[llvm] r218787 - Move the complex address expression out of DIVariable and into an extra

Manuel Klimek klimek at google.com
Thu Oct 2 05:49:18 PDT 2014


This apparently leads to clang segfaults in our internal builds...

On Wed Oct 01 2014 at 9:11:14 PM Adrian Prantl <aprantl at apple.com> wrote:

> Author: adrian
> Date: Wed Oct  1 13:55:02 2014
> New Revision: 218787
>
> URL: http://llvm.org/viewvc/llvm-project?rev=218787&view=rev
> Log:
> Move the complex address expression out of DIVariable and into an extra
> argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.
>
> Previously, DIVariable was a variable-length field that has an optional
> reference to a Metadata array consisting of a variable number of
> complex address expressions. In the case of OpPiece expressions this is
> wasting a lot of storage in IR, because when an aggregate type is, e.g.,
> SROA'd into all of its n individual members, the IR will contain n copies
> of the DIVariable, all alike, only differing in the complex address
> reference at the end.
>
> By making the complex address into an extra argument of the
> dbg.value/dbg.declare intrinsics, all of the pieces can reference the
> same variable and the complex address expressions can be uniqued across
> the CU, too.
> Down the road, this will allow us to move other flags, such as
> "indirection" out of the DIVariable, too.
>
> The new intrinsics look like this:
> declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata
> %expr)
> declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata
> %var, metadata %expr)
>
> This patch adds a new LLVM-local tag to DIExpressions, so we can detect
> and pretty-print DIExpression metadata nodes.
>
> What this patch doesn't do:
>
> This patch does not touch the "Indirect" field in DIVariable; but moving
> that into the expression would be a natural next step.
>
> http://reviews.llvm.org/D4919
> rdar://problem/17994491
>
> Thanks to dblaikie and dexonsmith for reviewing this patch!
>
> Note: I accidentally committed a bogus older version of this patch
> previously.
>
> Modified:
>     llvm/trunk/docs/SourceLevelDebugging.rst
>     llvm/trunk/include/llvm/CodeGen/MachineInstr.h
>     llvm/trunk/include/llvm/CodeGen/MachineInstrBuilder.h
>     llvm/trunk/include/llvm/CodeGen/MachineModuleInfo.h
>     llvm/trunk/include/llvm/CodeGen/SelectionDAG.h
>     llvm/trunk/include/llvm/IR/DIBuilder.h
>     llvm/trunk/include/llvm/IR/DebugInfo.h
>     llvm/trunk/include/llvm/IR/IntrinsicInst.h
>     llvm/trunk/include/llvm/IR/Intrinsics.td
>     llvm/trunk/include/llvm/Support/Dwarf.h
>     llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
>     llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
>     llvm/trunk/lib/CodeGen/AsmPrinter/DebugLocEntry.h
>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
>     llvm/trunk/lib/CodeGen/InlineSpiller.cpp
>     llvm/trunk/lib/CodeGen/LiveDebugVariables.cpp
>     llvm/trunk/lib/CodeGen/MachineInstr.cpp
>     llvm/trunk/lib/CodeGen/RegAllocFast.cpp
>     llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp
>     llvm/trunk/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
>     llvm/trunk/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
>     llvm/trunk/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
>     llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
>     llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
>     llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
>     llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
>     llvm/trunk/lib/IR/AutoUpgrade.cpp
>     llvm/trunk/lib/IR/DIBuilder.cpp
>     llvm/trunk/lib/IR/DebugInfo.cpp
>     llvm/trunk/lib/Support/Dwarf.cpp
>     llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp
>     llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.h
>     llvm/trunk/lib/Target/X86/X86FastISel.cpp
>     llvm/trunk/lib/Transforms/Scalar/SROA.cpp
>     llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
>     llvm/trunk/lib/Transforms/Utils/Local.cpp
>     llvm/trunk/test/Analysis/GlobalsModRef/pr12351.ll
>     llvm/trunk/test/Assembler/2010-02-05-FunctionLocalMetadataBecomesNu
> ll.ll
>     llvm/trunk/test/Assembler/functionlocal-metadata.ll
>     llvm/trunk/test/CodeGen/AArch64/aarch64-2014-08-11-
> MachineCombinerCrash.ll
>     llvm/trunk/test/CodeGen/AArch64/arm64-2011-03-17-AsmPrinterCrash.ll
>     llvm/trunk/test/CodeGen/ARM/2009-10-16-Scope.ll
>     llvm/trunk/test/CodeGen/ARM/2010-04-15-ScavengerDebugValue.ll
>     llvm/trunk/test/CodeGen/ARM/2010-06-25-Thumb2ITInvalidIterator.ll
>     llvm/trunk/test/CodeGen/ARM/2010-08-04-StackVariable.ll
>     llvm/trunk/test/CodeGen/ARM/2011-01-19-MergedGlobalDbg.ll
>     llvm/trunk/test/CodeGen/ARM/2011-08-02-MergedGlobalDbg.ll
>     llvm/trunk/test/CodeGen/ARM/coalesce-dbgvalue.ll
>     llvm/trunk/test/CodeGen/ARM/debug-info-arg.ll
>     llvm/trunk/test/CodeGen/ARM/debug-info-blocks.ll
>     llvm/trunk/test/CodeGen/ARM/debug-info-branch-folding.ll
>     llvm/trunk/test/CodeGen/ARM/debug-info-d16-reg.ll
>     llvm/trunk/test/CodeGen/ARM/debug-info-qreg.ll
>     llvm/trunk/test/CodeGen/ARM/debug-info-s16-reg.ll
>     llvm/trunk/test/CodeGen/ARM/debug-info-sreg2.ll
>     llvm/trunk/test/CodeGen/Generic/dbg_value.ll
>     llvm/trunk/test/CodeGen/Hexagon/hwloop-dbg.ll
>     llvm/trunk/test/CodeGen/Inputs/DbgValueOtherTargets.ll
>     llvm/trunk/test/CodeGen/PowerPC/dbg.ll
>     llvm/trunk/test/CodeGen/PowerPC/pr17168.ll
>     llvm/trunk/test/CodeGen/Thumb/2010-07-15-debugOrdering.ll
>     llvm/trunk/test/CodeGen/X86/2009-02-12-DebugInfoVLA.ll
>     llvm/trunk/test/CodeGen/X86/2009-10-16-Scope.ll
>     llvm/trunk/test/CodeGen/X86/2010-01-18-DbgValue.ll
>     llvm/trunk/test/CodeGen/X86/2010-02-01-DbgValueCrash.ll
>     llvm/trunk/test/CodeGen/X86/2010-05-25-DotDebugLoc.ll
>     llvm/trunk/test/CodeGen/X86/2010-05-26-DotDebugLoc.ll
>     llvm/trunk/test/CodeGen/X86/2010-05-28-Crash.ll
>     llvm/trunk/test/CodeGen/X86/2010-06-01-DeadArg-DbgInfo.ll
>     llvm/trunk/test/CodeGen/X86/2010-07-06-DbgCrash.ll
>     llvm/trunk/test/CodeGen/X86/2010-08-04-StackVariable.ll
>     llvm/trunk/test/CodeGen/X86/2010-11-02-DbgParameter.ll
>     llvm/trunk/test/CodeGen/X86/2011-01-24-DbgValue-Before-Use.ll
>     llvm/trunk/test/CodeGen/X86/2012-11-30-handlemove-dbg.ll
>     llvm/trunk/test/CodeGen/X86/2012-11-30-misched-dbg.ll
>     llvm/trunk/test/CodeGen/X86/2012-11-30-regpres-dbg.ll
>     llvm/trunk/test/CodeGen/X86/MachineSink-DbgValue.ll
>     llvm/trunk/test/CodeGen/X86/StackColoring-dbg.ll
>     llvm/trunk/test/CodeGen/X86/dbg-changes-codegen-branch-folding.ll
>     llvm/trunk/test/CodeGen/X86/dbg-changes-codegen.ll
>     llvm/trunk/test/CodeGen/X86/fpstack-debuginstr-kill.ll
>     llvm/trunk/test/CodeGen/X86/stack-protector-dbginfo.ll
>     llvm/trunk/test/CodeGen/XCore/dwarf_debug.ll
>     llvm/trunk/test/DebugInfo/2009-11-10-CurrentFn.ll
>     llvm/trunk/test/DebugInfo/2010-03-12-llc-crash.ll
>     llvm/trunk/test/DebugInfo/2010-03-19-DbgDeclare.ll
>     llvm/trunk/test/DebugInfo/2010-03-24-MemberFn.ll
>     llvm/trunk/test/DebugInfo/2010-03-30-InvalidDbgInfoCrash.ll
>     llvm/trunk/test/DebugInfo/2010-04-06-NestedFnDbgInfo.ll
>     llvm/trunk/test/DebugInfo/2010-05-03-DisableFramePtr.ll
>     llvm/trunk/test/DebugInfo/2010-05-03-OriginDIE.ll
>     llvm/trunk/test/DebugInfo/2010-06-29-InlinedFnLocalVar.ll
>     llvm/trunk/test/DebugInfo/2010-10-01-crash.ll
>     llvm/trunk/test/DebugInfo/AArch64/struct_by_value.ll
>     llvm/trunk/test/DebugInfo/ARM/PR16736.ll
>     llvm/trunk/test/DebugInfo/ARM/lowerbdgdeclare_vla.ll
>     llvm/trunk/test/DebugInfo/ARM/s-super-register.ll
>     llvm/trunk/test/DebugInfo/ARM/selectiondag-deadcode.ll
>     llvm/trunk/test/DebugInfo/Mips/delay-slot.ll
>     llvm/trunk/test/DebugInfo/PR20038.ll
>     llvm/trunk/test/DebugInfo/SystemZ/variable-loc.ll
>     llvm/trunk/test/DebugInfo/X86/2010-04-13-PubType.ll
>     llvm/trunk/test/DebugInfo/X86/2011-09-26-GlobalVarContext.ll
