[llvm] r259696 - [DWARFDebug] Fix another case of overlapping ranges
Hans Wennborg via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 8 10:36:12 PST 2016
r260121.
Thanks,
Hans
On Mon, Feb 8, 2016 at 9:48 AM, Adrian Prantl <aprantl at apple.com> wrote:
> Yes, this should be a safe fix.
>
> thanks,
> adrian
>
>> On Feb 8, 2016, at 9:47 AM, Hans Wennborg <hans at chromium.org> wrote:
>>
>> It was suggested this should be merged to 3.8. Adrian, does that sound
>> good to you as well?
>>
>> Thanks,
>> Hans
>>
>> On Wed, Feb 3, 2016 at 1:13 PM, Keno Fischer via llvm-commits
>> <llvm-commits at lists.llvm.org> wrote:
>>> Author: kfischer
>>> Date: Wed Feb 3 15:13:33 2016
>>> New Revision: 259696
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=259696&view=rev
>>> Log:
>>> [DWARFDebug] Fix another case of overlapping ranges
>>>
>>> Summary:
>>> In r257979, I added code to ensure that we wouldn't merge DebugLocEntries if
>>> the pieces they describe overlap. Unfortunately, I failed to cover the case,
>>> where there may have multiple active Expressions in the entry, in which case we
>>> need to make sure that no two values overlap before we can perform the merge.
>>>
>>> This fixed PR26148.
>>>
>>> Reviewers: aprantl
>>> Differential Revision: http://reviews.llvm.org/D16742
>>>
>>> Added:
>>> llvm/trunk/test/DebugInfo/X86/PR26148.ll
>>> Modified:
>>> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>>
>>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=259696&r1=259695&r2=259696&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
>>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Wed Feb 3 15:13:33 2016
>>> @@ -788,16 +788,27 @@ static DebugLocEntry::Value getDebugLocV
>>> llvm_unreachable("Unexpected 4-operand DBG_VALUE instruction!");
>>> }
>>>
>>> -/// Determine whether two variable pieces overlap.
>>> -static bool piecesOverlap(const DIExpression *P1, const DIExpression *P2) {
>>> - if (!P1->isBitPiece() || !P2->isBitPiece())
>>> - return true;
>>> +// Determine the relative position of the pieces described by P1 and P2.
>>> +// Returns -1 if P1 is entirely before P2, 0 if P1 and P2 overlap,
>>> +// 1 if P1 is entirely after P2.
>>> +static int pieceCmp(const DIExpression *P1, const DIExpression *P2) {
>>> unsigned l1 = P1->getBitPieceOffset();
>>> unsigned l2 = P2->getBitPieceOffset();
>>> unsigned r1 = l1 + P1->getBitPieceSize();
>>> unsigned r2 = l2 + P2->getBitPieceSize();
>>> - // True where [l1,r1[ and [r1,r2[ overlap.
>>> - return (l1 < r2) && (l2 < r1);
>>> + if (r1 <= l2)
>>> + return -1;
>>> + else if (r2 <= l1)
>>> + return 1;
>>> + else
>>> + return 0;
>>> +}
>>> +
>>> +/// Determine whether two variable pieces overlap.
>>> +static bool piecesOverlap(const DIExpression *P1, const DIExpression *P2) {
>>> + if (!P1->isBitPiece() || !P2->isBitPiece())
>>> + return true;
>>> + return pieceCmp(P1, P2) == 0;
>>> }
>>>
>>> /// \brief If this and Next are describing different pieces of the same
>>> @@ -806,14 +817,32 @@ static bool piecesOverlap(const DIExpres
>>> /// 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;
>>> + auto *FirstExpr = cast<DIExpression>(Values[0].Expression);
>>> + auto *FirstNextExpr = cast<DIExpression>(Next.Values[0].Expression);
>>> + if (!FirstExpr->isBitPiece() || !FirstNextExpr->isBitPiece())
>>> + return false;
>>> +
>>> + // We can only merge entries if none of the pieces overlap any others.
>>> + // In doing so, we can take advantage of the fact that both lists are
>>> + // sorted.
