[llvm] r230054 - Introduce bitset metadata format and bitset lowering pass.

Rafael EspĂ­ndola rafael.espindola at gmail.com
Fri Feb 20 16:04:08 PST 2015


This broke the gold plugin. I am now getting errors like

LLVM ERROR: Data layout required

test/tools/gold/emit-llvm.ll fail for example.

On 20 February 2015 at 15:30, Peter Collingbourne <peter at pcc.me.uk> wrote:
> Author: pcc
> Date: Fri Feb 20 14:30:47 2015
> New Revision: 230054
>
> URL: http://llvm.org/viewvc/llvm-project?rev=230054&view=rev
> Log:
> Introduce bitset metadata format and bitset lowering pass.
>
> This patch introduces a new mechanism that allows IR modules to co-operatively
> build pointer sets corresponding to addresses within a given set of
> globals. One particular use case for this is to allow a C++ program to
> efficiently verify (at each call site) that a vtable pointer is in the set
> of valid vtable pointers for the class or its derived classes. One way of
> doing this is for a toolchain component to build, for each class, a bit set
> that maps to the memory region allocated for the vtables, such that each 1
> bit in the bit set maps to a valid vtable for that class, and lay out the
> vtables next to each other, to minimize the total size of the bit sets.
>
> The patch introduces a metadata format for representing pointer sets, an
> '@llvm.bitset.test' intrinsic and an LTO lowering pass that lays out the globals
> and builds the bitsets, and documents the new feature.
>
> Differential Revision: http://reviews.llvm.org/D7288
>
> Added:
>     llvm/trunk/docs/BitSets.rst
>     llvm/trunk/include/llvm/Transforms/IPO/LowerBitSets.h
>     llvm/trunk/lib/Transforms/IPO/LowerBitSets.cpp
>     llvm/trunk/test/Transforms/LowerBitSets/
>     llvm/trunk/test/Transforms/LowerBitSets/constant.ll
>     llvm/trunk/test/Transforms/LowerBitSets/simple.ll
>     llvm/trunk/test/Transforms/LowerBitSets/single-offset.ll
>     llvm/trunk/unittests/Transforms/IPO/
>     llvm/trunk/unittests/Transforms/IPO/CMakeLists.txt
>     llvm/trunk/unittests/Transforms/IPO/LowerBitSets.cpp
>     llvm/trunk/unittests/Transforms/IPO/Makefile
>       - copied, changed from r230053, llvm/trunk/unittests/Transforms/Makefile
> Modified:
>     llvm/trunk/docs/LangRef.rst
>     llvm/trunk/docs/index.rst
>     llvm/trunk/include/llvm/ADT/EquivalenceClasses.h
>     llvm/trunk/include/llvm/ADT/PointerUnion.h
>     llvm/trunk/include/llvm/IR/Intrinsics.td
>     llvm/trunk/include/llvm/InitializePasses.h
>     llvm/trunk/include/llvm/Transforms/IPO.h
>     llvm/trunk/lib/Transforms/IPO/CMakeLists.txt
>     llvm/trunk/lib/Transforms/IPO/IPO.cpp
>     llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
>     llvm/trunk/unittests/Transforms/CMakeLists.txt
>     llvm/trunk/unittests/Transforms/Makefile
>
> Added: llvm/trunk/docs/BitSets.rst
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/BitSets.rst?rev=230054&view=auto
> ==============================================================================
> --- llvm/trunk/docs/BitSets.rst (added)
> +++ llvm/trunk/docs/BitSets.rst Fri Feb 20 14:30:47 2015
> @@ -0,0 +1,66 @@
> +=======
> +Bitsets
> +=======
> +
> +This is a mechanism that allows IR modules to co-operatively build pointer
> +sets corresponding to addresses within a given set of globals. One example
> +of a use case for this is to allow a C++ program to efficiently verify (at
> +each call site) that a vtable pointer is in the set of valid vtable pointers
> +for the type of the class or its derived classes.
> +
> +To use the mechanism, a client creates a global metadata node named
> +``llvm.bitsets``.  Each element is a metadata node with three elements:
> +the first is a metadata string containing an identifier for the bitset,
> +the second is a global variable and the third is a byte offset into the
> +global variable.
> +
> +This will cause a link-time optimization pass to generate bitsets from the
> +memory addresses referenced from the elements of the bitset metadata. The pass
> +will lay out the referenced globals consecutively, so their definitions must
> +be available at LTO time. An intrinsic, :ref:`llvm.bitset.test <bitset.test>`,
> +generates code to test whether a given pointer is a member of a bitset.
> +
> +:Example:
> +
> +::
> +
> +    target datalayout = "e-p:32:32"
> +
> +    @a = internal global i32 0
> +    @b = internal global i32 0
> +    @c = internal global i32 0
> +    @d = internal global [2 x i32] [i32 0, i32 0]
> +
> +    !llvm.bitsets = !{!0, !1, !2, !3, !4}
> +
> +    !0 = !{!"bitset1", i32* @a, i32 0}
> +    !1 = !{!"bitset1", i32* @b, i32 0}
> +    !2 = !{!"bitset2", i32* @b, i32 0}
> +    !3 = !{!"bitset2", i32* @c, i32 0}
> +    !4 = !{!"bitset2", i32* @d, i32 4}
> +
> +    declare i1 @llvm.bitset.test(i8* %ptr, metadata %bitset) nounwind readnone
> +
> +    define i1 @foo(i32* %p) {
> +      %pi8 = bitcast i32* %p to i8*
> +      %x = call i1 @llvm.bitset.test(i8* %pi8, metadata !"bitset1")
> +      ret i1 %x
> +    }
> +
> +    define i1 @bar(i32* %p) {
> +      %pi8 = bitcast i32* %p to i8*
> +      %x = call i1 @llvm.bitset.test(i8* %pi8, metadata !"bitset2")
> +      ret i1 %x
> +    }
> +
> +    define void @main() {
> +      %a1 = call i1 @foo(i32* @a) ; returns 1
> +      %b1 = call i1 @foo(i32* @b) ; returns 1
> +      %c1 = call i1 @foo(i32* @c) ; returns 0
> +      %a2 = call i1 @bar(i32* @a) ; returns 0
> +      %b2 = call i1 @bar(i32* @b) ; returns 1
> +      %c2 = call i1 @bar(i32* @c) ; returns 1
> +      %d02 = call i1 @bar(i32* getelementptr ([2 x i32]* @d, i32 0, i32 0)) ; returns 0
> +      %d12 = call i1 @bar(i32* getelementptr ([2 x i32]* @d, i32 0, i32 1)) ; returns 1
> +      ret void
> +    }
>
> Modified: llvm/trunk/docs/LangRef.rst
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.rst?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/docs/LangRef.rst (original)
> +++ llvm/trunk/docs/LangRef.rst Fri Feb 20 14:30:47 2015
> @@ -3308,6 +3308,12 @@ the loop identifier metadata node direct
>     !1 = !{!1} ; an identifier for the inner loop
>     !2 = !{!2} ; an identifier for the outer loop
>
> +'``llvm.bitsets``'
> +^^^^^^^^^^^^^^^^^^
> +
> +The ``llvm.bitsets`` global metadata is used to implement
> +:doc:`bitsets <BitSets>`.
> +
>  Module Flags Metadata
>  =====================
>
> @@ -9891,6 +9897,31 @@ sufficient overall improvement in code q
>  that the optimizer can otherwise deduce or facts that are of little use to the
>  optimizer.
>
> +.. _bitset.test:
> +
> +'``llvm.bitset.test``' Intrinsic
> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Syntax:
> +"""""""
> +
> +::
> +
> +      declare i1 @llvm.bitset.test(i8* %ptr, metadata %bitset) nounwind readnone
> +
> +
> +Arguments:
> +""""""""""
> +
> +The first argument is a pointer to be tested. The second argument is a
> +metadata string containing the name of a :doc:`bitset <BitSets>`.