>     llvm/trunk/test/DebugInfo/X86/2011-12-16-BadStructRef.ll
>     llvm/trunk/test/DebugInfo/X86/DW_AT_byte_size.ll
>     llvm/trunk/test/DebugInfo/X86/DW_AT_linkage_name.ll
>     llvm/trunk/test/DebugInfo/X86/DW_AT_location-reference.ll
>     llvm/trunk/test/DebugInfo/X86/DW_AT_object_pointer.ll
>     llvm/trunk/test/DebugInfo/X86/aligned_stack_var.ll
>     llvm/trunk/test/DebugInfo/X86/arguments.ll
>     llvm/trunk/test/DebugInfo/X86/array.ll
>     llvm/trunk/test/DebugInfo/X86/array2.ll
>     llvm/trunk/test/DebugInfo/X86/block-capture.ll
>     llvm/trunk/test/DebugInfo/X86/byvalstruct.ll
>     llvm/trunk/test/DebugInfo/X86/cu-ranges-odr.ll
>     llvm/trunk/test/DebugInfo/X86/cu-ranges.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-byval-parameter.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-const-int.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-const.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-declare-arg.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-declare.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-i128-const.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-merge-loc-entry.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-prolog-end.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-value-dag-combine.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-value-inlined-parameter.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-value-isel.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-value-location.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-value-range.ll
>     llvm/trunk/test/DebugInfo/X86/dbg-value-terminator.ll
>     llvm/trunk/test/DebugInfo/X86/dbg_value_direct.ll
>     llvm/trunk/test/DebugInfo/X86/debug-info-block-captured-self.ll
>     llvm/trunk/test/DebugInfo/X86/debug-info-blocks.ll
>     llvm/trunk/test/DebugInfo/X86/debug-info-static-member.ll
>     llvm/trunk/test/DebugInfo/X86/debug-loc-asan.ll
>     llvm/trunk/test/DebugInfo/X86/debug-loc-offset.ll
>     llvm/trunk/test/DebugInfo/X86/debug-ranges-offset.ll
>     llvm/trunk/test/DebugInfo/X86/decl-derived-member.ll
>     llvm/trunk/test/DebugInfo/X86/dwarf-aranges-no-dwarf-labels.ll
>     llvm/trunk/test/DebugInfo/X86/dwarf-public-names.ll
>     llvm/trunk/test/DebugInfo/X86/earlydup-crash.ll
>     llvm/trunk/test/DebugInfo/X86/elf-names.ll
>     llvm/trunk/test/DebugInfo/X86/empty-and-one-elem-array.ll
>     llvm/trunk/test/DebugInfo/X86/ending-run.ll
>     llvm/trunk/test/DebugInfo/X86/fission-ranges.ll
>     llvm/trunk/test/DebugInfo/X86/formal_parameter.ll
>     llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll
>     llvm/trunk/test/DebugInfo/X86/gnu-public-names.ll
>     llvm/trunk/test/DebugInfo/X86/inline-member-function.ll
>     llvm/trunk/test/DebugInfo/X86/inline-seldag-test.ll
>     llvm/trunk/test/DebugInfo/X86/instcombine-instrinsics.ll
>     llvm/trunk/test/DebugInfo/X86/lexical_block.ll
>     llvm/trunk/test/DebugInfo/X86/line-info.ll
>     llvm/trunk/test/DebugInfo/X86/linkage-name.ll
>     llvm/trunk/test/DebugInfo/X86/misched-dbg-value.ll
>     llvm/trunk/test/DebugInfo/X86/multiple-at-const-val.ll
>     llvm/trunk/test/DebugInfo/X86/nodebug_with_debug_loc.ll
>     llvm/trunk/test/DebugInfo/X86/objc-property-void.ll
>     llvm/trunk/test/DebugInfo/X86/op_deref.ll
>     llvm/trunk/test/DebugInfo/X86/parameters.ll
>     llvm/trunk/test/DebugInfo/X86/pieces-1.ll
>     llvm/trunk/test/DebugInfo/X86/pieces-2.ll
>     llvm/trunk/test/DebugInfo/X86/pieces-3.ll
>     llvm/trunk/test/DebugInfo/X86/pr11300.ll
>     llvm/trunk/test/DebugInfo/X86/pr12831.ll
>     llvm/trunk/test/DebugInfo/X86/pr19307.ll
>     llvm/trunk/test/DebugInfo/X86/recursive_inlining.ll
>     llvm/trunk/test/DebugInfo/X86/reference-argument.ll
>     llvm/trunk/test/DebugInfo/X86/rvalue-ref.ll
>     llvm/trunk/test/DebugInfo/X86/sret.ll
>     llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
>     llvm/trunk/test/DebugInfo/X86/subrange-type.ll
>     llvm/trunk/test/DebugInfo/X86/subreg.ll
>     llvm/trunk/test/DebugInfo/X86/subregisters.ll
>     llvm/trunk/test/DebugInfo/X86/union-template.ll
>     llvm/trunk/test/DebugInfo/X86/vla.ll
>     llvm/trunk/test/DebugInfo/array.ll
>     llvm/trunk/test/DebugInfo/cross-cu-inlining.ll
>     llvm/trunk/test/DebugInfo/cross-cu-linkonce-distinct.ll
>     llvm/trunk/test/DebugInfo/cross-cu-linkonce.ll
>     llvm/trunk/test/DebugInfo/cu-range-hole.ll
>     llvm/trunk/test/DebugInfo/cu-ranges.ll
>     llvm/trunk/test/DebugInfo/dead-argument-order.ll
>     llvm/trunk/test/DebugInfo/debug-info-qualifiers.ll
>     llvm/trunk/test/DebugInfo/dwarf-public-names.ll
>     llvm/trunk/test/DebugInfo/enum-types.ll
>     llvm/trunk/test/DebugInfo/enum.ll
>     llvm/trunk/test/DebugInfo/incorrect-variable-debugloc.ll
>     llvm/trunk/test/DebugInfo/inheritance.ll
>     llvm/trunk/test/DebugInfo/inline-debug-info-multiret.ll
>     llvm/trunk/test/DebugInfo/inline-debug-info.ll
>     llvm/trunk/test/DebugInfo/inline-scopes.ll
>     llvm/trunk/test/DebugInfo/inlined-arguments.ll
>     llvm/trunk/test/DebugInfo/inlined-vars.ll
>     llvm/trunk/test/DebugInfo/member-order.ll
>     llvm/trunk/test/DebugInfo/missing-abstract-variable.ll
>     llvm/trunk/test/DebugInfo/namespace.ll
>     llvm/trunk/test/DebugInfo/namespace_inline_function_definition.ll
>     llvm/trunk/test/DebugInfo/restrict.ll
>     llvm/trunk/test/DebugInfo/sugared-constants.ll
>     llvm/trunk/test/DebugInfo/tu-composite.ll
>     llvm/trunk/test/DebugInfo/two-cus-from-same-file.ll
>     llvm/trunk/test/DebugInfo/unconditional-branch.ll
>     llvm/trunk/test/DebugInfo/varargs.ll
>     llvm/trunk/test/Instrumentation/AddressSanitizer/coverage-dbg.ll
>     llvm/trunk/test/Instrumentation/AddressSanitizer/coverage2-dbg.ll
>     llvm/trunk/test/Instrumentation/AddressSanitizer/debug_info.ll
>     llvm/trunk/test/Instrumentation/MemorySanitizer/store-origin.ll
>     llvm/trunk/test/JitListener/test-common-symbols.ll
>     llvm/trunk/test/JitListener/test-inline.ll
>     llvm/trunk/test/JitListener/test-parameters.ll
>     llvm/trunk/test/Linker/2011-08-18-unique-class-type.ll
>     llvm/trunk/test/Linker/2011-08-18-unique-class-type2.ll
>     llvm/trunk/test/Linker/DbgDeclare.ll
>     llvm/trunk/test/Linker/DbgDeclare2.ll
>     llvm/trunk/test/Linker/Inputs/type-unique-inheritance-a.ll
>     llvm/trunk/test/Linker/Inputs/type-unique-inheritance-b.ll
>     llvm/trunk/test/Linker/Inputs/type-unique-simple2-a.ll
>     llvm/trunk/test/Linker/Inputs/type-unique-simple2-b.ll
>     llvm/trunk/test/Linker/type-unique-odr-a.ll
>     llvm/trunk/test/Linker/type-unique-odr-b.ll
>     llvm/trunk/test/Linker/type-unique-simple-a.ll
>     llvm/trunk/test/Linker/type-unique-simple-b.ll
>     llvm/trunk/test/Linker/type-unique-simple2-a.ll
>     llvm/trunk/test/Linker/type-unique-simple2-b.ll
>     llvm/trunk/test/Linker/type-unique-type-array-a.ll
>     llvm/trunk/test/Linker/type-unique-type-array-b.ll
>     llvm/trunk/test/Transforms/AddDiscriminators/no-discriminators.ll
>     llvm/trunk/test/Transforms/DeadArgElim/2010-04-30-DbgInfo.ll
>     llvm/trunk/test/Transforms/DeadStoreElimination/inst-limits.ll
>     llvm/trunk/test/Transforms/GCOVProfiling/linezero.ll
>     llvm/trunk/test/Transforms/GlobalOpt/2009-03-05-dbg.ll
>     llvm/trunk/test/Transforms/Inline/ignore-debug-info.ll
>     llvm/trunk/test/Transforms/InstCombine/debuginfo.ll
>     llvm/trunk/test/Transforms/LICM/debug-value.ll
>     llvm/trunk/test/Transforms/LoopIdiom/debug-line.ll
>     llvm/trunk/test/Transforms/LoopRotate/dbgvalue.ll
>     llvm/trunk/test/Transforms/LoopStrengthReduce/pr12018.ll
>     llvm/trunk/test/Transforms/LoopVectorize/dbg.value.ll
>     llvm/trunk/test/Transforms/LoopVectorize/debugloc.ll
>     llvm/trunk/test/Transforms/Mem2Reg/ConvertDebugInfo.ll
>     llvm/trunk/test/Transforms/Mem2Reg/ConvertDebugInfo2.ll
>     llvm/trunk/test/Transforms/ObjCARC/allocas.ll
>     llvm/trunk/test/Transforms/ObjCARC/basic.ll
