forked from OSchip/llvm-project
[DwarfDebug] Refuse to emit DW_OP_LLVM_arg values wider than 64 bits
DwarfExpression::addUnsignedConstant(const APInt &Value) only supports wider-than-64-bit values when it is used to emit a top-level DWARF expression representing the location of a variable. Before this change, it was possible to call addUnsignedConstant on >64 bit values within a subexpression when substituting DW_OP_LLVM_arg values. This can trigger an assertion failure (e.g. PR52584, PR52333) when it happens in a fragment (DW_OP_LLVM_fragment) expression, as addUnsignedConstant on >64 bit values splits the constant into separate DW_OP_pieces, which modifies DwarfExpression::OffsetInBits. This change papers over the assertion errors by bailing on overly wide DW_OP_LLVM_arg values. A more comprehensive fix might be to be to split wide values into pointer-sized fragments. [0] https://github.com/llvm/llvm-project/blob/e71fa03/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp#L799-L805 Patch by Ricky Zhou! Differential Revision: https://reviews.llvm.org/D115343
This commit is contained in:
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@ -789,7 +789,7 @@ DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
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const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
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const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
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auto AddEntry = [&](const DbgValueLocEntry &Entry,
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auto AddEntry = [&](const DbgValueLocEntry &Entry,
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DIExpressionCursor &Cursor) {
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DIExpressionCursor &Cursor) {
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if (Entry.isLocation()) {
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if (Entry.isLocation()) {
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if (!DwarfExpr.addMachineRegExpression(TRI, Cursor,
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if (!DwarfExpr.addMachineRegExpression(TRI, Cursor,
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Entry.getLoc().getReg()))
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Entry.getLoc().getReg()))
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@ -798,11 +798,19 @@ DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
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// If there is an expression, emit raw unsigned bytes.
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// If there is an expression, emit raw unsigned bytes.
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DwarfExpr.addUnsignedConstant(Entry.getInt());
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DwarfExpr.addUnsignedConstant(Entry.getInt());
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} else if (Entry.isConstantFP()) {
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} else if (Entry.isConstantFP()) {
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// DwarfExpression does not support arguments wider than 64 bits
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// (see PR52584).
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// TODO: Consider chunking expressions containing overly wide
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// arguments into separate pointer-sized fragment expressions.
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APInt RawBytes = Entry.getConstantFP()->getValueAPF().bitcastToAPInt();
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APInt RawBytes = Entry.getConstantFP()->getValueAPF().bitcastToAPInt();
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DwarfExpr.addUnsignedConstant(RawBytes);
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if (RawBytes.getBitWidth() > 64)
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return false;
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DwarfExpr.addUnsignedConstant(RawBytes.getZExtValue());
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} else if (Entry.isConstantInt()) {
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} else if (Entry.isConstantInt()) {
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APInt RawBytes = Entry.getConstantInt()->getValue();
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APInt RawBytes = Entry.getConstantInt()->getValue();
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DwarfExpr.addUnsignedConstant(RawBytes);
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if (RawBytes.getBitWidth() > 64)
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return false;
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DwarfExpr.addUnsignedConstant(RawBytes.getZExtValue());
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} else if (Entry.isTargetIndexLocation()) {
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} else if (Entry.isTargetIndexLocation()) {
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TargetIndexLocation Loc = Entry.getTargetIndexLocation();
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TargetIndexLocation Loc = Entry.getTargetIndexLocation();
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// TODO TargetIndexLocation is a target-independent. Currently only the
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// TODO TargetIndexLocation is a target-independent. Currently only the
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@ -815,11 +823,12 @@ DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
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return true;
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return true;
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};
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};
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DwarfExpr.addExpression(
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if (!DwarfExpr.addExpression(
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std::move(Cursor),
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std::move(Cursor),
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[&](unsigned Idx, DIExpressionCursor &Cursor) -> bool {
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[&](unsigned Idx, DIExpressionCursor &Cursor) -> bool {
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return AddEntry(DVal->getLocEntries()[Idx], Cursor);
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return AddEntry(DVal->getLocEntries()[Idx], Cursor);
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});
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}))
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return VariableDie;
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// Now attach the location information to the DIE.
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// Now attach the location information to the DIE.
