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Merging r257977:
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r257977 | kfischer | 2016-01-15 17:11:33 -0800 (Fri, 15 Jan 2016) | 1 line

[DwarfDebug] Move MergeValues to .cpp, NFC
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Merging r257979:
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r257979 | kfischer | 2016-01-15 17:15:32 -0800 (Fri, 15 Jan 2016) | 11 lines

[DwarfDebug] Don't merge DebugLocEntries if their pieces overlap

Summary:
Later in DWARF emission we check that DebugLocEntries have
non-overlapping pieces, so we should create any such entries
by merging here.

Fixes PR26163.

Reviewers: aprantl
Differential Revision: http://reviews.llvm.org/D16249
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llvm-svn: 258267
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zmodem committed Jan 20, 2016
1 parent cfc786b commit 5b3feb5
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Showing 3 changed files with 126 additions and 12 deletions.
13 changes: 1 addition & 12 deletions llvm/lib/CodeGen/AsmPrinter/DebugLocEntry.h
Original file line number Diff line number Diff line change
Expand Up @@ -93,18 +93,7 @@ class DebugLocEntry {
/// variable, merge them by appending Next's values to the current
/// list of values.
/// Return true if the merge was successful.
bool MergeValues(const DebugLocEntry &Next) {
if (Begin == Next.Begin) {
auto *Expr = cast_or_null<DIExpression>(Values[0].Expression);
auto *NextExpr = cast_or_null<DIExpression>(Next.Values[0].Expression);
if (Expr->isBitPiece() && NextExpr->isBitPiece()) {
addValues(Next.Values);
End = Next.End;
return true;
}
}
return false;
}
bool MergeValues(const DebugLocEntry &Next);

/// \brief Attempt to merge this DebugLocEntry with Next and return
/// true if the merge was successful. Entries can be merged if they
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18 changes: 18 additions & 0 deletions llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -805,6 +805,24 @@ static bool piecesOverlap(const DIExpression *P1, const DIExpression *P2) {
return (l1 < r2) && (l2 < r1);
}

/// \brief If this and Next are describing different pieces of the same
/// variable, merge them by appending Next's values to the current
/// list of values.
/// Return true if the merge was successful.
bool DebugLocEntry::MergeValues(const DebugLocEntry &Next) {
if (Begin == Next.Begin) {
auto *Expr = cast_or_null<DIExpression>(Values[0].Expression);
auto *NextExpr = cast_or_null<DIExpression>(Next.Values[0].Expression);
if (Expr->isBitPiece() && NextExpr->isBitPiece() &&
!piecesOverlap(Expr, NextExpr)) {
addValues(Next.Values);
End = Next.End;
return true;
}
}
return false;
}

/// Build the location list for all DBG_VALUEs in the function that
/// describe the same variable. If the ranges of several independent
/// pieces of the same variable overlap partially, split them up and
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107 changes: 107 additions & 0 deletions llvm/test/DebugInfo/ARM/PR26163.ll
Original file line number Diff line number Diff line change
@@ -0,0 +1,107 @@
; RUN: llc -filetype=obj -o - < %s | llvm-dwarfdump - | FileCheck %s
;
; Checks that we're creating two ranges, one that terminates immediately
; and one that spans the rest of the function. This isn't necessarily the
; best thing to do here (and also not necessarily correct, since the first
; one has a bit_piece), but it is what is currently being emitted, any
; change here needs to be intentional, so the test is very specific.
;
; CHECK: .debug_loc contents:
; CHECK: 0x00000000: Beginning address offset: 0x0000000000000004
; CHECK: Ending address offset: 0x0000000000000004
; CHECK: Location description: 10 00 9f
; CHECK: Beginning address offset: 0x0000000000000004
; CHECK: Ending address offset: 0x0000000000000014
; CHECK: Location description: 10 00 9f

; Created form the following test case (PR26163) with
; clang -cc1 -triple armv4t--freebsd11.0-gnueabi -emit-obj -debug-info-kind=standalone -O2 -x c test.c
;
; typedef unsigned int size_t;
; struct timeval {
; long long tv_sec;
; int tv_usec;
; };
;
; void *memset(void *, int, size_t);
; void foo(void);
;
; static void
; bar(int value)
; {
; struct timeval lifetime;
;
; memset(&lifetime, 0, sizeof(struct timeval));
; lifetime.tv_sec = value;
;
; foo();
; }
;
; int
; parse_config_file(void)
; {
; int value;
;
; bar(value);
; return (0);
; }

target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "armv4t--freebsd11.0-gnueabi"