>>> + for (unsigned i = 0, j = 0; i < Values.size(); ++i) {
>>> + for (; j < Next.Values.size(); ++j) {
>>> + int res = pieceCmp(cast<DIExpression>(Values[i].Expression),
>>> + cast<DIExpression>(Next.Values[j].Expression));
>>> + if (res == 0) // The two expressions overlap, we can't merge.
>>> + return false;
>>> + // Values[i] is entirely before Next.Values[j],
>>> + // so go back to the next entry of Values.
>>> + else if (res == -1)
>>> + break;
>>> + // Next.Values[j] is entirely before Values[i], so go on to the
>>> + // next entry of Next.Values.
>>> + }
>>> }
>>> +
>>> + addValues(Next.Values);
>>> + End = Next.End;
>>> + return true;
>>> }
>>> return false;
>>> }
>>>
>>> Added: llvm/trunk/test/DebugInfo/X86/PR26148.ll
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/PR26148.ll?rev=259696&view=auto
>>> ==============================================================================
>>> --- llvm/trunk/test/DebugInfo/X86/PR26148.ll (added)
>>> +++ llvm/trunk/test/DebugInfo/X86/PR26148.ll Wed Feb 3 15:13:33 2016
>>> @@ -0,0 +1,102 @@
>>> +; RUN: llc -filetype=obj -o - < %s | llvm-dwarfdump - | FileCheck %s
>>> +;
>>> +; Created using clang -g -O3 from:
>>> +; struct S0 {
>>> +; short f0;
>>> +; int f3;
>>> +; } a;
>>> +; void fn1(short p1) {
>>> +; struct S0 b, c = {3};
>>> +; b.f3 = p1;
>>> +; a = b = c;
>>> +; }
>>> +;
>>> +; int main() { return 0; }
>>> +;
>>> +; This is similar to the bug in test/DebugInfo/ARM/PR26163.ll, except that there is an
>>> +; extra non-overlapping range first. Thus, we make sure that the backend actually looks
>>> +; at all expressions when determining whether to merge ranges, not just the first one.
>>> +; AS in 26163, we expect two ranges (as opposed to one), the first one being zero sized
>>> +;
>>> +;
>>> +; CHECK: 0x00000000: Beginning address offset: 0x0000000000000004
>>> +; CHECK: Ending address offset: 0x0000000000000004
>>> +; CHECK: Location description: 10 03 55 93 04
>>> +; CHECK: Beginning address offset: 0x0000000000000004
>>> +; CHECK: Ending address offset: 0x0000000000000014
>>> +; CHECK: Location description: 10 03 10 00
>>> +
>>> +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
>>> +target triple = "x86_64-apple-macosx10.11.0"
>>> +
>>> +%struct.S0 = type { i16, i32 }
>>> +
>>> + at a = common global %struct.S0 zeroinitializer, align 4
>>> +
>>> +declare void @llvm.dbg.declare(metadata, metadata, metadata)
>>> +declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
>>> +
>>> +; The attributes are here to force the zero-sized range not to be at the start of
>>> +; the function, which has special interpretation in DWARF. The fact that this happens
>>> +; at all is probably an LLVM bug.
