1575583f2a
This patch adds support to the instruction-referencing LiveDebugValues implementation for emitting entry values. The instruction referencing implementations tracking by value rather than location means that we can get around two of the issues with VarLocs. DBG_VALUE instructions that re-assign the same value to a variable are no longer a problem, because we can "see through" to the value being assigned. We also don't need to do anything special during the dataflow stages: the "variable value problem" doesn't need to know whether a value is available most of the time, and the times it deoes need to know are always when entry values need to be terminated. The patch modifies the "TransferTracker" class, adding methods to identify when a variable ias an entry value candidate, and when a machine value is an entry value. recoverAsEntryValue tests these two things and emits an entry-value expression if they're true. It's used when we clobber or otherwise lose a value and can't find a replacement location for the value it contained. Differential Revision: https://reviews.llvm.org/D88406
88 lines
3.6 KiB
LLVM
88 lines
3.6 KiB
LLVM
; RUN: llc -debug-entry-values -filetype=asm -o - %s | FileCheck %s
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; RUN: llc -force-instr-ref-livedebugvalues=1 -debug-entry-values -filetype=asm -o - %s | FileCheck %s
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; The q0 register does not have a DWARF register number, and is instead emitted
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; as a composite location description with two sub-registers. Previously we
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; emitted a single DW_OP_entry_value wrapping that whole composite location
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; description, but that is not valid DWARF; DW_OP_entry_value operations can
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; only hold DWARF expressions and register location descriptions.
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;
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; In the future we may want to emit a composite location description where each
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; DW_OP_regx operation is wrapped in an entry value operation, but for now
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; just verify that no invalid DWARF is emitted.
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target datalayout = "E-m:e-i64:64-n32:64-S128"
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target triple = "sparc64"
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; Based on the following C reproducer:
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;
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; volatile long double global;
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; extern void clobber();
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; int foo(long double p) {
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; global = p;
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; clobber();
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; return 123;
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; }
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; Verify that we got an entry value in the DIExpression...
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; CHECK: DEBUG_VALUE: foo:p <- [DW_OP_LLVM_entry_value 1] $q0
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; ... but that no entry value location was emitted:
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; CHECK: .half 8 ! Loc expr size
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; CHECK-NEXT: .byte 144 ! sub-register DW_OP_regx
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; CHECK-NEXT: .byte 72 ! 72
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; CHECK-NEXT: .byte 147 ! DW_OP_piece
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; CHECK-NEXT: .byte 8 ! 8
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; CHECK-NEXT: .byte 144 ! sub-register DW_OP_regx
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; CHECK-NEXT: .byte 73 ! 73
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; CHECK-NEXT: .byte 147 ! DW_OP_piece
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; CHECK-NEXT: .byte 8 ! 8
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; CHECK-NEXT: .xword 0
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; CHECK-NEXT: .xword 0
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@global = common global fp128 0xL00000000000000000000000000000000, align 16, !dbg !0
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; Function Attrs: nounwind
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define signext i32 @foo(fp128 %p) #0 !dbg !12 {
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entry:
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call void @llvm.dbg.value(metadata fp128 %p, metadata !17, metadata !DIExpression()), !dbg !18
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store volatile fp128 %p, fp128* @global, align 16, !dbg !19
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tail call void @clobber(), !dbg !20
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ret i32 123, !dbg !21
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}
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declare void @clobber()
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; Function Attrs: nounwind readnone speculatable willreturn
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declare void @llvm.dbg.value(metadata, metadata, metadata) #1
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attributes #0 = { nounwind }
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attributes #1 = { nounwind readnone speculatable willreturn }
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!llvm.dbg.cu = !{!2}
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!llvm.module.flags = !{!8, !9, !10}
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!llvm.ident = !{!11}
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!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
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!1 = distinct !DIGlobalVariable(name: "global", scope: !2, file: !3, line: 1, type: !6, isLocal: false, isDefinition: true)
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!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None)
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!3 = !DIFile(filename: "entry-value-complex-reg-expr.c", directory: "/")
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!4 = !{}
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!5 = !{!0}
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!6 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !7)
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!7 = !DIBasicType(name: "long double", size: 128, encoding: DW_ATE_float)
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!8 = !{i32 2, !"Dwarf Version", i32 4}
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!9 = !{i32 2, !"Debug Info Version", i32 3}
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!10 = !{i32 1, !"wchar_size", i32 4}
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!11 = !{!"clang version 10.0.0"}
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!12 = distinct !DISubprogram(name: "foo", scope: !3, file: !3, line: 3, type: !13, scopeLine: 3, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !16)
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!13 = !DISubroutineType(types: !14)
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!14 = !{!15, !7}
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!15 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!16 = !{!17}
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!17 = !DILocalVariable(name: "p", arg: 1, scope: !12, file: !3, line: 3, type: !7)
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!18 = !DILocation(line: 0, scope: !12)
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!19 = !DILocation(line: 4, scope: !12)
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!20 = !DILocation(line: 5, scope: !12)
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!21 = !DILocation(line: 6, scope: !12)
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