> +
> +Overview:
> +"""""""""
> +
> +The ``llvm.bitset.test`` intrinsic tests whether the given pointer is a
> +member of the given bitset.
> +
>  '``llvm.donothing``' Intrinsic
>  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>
> Modified: llvm/trunk/docs/index.rst
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/index.rst?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/docs/index.rst (original)
> +++ llvm/trunk/docs/index.rst Fri Feb 20 14:30:47 2015
> @@ -244,6 +244,7 @@ For API clients and LLVM developers.
>     CoverageMappingFormat
>     Statepoints
>     MergeFunctions
> +   BitSets
>
>  :doc:`WritingAnLLVMPass`
>     Information on how to write LLVM transformations and analyses.
>
> Modified: llvm/trunk/include/llvm/ADT/EquivalenceClasses.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/EquivalenceClasses.h?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/ADT/EquivalenceClasses.h (original)
> +++ llvm/trunk/include/llvm/ADT/EquivalenceClasses.h Fri Feb 20 14:30:47 2015
> @@ -255,7 +255,7 @@ public:
>        assert(Node != nullptr && "Dereferencing end()!");
>        return Node->getData();
>      }
> -    reference operator->() const { return operator*(); }
> +    pointer operator->() const { return &operator*(); }
>
>      member_iterator &operator++() {
>        assert(Node != nullptr && "++'d off the end of the list!");
>
> Modified: llvm/trunk/include/llvm/ADT/PointerUnion.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/PointerUnion.h?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/ADT/PointerUnion.h (original)
> +++ llvm/trunk/include/llvm/ADT/PointerUnion.h Fri Feb 20 14:30:47 2015
> @@ -195,6 +195,12 @@ namespace llvm {
>      return lhs.getOpaqueValue() != rhs.getOpaqueValue();
>    }
>
> +  template<typename PT1, typename PT2>
> +  static bool operator<(PointerUnion<PT1, PT2> lhs,
> +                        PointerUnion<PT1, PT2> rhs) {
> +    return lhs.getOpaqueValue() < rhs.getOpaqueValue();
> +  }
> +
>    // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
>    // # low bits available = min(PT1bits,PT2bits)-1.
>    template<typename PT1, typename PT2>
>
> Modified: llvm/trunk/include/llvm/IR/Intrinsics.td
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/Intrinsics.td?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/IR/Intrinsics.td (original)
> +++ llvm/trunk/include/llvm/IR/Intrinsics.td Fri Feb 20 14:30:47 2015
> @@ -603,6 +603,10 @@ def int_masked_scatter: Intrinsic<[],
>                                     LLVMVectorSameWidth<0, llvm_i1_ty>],
>                                    [IntrReadWriteArgMem]>;
>
> +// Intrinsics to support bit sets.
> +def int_bitset_test : Intrinsic<[llvm_i1_ty], [llvm_ptr_ty, llvm_metadata_ty],
> +                                [IntrNoMem]>;
> +
>  //===----------------------------------------------------------------------===//
>  // Target-specific intrinsics
>  //===----------------------------------------------------------------------===//
>
> Modified: llvm/trunk/include/llvm/InitializePasses.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/InitializePasses.h?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/InitializePasses.h (original)
> +++ llvm/trunk/include/llvm/InitializePasses.h Fri Feb 20 14:30:47 2015
> @@ -178,6 +178,7 @@ void initializeLoopUnrollPass(PassRegist
>  void initializeLoopUnswitchPass(PassRegistry&);
>  void initializeLoopIdiomRecognizePass(PassRegistry&);
>  void initializeLowerAtomicPass(PassRegistry&);
> +void initializeLowerBitSetsPass(PassRegistry&);
>  void initializeLowerExpectIntrinsicPass(PassRegistry&);
>  void initializeLowerIntrinsicsPass(PassRegistry&);
>  void initializeLowerInvokePass(PassRegistry&);
>
> Modified: llvm/trunk/include/llvm/Transforms/IPO.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/IPO.h?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/IPO.h (original)
> +++ llvm/trunk/include/llvm/Transforms/IPO.h Fri Feb 20 14:30:47 2015
> @@ -199,6 +199,10 @@ ModulePass *createMetaRenamerPass();
>  /// manager.
>  ModulePass *createBarrierNoopPass();
>
> +/// \brief This pass lowers bitset metadata and the llvm.bitset.test intrinsic
> +/// to bitsets.
> +ModulePass *createLowerBitSetsPass();
> +
>  } // End llvm namespace
>
>  #endif
>
> Added: llvm/trunk/include/llvm/Transforms/IPO/LowerBitSets.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/IPO/LowerBitSets.h?rev=230054&view=auto
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/IPO/LowerBitSets.h (added)
> +++ llvm/trunk/include/llvm/Transforms/IPO/LowerBitSets.h Fri Feb 20 14:30:47 2015
> @@ -0,0 +1,78 @@
> +//===- LowerBitSets.h - Bitset lowering pass --------------------*- C++ -*-===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
> +//===----------------------------------------------------------------------===//
> +//
> +// This file defines parts of the bitset lowering pass implementation that may
> +// be usefully unit tested.
> +//
> +//===----------------------------------------------------------------------===//
> +
> +#ifndef LLVM_TRANSFORMS_IPO_LOWERBITSETS_H
> +#define LLVM_TRANSFORMS_IPO_LOWERBITSETS_H
> +
> +#include "llvm/ADT/DenseMap.h"
> +#include "llvm/ADT/SmallVector.h"
> +
> +#include <stdint.h>
> +#include <limits>
> +#include <vector>
> +
> +namespace llvm {
> +
> +class DataLayout;
> +class GlobalVariable;
> +class Value;
> +
> +struct BitSetInfo {
> +  // The actual bitset.
> +  std::vector<uint8_t> Bits;
> +
> +  // The byte offset into the combined global represented by the bitset.
> +  uint64_t ByteOffset;
> +
> +  // The size of the bitset in bits.
> +  uint64_t BitSize;
> +
> +  // Log2 alignment of the bit set relative to the combined global.
> +  // For example, a log2 alignment of 3 means that bits in the bitset
> +  // represent addresses 8 bytes apart.
> +  unsigned AlignLog2;
> +
> +  bool isSingleOffset() const {
> +    return Bits.size() == 1 && Bits[0] == 1;
> +  }
> +
> +  bool containsGlobalOffset(uint64_t Offset) const;
> +
> +  bool containsValue(const DataLayout *DL,
> +                     const DenseMap<GlobalVariable *, uint64_t> &GlobalLayout,
> +                     Value *V, uint64_t COffset = 0) const;
> +
> +};
> +
> +struct BitSetBuilder {
> +  SmallVector<uint64_t, 16> Offsets;
> +  uint64_t Min, Max;
> +
> +  BitSetBuilder() : Min(std::numeric_limits<uint64_t>::max()), Max(0) {}
> +
> +  void addOffset(uint64_t Offset) {
> +    if (Min > Offset)
> +      Min = Offset;
> +    if (Max < Offset)
> +      Max = Offset;
> +
> +    Offsets.push_back(Offset);
> +  }
> +
> +  BitSetInfo build();
> +};
> +
> +} // namespace llvm
> +
> +#endif
>
> Modified: llvm/trunk/lib/Transforms/IPO/CMakeLists.txt
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/CMakeLists.txt?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/CMakeLists.txt (original)
> +++ llvm/trunk/lib/Transforms/IPO/CMakeLists.txt Fri Feb 20 14:30:47 2015
> @@ -14,6 +14,7 @@ add_llvm_library(LLVMipo
>    Inliner.cpp
>    Internalize.cpp
>    LoopExtractor.cpp
> +  LowerBitSets.cpp
>    MergeFunctions.cpp
>    PartialInlining.cpp
>    PassManagerBuilder.cpp
>
> Modified: llvm/trunk/lib/Transforms/IPO/IPO.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/IPO.cpp?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/IPO.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/IPO.cpp Fri Feb 20 14:30:47 2015
> @@ -36,6 +36,7 @@ void llvm::initializeIPO(PassRegistry &R
>    initializeLoopExtractorPass(Registry);
>    initializeBlockExtractorPassPass(Registry);
>    initializeSingleLoopExtractorPass(Registry);
> +  initializeLowerBitSetsPass(Registry);
>    initializeMergeFunctionsPass(Registry);
>    initializePartialInlinerPass(Registry);
>    initializePruneEHPass(Registry);
>
> Added: llvm/trunk/lib/Transforms/IPO/LowerBitSets.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/LowerBitSets.cpp?rev=230054&view=auto
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/LowerBitSets.cpp (added)
> +++ llvm/trunk/lib/Transforms/IPO/LowerBitSets.cpp Fri Feb 20 14:30:47 2015
> @@ -0,0 +1,526 @@
> +//===-- LowerBitSets.cpp - Bitset lowering pass ---------------------------===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
> +//===----------------------------------------------------------------------===//
> +//
> +// This pass lowers bitset metadata and calls to the llvm.bitset.test intrinsic.