%struct.timeval = type { i64, i32 }

declare void @llvm.dbg.declare(metadata, metadata, metadata)
declare void @llvm.dbg.value(metadata, i64, metadata, metadata)

declare void @foo()

define i32 @parse_config_file() !dbg !4 {
entry:
tail call void @llvm.dbg.value(metadata i32 0, i64 0, metadata !15, metadata !26), !dbg !27
tail call void @llvm.dbg.declare(metadata %struct.timeval* undef, metadata !16, metadata !26), !dbg !29
tail call void @llvm.dbg.value(metadata i64 0, i64 0, metadata !16, metadata !30), !dbg !29
tail call void @llvm.dbg.value(metadata i32 0, i64 0, metadata !16, metadata !31), !dbg !29
tail call void @foo() #3, !dbg !32
ret i32 0, !dbg !33
}


!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!22, !23, !24}
!llvm.ident = !{!25}

!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.9.0 (https://github.com/llvm-mirror/clang 89dda3855cda574f355e6defa1d77bdae5053994) (llvm/trunk 257891)", isOptimized: true, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3)
!1 = !DIFile(filename: "<stdin>", directory: "/home/ubuntu/bugs")
!2 = !{}
!3 = !{!4, !11}
!4 = distinct !DISubprogram(name: "parse_config_file", scope: !5, file: !5, line: 22, type: !6, isLocal: false, isDefinition: true, scopeLine: 23, flags: DIFlagPrototyped, isOptimized: true, variables: !9)
!5 = !DIFile(filename: "test.c", directory: "/home/ubuntu/bugs")
!6 = !DISubroutineType(types: !7)
!7 = !{!8}
!8 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
!9 = !{!10}
!10 = !DILocalVariable(name: "value", scope: !4, file: !5, line: 24, type: !8)
!11 = distinct !DISubprogram(name: "bar", scope: !5, file: !5, line: 11, type: !12, isLocal: true, isDefinition: true, scopeLine: 12, flags: DIFlagPrototyped, isOptimized: true, variables: !14)
!12 = !DISubroutineType(types: !13)
!13 = !{null, !8}
!14 = !{!15, !16}
!15 = !DILocalVariable(name: "value", arg: 1, scope: !11, file: !5, line: 11, type: !8)
!16 = !DILocalVariable(name: "lifetime", scope: !11, file: !5, line: 13, type: !17)
!17 = !DICompositeType(tag: DW_TAG_structure_type, name: "timeval", file: !5, line: 2, size: 128, align: 64, elements: !18)
!18 = !{!19, !21}
!19 = !DIDerivedType(tag: DW_TAG_member, name: "tv_sec", scope: !17, file: !5, line: 3, baseType: !20, size: 64, align: 64)
!20 = !DIBasicType(name: "long long int", size: 64, align: 64, encoding: DW_ATE_signed)
!21 = !DIDerivedType(tag: DW_TAG_member, name: "tv_usec", scope: !17, file: !5, line: 4, baseType: !8, size: 32, align: 32, offset: 64)
!22 = !{i32 2, !"Debug Info Version", i32 3}
!23 = !{i32 1, !"wchar_size", i32 4}
!24 = !{i32 1, !"min_enum_size", i32 4}
!25 = !{!"clang version 3.9.0 (https://github.com/llvm-mirror/clang 89dda3855cda574f355e6defa1d77bdae5053994) (llvm/trunk 257891)"}
!26 = !DIExpression()
!27 = !DILocation(line: 11, scope: !11, inlinedAt: !28)
!28 = distinct !DILocation(line: 26, scope: !4)
!29 = !DILocation(line: 13, scope: !11, inlinedAt: !28)
!30 = !DIExpression(DW_OP_bit_piece, 0, 64)
!31 = !DIExpression(DW_OP_bit_piece, 0, 32)
!32 = !DILocation(line: 18, scope: !11, inlinedAt: !28)
!33 = !DILocation(line: 27, scope: !4)

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