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1--- |2 ; RUN: llc %s -mtriple=x86_64 -run-pass=livedebugvalues -o - -experimental-debug-variable-locations | FileCheck %s -implicit-check-not=DBG_VALUE3 4 ; The MIR below represents a pathalogical case for value-tracking5 ; LiveDebugValues. The code structure is eight nested loops, with loop heads6 ; from bb.1 to bb.8, a central block bb.9 that does nothing, and loop ends7 ; from bb.10 to bb.17. The CMP's and jumps might be broken; the only8 ; important part is that it looks like nested loops to LiveDebugValues.9 ;10 ; The variable location is always $rsi, which enters the function live.11 ; There's also a def of $rsi in bb.14, in a loop tail, half way into the12 ; loop nest.s.13 ;14 ; This presents a serious problem: the outer four loops each implicitly have15 ; a PHI value for $rsi, because the block could be entered on a path straight16 ; from entry, or from bb.14 where $rsi is def'd. While the innermost four17 ; loops have a value of $rsi that is live-through each loop from bb.518 ; onwards.19 ;20 ; Value-tracking LiveDebugValues _must_ correctly identify each PHI value.21 ; Observe the DBG_VALUE in bb.2: this variable location musn't be propagated22 ; any further, because there's a path to either successor that goes through23 ; bb.14 where the value is overwritten.Value tracking needs to identify the24 ; PHI value on entry to the block; and that each successor has a different25 ; PHI value in that register.26 ;27 ; Likewise, we mustn't identify values as PHIs which aren't. Entering bb.528 ; has a PHI value (from bb.4) in $rsi. There are no paths to bb.5 that pass29 ; through the clobbering bb.14, which don't also pass through bb.4: thus30 ; that value is live-through the innermost four loops. If we31 ; over-approximated where PHIs happened, we would lose variable location32 ; coverage here, by not propagating the variable location through the inner33 ; loops.34 ;35 ; Getting this right requires the lattice descent (described in the36 ; implementation) to search loop head PHI values, until one is found that is37 ; live-through a loop.38 39 ; This location in bb.2 should not be propagated further,40 ; CHECK-LABEL: bb.2:41 ; CHECK: DBG_VALUE $rsi, $noreg42 43 ; This location should be live through the inner loops, til bb.1444 ; CHECK-LABEL: bb.5:45 ; CHECK: DBG_VALUE $rsi, $noreg46 ; CHECK-LABEL: bb.6:47 ; CHECK: DBG_VALUE $rsi, $noreg48 ; CHECK-LABEL: bb.7:49 ; CHECK: DBG_VALUE $rsi, $noreg50 ; CHECK-LABEL: bb.8:51 ; CHECK: DBG_VALUE $rsi, $noreg52 ; CHECK-LABEL: bb.9:53 ; CHECK: DBG_VALUE $rsi, $noreg54 ; CHECK-LABEL: bb.10:55 ; CHECK: DBG_VALUE $rsi, $noreg56 ; CHECK-LABEL: bb.11:57 ; CHECK: DBG_VALUE $rsi, $noreg58 ; CHECK-LABEL: bb.12:59 ; CHECK: DBG_VALUE $rsi, $noreg60 ; CHECK-LABEL: bb.13:61 ; CHECK: DBG_VALUE $rsi, $noreg62 63 declare i64 @bees(i64 %arg);64 65 define i32 @chiasm(i64 %arg) local_unnamed_addr !dbg !12 {66 entry:67 br label %bb1, !dbg !1768 bb1:69 br label %bb2, !dbg !1770 bb2:71 br label %bb3, !dbg !1772 bb3:73 ret i32 0, !dbg !1774 }75 76 !llvm.dbg.cu = !{!0}77 !llvm.module.flags = !{!7, !8, !9, !10}78 !llvm.ident = !{!11}79 !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)80 !1 = !DIFile(filename: "main.cpp", directory: "F:\")81 !2 = !{}82 !3 = !{!4}83 !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())84 !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)85 !