>     llvm/trunk/test/Transforms/ObjCARC/ensure-that-exception-
> unwind-path-is-visited.ll
>     llvm/trunk/test/Transforms/SLPVectorizer/X86/debug_info.ll
>     llvm/trunk/test/Transforms/SampleProfile/branch.ll
>     llvm/trunk/test/Transforms/ScalarRepl/debuginfo-preserved.ll
>     llvm/trunk/test/Transforms/Scalarizer/dbginfo.ll
>     llvm/trunk/test/Transforms/SimplifyCFG/branch-fold-dbg.ll
>     llvm/trunk/test/Transforms/SimplifyCFG/hoist-dbgvalue.ll
>     llvm/trunk/test/Transforms/StripSymbols/2010-06-30-StripDebug.ll
>     llvm/trunk/test/Transforms/StripSymbols/strip-dead-debug-info.ll
>     llvm/trunk/unittests/Transforms/Utils/Cloning.cpp
>
> Modified: llvm/trunk/docs/SourceLevelDebugging.rst
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/
> SourceLevelDebugging.rst?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/docs/SourceLevelDebugging.rst (original)
> +++ llvm/trunk/docs/SourceLevelDebugging.rst Wed Oct  1 13:55:02 2014
> @@ -571,7 +571,7 @@ Local variables
>      metadata, ;; Reference to the type descriptor
>      i32,      ;; flags
>      metadata  ;; (optional) Reference to inline location
> -    metadata  ;; (optional) Reference to a complex expression (see below)
> +    metadata  ;; (optional) Reference to a complex expression.
>    }
>
>  These descriptors are used to define variables local to a sub program.
> The
> @@ -590,7 +590,20 @@ The context is either the subprogram or
>  Name the source variable name.  Context and line indicate where the
> variable
>  was defined.  Type descriptor defines the declared type of the variable.
>
> -The ``OpPiece`` operator is used for (typically larger aggregate)
> +Complex Expressions
> +^^^^^^^^^^^^^^^^^^^
> +.. code-block:: llvm
> +
> +  !8 = metadata !{
> +    i32,      ;; DW_TAG_expression
> +    ...
> +  }
> +
> +Complex expressions describe variable storage locations in terms of
> +prefix-notated DWARF expressions. Currently the only supported
> +operators are ``DW_OP_plus``, ``DW_OP_deref``, and ``DW_OP_piece``.
> +
> +The ``DW_OP_piece`` operator is used for (typically larger aggregate)
>  variables that are fragmented across several locations. It takes two
>  i32 arguments, an offset and a size in bytes to describe which piece
>  of the variable is at this location.
>
> Modified: llvm/trunk/include/llvm/CodeGen/MachineInstr.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/
> llvm/CodeGen/MachineInstr.h?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/include/llvm/CodeGen/MachineInstr.h (original)
> +++ llvm/trunk/include/llvm/CodeGen/MachineInstr.h Wed Oct  1 13:55:02
> 2014
> @@ -244,12 +244,22 @@ public:
>    ///
>    DebugLoc getDebugLoc() const { return debugLoc; }
>
> -  /// getDebugVariable() - Return the debug variable referenced by
> +  /// \brief Return the debug variable referenced by
>    /// this DBG_VALUE instruction.
>    DIVariable getDebugVariable() const {
>      assert(isDebugValue() && "not a DBG_VALUE");
> -    const MDNode *Var = getOperand(getNumOperands() - 1).getMetadata();
> -    return DIVariable(Var);
> +    DIVariable Var(getOperand(2).getMetadata());
> +    assert(Var.Verify() && "not a DIVariable");
> +    return Var;
> +  }
> +
> +  /// \brief Return the complex address expression referenced by
> +  /// this DBG_VALUE instruction.
> +  DIExpression getDebugExpression() const {
> +    assert(isDebugValue() && "not a DBG_VALUE");
> +    DIExpression Expr(getOperand(3).getMetadata());
> +    assert(Expr.Verify() && "not a DIExpression");
> +    return Expr;
>    }
>
>    /// emitError - Emit an error referring to the source location of this
>
> Modified: llvm/trunk/include/llvm/CodeGen/MachineInstrBuilder.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/
> MachineInstrBuilder.h?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/include/llvm/CodeGen/MachineInstrBuilder.h (original)
> +++ llvm/trunk/include/llvm/CodeGen/MachineInstrBuilder.h Wed Oct  1
> 13:55:02 2014
> @@ -170,6 +170,8 @@ public:
>
>    const MachineInstrBuilder &addMetadata(const MDNode *MD) const {
>      MI->addOperand(*MF, MachineOperand::CreateMetadata(MD));
> +    assert((MI->isDebugValue() ? MI->getDebugVariable().Verify() : true)
> &&
> +           "first MDNode argument of a DBG_VALUE not a DIVariable");
>      return *this;
>    }
>
> @@ -345,24 +347,25 @@ inline MachineInstrBuilder BuildMI(Machi
>  /// address.  The convention is that a DBG_VALUE is indirect iff the
>  /// second operand is an immediate.
>  ///
> -inline MachineInstrBuilder BuildMI(MachineFunction &MF,
> -                                   DebugLoc DL,
> -                                   const MCInstrDesc &MCID,
> -                                   bool IsIndirect,
> -                                   unsigned Reg,
> -                                   unsigned Offset,
> -                                   const MDNode *MD) {
> +inline MachineInstrBuilder BuildMI(MachineFunction &MF, DebugLoc DL,
> +                                   const MCInstrDesc &MCID, bool
> IsIndirect,
> +                                   unsigned Reg, unsigned Offset,
> +                                   const MDNode *Variable, const MDNode
> *Expr) {
> +  assert(DIVariable(Variable).Verify() && "not a DIVariable");
> +  assert(DIExpression(Expr).Verify() && "not a DIExpression");
>    if (IsIndirect)
>      return BuildMI(MF, DL, MCID)
> -      .addReg(Reg, RegState::Debug)
> -      .addImm(Offset)
> -      .addMetadata(MD);
> +        .addReg(Reg, RegState::Debug)
> +        .addImm(Offset)
> +        .addMetadata(Variable)
> +        .addMetadata(Expr);
>    else {
>      assert(Offset == 0 && "A direct address cannot have an offset.");
>      return BuildMI(MF, DL, MCID)
> -      .addReg(Reg, RegState::Debug)
> -      .addReg(0U, RegState::Debug)
> -      .addMetadata(MD);
> +        .addReg(Reg, RegState::Debug)
> +        .addReg(0U, RegState::Debug)
> +        .addMetadata(Variable)
> +        .addMetadata(Expr);
>    }
>  }
>
> @@ -371,15 +374,15 @@ inline MachineInstrBuilder BuildMI(Machi
>  /// address and inserts it at position I.
>  ///
>  inline MachineInstrBuilder BuildMI(MachineBasicBlock &BB,
> -                                   MachineBasicBlock::iterator I,
> -                                   DebugLoc DL,
> -                                   const MCInstrDesc &MCID,
> -                                   bool IsIndirect,
> -                                   unsigned Reg,
> -                                   unsigned Offset,
> -                                   const MDNode *MD) {
> +                                   MachineBasicBlock::iterator I,
> DebugLoc DL,
> +                                   const MCInstrDesc &MCID, bool
> IsIndirect,
> +                                   unsigned Reg, unsigned Offset,
> +                                   const MDNode *Variable, const MDNode
> *Expr) {
> +  assert(DIVariable(Variable).Verify() && "not a DIVariable");
> +  assert(DIExpression(Expr).Verify() && "not a DIExpression");
>    MachineFunction &MF = *BB.getParent();
> -  MachineInstr *MI = BuildMI(MF, DL, MCID, IsIndirect, Reg, Offset, MD);
> +  MachineInstr *MI =
> +      BuildMI(MF, DL, MCID, IsIndirect, Reg, Offset, Variable, Expr);
>    BB.insert(I, MI);
>    return MachineInstrBuilder(MF, MI);
>  }
>
> Modified: llvm/trunk/include/llvm/CodeGen/MachineModuleInfo.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/
> MachineModuleInfo.h?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/include/llvm/CodeGen/MachineModuleInfo.h (original)
> +++ llvm/trunk/include/llvm/CodeGen/MachineModuleInfo.h Wed Oct  1
> 13:55:02 2014
> @@ -166,6 +166,7 @@ public:
>
>    struct VariableDbgInfo {
>      TrackingVH<MDNode> Var;
> +    TrackingVH<MDNode> Expr;
>      unsigned Slot;
>      DebugLoc Loc;
>    };
> @@ -390,8 +391,9 @@ public:
>
>    /// setVariableDbgInfo - Collect information used to emit debugging
>    /// information of a variable.
