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[LiveDebugValues] Terminate open ranges on DBG_VALUE $noreg 

In D68209, LiveDebugValues::transferDebugValue had a call to
OpenRanges.erase shifted, and by accident this led to a code path where
DBG_VALUEs of $noreg would not have their open range terminated, allowing
variable locations to extend past blocks where they were terminated.

This patch correctly terminates the open range, if present, when such a
DBG_VAUE is encountered, and adds a test for this behaviour.

Differential Revision: https://reviews.llvm.org/D78218
This commit is contained in:
Jeremy Morse 2020-04-16 10:24:47 +01:00
parent 7b9c6c16c3
commit c8d6fa5134
2 changed files with 70 additions and 1 deletions
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4
llvm/lib/CodeGen/LiveDebugValues.cpp
View File

@ -968,9 +968,11 @@ void LiveDebugValues::transferDebugValue(const MachineInstr &MI,
} else if (MI.hasOneMemOperand()) {
llvm_unreachable("DBG_VALUE with mem operand encountered after regalloc?");
} else {
// This must be an undefined location. We should leave OpenRanges closed.
// This must be an undefined location. If it has an open range, erase it.
assert(MI.getOperand(0).isReg() && MI.getOperand(0).getReg() == 0 &&
"Unexpected non-undef DBG_VALUE encountered");
VarLoc VL(MI, LS);
OpenRanges.erase(VL);
}
}

67
llvm/test/DebugInfo/MIR/X86/livedebugvalues_loop_terminated.mir Normal file
View File

@ -0,0 +1,67 @@
--- |
; RUN: llc %s -march=x86-64 -run-pass=livedebugvalues -o - | FileCheck %s -implicit-check-not=DBG_VALUE
; Check that DBG_VALUE instructions are not propagated into a loop that
; explicitly terminates its location.
; CHECK: ![[VARNO:[0-9]+]] = !DILocalVariable(name: "myVar"
; CHECK-LABEL: bb.0.entry:
; CHECK: DBG_VALUE $ebx, $noreg, ![[VARNO]], !DIExpression(),
; CHECK-LABEL: bb.2.bb2:
; CHECK: DBG_VALUE $noreg, $noreg, ![[VARNO]], !DIExpression(),
define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
entry:
br label %bb1, !dbg !17
bb1:
br label %bb2, !dbg !17
bb2:
br label %bb3, !dbg !17
bb3:
ret i32 0, !dbg !17
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!7, !8, !9, !10}
!llvm.ident = !{!11}
!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)
!1 = !DIFile(filename: "main.cpp", directory: "F:\test")
!2 = !{}
!3 = !{!4}
!4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
!5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!7 = !{i32 2, !"Dwarf Version", i32 4}
!8 = !{i32 2, !"Debug Info Version", i32 3}
!9 = !{i32 1, !"wchar_size", i32 2}
!10 = !{i32 7, !"PIC Level", i32 2}
!11 = !{!"clang version 10.0.0"}
!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)
!13 = !DISubroutineType(types: !14)
!14 = !{!6, !6}
!15 = !{!16}
!16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
!17 = !DILocation(line: 10, scope: !12)
...
---
name: _Z8bb_to_bb
body: |
bb.0.entry:
successors: %bb.1
$ebx = MOV32ri 0, debug-location !17
DBG_VALUE $ebx, $noreg, !16, !DIExpression(), debug-location !17
bb.1.bb1:
successors: %bb.2
$eax = MOV32ri 0, debug-location !17
bb.2.bb2:
successors: %bb.1, %bb.3
$ecx = MOV32ri 1, debug-location !17
DBG_VALUE $noreg, $noreg, !16, !DIExpression(), debug-location !17
JCC_1 %bb.1, 4, implicit killed $eflags
bb.3.bb3:
RETQ $eax, debug-location !17
...