> +// See http://llvm.org/docs/LangRef.html#bitsets for more information.
> +//
> +//===----------------------------------------------------------------------===//
> +
> +#include "llvm/Transforms/IPO/LowerBitSets.h"
> +#include "llvm/Transforms/IPO.h"
> +#include "llvm/ADT/EquivalenceClasses.h"
> +#include "llvm/ADT/Statistic.h"
> +#include "llvm/IR/Constant.h"
> +#include "llvm/IR/Constants.h"
> +#include "llvm/IR/GlobalVariable.h"
> +#include "llvm/IR/IRBuilder.h"
> +#include "llvm/IR/Instructions.h"
> +#include "llvm/IR/Intrinsics.h"
> +#include "llvm/IR/Module.h"
> +#include "llvm/IR/Operator.h"
> +#include "llvm/Pass.h"
> +#include "llvm/Transforms/Utils/BasicBlockUtils.h"
> +
> +using namespace llvm;
> +
> +#define DEBUG_TYPE "lowerbitsets"
> +
> +STATISTIC(NumBitSetsCreated, "Number of bitsets created");
> +STATISTIC(NumBitSetCallsLowered, "Number of bitset calls lowered");
> +STATISTIC(NumBitSetDisjointSets, "Number of disjoint sets of bitsets");
> +
> +bool BitSetInfo::containsGlobalOffset(uint64_t Offset) const {
> +  if (Offset < ByteOffset)
> +    return false;
> +
> +  if ((Offset - ByteOffset) % (uint64_t(1) << AlignLog2) != 0)
> +    return false;
> +
> +  uint64_t BitOffset = (Offset - ByteOffset) >> AlignLog2;
> +  if (BitOffset >= BitSize)
> +    return false;
> +
> +  return (Bits[BitOffset / 8] >> (BitOffset % 8)) & 1;
> +}
> +
> +bool BitSetInfo::containsValue(
> +    const DataLayout *DL,
> +    const DenseMap<GlobalVariable *, uint64_t> &GlobalLayout, Value *V,
> +    uint64_t COffset) const {
> +  if (auto GV = dyn_cast<GlobalVariable>(V)) {
> +    auto I = GlobalLayout.find(GV);
> +    if (I == GlobalLayout.end())
> +      return false;
> +    return containsGlobalOffset(I->second + COffset);
> +  }
> +
> +  if (auto GEP = dyn_cast<GEPOperator>(V)) {
> +    APInt APOffset(DL->getPointerSizeInBits(0), 0);
> +    bool Result = GEP->accumulateConstantOffset(*DL, APOffset);
> +    if (!Result)
> +      return false;
> +    COffset += APOffset.getZExtValue();
> +    return containsValue(DL, GlobalLayout, GEP->getPointerOperand(),
> +                         COffset);
> +  }
> +
> +  if (auto Op = dyn_cast<Operator>(V)) {
> +    if (Op->getOpcode() == Instruction::BitCast)
> +      return containsValue(DL, GlobalLayout, Op->getOperand(0), COffset);
> +
> +    if (Op->getOpcode() == Instruction::Select)
> +      return containsValue(DL, GlobalLayout, Op->getOperand(1), COffset) &&
> +             containsValue(DL, GlobalLayout, Op->getOperand(2), COffset);
> +  }
> +
> +  return false;
> +}
> +
> +BitSetInfo BitSetBuilder::build() {
> +  if (Min > Max)
> +    Min = 0;
> +
> +  // Normalize each offset against the minimum observed offset, and compute
> +  // the bitwise OR of each of the offsets. The number of trailing zeros
> +  // in the mask gives us the log2 of the alignment of all offsets, which
> +  // allows us to compress the bitset by only storing one bit per aligned
> +  // address.
> +  uint64_t Mask = 0;
> +  for (uint64_t &Offset : Offsets) {
> +    Offset -= Min;
> +    Mask |= Offset;
> +  }
> +
> +  BitSetInfo BSI;
> +  BSI.ByteOffset = Min;
> +
> +  BSI.AlignLog2 = 0;
> +  // FIXME: Can probably do something smarter if all offsets are 0.
> +  if (Mask != 0)
> +    BSI.AlignLog2 = countTrailingZeros(Mask, ZB_Undefined);
> +
> +  // Build the compressed bitset while normalizing the offsets against the
> +  // computed alignment.
> +  BSI.BitSize = ((Max - Min) >> BSI.AlignLog2) + 1;
> +  uint64_t ByteSize = (BSI.BitSize + 7) / 8;
> +  BSI.Bits.resize(ByteSize);
> +  for (uint64_t Offset : Offsets) {
> +    Offset >>= BSI.AlignLog2;
> +    BSI.Bits[Offset / 8] |= 1 << (Offset % 8);
> +  }
> +
> +  return BSI;
> +}
> +
> +namespace {
> +
> +struct LowerBitSets : public ModulePass {
> +  static char ID;
> +  LowerBitSets() : ModulePass(ID) {
> +    initializeLowerBitSetsPass(*PassRegistry::getPassRegistry());
> +  }
> +
> +  const DataLayout *DL;
> +  IntegerType *Int1Ty;
> +  IntegerType *Int32Ty;
> +  Type *Int32PtrTy;
> +  IntegerType *Int64Ty;
> +  Type *IntPtrTy;
> +
> +  // The llvm.bitsets named metadata.
> +  NamedMDNode *BitSetNM;
> +
> +  // Mapping from bitset mdstrings to the call sites that test them.
