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1# RUN: llc %s -mtriple=x86_64 -run-pass=livedebugvalues -o - \2# RUN: -experimental-debug-variable-locations=true \3# RUN: | FileCheck %s -implicit-check-not=DBG_VALUE \4# RUN: --check-prefixes=CHECK,COMMON5#6# This test is designed to stimulate a simplification of variable-value7# propagation in InstrRefBasedLDV. When we only have a single assignment of8# a variable, we don't have to completely enumerate all the PHIs the variable9# has and then value propagate through them: the variable value is available10# only in those blocks dominated by the assignment. Example in this test:11#12# entry13# / | \14# / v \15# / bb1 \ <--- Single variable assignment happens here16# / / \ \17# / v v \18# | bb2 bb3 |19# | \ / |20# | v v |21# | bb4 |22# \ / \ /23# v v v v24# bb5 bb6 <--- Dominance frontier is here25#26# The general InstrRefBasedLDV algorithm takes this CFG, places PHIs at bb5 and27# bb6, then value-propagates until it's determined that they can't be28# eliminated. Then, we determine that there's no machine location for such PHIs,29# and no variable location is emitted.30#31# The fast way of doing this: observe that the variable value can never extend32# past the dominance frontier of the block where the assignment happens. So33# just propagate the variable value into the dominated blocks, and avoid the34# general algorithm.35#36# Doing so introduces a functional change: VarLocBasedLDV won't propagate37# variable locations through out-of-scope blocks, and InstrRefBasedLDV tries to38# replicate VarLocBasedLDV most of the time. In the MIR below, bb2 is out of39# scope. This effectively becomes another variable assignment (of undef), which40# requires full SSA and value propagation to emulate what VarLocBasedLDV did.41# Applying this speed optimisation makes us diverge from what VarLocBasedLDV42# does by not treating the out-of-scope block as an effective undef assignment,43# hence this test.44#45# CHECK-LABEL: bb.1:46# CHECK: DBG_VALUE47# CHECK-LABEL: bb.2:48## No location here because it's out-of-scope.49# CHECK-LABEL: bb.3:50# CHECK: DBG_VALUE51# CHECK-LABEL: bb.4:52# CHECK: DBG_VALUE53#54## VarLocBasedLDV will take the DBG_VALUE in the assignment block, propagate55## to bb.3, but not into bb.4 because of the intervening out-of-scope block.56## Disabled actual testing of this because it's just for comparison purposes.57#58# varloc-label: bb.1:59# varloc: DBG_VALUE60# varloc-label: bb.2:61## No location here because it's out-of-scope.62# varloc-label: bb.3:63# varloc: DBG_VALUE64#65## Common tail for 'test2' -- this is checking that the assignment of undef or66## $noreg in single-assignment mode doesn't lead to trouble further down the67## line, specifically assertion failures.68#69# COMMON-LABEL: name: test270# COMMON: DBG_VALUE $noreg71--- |72 define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {73 entry:74 ret i32 0, !dbg !1775 }76 77 define i32 @test2() local_unnamed_addr !dbg !112 {78 entry:79 ret i32 0, !dbg !11780 }81 82 !llvm.dbg.cu = !{!0}83 !llvm.module.flags = !{!7, !8, !9, !10}84 !llvm.ident = !{!11}85 86 !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)87 !1 = !DIFile(filename: "main.cpp", directory: "F:\")88 !2 = !{}89 !3 = !{!4}90 !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())91 !5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)92 !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)93 !7 = !{i32 2, !"Dwarf Version", i32 4}94 !8 = !{i32 2, !"Debug Info Version", i32 3}95 !9 = !{i32 1, !"wchar_size", i32 2}96 !10 = !{i32 7, !"PIC Level", i32 2}97 !11 = !{!"clang"}98 !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)99 !13 = !DISubroutineType(types: !14)100 !14 = !{!6, !6}101 !15 = !{!16}102 !16 = !DILocalVariable(name: "myVar", scope: !18, file: !1, line: 7, type: !6)103 !17 = !DILocation(line: 10, scope: !18)104 !18 = distinct !DILexicalBlock(scope: !12, file: !1, line: 1, column: 1)105 !19 = distinct !DILexicalBlock(scope: !12, file: !1, line: 1, column: 1)106 !20 = !DILocation(line: 10, scope: !19)107 !112 = distinct !DISubprogram(name: "test2", linkageName: "102", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !115)108 !115 = !{!116}109 !116 = !DILocalVariable(name: "myVar", scope: !118, file: !1, line: 7, type: !6)110 !117 = !DILocation(line: 10, scope: !118)111 !118 = distinct !DILexicalBlock(scope: !112, file: !1, line: 1, column: 1)112 !119 = distinct !DILexicalBlock(scope: !112, file: !1, line: 1, column: 1)113 !120 = !DILocation(line: 10, scope: !119)114 115...116---117name: _Z8bb_to_bb118debugInstrRef: true119debugValueSubstitutions:120 - { srcinst: 4, srcop: 0, dstinst: 3, dstop: 0, subreg: 0 }121body: |122 bb.0.entry:123 successors: %bb.1, %bb.5, %bb.6124 125 $rax = MOV64ri 1, debug-instr-number 1, debug-location !17126 JCC_1 %bb.5, 1, implicit $eflags127 JCC_1 %bb.6, 2, implicit $eflags128 JMP_1 %bb.1129 130 bb.1:131 successors: %bb.2, %bb.3132 133 DBG_VALUE $rax, $noreg, !16, !DIExpression(), debug-location !17134 JCC_1 %bb.3, 1, implicit $eflags, debug-location !17135 136 bb.2:137 successors: %bb.4138 139 JMP_1 %bb.4, debug-location !20140 141 bb.3:142 successors: %bb.4143 144 JMP_1 %bb.4, debug-location !17145 146 bb.4:147 successors: %bb.5, %bb.6148 149 JCC_1 %bb.5, 1, implicit $eflags, debug-location !17150 JMP_1 %bb.6, debug-location !17151 152 bb.5:153 RET 0, debug-location !17154 155 bb.6:156 RET 0, debug-location !17157...158---159name: test2160debugValueSubstitutions:161 - { srcinst: 4, srcop: 0, dstinst: 3, dstop: 0, subreg: 0 }162body: |163 bb.0.entry:164 successors: %bb.1, %bb.5, %bb.6165 166 $rax = MOV64ri 1, debug-instr-number 1, debug-location !117167 JCC_1 %bb.5, 1, implicit $eflags168 JCC_1 %bb.6, 2, implicit $eflags169 JMP_1 %bb.1170 171 bb.1:172 successors: %bb.2, %bb.3173 174 DBG_VALUE $noreg, $noreg, !116, !DIExpression(), debug-location !117175 JCC_1 %bb.3, 1, implicit $eflags, debug-location !117176 177 bb.2:178 successors: %bb.4179 180 JMP_1 %bb.4, debug-location !120181 182 bb.3:183 successors: %bb.4184 185 JMP_1 %bb.4, debug-location !117186 187 bb.4:188 successors: %bb.5, %bb.6189 190 JCC_1 %bb.5, 1, implicit $eflags, debug-location !117191 JMP_1 %bb.6, debug-location !117192 193 bb.5:194 RET 0, debug-location !117195 196 bb.6:197 RET 0, debug-location !117198