198 lines
6.7 KiB
Text
198 lines
6.7 KiB
Text
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# RUN: llc %s -march=x86-64 -run-pass=livedebugvalues -o - \
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# RUN: -experimental-debug-variable-locations=true \
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# RUN: | FileCheck %s -implicit-check-not=DBG_VALUE \
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# RUN: --check-prefixes=CHECK,COMMON
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#
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# This test is designed to stimulate a simplification of variable-value
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# propagation in InstrRefBasedLDV. When we only have a single assignment of
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# a variable, we don't have to completely enumerate all the PHIs the variable
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# has and then value propagate through them: the variable value is available
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# only in those blocks dominated by the assignment. Example in this test:
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#
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# entry
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# / | \
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# / v \
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# / bb1 \ <--- Single variable assignment happens here
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# / / \ \
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# / v v \
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# | bb2 bb3 |
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# | \ / |
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# | v v |
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# | bb4 |
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# \ / \ /
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# v v v v
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# bb5 bb6 <--- Dominance frontier is here
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#
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# The general InstrRefBasedLDV algorithm takes this CFG, places PHIs at bb5 and
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# bb6, then value-propagates until it's determined that they can't be
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# eliminated. Then, we determine that there's no machine location for such PHIs,
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# and no variable location is emitted.
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#
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# The fast way of doing this: observe that the variable value can never extend
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# past the dominance frontier of the block where the assignment happens. So
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# just propagate the variable value into the dominated blocks, and avoid the
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# general algorithm.
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#
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# Doing so introduces a functional change: VarLocBasedLDV won't propagate
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# variable locations through out-of-scope blocks, and InstrRefBasedLDV tries to
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# replicate VarLocBasedLDV most of the time. In the MIR below, bb2 is out of
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# scope. This effectively becomes another variable assignment (of undef), which
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# requires full SSA and value propagation to emulate what VarLocBasedLDV did.
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# Applying this speed optimisation makes us diverge from what VarLocBasedLDV
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# does by not treating the out-of-scope block as an effective undef assignment,
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# hence this test.
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#
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# CHECK-LABEL: bb.1:
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# CHECK: DBG_VALUE
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# CHECK-LABEL: bb.2:
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## No location here because it's out-of-scope.
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# CHECK-LABEL: bb.3:
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# CHECK: DBG_VALUE
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# CHECK-LABEL: bb.4:
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# CHECK: DBG_VALUE
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#
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## VarLocBasedLDV will take the DBG_VALUE in the assignment block, propagate
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## to bb.3, but not into bb.4 because of the intervening out-of-scope block.
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## Disabled actual testing of this because it's just for comparison purposes.
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#
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# varloc-label: bb.1:
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# varloc: DBG_VALUE
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# varloc-label: bb.2:
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## No location here because it's out-of-scope.
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# varloc-label: bb.3:
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# varloc: DBG_VALUE
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#
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## Common tail for 'test2' -- this is checking that the assignment of undef or
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## $noreg in single-assignment mode doesn't lead to trouble further down the
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## line, specifically assertion failures.
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#
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# COMMON-LABEL: name: test2
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# COMMON: DBG_VALUE $noreg
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--- |
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define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
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entry:
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ret i32 0, !dbg !17
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}
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define i32 @test2() local_unnamed_addr !dbg !112 {
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entry:
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ret i32 0, !dbg !117
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}
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!7, !8, !9, !10}
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!llvm.ident = !{!11}
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!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)
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!1 = !DIFile(filename: "main.cpp", directory: "F:\")
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!2 = !{}
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!3 = !{!4}
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!4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
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!5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
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!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!7 = !{i32 2, !"Dwarf Version", i32 4}
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!8 = !{i32 2, !"Debug Info Version", i32 3}
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!9 = !{i32 1, !"wchar_size", i32 2}
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!10 = !{i32 7, !"PIC Level", i32 2}
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!11 = !{!"clang"}
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!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)
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!13 = !DISubroutineType(types: !14)
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!14 = !{!6, !6}
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!15 = !{!16}
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!16 = !DILocalVariable(name: "myVar", scope: !18, file: !1, line: 7, type: !6)
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!17 = !DILocation(line: 10, scope: !18)
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!18 = distinct !DILexicalBlock(scope: !12, file: !1, line: 1, column: 1)
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!19 = distinct !DILexicalBlock(scope: !12, file: !1, line: 1, column: 1)
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!20 = !DILocation(line: 10, scope: !19)
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!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)
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!115 = !{!116}
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!116 = !DILocalVariable(name: "myVar", scope: !118, file: !1, line: 7, type: !6)
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!117 = !DILocation(line: 10, scope: !118)
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!118 = distinct !DILexicalBlock(scope: !112, file: !1, line: 1, column: 1)
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!119 = distinct !DILexicalBlock(scope: !112, file: !1, line: 1, column: 1)
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!120 = !DILocation(line: 10, scope: !119)
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...
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---
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name: _Z8bb_to_bb
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debugInstrRef: true
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debugValueSubstitutions:
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- { srcinst: 4, srcop: 0, dstinst: 3, dstop: 0, subreg: 0 }
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body: |
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bb.0.entry:
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successors: %bb.1, %bb.5, %bb.6
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$rax = MOV64ri 1, debug-instr-number 1, debug-location !17
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JCC_1 %bb.5, 1, implicit $eflags
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JCC_1 %bb.6, 2, implicit $eflags
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JMP_1 %bb.1
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bb.1:
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successors: %bb.2, %bb.3
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DBG_VALUE $rax, $noreg, !16, !DIExpression(), debug-location !17
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JCC_1 %bb.3, 1, implicit $eflags, debug-location !17
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bb.2:
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successors: %bb.4
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JMP_1 %bb.4, debug-location !20
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bb.3:
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successors: %bb.4
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JMP_1 %bb.4, debug-location !17
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bb.4:
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successors: %bb.5, %bb.6
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JCC_1 %bb.5, 1, implicit $eflags, debug-location !17
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JMP_1 %bb.6, debug-location !17
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bb.5:
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RET 0, debug-location !17
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bb.6:
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RET 0, debug-location !17
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...
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---
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name: test2
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debugValueSubstitutions:
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- { srcinst: 4, srcop: 0, dstinst: 3, dstop: 0, subreg: 0 }
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body: |
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bb.0.entry:
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successors: %bb.1, %bb.5, %bb.6
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$rax = MOV64ri 1, debug-instr-number 1, debug-location !117
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JCC_1 %bb.5, 1, implicit $eflags
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JCC_1 %bb.6, 2, implicit $eflags
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JMP_1 %bb.1
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bb.1:
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successors: %bb.2, %bb.3
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DBG_VALUE $noreg, $noreg, !116, !DIExpression(), debug-location !117
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JCC_1 %bb.3, 1, implicit $eflags, debug-location !117
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bb.2:
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successors: %bb.4
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JMP_1 %bb.4, debug-location !120
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bb.3:
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successors: %bb.4
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JMP_1 %bb.4, debug-location !117
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bb.4:
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successors: %bb.5, %bb.6
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JCC_1 %bb.5, 1, implicit $eflags, debug-location !117
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JMP_1 %bb.6, debug-location !117
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bb.5:
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RET 0, debug-location !117
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bb.6:
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RET 0, debug-location !117
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