> +  DenseMap<MDString *, std::vector<CallInst *>> BitSetTestCallSites;
> +
> +  BitSetInfo
> +  buildBitSet(MDString *BitSet,
> +              const DenseMap<GlobalVariable *, uint64_t> &GlobalLayout);
> +  Value *createBitSetTest(IRBuilder<> &B, const BitSetInfo &BSI,
> +                          GlobalVariable *BitSetGlobal, Value *BitOffset);
> +  void
> +  lowerBitSetCall(CallInst *CI, const BitSetInfo &BSI,
> +                  GlobalVariable *BitSetGlobal, GlobalVariable *CombinedGlobal,
> +                  const DenseMap<GlobalVariable *, uint64_t> &GlobalLayout);
> +  void buildBitSetsFromGlobals(Module &M,
> +                               const std::vector<MDString *> &BitSets,
> +                               const std::vector<GlobalVariable *> &Globals);
> +  bool buildBitSets(Module &M);
> +  bool eraseBitSetMetadata(Module &M);
> +
> +  bool doInitialization(Module &M) override;
> +  bool runOnModule(Module &M) override;
> +};
> +
> +} // namespace
> +
> +INITIALIZE_PASS_BEGIN(LowerBitSets, "lowerbitsets",
> +                "Lower bitset metadata", false, false)
> +INITIALIZE_PASS_END(LowerBitSets, "lowerbitsets",
> +                "Lower bitset metadata", false, false)
> +char LowerBitSets::ID = 0;
> +
> +ModulePass *llvm::createLowerBitSetsPass() { return new LowerBitSets; }
> +
> +bool LowerBitSets::doInitialization(Module &M) {
> +  DL = M.getDataLayout();
> +  if (!DL)
> +    report_fatal_error("Data layout required");
> +
> +  Int1Ty = Type::getInt1Ty(M.getContext());
> +  Int32Ty = Type::getInt32Ty(M.getContext());
> +  Int32PtrTy = PointerType::getUnqual(Int32Ty);
> +  Int64Ty = Type::getInt64Ty(M.getContext());
> +  IntPtrTy = DL->getIntPtrType(M.getContext(), 0);
> +
> +  BitSetNM = M.getNamedMetadata("llvm.bitsets");
> +
> +  BitSetTestCallSites.clear();
> +
> +  return false;
> +}
> +
> +/// Build a bit set for \param BitSet using the object layouts in
> +/// \param GlobalLayout.
> +BitSetInfo LowerBitSets::buildBitSet(
> +    MDString *BitSet,
> +    const DenseMap<GlobalVariable *, uint64_t> &GlobalLayout) {
> +  BitSetBuilder BSB;
> +
> +  // Compute the byte offset of each element of this bitset.
> +  if (BitSetNM) {
> +    for (MDNode *Op : BitSetNM->operands()) {
> +      if (Op->getOperand(0) != BitSet || !Op->getOperand(1))
> +        continue;
> +      auto OpGlobal = cast<GlobalVariable>(
> +          cast<ConstantAsMetadata>(Op->getOperand(1))->getValue());
> +      uint64_t Offset =
> +          cast<ConstantInt>(cast<ConstantAsMetadata>(Op->getOperand(2))
> +                                ->getValue())->getZExtValue();
> +
> +      Offset += GlobalLayout.find(OpGlobal)->second;
> +
> +      BSB.addOffset(Offset);
> +    }
> +  }
> +
> +  return BSB.build();
> +}
> +
> +/// Build a test that bit \param BitOffset mod sizeof(Bits)*8 is set in
> +/// \param Bits. This pattern matches to the bt instruction on x86.
> +static Value *createMaskedBitTest(IRBuilder<> &B, Value *Bits,
> +                                  Value *BitOffset) {
> +  auto BitsType = cast<IntegerType>(Bits->getType());
> +  unsigned BitWidth = BitsType->getBitWidth();
> +
> +  BitOffset = B.CreateZExtOrTrunc(BitOffset, BitsType);
> +  Value *BitIndex =
> +      B.CreateAnd(BitOffset, ConstantInt::get(BitsType, BitWidth - 1));
> +  Value *BitMask = B.CreateShl(ConstantInt::get(BitsType, 1), BitIndex);
> +  Value *MaskedBits = B.CreateAnd(Bits, BitMask);
> +  return B.CreateICmpNE(MaskedBits, ConstantInt::get(BitsType, 0));
> +}
> +
> +/// Build a test that bit \param BitOffset is set in \param BSI, where
> +/// \param BitSetGlobal is a global containing the bits in \param BSI.
> +Value *LowerBitSets::createBitSetTest(IRBuilder<> &B, const BitSetInfo &BSI,
> +                                      GlobalVariable *BitSetGlobal,
> +                                      Value *BitOffset) {
> +  if (BSI.Bits.size() <= 8) {
> +    // If the bit set is sufficiently small, we can avoid a load by bit testing
> +    // a constant.
> +    IntegerType *BitsTy;
> +    if (BSI.Bits.size() <= 4)
> +      BitsTy = Int32Ty;
> +    else
> +      BitsTy = Int64Ty;
> +
> +    uint64_t Bits = 0;
> +    for (auto I = BSI.Bits.rbegin(), E = BSI.Bits.rend(); I != E; ++I) {
> +      Bits <<= 8;
> +      Bits |= *I;
> +    }
> +    Constant *BitsConst = ConstantInt::get(BitsTy, Bits);
> +    return createMaskedBitTest(B, BitsConst, BitOffset);
> +  } else {
> +    // TODO: We might want to use the memory variant of the bt instruction
> +    // with the previously computed bit offset at -Os. This instruction does
> +    // exactly what we want but has been benchmarked as being slower than open
> +    // coding the load+bt.
> +    Value *BitSetGlobalOffset =
> +        B.CreateLShr(BitOffset, ConstantInt::get(IntPtrTy, 5));
> +    Value *BitSetEntryAddr = B.CreateGEP(
> +        ConstantExpr::getBitCast(BitSetGlobal, Int32PtrTy), BitSetGlobalOffset);
> +    Value *BitSetEntry = B.CreateLoad(BitSetEntryAddr);
> +
> +    return createMaskedBitTest(B, BitSetEntry, BitOffset);
> +  }
> +}
> +
> +/// Lower a llvm.bitset.test call to its implementation.
> +void LowerBitSets::lowerBitSetCall(
> +    CallInst *CI, const BitSetInfo &BSI, GlobalVariable *BitSetGlobal,
> +    GlobalVariable *CombinedGlobal,
> +    const DenseMap<GlobalVariable *, uint64_t> &GlobalLayout) {
> +  Value *Ptr = CI->getArgOperand(0);
> +
> +  if (BSI.containsValue(DL, GlobalLayout, Ptr)) {
> +    CI->replaceAllUsesWith(
> +        ConstantInt::getTrue(BitSetGlobal->getParent()->getContext()));
> +    CI->eraseFromParent();
> +    return;
> +  }
> +
> +  Constant *GlobalAsInt = ConstantExpr::getPtrToInt(CombinedGlobal, IntPtrTy);
> +  Constant *OffsetedGlobalAsInt = ConstantExpr::getAdd(
> +      GlobalAsInt, ConstantInt::get(IntPtrTy, BSI.ByteOffset));
> +
> +  BasicBlock *InitialBB = CI->getParent();
> +
> +  IRBuilder<> B(CI);
> +
> +  Value *PtrAsInt = B.CreatePtrToInt(Ptr, IntPtrTy);
> +
> +  if (BSI.isSingleOffset()) {
> +    Value *Eq = B.CreateICmpEQ(PtrAsInt, OffsetedGlobalAsInt);
> +    CI->replaceAllUsesWith(Eq);
> +    CI->eraseFromParent();
> +    return;
> +  }
> +
> +  Value *PtrOffset = B.CreateSub(PtrAsInt, OffsetedGlobalAsInt);
> +
> +  Value *BitOffset;
> +  if (BSI.AlignLog2 == 0) {
> +    BitOffset = PtrOffset;
> +  } else {
> +    // We need to check that the offset both falls within our range and is
> +    // suitably aligned. We can check both properties at the same time by
> +    // performing a right rotate by log2(alignment) followed by an integer
> +    // comparison against the bitset size. The rotate will move the lower
> +    // order bits that need to be zero into the higher order bits of the
> +    // result, causing the comparison to fail if they are nonzero. The rotate
> +    // also conveniently gives us a bit offset to use during the load from
> +    // the bitset.