> -  void setVariableDbgInfo(MDNode *N, unsigned Slot, DebugLoc Loc) {
> -    VariableDbgInfo Info = { N, Slot, Loc };
> +  void setVariableDbgInfo(MDNode *Var, MDNode *Expr, unsigned Slot,
> +                          DebugLoc Loc) {
> +    VariableDbgInfo Info = {Var, Expr, Slot, Loc};
>      VariableDbgInfos.push_back(std::move(Info));
>    }
>
>
> Modified: llvm/trunk/include/llvm/CodeGen/SelectionDAG.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/
> llvm/CodeGen/SelectionDAG.h?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/include/llvm/CodeGen/SelectionDAG.h (original)
> +++ llvm/trunk/include/llvm/CodeGen/SelectionDAG.h Wed Oct  1 13:55:02
> 2014
> @@ -984,15 +984,18 @@ public:
>
>    /// getDbgValue - Creates a SDDbgValue node.
>    ///
> -  SDDbgValue *getDbgValue(MDNode *MDPtr, SDNode *N, unsigned R,
> -                         bool IsIndirect, uint64_t Off,
> -                          DebugLoc DL, unsigned O);
> -  /// Constant.
> -  SDDbgValue *getConstantDbgValue(MDNode *MDPtr, const Value *C, uint64_t
> Off,
> -                                 DebugLoc DL, unsigned O);
> -  /// Frame index.
> -  SDDbgValue *getFrameIndexDbgValue(MDNode *MDPtr, unsigned FI, uint64_t
> Off,
> -                                   DebugLoc DL, unsigned O);
> +  /// SDNode
> +  SDDbgValue *getDbgValue(MDNode *Var, MDNode *Expr, SDNode *N, unsigned
> R,
> +                          bool IsIndirect, uint64_t Off, DebugLoc DL,
> +                          unsigned O);
> +
> +  /// Constant
> +  SDDbgValue *getConstantDbgValue(MDNode *Var, MDNode *Expr, const Value
> *C,
> +                                  uint64_t Off, DebugLoc DL, unsigned O);
> +
> +  /// FrameIndex
> +  SDDbgValue *getFrameIndexDbgValue(MDNode *Var, MDNode *Expr, unsigned
> FI,
> +                                    uint64_t Off, DebugLoc DL, unsigned
> O);
>
>    /// RemoveDeadNode - Remove the specified node from the system. If any
> of its
>    /// operands then becomes dead, remove them as well. Inform
> UpdateListener
>
> Modified: llvm/trunk/include/llvm/IR/DIBuilder.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/
> llvm/IR/DIBuilder.h?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/include/llvm/IR/DIBuilder.h (original)
> +++ llvm/trunk/include/llvm/IR/DIBuilder.h Wed Oct  1 13:55:02 2014
> @@ -85,7 +85,6 @@ namespace llvm {
>
>      public:
>      explicit DIBuilder(Module &M);
> -    enum ComplexAddrKind { OpPlus=1, OpDeref, OpPiece };
>      enum DebugEmissionKind { FullDebug=1, LineTablesOnly };
>
>      /// finalize - Construct any deferred debug info descriptors.
> @@ -501,33 +500,18 @@ namespace llvm {
>                                     unsigned Flags = 0,
>                                     unsigned ArgNo = 0);
>
> -
> -    /// createComplexVariable - Create a new descriptor for the specified
> +    /// createExpression - Create a new descriptor for the specified
>      /// variable which has a complex address expression for its address.
> -    /// @param Tag         Dwarf TAG. Usually DW_TAG_auto_variable or
> -    ///                    DW_TAG_arg_variable.
> -    /// @param Scope       Variable scope.
> -    /// @param Name        Variable name.
> -    /// @param F           File where this variable is defined.
> -    /// @param LineNo      Line number.
> -    /// @param Ty          Variable Type
>      /// @param Addr        An array of complex address operations.
> -    /// @param ArgNo       If this variable is an argument then this
> argument's
> -    ///                    number. 1 indicates 1st argument.
> -    DIVariable createComplexVariable(unsigned Tag, DIDescriptor Scope,
> -                                     StringRef Name, DIFile F, unsigned
> LineNo,
> -                                     DITypeRef Ty, ArrayRef<Value *> Addr,
> -                                     unsigned ArgNo = 0);
> +    DIExpression createExpression(ArrayRef<Value *> Addr = None);
>
> -    /// createVariablePiece - Create a descriptor to describe one part
> +    /// createPieceExpression - Create a descriptor to describe one part
>      /// of aggregate variable that is fragmented across multiple Values.
>      ///
> -    /// @param Variable      Variable that is partially represented by
> this.
>      /// @param OffsetInBytes Offset of the piece in bytes.
>      /// @param SizeInBytes   Size of the piece in bytes.
> -    DIVariable createVariablePiece(DIVariable Variable,
> -                                   unsigned OffsetInBytes,
> -                                   unsigned SizeInBytes);
> +    DIExpression createPieceExpression(unsigned OffsetInBytes,
> +                                       unsigned SizeInBytes);
>
>      /// createFunction - Create a new descriptor for the specified
> subprogram.
>      /// See comments in DISubprogram for descriptions of these fields.
> @@ -675,34 +659,37 @@ namespace llvm {
>      /// insertDeclare - Insert a new llvm.dbg.declare intrinsic call.
>      /// @param Storage     llvm::Value of the variable
>      /// @param VarInfo     Variable's debug info descriptor.
> +    /// @param Expr         A complex location expression.
>      /// @param InsertAtEnd Location for the new intrinsic.
>      Instruction *insertDeclare(llvm::Value *Storage, DIVariable VarInfo,
> -                               BasicBlock *InsertAtEnd);
> +                               DIExpression Expr, BasicBlock
> *InsertAtEnd);
>
>      /// insertDeclare - Insert a new llvm.dbg.declare intrinsic call.
>      /// @param Storage      llvm::Value of the variable
>      /// @param VarInfo      Variable's debug info descriptor.
> +    /// @param Expr         A complex location expression.
>      /// @param InsertBefore Location for the new intrinsic.
>      Instruction *insertDeclare(llvm::Value *Storage, DIVariable VarInfo,
> -                               Instruction *InsertBefore);
> -
> +                               DIExpression Expr, Instruction
> *InsertBefore);
>
>      /// insertDbgValueIntrinsic - Insert a new llvm.dbg.value intrinsic
> call.
>      /// @param Val          llvm::Value of the variable
>      /// @param Offset       Offset
>      /// @param VarInfo      Variable's debug info descriptor.
> +    /// @param Expr         A complex location expression.
>      /// @param InsertAtEnd Location for the new intrinsic.
>      Instruction *insertDbgValueIntrinsic(llvm::Value *Val, uint64_t
> Offset,
> -                                         DIVariable VarInfo,
> +                                         DIVariable VarInfo, DIExpression
> Expr,
>                                           BasicBlock *InsertAtEnd);
>
>      /// insertDbgValueIntrinsic - Insert a new llvm.dbg.value intrinsic
> call.
>      /// @param Val          llvm::Value of the variable
>      /// @param Offset       Offset
>      /// @param VarInfo      Variable's debug info descriptor.
> +    /// @param Expr         A complex location expression.
>      /// @param InsertBefore Location for the new intrinsic.
>      Instruction *insertDbgValueIntrinsic(llvm::Value *Val, uint64_t
> Offset,
> -                                         DIVariable VarInfo,
> +                                         DIVariable VarInfo, DIExpression
> Expr,
>                                           Instruction *InsertBefore);
>    };
>  } // end namespace llvm
>
> Modified: llvm/trunk/include/llvm/IR/DebugInfo.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/
> llvm/IR/DebugInfo.h?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/include/llvm/IR/DebugInfo.h (original)
> +++ llvm/trunk/include/llvm/IR/DebugInfo.h Wed Oct  1 13:55:02 2014
> @@ -150,6 +150,7 @@ public:
>    bool isTemplateValueParameter() const;
>    bool isObjCProperty() const;
>    bool isImportedEntity() const;
> +  bool isExpression() const;
>
>    /// print - print descriptor.
>    void print(raw_ostream &OS) const;
> @@ -720,20 +721,6 @@ public:
>    /// Verify - Verify that a variable descriptor is well formed.
>    bool Verify() const;
>
> -  /// HasComplexAddr - Return true if the variable has a complex address.
> -  bool hasComplexAddress() const { return getNumAddrElements() > 0; }
> -
> -  /// \brief Return the size of this variable's complex address or
> -  /// zero if there is none.
> -  unsigned getNumAddrElements() const {
> -    if (DbgNode->getNumOperands() < 9)
> -      return 0;
> -    return getDescriptorField(8)->getNumOperands();
> -  }
> -
> -  /// \brief return the Idx'th complex address element.