>>> +attributes #0 = { "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" }
>>> +define void @fn1(i16 signext %p1) #0 !dbg !4 {
>>> +entry:
>>> + tail call void @llvm.dbg.value(metadata i16 %p1, i64 0, metadata !9, metadata !26), !dbg !27
>>> + tail call void @llvm.dbg.declare(metadata %struct.S0* undef, metadata !10, metadata !26), !dbg !28
>>> + tail call void @llvm.dbg.declare(metadata %struct.S0* undef, metadata !16, metadata !26), !dbg !29
>>> + tail call void @llvm.dbg.value(metadata i32 3, 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 @llvm.dbg.value(metadata i16 %p1, i64 0, metadata !10, metadata !32), !dbg !28
>>> + tail call void @llvm.dbg.value(metadata i32 3, i64 0, metadata !10, metadata !30), !dbg !28
>>> + tail call void @llvm.dbg.value(metadata i32 0, i64 0, metadata !10, metadata !31), !dbg !28
>>> + store i32 3, i32* bitcast (%struct.S0* @a to i32*), align 4, !dbg !33
>>> + store i32 0, i32* getelementptr inbounds (%struct.S0, %struct.S0* @a, i64 0, i32 1), align 4, !dbg !33
>>> + ret void, !dbg !34
>>> +}
>>> +
>>> +define i32 @main() !dbg !17 {
>>> +entry:
>>> + ret i32 0, !dbg !35
>>> +}
>>> +
>>> +!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 8f258397c5afd7a708bd95770c718e81d08fb11a) (https://github.com/llvm-mirror/llvm 18481855bdfa1b4a424f81be8525db002671348d)", isOptimized: true, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3, globals: !20)
>>> +!1 = !DIFile(filename: "small.c", directory: "/Users/kfischer/Projects/clangbug")
>>> +!2 = !{}
>>> +!3 = !{!4, !17}
>>> +!4 = distinct !DISubprogram(name: "fn1", scope: !1, file: !1, line: 5, type: !5, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, variables: !8)
>>> +!5 = !DISubroutineType(types: !6)
>>> +!6 = !{null, !7}
>>> +!7 = !DIBasicType(name: "short", size: 16, align: 16, encoding: DW_ATE_signed)
>>> +!8 = !{!9, !10, !16}
>>> +!9 = !DILocalVariable(name: "p1", arg: 1, scope: !4, file: !1, line: 5, type: !7)
>>> +!10 = !DILocalVariable(name: "b", scope: !4, file: !1, line: 6, type: !11)
>>> +!11 = !DICompositeType(tag: DW_TAG_structure_type, name: "S0", file: !1, line: 1, size: 64, align: 32, elements: !12)
>>> +!12 = !{!13, !14}
>>> +!13 = !DIDerivedType(tag: DW_TAG_member, name: "f0", scope: !11, file: !1, line: 2, baseType: !7, size: 16, align: 16)
>>> +!14 = !DIDerivedType(tag: DW_TAG_member, name: "f3", scope: !11, file: !1, line: 3, baseType: !15, size: 32, align: 32, offset: 32)
>>> +!15 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
>>> +!16 = !DILocalVariable(name: "c", scope: !4, file: !1, line: 6, type: !11)
>>> +!17 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 11, type: !18, isLocal: false, isDefinition: true, scopeLine: 11, isOptimized: true, variables: !2)
>>> +!18 = !DISubroutineType(types: !19)
>>> +!19 = !{!15}
>>> +!20 = !{!21}
>>> +!21 = !DIGlobalVariable(name: "a", scope: !0, file: !1, line: 4, type: !11, isLocal: false, isDefinition: true, variable: %struct.S0* @a)
>>> +!22 = !{i32 2, !"Dwarf Version", i32 2}
>>> +!23 = !{i32 2, !"Debug Info Version", i32 3}
>>> +!24 = !{i32 1, !"PIC Level", i32 2}
>>> +!25 = !{!"clang version 3.9.0 (https://github.com/llvm-mirror/clang 8f258397c5afd7a708bd95770c718e81d08fb11a) (https://github.com/llvm-mirror/llvm 18481855bdfa1b4a424f81be8525db002671348d)"}
>>> +!26 = !DIExpression()
>>> +!27 = !DILocation(line: 5, column: 16, scope: !4)
>>> +!28 = !DILocation(line: 6, column: 13, scope: !4)
>>> +!29 = !DILocation(line: 6, column: 16, scope: !4)
>>> +!30 = !DIExpression(DW_OP_bit_piece, 0, 32)
>>> +!31 = !DIExpression(DW_OP_bit_piece, 32, 32)
>>> +!32 = !DIExpression(DW_OP_bit_piece, 32, 16)
>>> +!33 = !DILocation(line: 8, column: 9, scope: !4)
>>> +!34 = !DILocation(line: 9, column: 1, scope: !4)
>>> +!35 = !DILocation(line: 11, column: 14, scope: !17)
>>>
>>>
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