> +    Value *OffsetSHR =
> +        B.CreateLShr(PtrOffset, ConstantInt::get(IntPtrTy, BSI.AlignLog2));
> +    Value *OffsetSHL = B.CreateShl(
> +        PtrOffset, ConstantInt::get(IntPtrTy, DL->getPointerSizeInBits(0) -
> +                                                  BSI.AlignLog2));
> +    BitOffset = B.CreateOr(OffsetSHR, OffsetSHL);
> +  }
> +
> +  Constant *BitSizeConst = ConstantInt::get(IntPtrTy, BSI.BitSize);
> +  Value *OffsetInRange = B.CreateICmpULT(BitOffset, BitSizeConst);
> +
> +  TerminatorInst *Term = SplitBlockAndInsertIfThen(OffsetInRange, CI, false);
> +  IRBuilder<> ThenB(Term);
> +
> +  // Now that we know that the offset is in range and aligned, load the
> +  // appropriate bit from the bitset.
> +  Value *Bit = createBitSetTest(ThenB, BSI, BitSetGlobal, BitOffset);
> +
> +  // The value we want is 0 if we came directly from the initial block
> +  // (having failed the range or alignment checks), or the loaded bit if
> +  // we came from the block in which we loaded it.
> +  B.SetInsertPoint(CI);
> +  PHINode *P = B.CreatePHI(Int1Ty, 2);
> +  P->addIncoming(ConstantInt::get(Int1Ty, 0), InitialBB);
> +  P->addIncoming(Bit, ThenB.GetInsertBlock());
> +
> +  CI->replaceAllUsesWith(P);
> +  CI->eraseFromParent();
> +}
> +
> +/// Given a disjoint set of bitsets and globals, layout the globals, build the
> +/// bit sets and lower the llvm.bitset.test calls.
> +void LowerBitSets::buildBitSetsFromGlobals(
> +    Module &M,
> +    const std::vector<MDString *> &BitSets,
> +    const std::vector<GlobalVariable *> &Globals) {
> +  // Build a new global with the combined contents of the referenced globals.
> +  std::vector<Constant *> GlobalInits;
> +  for (GlobalVariable *G : Globals)
> +    GlobalInits.push_back(G->getInitializer());
> +  Constant *NewInit = ConstantStruct::getAnon(M.getContext(), GlobalInits);
> +  auto CombinedGlobal =
> +      new GlobalVariable(M, NewInit->getType(), /*isConstant=*/true,
> +                         GlobalValue::PrivateLinkage, NewInit);
> +
> +  const StructLayout *CombinedGlobalLayout =
> +      DL->getStructLayout(cast<StructType>(NewInit->getType()));
> +
> +  // Compute the offsets of the original globals within the new global.
> +  DenseMap<GlobalVariable *, uint64_t> GlobalLayout;
> +  for (unsigned I = 0; I != Globals.size(); ++I)
> +    GlobalLayout[Globals[I]] = CombinedGlobalLayout->getElementOffset(I);
> +
> +  // For each bitset in this disjoint set...
> +  for (MDString *BS : BitSets) {
> +    // Build the bitset.
> +    BitSetInfo BSI = buildBitSet(BS, GlobalLayout);
> +
> +    // Create a global in which to store it.
> +    ++NumBitSetsCreated;
> +    Constant *BitsConst = ConstantDataArray::get(M.getContext(), BSI.Bits);
> +    auto BitSetGlobal = new GlobalVariable(
> +        M, BitsConst->getType(), /*isConstant=*/true,
> +        GlobalValue::PrivateLinkage, BitsConst, BS->getString() + ".bits");
> +
> +    // Lower each call to llvm.bitset.test for this bitset.
> +    for (CallInst *CI : BitSetTestCallSites[BS]) {
> +      ++NumBitSetCallsLowered;
> +      lowerBitSetCall(CI, BSI, BitSetGlobal, CombinedGlobal, GlobalLayout);
> +    }
> +  }
> +
> +  // Build aliases pointing to offsets into the combined global for each
> +  // global from which we built the combined global, and replace references
> +  // to the original globals with references to the aliases.
> +  for (unsigned I = 0; I != Globals.size(); ++I) {
> +    Constant *CombinedGlobalIdxs[] = {ConstantInt::get(Int32Ty, 0),
> +                                      ConstantInt::get(Int32Ty, I)};
> +    Constant *CombinedGlobalElemPtr =
> +        ConstantExpr::getGetElementPtr(CombinedGlobal, CombinedGlobalIdxs);
> +    GlobalAlias *GAlias = GlobalAlias::create(
> +        Globals[I]->getType()->getElementType(),
> +        Globals[I]->getType()->getAddressSpace(), Globals[I]->getLinkage(),
> +        "", CombinedGlobalElemPtr, &M);
> +    GAlias->takeName(Globals[I]);
> +    Globals[I]->replaceAllUsesWith(GAlias);
> +    Globals[I]->eraseFromParent();
> +  }
> +}
> +
> +/// Lower all bit sets in this module.
> +bool LowerBitSets::buildBitSets(Module &M) {
> +  Function *BitSetTestFunc =
> +      M.getFunction(Intrinsic::getName(Intrinsic::bitset_test));
> +  if (!BitSetTestFunc)
> +    return false;
> +
> +  // Equivalence class set containing bitsets and the globals they reference.
> +  // This is used to partition the set of bitsets in the module into disjoint
> +  // sets.
> +  typedef EquivalenceClasses<PointerUnion<GlobalVariable *, MDString *>>
> +      GlobalClassesTy;
> +  GlobalClassesTy GlobalClasses;
> +
> +  for (const Use &U : BitSetTestFunc->uses()) {
> +    auto CI = cast<CallInst>(U.getUser());
> +
> +    auto BitSetMDVal = dyn_cast<MetadataAsValue>(CI->getArgOperand(1));
> +    if (!BitSetMDVal || !isa<MDString>(BitSetMDVal->getMetadata()))
> +      report_fatal_error(
> +          "Second argument of llvm.bitset.test must be metadata string");
> +    auto BitSet = cast<MDString>(BitSetMDVal->getMetadata());
> +
> +    // Add the call site to the list of call sites for this bit set. We also use
> +    // BitSetTestCallSites to keep track of whether we have seen this bit set
> +    // before. If we have, we don't need to re-add the referenced globals to the
> +    // equivalence class.
> +    std::pair<DenseMap<MDString *, std::vector<CallInst *>>::iterator,
> +              bool> Ins =
> +        BitSetTestCallSites.insert(
> +            std::make_pair(BitSet, std::vector<CallInst *>()));
> +    Ins.first->second.push_back(CI);
> +    if (!Ins.second)
> +      continue;
> +
> +    // Add the bitset to the equivalence class.
> +    GlobalClassesTy::iterator GCI = GlobalClasses.insert(BitSet);
> +    GlobalClassesTy::member_iterator CurSet = GlobalClasses.findLeader(GCI);
> +
> +    if (!BitSetNM)
> +      continue;
> +
> +    // Verify the bitset metadata and add the referenced globals to the bitset's
> +    // equivalence class.
> +    for (MDNode *Op : BitSetNM->operands()) {
> +      if (Op->getNumOperands() != 3)
> +        report_fatal_error(
> +            "All operands of llvm.bitsets metadata must have 3 elements");
> +
> +      if (Op->getOperand(0) != BitSet || !Op->getOperand(1))
> +        continue;
> +
> +      auto OpConstMD = dyn_cast<ConstantAsMetadata>(Op->getOperand(1));
> +      if (!OpConstMD)
> +        report_fatal_error("Bit set element must be a constant");
> +      auto OpGlobal = dyn_cast<GlobalVariable>(OpConstMD->getValue());
> +      if (!OpGlobal)
> +        report_fatal_error("Bit set element must refer to global");
> +
> +      auto OffsetConstMD = dyn_cast<ConstantAsMetadata>(Op->getOperand(2));
> +      if (!OffsetConstMD)
> +        report_fatal_error("Bit set element offset must be a constant");
> +      auto OffsetInt = dyn_cast<ConstantInt>(OffsetConstMD->getValue());
> +      if (!OffsetInt)
> +        report_fatal_error(
> +            "Bit set element offset must be an integer constant");
> +
> +      CurSet = GlobalClasses.unionSets(
> +          CurSet, GlobalClasses.findLeader(GlobalClasses.insert(OpGlobal)));
> +    }
> +  }
> +
> +  if (GlobalClasses.empty())
> +    return false;
> +
> +  // For each disjoint set we found...