> -  uint64_t getAddrElement(unsigned Idx) const;
> -
>    /// isBlockByrefVariable - Return true if the variable was declared as
>    /// a "__block" variable (Apple Blocks).
>    bool isBlockByrefVariable(const DITypeIdentifierMap &Map) const {
> @@ -744,6 +731,35 @@ public:
>    /// information for an inlined function arguments.
>    bool isInlinedFnArgument(const Function *CurFn);
>
> +  /// Return the size reported by the variable's type.
> +  unsigned getSizeInBits(const DITypeIdentifierMap &Map);
> +
> +  void printExtendedName(raw_ostream &OS) const;
> +};
> +
> +/// DIExpression - A complex location expression.
> +class DIExpression : public DIDescriptor {
> +  friend class DIDescriptor;
> +  void printInternal(raw_ostream &OS) const;
> +
> +public:
> +  explicit DIExpression(const MDNode *N = nullptr) : DIDescriptor(N) {}
> +
> +  /// Verify - Verify that a variable descriptor is well formed.
> +  bool Verify() const;
> +
> +  /// \brief Return the number of elements in the complex expression.
> +  unsigned getNumElements() const {
> +    if (!DbgNode)
> +      return 0;
> +    unsigned N = DbgNode->getNumOperands();
> +    assert(N > 0 && "missing tag");
> +    return N - 1;
> +  }
> +
> +  /// \brief return the Idx'th complex address element.
> +  uint64_t getElement(unsigned Idx) const;
> +
>    /// isVariablePiece - Return whether this is a piece of an aggregate
>    /// variable.
>    bool isVariablePiece() const;
> @@ -751,11 +767,6 @@ public:
>    uint64_t getPieceOffset() const;
>    /// getPieceSize - Return the size of this piece in bytes.
>    uint64_t getPieceSize() const;
> -
> -  /// Return the size reported by the variable's type.
> -  unsigned getSizeInBits(const DITypeIdentifierMap &Map);
> -
> -  void printExtendedName(raw_ostream &OS) const;
>  };
>
>  /// DILocation - This object holds location information. This object
> @@ -872,9 +883,6 @@ DIVariable createInlinedVariable(MDNode
>  /// cleanseInlinedVariable - Remove inlined scope from the variable.
>  DIVariable cleanseInlinedVariable(MDNode *DV, LLVMContext &VMContext);
>
> -/// getEntireVariable - Remove OpPiece exprs from the variable.
> -DIVariable getEntireVariable(DIVariable DV);
> -
>  /// Construct DITypeIdentifierMap by going through retained types of each
> CU.
>  DITypeIdentifierMap generateDITypeIdentifierMap(const NamedMDNode
> *CU_Nodes);
>
>
> Modified: llvm/trunk/include/llvm/IR/IntrinsicInst.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/
> llvm/IR/IntrinsicInst.h?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/include/llvm/IR/IntrinsicInst.h (original)
> +++ llvm/trunk/include/llvm/IR/IntrinsicInst.h Wed Oct  1 13:55:02 2014
> @@ -82,6 +82,7 @@ namespace llvm {
>    public:
>      Value *getAddress() const;
>      MDNode *getVariable() const { return cast<MDNode>(getArgOperand(1));
> }
> +    MDNode *getExpression() const { return cast<MDNode>(getArgOperand(2));
> }
>
>      // Methods for support type inquiry through isa, cast, and dyn_cast:
>      static inline bool classof(const IntrinsicInst *I) {
> @@ -103,6 +104,7 @@ namespace llvm {
>                            const_cast<Value*>(getArgOperand(1)))->
> getZExtValue();
>      }
>      MDNode *getVariable() const { return cast<MDNode>(getArgOperand(2));
> }
> +    MDNode *getExpression() const { return cast<MDNode>(getArgOperand(3));
> }
>
>      // Methods for support type inquiry through isa, cast, and dyn_cast:
>      static inline bool classof(const IntrinsicInst *I) {
>
> Modified: llvm/trunk/include/llvm/IR/Intrinsics.td
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/
> llvm/IR/Intrinsics.td?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/include/llvm/IR/Intrinsics.td (original)
> +++ llvm/trunk/include/llvm/IR/Intrinsics.td Wed Oct  1 13:55:02 2014
> @@ -373,9 +373,12 @@ let Properties = [IntrNoMem] in {
>  // places.
>  let Properties = [IntrNoMem] in {
>    def int_dbg_declare      : Intrinsic<[],
> -                                       [llvm_metadata_ty,
> llvm_metadata_ty]>;
> +                                       [llvm_metadata_ty,
> +                                       llvm_metadata_ty,
> +                                       llvm_metadata_ty]>;
>    def int_dbg_value        : Intrinsic<[],
>                                         [llvm_metadata_ty, llvm_i64_ty,
> +                                        llvm_metadata_ty,
>                                          llvm_metadata_ty]>;
>  }
>
>
> Modified: llvm/trunk/include/llvm/Support/Dwarf.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/
> llvm/Support/Dwarf.h?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/include/llvm/Support/Dwarf.h (original)
> +++ llvm/trunk/include/llvm/Support/Dwarf.h Wed Oct  1 13:55:02 2014
> @@ -53,6 +53,7 @@ enum LLVMConstants : uint32_t {
>
>    DW_TAG_auto_variable = 0x100, // Tag for local (auto) variables.
>    DW_TAG_arg_variable = 0x101,  // Tag for argument variables.
> +  DW_TAG_expression = 0x102,    // Tag for complex address expressions.
>
>    DW_TAG_user_base = 0x1000, // Recommended base for user tags.
>
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> CodeGen/AsmPrinter/AsmPrinter.cpp?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp Wed Oct  1 13:55:02
> 2014
> @@ -614,8 +614,8 @@ static void emitKill(const MachineInstr
>  /// of DBG_VALUE, returning true if it was able to do so.  A false return
>  /// means the target will need to handle MI in EmitInstruction.
>  static bool emitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP)
> {
> -  // This code handles only the 3-operand target-independent form.
> -  if (MI->getNumOperands() != 3)
> +  // This code handles only the 4-operand target-independent form.
> +  if (MI->getNumOperands() != 4)
>      return false;
>
>    SmallString<128> Str;
> @@ -629,9 +629,11 @@ static bool emitDebugValueComment(const
>        OS << Name << ":";
>    }
>    OS << V.getName();
> -  if (V.isVariablePiece())
> -    OS << " [piece offset=" << V.getPieceOffset()
> -       << " size="<<V.getPieceSize()<<"]";
> +
> +  DIExpression Expr = MI->getDebugExpression();
> +  if (Expr.isVariablePiece())
> +    OS << " [piece offset=" << Expr.getPieceOffset()
> +       << " size=" << Expr.getPieceSize() << "]";
>    OS << " <- ";
>
>    // The second operand is only an offset if it's an immediate.
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp?rev=218787&r1=218786&r2=
> 218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
> (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp Wed
> Oct  1 13:55:02 2014
> @@ -27,7 +27,7 @@ namespace llvm {
>  // In the other case, returns 0.
>  static unsigned isDescribedByReg(const MachineInstr &MI) {
>    assert(MI.isDebugValue());
> -  assert(MI.getNumOperands() == 3);
> +  assert(MI.getNumOperands() == 4);
>    // If location of variable is described using a register (directly or
>    // indirecltly), this register is always a first operand.
>    return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0;
> @@ -37,7 +37,7 @@ void DbgValueHistoryMap::startInstrRange
>                                           const MachineInstr &MI) {
>    // Instruction range should start with a DBG_VALUE instruction for the
>    // variable.
> -  assert(MI.isDebugValue() && getEntireVariable(MI.getDebugVariable())
> == Var);
> +  assert(MI.isDebugValue() && "not a DBG_VALUE");
>    auto &Ranges = VarInstrRanges[Var];
>    if (!Ranges.empty() && Ranges.back().second == nullptr &&
>        Ranges.back().first->isIdenticalTo(&MI)) {
> @@ -193,7 +193,7 @@ void calculateDbgValueHistory(const Mach
>        // Use the base variable (without any DW_OP_piece expressions)
>        // as index into History. The full variables including the
>        // piece expressions are attached to the MI.
> -      DIVariable Var = getEntireVariable(MI.getDebugVariable());
> +      DIVariable Var = MI.getDebugVariable();
>
>        if (unsigned PrevReg = Result.getRegisterForVar(Var))
>          dropRegDescribedVar(RegVars, PrevReg, Var);
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DebugLocEntry.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> CodeGen/AsmPrinter/DebugLocEntry.h?rev=218787&r1=
> 218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DebugLocEntry.h (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DebugLocEntry.h Wed Oct  1 13:55:02
> 2014
> @@ -26,25 +26,30 @@ class DebugLocEntry {
>  public:
>    /// A single location or constant.
