diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp --- a/llvm/lib/Transforms/Utils/Local.cpp +++ b/llvm/lib/Transforms/Utils/Local.cpp @@ -1724,6 +1724,9 @@ void llvm::salvageDebugInfoForDbgValues( Instruction &I, ArrayRef DbgUsers) { + // This is an arbitrary chosen limit on the maximum number of values we can + // salvage up to in a DIArgList, used for performance reasons. + const unsigned MaxDebugArgs = 16; bool Salvaged = false; for (auto *DII : DbgUsers) { @@ -1748,11 +1751,15 @@ DII->replaceVariableLocationOp(&I, I.getOperand(0)); if (AdditionalValues.empty()) { DII->setExpression(SalvagedExpr); - } else if (isa(DII)) { + } else if (isa(DII) && + DII->getNumVariableLocationOps() + AdditionalValues.size() <= + MaxDebugArgs) { DII->addVariableLocationOps(AdditionalValues, SalvagedExpr); } else { // Do not salvage using DIArgList for dbg.addr/dbg.declare, as it is // currently only valid for stack value expressions. + // Also do not salvage if the resulting DIArgList would contain an + // unreasonably large number of values. Value *Undef = UndefValue::get(I.getOperand(0)->getType()); DII->replaceVariableLocationOp(I.getOperand(0), Undef); } diff --git a/llvm/test/DebugInfo/limit-arglist-size.ll b/llvm/test/DebugInfo/limit-arglist-size.ll new file mode 100644 --- /dev/null +++ b/llvm/test/DebugInfo/limit-arglist-size.ll @@ -0,0 +1,63 @@ +; RUN: opt -S -instcombine %s -o - | FileCheck %s + +; For performance reasons, we currently limit the number of values that can be +; referenced by a dbg.value to 16. This test checks that we do not exceed this +; limit during salvaging. + +; CHECK: DIArgList(i32 undef +; CHECK-NOT: DW_OP_LLVM_arg, 16 + +target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +define i32 @_Z3foov() local_unnamed_addr !dbg !9 { +entry: + %call = call i32 @_Z3barv(), !dbg !14 + %call1 = call i32 @_Z3barv(), !dbg !14 + %add = add nsw i32 %call, %call1, !dbg !14 + %call2 = call i32 @_Z3barv(), !dbg !14 + %call4 = call i32 @_Z3barv(), !dbg !14 + %call6 = call i32 @_Z3barv(), !dbg !14 + %call8 = call i32 @_Z3barv(), !dbg !14 + %call10 = call i32 @_Z3barv(), !dbg !14 + %call12 = call i32 @_Z3barv(), !dbg !14 + %call14 = call i32 @_Z3barv(), !dbg !14 + %call16 = call i32 @_Z3barv(), !dbg !14 + %call18 = call i32 @_Z3barv(), !dbg !14 + %call20 = call i32 @_Z3barv(), !dbg !14 + %call22 = call i32 @_Z3barv(), !dbg !14 + %call24 = call i32 @_Z3barv(), !dbg !14 + %call26 = call i32 @_Z3barv(), !dbg !14 + %call28 = call i32 @_Z3barv(), !dbg !14 + %call30 = call i32 @_Z3barv(), !dbg !14 + call void @llvm.dbg.value(metadata !DIArgList(i32 %add, i32 %call30, i32 %call28, i32 %call26, i32 %call24, i32 %call22, i32 %call20, i32 %call18, i32 %call16, i32 %call14, i32 %call12, i32 %call10, i32 %call8, i32 %call6, i32 %call4, i32 %call2), metadata !15, metadata !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 15, DW_OP_plus, DW_OP_LLVM_arg, 14, DW_OP_plus, DW_OP_LLVM_arg, 13, DW_OP_plus, DW_OP_LLVM_arg, 12, DW_OP_plus, DW_OP_LLVM_arg, 11, DW_OP_plus, DW_OP_LLVM_arg, 10, DW_OP_plus, DW_OP_LLVM_arg, 9, DW_OP_plus, DW_OP_LLVM_arg, 8, DW_OP_plus, DW_OP_LLVM_arg, 7, DW_OP_plus, DW_OP_LLVM_arg, 6, DW_OP_plus, DW_OP_LLVM_arg, 5, DW_OP_plus, DW_OP_LLVM_arg, 4, DW_OP_plus, DW_OP_LLVM_arg, 3, DW_OP_plus, DW_OP_LLVM_arg, 2, DW_OP_plus, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_stack_value)), !dbg !16 + %call32 = call i32 @_Z3barv(), !dbg !17 + ret i32 %call32, !dbg !17 +} + +declare dso_local i32 @_Z3barv() local_unnamed_addr + +declare void @llvm.dbg.value(metadata, metadata, metadata) + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!3, !4, !5, !6, !7} +!llvm.ident = !{!8} + +!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 13.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None) +!1 = !DIFile(filename: "limit-arglist-size.cpp", directory: "/") +!2 = !{} +!3 = !{i32 7, !"Dwarf Version", i32 4} +!4 = !{i32 2, !"Debug Info Version", i32 3} +!5 = !{i32 1, !"wchar_size", i32 4} +!6 = !{i32 7, !"uwtable", i32 1} +!7 = !{i32 7, !"frame-pointer", i32 2} +!8 = !{!"clang version 13.0.0"} +!9 = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov", scope: !10, file: !10, line: 3, type: !11, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2) +!10 = !DIFile(filename: "./limit-arglist-size.cpp", directory: "/") +!11 = !DISubroutineType(types: !12) +!12 = !{!13} +!13 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +!14 = !DILocation(line: 4, scope: !9) +!15 = !DILocalVariable(name: "v16", scope: !9, file: !10, line: 4, type: !13) +!16 = !DILocation(line: 0, scope: !9) +!17 = !DILocation(line: 5, scope: !9)