> +  for (GlobalClassesTy::iterator I = GlobalClasses.begin(),
> +                                 E = GlobalClasses.end();
> +       I != E; ++I) {
> +    if (!I->isLeader()) continue;
> +
> +    ++NumBitSetDisjointSets;
> +
> +    // Build the list of bitsets and referenced globals in this disjoint set.
> +    std::vector<MDString *> BitSets;
> +    std::vector<GlobalVariable *> Globals;
> +    for (GlobalClassesTy::member_iterator MI = GlobalClasses.member_begin(I);
> +         MI != GlobalClasses.member_end(); ++MI) {
> +      if ((*MI).is<MDString *>())
> +        BitSets.push_back(MI->get<MDString *>());
> +      else
> +        Globals.push_back(MI->get<GlobalVariable *>());
> +    }
> +
> +    // Order bitsets and globals by name for determinism. TODO: We may later
> +    // want to use a more sophisticated ordering that lays out globals so as to
> +    // minimize the sizes of the bitsets.
> +    std::sort(BitSets.begin(), BitSets.end(), [](MDString *S1, MDString *S2) {
> +      return S1->getString() < S2->getString();
> +    });
> +    std::sort(Globals.begin(), Globals.end(),
> +              [](GlobalVariable *GV1, GlobalVariable *GV2) {
> +                return GV1->getName() < GV2->getName();
> +              });
> +
> +    // Build the bitsets from this disjoint set.
> +    buildBitSetsFromGlobals(M, BitSets, Globals);
> +  }
> +
> +  return true;
> +}
> +
> +bool LowerBitSets::eraseBitSetMetadata(Module &M) {
> +  if (!BitSetNM)
> +    return false;
> +
> +  M.eraseNamedMetadata(BitSetNM);
> +  return true;
> +}
> +
> +bool LowerBitSets::runOnModule(Module &M) {
> +  bool Changed = buildBitSets(M);
> +  Changed |= eraseBitSetMetadata(M);
> +  return Changed;
> +}
>
> Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Fri Feb 20 14:30:47 2015
> @@ -474,6 +474,9 @@ void PassManagerBuilder::addLTOOptimizat
>
>    PM.add(createJumpThreadingPass());
>
> +  // Lower bitset metadata to bitsets.
> +  PM.add(createLowerBitSetsPass());
> +
>    // Delete basic blocks, which optimization passes may have killed.
>    PM.add(createCFGSimplificationPass());
>
>
> Added: llvm/trunk/test/Transforms/LowerBitSets/constant.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LowerBitSets/constant.ll?rev=230054&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/LowerBitSets/constant.ll (added)
> +++ llvm/trunk/test/Transforms/LowerBitSets/constant.ll Fri Feb 20 14:30:47 2015
> @@ -0,0 +1,34 @@
> +; RUN: opt -S -lowerbitsets < %s | FileCheck %s
> +
> +target datalayout = "e-p:32:32"
> +
> + at a = constant i32 1
> + at b = constant [2 x i32] [i32 2, i32 3]
> +
> +!0 = !{!"bitset1", i32* @a, i32 0}
> +!1 = !{!"bitset1", [2 x i32]* @b, i32 4}
> +
> +!llvm.bitsets = !{ !0, !1 }
> +
> +declare i1 @llvm.bitset.test(i8* %ptr, metadata %bitset) nounwind readnone
> +
> +; CHECK: @foo(
> +define i1 @foo() {
> +  ; CHECK: ret i1 true
> +  %x = call i1 @llvm.bitset.test(i8* bitcast (i32* @a to i8*), metadata !"bitset1")
> +  ret i1 %x
> +}
> +
> +; CHECK: @bar(
> +define i1 @bar() {
> +  ; CHECK: ret i1 true
> +  %x = call i1 @llvm.bitset.test(i8* bitcast (i32* getelementptr ([2 x i32]* @b, i32 0, i32 1) to i8*), metadata !"bitset1")
> +  ret i1 %x
> +}
> +
> +; CHECK: @baz(
> +define i1 @baz() {
> +  ; CHECK-NOT: ret i1 true
> +  %x = call i1 @llvm.bitset.test(i8* bitcast (i32* getelementptr ([2 x i32]* @b, i32 0, i32 0) to i8*), metadata !"bitset1")
> +  ret i1 %x
> +}
>
> Added: llvm/trunk/test/Transforms/LowerBitSets/simple.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LowerBitSets/simple.ll?rev=230054&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/LowerBitSets/simple.ll (added)
> +++ llvm/trunk/test/Transforms/LowerBitSets/simple.ll Fri Feb 20 14:30:47 2015
> @@ -0,0 +1,127 @@
> +; RUN: opt -S -lowerbitsets < %s | FileCheck %s
> +; RUN: opt -S -O3 < %s | FileCheck -check-prefix=CHECK-NODISCARD %s
> +
> +target datalayout = "e-p:32:32"
> +
> +; CHECK: [[G:@[^ ]*]] = private constant { i32, [63 x i32], i32, [2 x i32] } { i32 1, [63 x i32] zeroinitializer, i32 3, [2 x i32] [i32 4, i32 5] }
> + at a = constant i32 1
> + at b = constant [63 x i32] zeroinitializer
> + at c = constant i32 3
> + at d = constant [2 x i32] [i32 4, i32 5]
> +
> +; Offset 0, 4 byte alignment
> +; CHECK: @bitset1.bits = private constant [9 x i8] c"\03\00\00\00\00\00\00\00\04"
> +!0 = !{!"bitset1", i32* @a, i32 0}
> +; CHECK-NODISCARD-DAG: !{!"bitset1", i32* @a, i32 0}
> +!1 = !{!"bitset1", [63 x i32]* @b, i32 0}
> +; CHECK-NODISCARD-DAG: !{!"bitset1", [63 x i32]* @b, i32 0}
> +!2 = !{!"bitset1", [2 x i32]* @d, i32 4}
> +; CHECK-NODISCARD-DAG: !{!"bitset1", [2 x i32]* @d, i32 4}
> +
> +; Offset 4, 4 byte alignment
> +; CHECK: @bitset2.bits = private constant [8 x i8] c"\01\00\00\00\00\00\00\80"
> +!3 = !{!"bitset2", [63 x i32]* @b, i32 0}
> +; CHECK-NODISCARD-DAG: !{!"bitset2", [63 x i32]* @b, i32 0}
> +!4 = !{!"bitset2", i32* @c, i32 0}
> +; CHECK-NODISCARD-DAG: !{!"bitset2", i32* @c, i32 0}
> +
> +; Offset 0, 256 byte alignment
> +; CHECK: @bitset3.bits = private constant [1 x i8] c"\03"
> +!5 = !{!"bitset3", i32* @a, i32 0}
> +; CHECK-NODISCARD-DAG: !{!"bitset3", i32* @a, i32 0}
> +!6 = !{!"bitset3", i32* @c, i32 0}
> +; CHECK-NODISCARD-DAG: !{!"bitset3", i32* @c, i32 0}
> +
> +; Entries whose second operand is null (the result of a global being DCE'd)
> +; should be ignored.