>    struct Value {
> -    Value(const MDNode *Var, int64_t i)
> -      : Variable(Var), EntryKind(E_Integer) {
> +    Value(const MDNode *Var, const MDNode *Expr, int64_t i)
> +        : Variable(Var), Expression(Expr), EntryKind(E_Integer) {
>        Constant.Int = i;
>      }
> -    Value(const MDNode *Var, const ConstantFP *CFP)
> -      : Variable(Var), EntryKind(E_ConstantFP) {
> +    Value(const MDNode *Var, const MDNode *Expr, const ConstantFP *CFP)
> +        : Variable(Var), Expression(Expr), EntryKind(E_ConstantFP) {
>        Constant.CFP = CFP;
>      }
> -    Value(const MDNode *Var, const ConstantInt *CIP)
> -      : Variable(Var), EntryKind(E_ConstantInt) {
> +    Value(const MDNode *Var, const MDNode *Expr, const ConstantInt *CIP)
> +        : Variable(Var), Expression(Expr), EntryKind(E_ConstantInt) {
>        Constant.CIP = CIP;
>      }
> -    Value(const MDNode *Var, MachineLocation Loc)
> -      : Variable(Var), EntryKind(E_Location), Loc(Loc) {
> +    Value(const MDNode *Var, const MDNode *Expr, MachineLocation Loc)
> +        : Variable(Var), Expression(Expr), EntryKind(E_Location),
> Loc(Loc) {
> +      assert(DIVariable(Var).Verify());
> +      assert(DIExpression(Expr).Verify());
>      }
>
>      // The variable to which this location entry corresponds.
>      const MDNode *Variable;
>
> +    // Any complex address location expression for this Value.
> +    const MDNode *Expression;
> +
>      // Type of entry that this represents.
>      enum EntryType { E_Location, E_Integer, E_ConstantFP, E_ConstantInt };
>      enum EntryType EntryKind;
> @@ -69,7 +74,8 @@ public:
>      MachineLocation getLoc() const { return Loc; }
>      const MDNode *getVariableNode() const { return Variable; }
>      DIVariable getVariable() const { return DIVariable(Variable); }
> -    bool isVariablePiece() const { return getVariable().isVariablePiece();
> }
> +    bool isVariablePiece() const { return getExpression().isVariablePiece();
> }
> +    DIExpression getExpression() const { return DIExpression(Expression);
> }
>      friend bool operator==(const Value &, const Value &);
>      friend bool operator<(const Value &, const Value &);
>    };
> @@ -90,11 +96,13 @@ public:
>    // list of values.
>    // Return true if the merge was successful.
>    bool MergeValues(const DebugLocEntry &Next) {
> -    if (Begin == Next.Begin && Values.size() > 0 && Next.Values.size() >
> 0) {
> +    if (Begin == Next.Begin) {
> +      DIExpression Expr(Values[0].Expression);
>        DIVariable Var(Values[0].Variable);
> +      DIExpression NextExpr(Next.Values[0].Expression);
>        DIVariable NextVar(Next.Values[0].Variable);
> -      if (Var.getName() == NextVar.getName() &&
> -          Var.isVariablePiece() && NextVar.isVariablePiece()) {
> +      if (Var == NextVar && Expr.isVariablePiece() &&
> +          NextExpr.isVariablePiece()) {
>          addValues(Next.Values);
>          End = Next.End;
>          return true;
> @@ -133,8 +141,10 @@ public:
>      std::sort(Values.begin(), Values.end());
>      Values.erase(std::unique(Values.begin(), Values.end(),
>                               [](const Value &A, const Value &B) {
> -                               return A.getVariable() == B.getVariable();
> -                               }), Values.end());
> +                   return A.getVariable() == B.getVariable() &&
> +                          A.getExpression() == B.getExpression();
> +                 }),
> +                 Values.end());
>    }
>  };
>
> @@ -144,7 +154,10 @@ inline bool operator==(const DebugLocEnt
>    if (A.EntryKind != B.EntryKind)
>      return false;
>
> -  if (A.getVariable() != B.getVariable())
> +  if (A.Expression != B.Expression)
> +    return false;
> +
> +  if (A.Variable != B.Variable)
>      return false;
>
>    switch (A.EntryKind) {
> @@ -163,7 +176,8 @@ inline bool operator==(const DebugLocEnt
>  /// Compare two pieces based on their offset.
>  inline bool operator<(const DebugLocEntry::Value &A,
>                        const DebugLocEntry::Value &B) {
> -  return A.getVariable().getPieceOffset() < B.getVariable().
> getPieceOffset();
> +  return A.getExpression().getPieceOffset() <
> +         B.getExpression().getPieceOffset();
>  }
>
>  }
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> CodeGen/AsmPrinter/DwarfDebug.cpp?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Wed Oct  1 13:55:02
> 2014
> @@ -901,7 +901,7 @@ void DwarfDebug::collectDeadVariables()
>          for (unsigned vi = 0, ve = Variables.getNumElements(); vi != ve;
> ++vi) {
>            DIVariable DV(Variables.getElement(vi));
>            assert(DV.isVariable());
> -          DbgVariable NewVar(DV, this);
> +          DbgVariable NewVar(DV, DIExpression(nullptr), this);
>            auto VariableDie = SPCU->constructVariableDIE(NewVar);
>            SPCU->applyVariableAttributes(NewVar, *VariableDie);
>            SPDIE->addChild(std::move(VariableDie));
> @@ -1121,7 +1121,7 @@ DbgVariable *DwarfDebug::getExistingAbst
>
>  void DwarfDebug::createAbstractVariable(const DIVariable &Var,
>                                          LexicalScope *Scope) {
> -  auto AbsDbgVariable = make_unique<DbgVariable>(Var, this);
> +  auto AbsDbgVariable = make_unique<DbgVariable>(Var, DIExpression(),
> this);
>    addScopeVariable(Scope, AbsDbgVariable.get());
>    AbstractVariables[Var] = std::move(AbsDbgVariable);
>  }
> @@ -1177,6 +1177,7 @@ void DwarfDebug::collectVariableInfoFrom
>        continue;
>      Processed.insert(VI.Var);
>      DIVariable DV(VI.Var);
> +    DIExpression Expr(VI.Expr);
>      LexicalScope *Scope = LScopes.findLexicalScope(VI.Loc);
>
>      // If variable scope is not found then skip this variable.
> @@ -1184,7 +1185,7 @@ void DwarfDebug::collectVariableInfoFrom
>        continue;
>
>      ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode());
> -    ConcreteVariables.push_back(make_unique<DbgVariable>(DV, this));
> +    ConcreteVariables.push_back(make_unique<DbgVariable>(DV, Expr,
> this));
>      DbgVariable *RegVar = ConcreteVariables.back().get();
>      RegVar->setFrameIndex(VI.Slot);
>      addScopeVariable(Scope, RegVar);
> @@ -1193,9 +1194,10 @@ void DwarfDebug::collectVariableInfoFrom
>
>  // Get .debug_loc entry for the instruction range starting at MI.
>  static DebugLocEntry::Value getDebugLocValue(const MachineInstr *MI) {
> +  const MDNode *Expr = MI->getDebugExpression();
>    const MDNode *Var = MI->getDebugVariable();
>
> -  assert(MI->getNumOperands() == 3);
> +  assert(MI->getNumOperands() == 4);
>    if (MI->getOperand(0).isReg()) {
>      MachineLocation MLoc;
>      // If the second operand is an immediate, this is a
> @@ -1204,20 +1206,20 @@ static DebugLocEntry::Value getDebugLocV
>        MLoc.set(MI->getOperand(0).getReg());
>      else
>        MLoc.set(MI->getOperand(0).getReg(), MI->getOperand(1).getImm());
> -    return DebugLocEntry::Value(Var, MLoc);
> +    return DebugLocEntry::Value(Var, Expr, MLoc);
>    }
>    if (MI->getOperand(0).isImm())
> -    return DebugLocEntry::Value(Var, MI->getOperand(0).getImm());
> +    return DebugLocEntry::Value(Var, Expr, MI->getOperand(0).getImm());
>    if (MI->getOperand(0).isFPImm())
> -    return DebugLocEntry::Value(Var, MI->getOperand(0).getFPImm());
> +    return DebugLocEntry::Value(Var, Expr, MI->getOperand(0).getFPImm());
>    if (MI->getOperand(0).isCImm())
> -    return DebugLocEntry::Value(Var, MI->getOperand(0).getCImm());
> +    return DebugLocEntry::Value(Var, Expr, MI->getOperand(0).getCImm());
>
> -  llvm_unreachable("Unexpected 3 operand DBG_VALUE instruction!");
> +  llvm_unreachable("Unexpected 4-operand DBG_VALUE instruction!");
>  }
>
>  /// Determine whether two variable pieces overlap.
> -static bool piecesOverlap(DIVariable P1, DIVariable P2) {
> +static bool piecesOverlap(DIExpression P1, DIExpression P2) {
>    if (!P1.isVariablePiece() || !P2.isVariablePiece())
>      return true;
>    unsigned l1 = P1.getPieceOffset();
> @@ -1268,11 +1270,11 @@ DwarfDebug::buildLocationList(SmallVecto
>      }
>
>      // If this piece overlaps with any open ranges, truncate them.
> -    DIVariable DIVar = Begin->getDebugVariable();
> +    DIExpression DIExpr = Begin->getDebugExpression();
>      auto Last = std::remove_if(OpenRanges.begin(), OpenRanges.end(),
>                                 [&](DebugLocEntry::Value R) {
> -                                 return piecesOverlap(DIVar,
> R.getVariable());
> -                               });
> +      return piecesOverlap(DIExpr, R.getExpression());
> +    });
>      OpenRanges.erase(Last, OpenRanges.end());
>
>      const MCSymbol *StartLabel = getLabelBeforeInsn(Begin);
> @@ -1294,7 +1296,7 @@ DwarfDebug::buildLocationList(SmallVecto
>      bool couldMerge = false;
>
>      // If this is a piece, it may belong to the current DebugLocEntry.
