[llvm] r259696 - [DWARFDebug] Fix another case of overlapping ranges
Hans Wennborg via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 8 09:47:02 PST 2016
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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