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)86 !7 = !{i32 2, !"Dwarf Version", i32 4}87 !8 = !{i32 2, !"Debug Info Version", i32 3}88 !9 = !{i32 1, !"wchar_size", i32 2}89 !10 = !{i32 7, !"PIC Level", i32 2}90 !11 = !{!"clang version 10.0.0"}91 !12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)92 !13 = !DISubroutineType(types: !14)93 !14 = !{!6, !6}94 !15 = !{!16}95 !16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)96 !17 = !DILocation(line: 10, scope: !12)97 98...99---100name: chiasm101tracksRegLiveness: true102liveins:103 - { reg: '$rdi', virtual-reg: '' }104stack:105 - { id: 0, name: '', type: spill-slot, offset: -8, size: 8, alignment: 8,106 stack-id: default, callee-saved-register: '', callee-saved-restored: true,107 debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }108body: |109 bb.0.entry:110 liveins: $rdi, $rsi111 112 bb.1:113 liveins: $rsi, $rdi114 CMP64ri8 renamable $rdi, 1, implicit-def $eflags, debug-location !17115 JCC_1 %bb.17, 4, implicit $eflags, debug-location !17116 117 bb.2:118 liveins: $rsi, $rdi119 DBG_VALUE $rsi, $noreg, !16, !DIExpression(), debug-location !17120 CMP64ri8 renamable $rdi, 2, implicit-def $eflags, debug-location !17121 JCC_1 %bb.16, 4, implicit $eflags, debug-location !17122 123 bb.3:124 liveins: $rsi, $rdi125 CMP64ri8 renamable $rdi, 3, implicit-def $eflags, debug-location !17126 JCC_1 %bb.15, 4, implicit $eflags, debug-location !17127 128 bb.4:129 liveins: $rsi, $rdi130 CMP64ri8 renamable $rdi, 4, implicit-def $eflags, debug-location !17131 JCC_1 %bb.14, 4, implicit $eflags, debug-location !17132 133 bb.5:134 liveins: $rsi, $rdi135 DBG_VALUE $rsi, $noreg, !16, !DIExpression(), debug-location !17136 CMP64ri8 renamable $rdi, 4, implicit-def $eflags, debug-location !17137 JCC_1 %bb.13, 4, implicit $eflags, debug-location !17138 139 bb.6:140 liveins: $rsi, $rdi141 CMP64ri8 renamable $rdi, 4, implicit-def $eflags, debug-location !17142 JCC_1 %bb.12, 4, implicit $eflags, debug-location !17143 144 bb.7:145 liveins: $rsi, $rdi146 CMP64ri8 renamable $rdi, 4, implicit-def $eflags, debug-location !17147 JCC_1 %bb.11, 4, implicit $eflags, debug-location !17148 149 bb.8:150 liveins: $rsi, $rdi151 CMP64ri8 renamable $rdi, 4, implicit-def $eflags, debug-location !17152 JCC_1 %bb.10, 4, implicit $eflags, debug-location !17153 154 bb.9:155 liveins: $rsi, $rdi, $eflags156 ;$rsi = MOV64ri 0, debug-location !17157 ;JMP_1 %bb.1, debug-location !17158 159 bb.10:160 liveins: $rsi, $rdi, $eflags161 JCC_1 %bb.8, 4, implicit $eflags, debug-location !17162 163 bb.11:164 liveins: $rsi, $rdi, $eflags165 JCC_1 %bb.7, 4, implicit $eflags, debug-location !17166 167 bb.12:168 liveins: $rsi, $rdi, $eflags169 JCC_1 %bb.6, 4, implicit $eflags, debug-location !17170 171 bb.13:172 liveins: $rsi, $rdi, $eflags173 JCC_1 %bb.5, 4, implicit $eflags, debug-location !17174 175 bb.14:176 liveins: $rsi, $rdi, $eflags177 $rsi = MOV64ri 0, debug-location !17178 JCC_1 %bb.4, 4, implicit $eflags, debug-location !17179 180 bb.15:181 liveins: $rsi, $rdi, $eflags182 JCC_1 %bb.3, 4, implicit $eflags, debug-location !17183 184 bb.16:185 liveins: $rsi, $rdi, $eflags186 JCC_1 %bb.2, 4, implicit $eflags, debug-location !17187 188 bb.17:189 liveins: $rsi, $rdi, $eflags190 JCC_1 %bb.1, 4, implicit $eflags, debug-location !17191 192 bb.18:193 liveins: $rsi, $rdi, $eflags194 RET64195 196...197