> -    if (DIVar.isVariablePiece()) {
> +    if (DIExpr.isVariablePiece()) {
>        // Add this value to the list of open ranges.
>        OpenRanges.push_back(Value);
>
> @@ -1320,10 +1322,14 @@ DwarfDebug::buildLocationList(SmallVecto
>      if (PrevEntry != DebugLoc.rend() && PrevEntry->MergeRanges(*
> CurEntry))
>        DebugLoc.pop_back();
>
> -    DEBUG(dbgs() << "Values:\n";
> -          for (auto Value : CurEntry->getValues())
> -            Value.getVariable()->dump();
> -          dbgs() << "-----\n");
> +    DEBUG({
> +      dbgs() << CurEntry->getValues().size() << " Values:\n";
> +      for (auto Value : CurEntry->getValues()) {
> +        Value.getVariable()->dump();
> +        Value.getExpression()->dump();
> +      }
> +      dbgs() << "-----\n";
> +    });
>    }
>  }
>
> @@ -1358,7 +1364,7 @@ DwarfDebug::collectVariableInfo(SmallPtr
>      if (!Scope)
>        continue;
>
> -    Processed.insert(getEntireVariable(DV));
> +    Processed.insert(DV);
>      const MachineInstr *MInsn = Ranges.front().first;
>      assert(MInsn->isDebugValue() && "History must begin with debug
> value");
>      ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode());
> @@ -1392,7 +1398,8 @@ DwarfDebug::collectVariableInfo(SmallPtr
>        continue;
>      if (LexicalScope *Scope = LScopes.findLexicalScope(DV.getContext()))
> {
>        ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode());
> -      ConcreteVariables.push_back(make_unique<DbgVariable>(DV, this));
> +      DIExpression NoExpr;
> +      ConcreteVariables.push_back(make_unique<DbgVariable>(DV, NoExpr,
> this));
>        addScopeVariable(Scope, ConcreteVariables.back().get());
>      }
>    }
> @@ -1580,18 +1587,17 @@ void DwarfDebug::beginFunction(const Mac
>
>      // The first mention of a function argument gets the FunctionBeginSym
>      // label, so arguments are visible when breaking at function entry.
> -    DIVariable DV(Ranges.front().first->getDebugVariable());
> -    if (DV.isVariable() && DV.getTag() == dwarf::DW_TAG_arg_variable &&
> -        getDISubprogram(DV.getContext()).describes(MF->getFunction())) {
> -      if (!DV.isVariablePiece())
> -        LabelsBeforeInsn[Ranges.front().first] = FunctionBeginSym;
> -      else {
> +    DIVariable DIVar(Ranges.front().first->getDebugVariable());
> +    if (DIVar.isVariable() && DIVar.getTag() ==
> dwarf::DW_TAG_arg_variable &&
> +        getDISubprogram(DIVar.getContext()).describes(MF->getFunction()))
> {
> +      LabelsBeforeInsn[Ranges.front().first] = FunctionBeginSym;
> +      if (Ranges.front().first->getDebugExpression().isVariablePiece()) {
>          // Mark all non-overlapping initial pieces.
>          for (auto I = Ranges.begin(); I != Ranges.end(); ++I) {
> -          DIVariable Piece = I->first->getDebugVariable();
> +          DIExpression Piece = I->first->getDebugExpression();
>            if (std::all_of(Ranges.begin(), I,
> -                          [&](DbgValueHistoryMap::InstrRange Pred){
> -                return !piecesOverlap(Piece,
> Pred.first->getDebugVariable());
> +                          [&](DbgValueHistoryMap::InstrRange Pred) {
> +                return !piecesOverlap(Piece, Pred.first->
> getDebugExpression());
>                }))
>              LabelsBeforeInsn[I->first] = FunctionBeginSym;
>            else
> @@ -2089,9 +2095,9 @@ void DwarfDebug::emitLocPieces(ByteStrea
>
>    unsigned Offset = 0;
>    for (auto Piece : Values) {
> -    DIVariable Var = Piece.getVariable();
> -    unsigned PieceOffset = Var.getPieceOffset();
> -    unsigned PieceSize = Var.getPieceSize();
> +    DIExpression Expr = Piece.getExpression();
> +    unsigned PieceOffset = Expr.getPieceOffset();
> +    unsigned PieceSize = Expr.getPieceSize();
>      assert(Offset <= PieceOffset && "overlapping or duplicate pieces");
>      if (Offset < PieceOffset) {
>        // The DWARF spec seriously mandates pieces with no locations for
> gaps.
> @@ -2102,8 +2108,9 @@ void DwarfDebug::emitLocPieces(ByteStrea
>      Offset += PieceSize;
>
>      const unsigned SizeOfByte = 8;
> -    assert(!Var.isIndirect() && "indirect address for piece");
>  #ifndef NDEBUG
> +    DIVariable Var = Piece.getVariable();
> +    assert(!Var.isIndirect() && "indirect address for piece");
>      unsigned VarSize = Var.getSizeInBits(Map);
>      assert(PieceSize+PieceOffset <= VarSize/SizeOfByte
>             && "piece is larger than or outside of variable");
> @@ -2149,24 +2156,25 @@ void DwarfDebug::emitDebugLocValue(ByteS
>      }
>    } else if (Value.isLocation()) {
>      MachineLocation Loc = Value.getLoc();
> -    if (!DV.hasComplexAddress())
> +    DIExpression Expr = Value.getExpression();
> +    if (!Expr)
>        // Regular entry.
>        Asm->EmitDwarfRegOp(Streamer, Loc, DV.isIndirect());
>      else {
>        // Complex address entry.
> -      unsigned N = DV.getNumAddrElements();
> +      unsigned N = Expr.getNumElements();
>        unsigned i = 0;
> -      if (N >= 2 && DV.getAddrElement(0) == DIBuilder::OpPlus) {
> +      if (N >= 2 && Expr.getElement(0) == dwarf::DW_OP_plus) {
>          if (Loc.getOffset()) {
>            i = 2;
>            Asm->EmitDwarfRegOp(Streamer, Loc, DV.isIndirect());
>            Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref");
>            Streamer.EmitInt8(dwarf::DW_OP_plus_uconst,
> "DW_OP_plus_uconst");
> -          Streamer.EmitSLEB128(DV.getAddrElement(1));
> +          Streamer.EmitSLEB128(Expr.getElement(1));
>          } else {
>            // If first address element is OpPlus then emit
>            // DW_OP_breg + Offset instead of DW_OP_reg + Offset.
> -          MachineLocation TLoc(Loc.getReg(), DV.getAddrElement(1));
> +          MachineLocation TLoc(Loc.getReg(), Expr.getElement(1));
>            Asm->EmitDwarfRegOp(Streamer, TLoc, DV.isIndirect());
>            i = 2;
>          }
> @@ -2176,14 +2184,14 @@ void DwarfDebug::emitDebugLocValue(ByteS
>
>        // Emit remaining complex address elements.
>        for (; i < N; ++i) {
> -        uint64_t Element = DV.getAddrElement(i);
> -        if (Element == DIBuilder::OpPlus) {
> +        uint64_t Element = Expr.getElement(i);
> +        if (Element == dwarf::DW_OP_plus) {
>            Streamer.EmitInt8(dwarf::DW_OP_plus_uconst,
> "DW_OP_plus_uconst");
> -          Streamer.EmitULEB128(DV.getAddrElement(++i));
> -        } else if (Element == DIBuilder::OpDeref) {
> +          Streamer.EmitULEB128(Expr.getElement(++i));
> +        } else if (Element == dwarf::DW_OP_deref) {
>            if (!Loc.isReg())
>              Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref");
> -        } else if (Element == DIBuilder::OpPiece) {
> +        } else if (Element == dwarf::DW_OP_piece) {
>            i += 3;
>            // handled in emitDebugLocEntry.
>          } else
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> CodeGen/AsmPrinter/DwarfDebug.h?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h Wed Oct  1 13:55:02
> 2014
> @@ -70,6 +70,7 @@ public:
>  /// \brief This class is used to track local variable information.
>  class DbgVariable {
>    DIVariable Var;             // Variable Descriptor.
> +  DIExpression Expr;          // Complex address location expression.
>    DIE *TheDIE;                // Variable DIE.
>    unsigned DotDebugLocOffset; // Offset in DotDebugLocEntries.
>    const MachineInstr *MInsn;  // DBG_VALUE instruction of the variable.
> @@ -78,18 +79,22 @@ class DbgVariable {
>
>  public:
>    /// Construct a DbgVariable from a DIVariable.
> -  DbgVariable(DIVariable V, DwarfDebug *DD)
> -      : Var(V), TheDIE(nullptr), DotDebugLocOffset(~0U), MInsn(nullptr),
> -        FrameIndex(~0), DD(DD) {}
> +  DbgVariable(DIVariable V, DIExpression E, DwarfDebug *DD)
> +      : Var(V), Expr(E), TheDIE(nullptr), DotDebugLocOffset(~0U),
> +        MInsn(nullptr), FrameIndex(~0), DD(DD) {
> +    assert(Var.Verify() && Expr.Verify());
> +  }
>
>    /// Construct a DbgVariable from a DEBUG_VALUE.
>    /// AbstractVar may be NULL.
