %noreg, !23, !DIExpression()
256 +# CHECK-NEXT: DBG_VALUE debug-use %rax, debug-use %noreg, !18, !DIExpression()
257 +# CHECK-NEXT: renamable %rax = BTS64rr killed renamable %rax, 0, implicit-def %eflags
258 +# CHECK-NEXT: DBG_VALUE debug-use %rax, debug-use %noreg, !18, !DIExpression()
259 +# CHECK-NEXT: dead renamable %rax = BTS64rr killed renamable %rax, 0, implicit-def %eflags
260 +
261 +# CHECK-LABEL: bb.5:
262 +# CHECK-NEXT: RET 0
|