> +!7 = !{!"bitset2", null, i32 0}
> +
> +!llvm.bitsets = !{ !0, !1, !2, !3, !4, !5, !6, !7 }
> +
> +; CHECK: @a = alias getelementptr inbounds ({ i32, [63 x i32], i32, [2 x i32] }* [[G]], i32 0, i32 0)
> +; CHECK: @b = alias getelementptr inbounds ({ i32, [63 x i32], i32, [2 x i32] }* [[G]], i32 0, i32 1)
> +; CHECK: @c = alias getelementptr inbounds ({ i32, [63 x i32], i32, [2 x i32] }* [[G]], i32 0, i32 2)
> +; CHECK: @d = alias getelementptr inbounds ({ i32, [63 x i32], i32, [2 x i32] }* [[G]], i32 0, i32 3)
> +
> +declare i1 @llvm.bitset.test(i8* %ptr, metadata %bitset) nounwind readnone
> +
> +; CHECK: @foo(i32* [[A0:%[^ ]*]])
> +define i1 @foo(i32* %p) {
> +  ; CHECK-NOT: llvm.bitset.test
> +
> +  ; CHECK: [[R0:%[^ ]*]] = bitcast i32* [[A0]] to i8*
> +  %pi8 = bitcast i32* %p to i8*
> +  ; CHECK: [[R1:%[^ ]*]] = ptrtoint i8* [[R0]] to i32
> +  ; CHECK: [[R2:%[^ ]*]] = sub i32 [[R1]], ptrtoint ({ i32, [63 x i32], i32, [2 x i32] }* [[G]] to i32)
> +  ; CHECK: [[R3:%[^ ]*]] = lshr i32 [[R2]], 2
> +  ; CHECK: [[R4:%[^ ]*]] = shl i32 [[R2]], 30
> +  ; CHECK: [[R5:%[^ ]*]] = or i32 [[R3]], [[R4]]
> +  ; CHECK: [[R6:%[^ ]*]] = icmp ult i32 [[R5]], 67
> +  ; CHECK: br i1 [[R6]]
> +
> +  ; CHECK: [[R8:%[^ ]*]] = lshr i32 [[R5]], 5
> +  ; CHECK: [[R9:%[^ ]*]] = getelementptr i32* bitcast ([9 x i8]* @bitset1.bits to i32*), i32 [[R8]]
> +  ; CHECK: [[R10:%[^ ]*]] = load i32* [[R9]]
> +  ; CHECK: [[R11:%[^ ]*]] = and i32 [[R5]], 31
> +  ; CHECK: [[R12:%[^ ]*]] = shl i32 1, [[R11]]
> +  ; CHECK: [[R13:%[^ ]*]] = and i32 [[R10]], [[R12]]
> +  ; CHECK: [[R14:%[^ ]*]] = icmp ne i32 [[R13]], 0
> +
> +  ; CHECK: [[R16:%[^ ]*]] = phi i1 [ false, {{%[^ ]*}} ], [ [[R14]], {{%[^ ]*}} ]
> +  %x = call i1 @llvm.bitset.test(i8* %pi8, metadata !"bitset1")
> +
> +  ; CHECK-NOT: llvm.bitset.test
> +  %y = call i1 @llvm.bitset.test(i8* %pi8, metadata !"bitset1")
> +
> +  ; CHECK: ret i1 [[R16]]
> +  ret i1 %x
> +}
> +
> +; CHECK: @bar(i32* [[B0:%[^ ]*]])
> +define i1 @bar(i32* %p) {
> +  ; CHECK: [[S0:%[^ ]*]] = bitcast i32* [[B0]] to i8*
> +  %pi8 = bitcast i32* %p to i8*
> +  ; CHECK: [[S1:%[^ ]*]] = ptrtoint i8* [[S0]] to i32
> +  ; CHECK: [[S2:%[^ ]*]] = sub i32 [[S1]], add (i32 ptrtoint ({ i32, [63 x i32], i32, [2 x i32] }* [[G]] to i32), i32 4)
> +  ; CHECK: [[S3:%[^ ]*]] = lshr i32 [[S2]], 2
> +  ; CHECK: [[S4:%[^ ]*]] = shl i32 [[S2]], 30
> +  ; CHECK: [[S5:%[^ ]*]] = or i32 [[S3]], [[S4]]
> +  ; CHECK: [[S6:%[^ ]*]] = icmp ult i32 [[S5]], 64
> +  ; CHECK: br i1 [[S6]]
> +
> +  ; CHECK: [[S8:%[^ ]*]] = zext i32 [[S5]] to i64
> +  ; CHECK: [[S9:%[^ ]*]] = and i64 [[S8]], 63
> +  ; CHECK: [[S10:%[^ ]*]] = shl i64 1, [[S9]]
> +  ; CHECK: [[S11:%[^ ]*]] = and i64 -9223372036854775807, [[S10]]
> +  ; CHECK: [[S12:%[^ ]*]] = icmp ne i64 [[S11]], 0
> +
> +  ; CHECK: [[S16:%[^ ]*]] = phi i1 [ false, {{%[^ ]*}} ], [ [[S12]], {{%[^ ]*}} ]
> +  %x = call i1 @llvm.bitset.test(i8* %pi8, metadata !"bitset2")
> +  ; CHECK: ret i1 [[S16]]
> +  ret i1 %x
> +}
> +
> +; CHECK: @baz(i32* [[C0:%[^ ]*]])
> +define i1 @baz(i32* %p) {
> +  ; CHECK: [[T0:%[^ ]*]] = bitcast i32* [[C0]] to i8*
> +  %pi8 = bitcast i32* %p to i8*
> +  ; CHECK: [[T1:%[^ ]*]] = ptrtoint i8* [[T0]] to i32
> +  ; CHECK: [[T2:%[^ ]*]] = sub i32 [[T1]], ptrtoint ({ i32, [63 x i32], i32, [2 x i32] }* [[G]] to i32)
> +  ; CHECK: [[T3:%[^ ]*]] = lshr i32 [[T2]], 8
> +  ; CHECK: [[T4:%[^ ]*]] = shl i32 [[T2]], 24
> +  ; CHECK: [[T5:%[^ ]*]] = or i32 [[T3]], [[T4]]
> +  ; CHECK: [[T6:%[^ ]*]] = icmp ult i32 [[T5]], 2
> +  ; CHECK: br i1 [[T6]]
> +
> +  ; CHECK: [[T8:%[^ ]*]] = and i32 [[T5]], 31
> +  ; CHECK: [[T9:%[^ ]*]] = shl i32 1, [[T8]]
> +  ; CHECK: [[T10:%[^ ]*]] = and i32 3, [[T9]]
> +  ; CHECK: [[T11:%[^ ]*]] = icmp ne i32 [[T10]], 0
> +
> +  ; CHECK: [[T16:%[^ ]*]] = phi i1 [ false, {{%[^ ]*}} ], [ [[T11]], {{%[^ ]*}} ]
> +  %x = call i1 @llvm.bitset.test(i8* %pi8, metadata !"bitset3")
> +  ; CHECK: ret i1 [[T16]]
> +  ret i1 %x
> +}
> +
> +; CHECK-NOT: !llvm.bitsets
>
> Added: llvm/trunk/test/Transforms/LowerBitSets/single-offset.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LowerBitSets/single-offset.ll?rev=230054&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/LowerBitSets/single-offset.ll (added)
> +++ llvm/trunk/test/Transforms/LowerBitSets/single-offset.ll Fri Feb 20 14:30:47 2015
> @@ -0,0 +1,40 @@
> +; RUN: opt -S -lowerbitsets < %s | FileCheck %s
> +
> +target datalayout = "e-p:32:32"
> +
> +; CHECK: [[G:@[^ ]*]] = private constant { i32, i32 }
> + at a = constant i32 1
> + at b = constant i32 2
> +
> +!0 = !{!"bitset1", i32* @a, i32 0}
> +!1 = !{!"bitset1", i32* @b, i32 0}
> +!2 = !{!"bitset2", i32* @a, i32 0}
> +!3 = !{!"bitset3", i32* @b, i32 0}
> +
> +!llvm.bitsets = !{ !0, !1, !2, !3 }
> +
> +declare i1 @llvm.bitset.test(i8* %ptr, metadata %bitset) nounwind readnone
> +
> +; CHECK: @foo(i8* [[A0:%[^ ]*]])
> +define i1 @foo(i8* %p) {
> +  ; CHECK: [[R0:%[^ ]*]] = ptrtoint i8* [[A0]] to i32
> +  ; CHECK: [[R1:%[^ ]*]] = icmp eq i32 [[R0]], ptrtoint ({ i32, i32 }* [[G]] to i32)
> +  %x = call i1 @llvm.bitset.test(i8* %p, metadata !"bitset2")
> +  ; CHECK: ret i1 [[R1]]
> +  ret i1 %x
> +}
> +
> +; CHECK: @bar(i8* [[B0:%[^ ]*]])
> +define i1 @bar(i8* %p) {
> +  ; CHECK: [[S0:%[^ ]*]] = ptrtoint i8* [[B0]] to i32