>    DbgVariable(const MachineInstr *DbgValue, DwarfDebug *DD)
> -      : Var(DbgValue->getDebugVariable()), TheDIE(nullptr),
> -        DotDebugLocOffset(~0U), MInsn(DbgValue), FrameIndex(~0), DD(DD) {}
> +      : Var(DbgValue->getDebugVariable()), Expr(DbgValue->
> getDebugExpression()),
> +        TheDIE(nullptr), DotDebugLocOffset(~0U), MInsn(DbgValue),
> +        FrameIndex(~0), DD(DD) {}
>
>    // Accessors.
>    DIVariable getVariable() const { return Var; }
> +  DIExpression getExpression() const { return Expr; }
>    void setDIE(DIE &D) { TheDIE = &D; }
>    DIE *getDIE() const { return TheDIE; }
>    void setDotDebugLocOffset(unsigned O) { DotDebugLocOffset = O; }
> @@ -124,14 +129,14 @@ public:
>
>    bool variableHasComplexAddress() const {
>      assert(Var.isVariable() && "Invalid complex DbgVariable!");
> -    return Var.hasComplexAddress();
> +    return Expr.getNumElements() > 0;
>    }
>    bool isBlockByrefVariable() const;
>    unsigned getNumAddrElements() const {
>      assert(Var.isVariable() && "Invalid complex DbgVariable!");
> -    return Var.getNumAddrElements();
> +    return Expr.getNumElements();
>    }
> -  uint64_t getAddrElement(unsigned i) const { return
> Var.getAddrElement(i); }
> +  uint64_t getAddrElement(unsigned i) const { return Expr.getElement(i); }
>    DIType getType() const;
>
>  private:
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> CodeGen/AsmPrinter/DwarfUnit.cpp?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Wed Oct  1 13:55:02
> 2014
> @@ -607,16 +607,20 @@ void DwarfUnit::addComplexAddress(const
>    unsigned N = DV.getNumAddrElements();
>    unsigned i = 0;
>    if (Location.isReg()) {
> -    if (N >= 2 && DV.getAddrElement(0) == DIBuilder::OpPlus) {
> +    if (N >= 2 && DV.getAddrElement(0) == dwarf::DW_OP_plus) {
> +      assert(!DV.getVariable().isIndirect() &&
> +             "double indirection not handled");
>        // If first address element is OpPlus then emit
>        // DW_OP_breg + Offset instead of DW_OP_reg + Offset.
>        addRegisterOffset(*Loc, Location.getReg(), DV.getAddrElement(1));
>        i = 2;
> -    } else if (N >= 2 && DV.getAddrElement(0) == DIBuilder::OpDeref) {
> -        addRegisterOpPiece(*Loc, Location.getReg(),
> -                           DV.getVariable().getPieceSize(),
> -                           DV.getVariable().getPieceOffset());
> -        i = 3;
> +    } else if (N >= 2 && DV.getAddrElement(0) == dwarf::DW_OP_deref) {
> +      assert(!DV.getVariable().isIndirect() &&
> +             "double indirection not handled");
> +      addRegisterOpPiece(*Loc, Location.getReg(),
> +                         DV.getExpression().getPieceSize(),
> +                         DV.getExpression().getPieceOffset());
> +      i = 3;
>      } else
>        addRegisterOpPiece(*Loc, Location.getReg());
>    } else
> @@ -624,15 +628,15 @@ void DwarfUnit::addComplexAddress(const
>
>    for (; i < N; ++i) {
>      uint64_t Element = DV.getAddrElement(i);
> -    if (Element == DIBuilder::OpPlus) {
> +    if (Element == dwarf::DW_OP_plus) {
>        addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_plus_uconst);
>        addUInt(*Loc, dwarf::DW_FORM_udata, DV.getAddrElement(++i));
>
> -    } else if (Element == DIBuilder::OpDeref) {
> +    } else if (Element == dwarf::DW_OP_deref) {
>        if (!Location.isReg())
>          addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
>
> -    } else if (Element == DIBuilder::OpPiece) {
> +    } else if (Element == dwarf::DW_OP_piece) {
>        const unsigned SizeOfByte = 8;
>        unsigned PieceOffsetInBits = DV.getAddrElement(++i)*SizeOfByte;
>        unsigned PieceSizeInBits = DV.getAddrElement(++i)*SizeOfByte;
> @@ -1861,7 +1865,7 @@ std::unique_ptr<DIE> DwarfUnit::construc
>
>    // Check if variable is described by a DBG_VALUE instruction.
>    if (const MachineInstr *DVInsn = DV.getMInsn()) {
> -    assert(DVInsn->getNumOperands() == 3);
> +    assert(DVInsn->getNumOperands() == 4);
>      if (DVInsn->getOperand(0).isReg()) {
>        const MachineOperand RegOp = DVInsn->getOperand(0);
>        // If the second operand is an immediate, this is an indirect value.
>
> Modified: llvm/trunk/lib/CodeGen/InlineSpiller.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> CodeGen/InlineSpiller.cpp?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/CodeGen/InlineSpiller.cpp (original)
> +++ llvm/trunk/lib/CodeGen/InlineSpiller.cpp Wed Oct  1 13:55:02 2014
> @@ -1224,12 +1224,16 @@ void InlineSpiller::spillAroundUses(unsi
>        // Modify DBG_VALUE now that the value is in a spill slot.
>        bool IsIndirect = MI->isIndirectDebugValue();
>        uint64_t Offset = IsIndirect ? MI->getOperand(1).getImm() : 0;
> -      const MDNode *MDPtr = MI->getOperand(2).getMetadata();
> +      const MDNode *Var = MI->getDebugVariable();
> +      const MDNode *Expr = MI->getDebugExpression();
>        DebugLoc DL = MI->getDebugLoc();
>        DEBUG(dbgs() << "Modifying debug info due to spill:" << "\t" <<
> *MI);
>        MachineBasicBlock *MBB = MI->getParent();
>        BuildMI(*MBB, MBB->erase(MI), DL, TII.get(TargetOpcode::DBG_VALUE))
> -          .addFrameIndex(StackSlot).addImm(Offset).addMetadata(MDPtr);
> +          .addFrameIndex(StackSlot)
> +          .addImm(Offset)
> +          .addMetadata(Var)
> +          .addMetadata(Expr);
>        continue;
>      }
>
>
> Modified: llvm/trunk/lib/CodeGen/LiveDebugVariables.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> CodeGen/LiveDebugVariables.cpp?rev=218787&r1=218786&r2=218787&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/CodeGen/LiveDebugVariables.cpp (original)
> +++ llvm/trunk/lib/CodeGen/LiveDebugVariables.cpp Wed Oct  1 13:55:02 2014
> @@ -110,7 +110,8 @@ public:
>  namespace {
>  class LDVImpl;
>  class UserValue {
> -  const MDNode *variable; ///< The debug info variable we are part of.
> +  const MDNode *Variable;   ///< The debug info variable we are part of.
> +  const MDNode *Expression; ///< Any complex address expression.
>    unsigned offset;        ///< Byte offset into variable.
>    bool IsIndirect;        ///< true if this is a register-indirect+offset
> value.
>    DebugLoc dl;            ///< The debug location for the variable. This
> is
> @@ -140,11 +141,10 @@ class UserValue {
>
>  public:
>    /// UserValue - Create a new UserValue.
> -  UserValue(const MDNode *var, unsigned o, bool i, DebugLoc L,
> -            LocMap::Allocator &alloc)
> -    : variable(var), offset(o), IsIndirect(i), dl(L), leader(this),
> -      next(nullptr), locInts(alloc)
> -  {}
> +  UserValue(const MDNode *var, const MDNode *expr, unsigned o, bool i,
> +            DebugLoc L, LocMap::Allocator &alloc)
> +      : Variable(var), Expression(expr), offset(o), IsIndirect(i), dl(L),
> +        leader(this), next(nullptr), locInts(alloc) {}
>
>    /// getLeader - Get the leader of this value's equivalence class.
>    UserValue *getLeader() {
> @@ -158,8 +158,10 @@ public:
>    UserValue *getNext() const { return next; }
>
>    /// match - Does this UserValue match the parameters?
> -  bool match(const MDNode *Var, unsigned Offset, bool indirect) const {
> -    return Var == variable && Offset == offset && indirect == IsIndirect;
> +  bool match(const MDNode *Var, const MDNode *Expr, unsigned Offset,
> +             bool indirect) const {
> +    return Var == Variable && Expr == Expression && Offset == offset &&
> +           indirect == IsIndirect;
>    }
>
>    /// merge - Merge equivalence classes.
> @@ -307,8 +309,8 @@ class LDVImpl {
>    UVMap userVarMap;
>
>    /// getUserValue - Find or create a UserValue.
> -  UserValue *getUserValue(const MDNode *Var, unsigned Offset,
> -                          bool IsIndirect, DebugLoc DL);
> +  UserValue *getUserValue(const MDNode *Var, const MDNode *Expr,
> +                          unsigned Offset, bool IsIndirect, DebugLoc DL);
>
>    /// lookupVirtReg - Find the EC leader for VirtReg or null.
>    UserValue *lookupVirtReg(unsigned VirtReg);
> @@ -361,7 +363,7 @@ public:
>  } // namespace
>
>  void UserValue::print(raw_ostream &OS, const TargetMachine *TM) {
> -  DIVariable DV(variable);
> +  DIVariable DV(Variable);
>    OS << "!\"";
>    DV.printExtendedName(OS);
>    OS << "\"\t";
> @@ -422,19 +424,20 @@ void UserValue::mapVirtRegs(LDVImpl *LDV
>        LDV->mapVirtReg(locations[i].getReg(), this);
>  }
>
> -UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset,
> -
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