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addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
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addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
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@ -463,15 +463,14 @@ static bool isMemoryLocation(DIExpressionCursor ExprCursor) {
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return true;
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return true;
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}
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}
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void DwarfExpression::addExpression(DIExpressionCursor &&ExprCursor,
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void DwarfExpression::addExpression(DIExpressionCursor &&ExprCursor) {
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unsigned FragmentOffsetInBits) {
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addExpression(std::move(ExprCursor),
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addExpression(std::move(ExprCursor),
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[](unsigned Idx, DIExpressionCursor &Cursor) -> bool {
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[](unsigned Idx, DIExpressionCursor &Cursor) -> bool {
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llvm_unreachable("unhandled opcode found in expression");
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llvm_unreachable("unhandled opcode found in expression");
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});
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});
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}
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}
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void DwarfExpression::addExpression(
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bool DwarfExpression::addExpression(
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DIExpressionCursor &&ExprCursor,
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DIExpressionCursor &&ExprCursor,
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llvm::function_ref<bool(unsigned, DIExpressionCursor &)> InsertArg) {
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llvm::function_ref<bool(unsigned, DIExpressionCursor &)> InsertArg) {
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// Entry values can currently only cover the initial register location,
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// Entry values can currently only cover the initial register location,
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@ -496,7 +495,7 @@ void DwarfExpression::addExpression(
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case dwarf::DW_OP_LLVM_arg:
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case dwarf::DW_OP_LLVM_arg:
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if (!InsertArg(Op->getArg(0), ExprCursor)) {
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if (!InsertArg(Op->getArg(0), ExprCursor)) {
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LocationKind = Unknown;
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LocationKind = Unknown;
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return;
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return false;
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}
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}
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break;
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break;
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case dwarf::DW_OP_LLVM_fragment: {
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case dwarf::DW_OP_LLVM_fragment: {
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@ -527,7 +526,7 @@ void DwarfExpression::addExpression(
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setSubRegisterPiece(0, 0);
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setSubRegisterPiece(0, 0);
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// Reset the location description kind.
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// Reset the location description kind.
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LocationKind = Unknown;
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LocationKind = Unknown;
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return;
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return true;
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}
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}
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case dwarf::DW_OP_plus_uconst:
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case dwarf::DW_OP_plus_uconst:
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assert(!isRegisterLocation());
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assert(!isRegisterLocation());
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@ -630,6 +629,8 @@ void DwarfExpression::addExpression(
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if (isImplicitLocation() && !isParameterValue())
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if (isImplicitLocation() && !isParameterValue())
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// Turn this into an implicit location description.
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// Turn this into an implicit location description.
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addStackValue();
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addStackValue();
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return true;
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}
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}
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/// add masking operations to stencil out a subregister.
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/// add masking operations to stencil out a subregister.
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@ -340,16 +340,17 @@ public:
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/// create one if necessary.
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/// create one if necessary.
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unsigned getOrCreateBaseType(unsigned BitSize, dwarf::TypeKind Encoding);
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unsigned getOrCreateBaseType(unsigned BitSize, dwarf::TypeKind Encoding);
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/// Emit all remaining operations in the DIExpressionCursor. The
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/// cursor must not contain any DW_OP_LLVM_arg operations.
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void addExpression(DIExpressionCursor &&Expr);
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/// Emit all remaining operations in the DIExpressionCursor.
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/// Emit all remaining operations in the DIExpressionCursor.
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///
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/// DW_OP_LLVM_arg operations are resolved by calling (\p InsertArg).
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/// \param FragmentOffsetInBits If this is one fragment out of multiple
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//
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/// locations, this is the offset of the
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/// \return false if any call to (\p InsertArg) returns false.
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/// fragment inside the entire variable.
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bool addExpression(
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void addExpression(DIExpressionCursor &&Expr,
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DIExpressionCursor &&Expr,
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unsigned FragmentOffsetInBits = 0);
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llvm::function_ref<bool(unsigned, DIExpressionCursor &)> InsertArg);
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void
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addExpression(DIExpressionCursor &&Expr,
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llvm::function_ref<bool(unsigned, DIExpressionCursor &)> InsertArg);
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/// If applicable, emit an empty DW_OP_piece / DW_OP_bit_piece to advance to
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/// If applicable, emit an empty DW_OP_piece / DW_OP_bit_piece to advance to
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/// the fragment described by \c Expr.
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/// the fragment described by \c Expr.
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@ -0,0 +1,33 @@
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; RUN: llc -mtriple=x86_64-unknown-linux-gnu -filetype=obj -o - %s \
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; RUN: | llvm-dwarfdump - \
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; RUN: | FileCheck %s
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; CHECK: DW_TAG_variable
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; CHECK-NOT: DW_AT_location
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; CHECK-NEXT: DW_AT_name ("arr")
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; CHECK-NOT: DW_AT_location
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; CHECK: DW_TAG
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define dso_local void @test() !dbg !4 {
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entry:
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call void @llvm.dbg.value(metadata !DIArgList(i128 0), metadata !7, metadata !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 127)), !dbg !12
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ret void, !dbg !12
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}
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declare void @llvm.dbg.value(metadata, metadata, metadata)
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!2, !3}
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!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
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!1 = !DIFile(filename: "test.c", directory: "")
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!2 = !{i32 7, !"Dwarf Version", i32 4}
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!3 = !{i32 2, !"Debug Info Version", i32 3}
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!4 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 1, type: !5, unit: !0)
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!5 = !DISubroutineType(types: !6)
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!6 = !{null}
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!7 = !DILocalVariable(name: "arr", scope: !4, file: !1, line: 1, type: !8)
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!8 = !DICompositeType(tag: DW_TAG_array_type, baseType: !9, size: 128, elements: !10)
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!9 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
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!10 = !{!11}
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!11 = !DISubrange(count: 16)
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!12 = !DILocation(line: 1, column: 1, scope: !4)
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