> +  ; CHECK: [[S1:%[^ ]*]] = icmp eq i32 [[S0]], add (i32 ptrtoint ({ i32, i32 }* [[G]] to i32), i32 4)
> +  %x = call i1 @llvm.bitset.test(i8* %p, metadata !"bitset3")
> +  ; CHECK: ret i1 [[S1]]
> +  ret i1 %x
> +}
> +
> +; CHECK: @x(
> +define i1 @x(i8* %p) {
> +  %x = call i1 @llvm.bitset.test(i8* %p, metadata !"bitset1")
> +  ret i1 %x
> +}
>
> Modified: llvm/trunk/unittests/Transforms/CMakeLists.txt
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Transforms/CMakeLists.txt?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/unittests/Transforms/CMakeLists.txt (original)
> +++ llvm/trunk/unittests/Transforms/CMakeLists.txt Fri Feb 20 14:30:47 2015
> @@ -1 +1,2 @@
> +add_subdirectory(IPO)
>  add_subdirectory(Utils)
>
> Added: llvm/trunk/unittests/Transforms/IPO/CMakeLists.txt
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Transforms/IPO/CMakeLists.txt?rev=230054&view=auto
> ==============================================================================
> --- llvm/trunk/unittests/Transforms/IPO/CMakeLists.txt (added)
> +++ llvm/trunk/unittests/Transforms/IPO/CMakeLists.txt Fri Feb 20 14:30:47 2015
> @@ -0,0 +1,9 @@
> +set(LLVM_LINK_COMPONENTS
> +  Core
> +  Support
> +  IPO
> +  )
> +
> +add_llvm_unittest(IPOTests
> +  LowerBitSets.cpp
> +  )
>
> Added: llvm/trunk/unittests/Transforms/IPO/LowerBitSets.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Transforms/IPO/LowerBitSets.cpp?rev=230054&view=auto
> ==============================================================================
> --- llvm/trunk/unittests/Transforms/IPO/LowerBitSets.cpp (added)
> +++ llvm/trunk/unittests/Transforms/IPO/LowerBitSets.cpp Fri Feb 20 14:30:47 2015
> @@ -0,0 +1,64 @@
> +//===- LowerBitSets.cpp - Unit tests for bitset lowering ------------------===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
> +//===----------------------------------------------------------------------===//
> +
> +#include "llvm/Transforms/IPO/LowerBitSets.h"
> +#include "gtest/gtest.h"
> +
> +using namespace llvm;
> +
> +TEST(LowerBitSets, BitSetBuilder) {
> +  struct {
> +    std::vector<uint64_t> Offsets;
> +    std::vector<uint8_t> Bits;
> +    uint64_t ByteOffset;
> +    uint64_t BitSize;
> +    unsigned AlignLog2;
> +    bool IsSingleOffset;
> +  } BSBTests[] = {
> +      {{}, {0}, 0, 1, 0, false},
> +      {{0}, {1}, 0, 1, 0, true},
> +      {{4}, {1}, 4, 1, 0, true},
> +      {{37}, {1}, 37, 1, 0, true},
> +      {{0, 1}, {3}, 0, 2, 0, false},
> +      {{0, 4}, {3}, 0, 2, 2, false},
> +      {{0, uint64_t(1) << 33}, {3}, 0, 2, 33, false},
> +      {{3, 7}, {3}, 3, 2, 2, false},
> +      {{0, 1, 7}, {131}, 0, 8, 0, false},
> +      {{0, 2, 14}, {131}, 0, 8, 1, false},
> +      {{0, 1, 8}, {3, 1}, 0, 9, 0, false},
> +      {{0, 2, 16}, {3, 1}, 0, 9, 1, false},
> +  };
> +
> +  for (auto &&T : BSBTests) {
> +    BitSetBuilder BSB;
> +    for (auto Offset : T.Offsets)
> +      BSB.addOffset(Offset);
> +
> +    BitSetInfo BSI = BSB.build();
> +
> +    EXPECT_EQ(T.Bits, BSI.Bits);
> +    EXPECT_EQ(T.ByteOffset, BSI.ByteOffset);
> +    EXPECT_EQ(T.BitSize, BSI.BitSize);
> +    EXPECT_EQ(T.AlignLog2, BSI.AlignLog2);
> +    EXPECT_EQ(T.IsSingleOffset, BSI.isSingleOffset());
> +
> +    for (auto Offset : T.Offsets)
> +      EXPECT_TRUE(BSI.containsGlobalOffset(Offset));
> +
> +    auto I = T.Offsets.begin();
> +    for (uint64_t NonOffset = 0; NonOffset != 256; ++NonOffset) {
> +      if (I != T.Offsets.end() && *I == NonOffset) {
> +        ++I;
> +        continue;
> +      }
> +
> +      EXPECT_FALSE(BSI.containsGlobalOffset(NonOffset));
> +    }
> +  }
> +}
>
> Copied: llvm/trunk/unittests/Transforms/IPO/Makefile (from r230053, llvm/trunk/unittests/Transforms/Makefile)
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Transforms/IPO/Makefile?p2=llvm/trunk/unittests/Transforms/IPO/Makefile&p1=llvm/trunk/unittests/Transforms/Makefile&r1=230053&r2=230054&rev=230054&view=diff
> ==============================================================================
> --- llvm/trunk/unittests/Transforms/Makefile (original)
> +++ llvm/trunk/unittests/Transforms/IPO/Makefile Fri Feb 20 14:30:47 2015
> @@ -1,4 +1,4 @@
> -##===- unittests/Transforms/Makefile -----------------------*- Makefile -*-===##
> +##===- unittests/Transforms/IPO/Makefile -------------------*- Makefile -*-===##
>  #
>  #                     The LLVM Compiler Infrastructure
>  #
> @@ -7,11 +7,9 @@
>  #
>  ##===----------------------------------------------------------------------===##
>
> -LEVEL = ../..
> +LEVEL = ../../..
> +TESTNAME = IPO
> +LINK_COMPONENTS := IPO
>
> -PARALLEL_DIRS = Utils
> -
> -include $(LEVEL)/Makefile.common
> -
> -clean::
> -       $(Verb) $(RM) -f *Tests
> +include $(LEVEL)/Makefile.config
> +include $(LLVM_SRC_ROOT)/unittests/Makefile.unittest
>
> Modified: llvm/trunk/unittests/Transforms/Makefile
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Transforms/Makefile?rev=230054&r1=230053&r2=230054&view=diff
> ==============================================================================
> --- llvm/trunk/unittests/Transforms/Makefile (original)
> +++ llvm/trunk/unittests/Transforms/Makefile Fri Feb 20 14:30:47 2015
> @@ -9,7 +9,7 @@
>
>  LEVEL = ../..
>
> -PARALLEL_DIRS = Utils
> +PARALLEL_DIRS = IPO Utils
>
>  include $(LEVEL)/Makefile.common
>
>
>
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