[llvm] r260312 - WholeProgramDevirt: introduce.

Sean Silva via llvm-commits llvm-commits at lists.llvm.org
Mon Feb 15 21:39:16 PST 2016


Does clang need to be passed a special flag for it to emit the bitset
information this uses?

-- Sean Silva

On Tue, Feb 9, 2016 at 2:50 PM, Peter Collingbourne via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: pcc
> Date: Tue Feb  9 16:50:34 2016
> New Revision: 260312
>
> URL: http://llvm.org/viewvc/llvm-project?rev=260312&view=rev
> Log:
> WholeProgramDevirt: introduce.
>
> This pass implements whole program optimization of virtual calls in cases
> where we know (via bitset information) that the list of callees is fixed.
> This
> includes the following:
>
> - Single implementation devirtualization: if a virtual call has a single
>   possible callee, replace all calls with a direct call to that callee.
>
> - Virtual constant propagation: if the virtual function's return type is an
>   integer <=64 bits and all possible callees are readnone, for each class
> and
>   each list of constant arguments: evaluate the function, store the return
>   value alongside the virtual table, and rewrite each virtual call as a
> load
>   from the virtual table.
>
> - Uniform return value optimization: if the conditions for virtual constant
>   propagation hold and each function returns the same constant value,
> replace
>   each virtual call with that constant.
>
> - Unique return value optimization for i1 return values: if the conditions
>   for virtual constant propagation hold and a single vtable's function
>   returns 0, or a single vtable's function returns 1, replace each virtual
>   call with a comparison of the vptr against that vtable's address.
>
> Differential Revision: http://reviews.llvm.org/D16795
>
> Added:
>     llvm/trunk/include/llvm/Transforms/IPO/WholeProgramDevirt.h
>     llvm/trunk/lib/Transforms/IPO/WholeProgramDevirt.cpp
>     llvm/trunk/test/Transforms/WholeProgramDevirt/
>     llvm/trunk/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/constant-arg.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/devirt-single-impl.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/non-array-vtable.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/uniform-retval-invoke.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/uniform-retval.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/unique-retval.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-accesses-memory.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-no-this.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-non-constant-arg.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-too-wide-ints.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-type-mismatch.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-uses-this.ll
>
> llvm/trunk/test/Transforms/WholeProgramDevirt/virtual-const-prop-begin.ll
>     llvm/trunk/test/Transforms/WholeProgramDevirt/virtual-const-prop-end.ll
>     llvm/trunk/unittests/Transforms/IPO/WholeProgramDevirt.cpp
> Modified:
>     llvm/trunk/include/llvm/InitializePasses.h
>     llvm/trunk/include/llvm/Transforms/IPO.h
>     llvm/trunk/include/llvm/Transforms/IPO/PassManagerBuilder.h
>     llvm/trunk/lib/Transforms/IPO/CMakeLists.txt
>     llvm/trunk/lib/Transforms/IPO/IPO.cpp
>     llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
>     llvm/trunk/test/tools/gold/X86/disable-verify.ll
>     llvm/trunk/unittests/Transforms/IPO/CMakeLists.txt
>
> Modified: llvm/trunk/include/llvm/InitializePasses.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/InitializePasses.h?rev=260312&r1=260311&r2=260312&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/InitializePasses.h (original)
> +++ llvm/trunk/include/llvm/InitializePasses.h Tue Feb  9 16:50:34 2016
> @@ -316,6 +316,7 @@ void initializeFuncletLayoutPass(PassReg
>  void initializeLoopLoadEliminationPass(PassRegistry&);
>  void initializeFunctionImportPassPass(PassRegistry &);
>  void initializeLoopVersioningPassPass(PassRegistry &);
> +void initializeWholeProgramDevirtPass(PassRegistry &);
>  }
>
>  #endif
>
> Modified: llvm/trunk/include/llvm/Transforms/IPO.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/IPO.h?rev=260312&r1=260311&r2=260312&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/IPO.h (original)
> +++ llvm/trunk/include/llvm/Transforms/IPO.h Tue Feb  9 16:50:34 2016
> @@ -226,6 +226,10 @@ ModulePass *createLowerBitSetsPass();
>  /// \brief This pass export CFI checks for use by external modules.
>  ModulePass *createCrossDSOCFIPass();
>
> +/// \brief This pass implements whole-program devirtualization using
> bitset
> +/// metadata.
> +ModulePass *createWholeProgramDevirtPass();
> +
>
>  //===----------------------------------------------------------------------===//
>  // SampleProfilePass - Loads sample profile data from disk and generates
>  // IR metadata to reflect the profile.
>
> Modified: llvm/trunk/include/llvm/Transforms/IPO/PassManagerBuilder.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/IPO/PassManagerBuilder.h?rev=260312&r1=260311&r2=260312&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/IPO/PassManagerBuilder.h (original)
> +++ llvm/trunk/include/llvm/Transforms/IPO/PassManagerBuilder.h Tue Feb  9
> 16:50:34 2016
> @@ -157,6 +157,7 @@ private:
>                           legacy::PassManagerBase &PM) const;
>    void addInitialAliasAnalysisPasses(legacy::PassManagerBase &PM) const;
>    void addLTOOptimizationPasses(legacy::PassManagerBase &PM);
> +  void addEarlyLTOOptimizationPasses(legacy::PassManagerBase &PM);
>    void addLateLTOOptimizationPasses(legacy::PassManagerBase &PM);
>    void addPGOInstrPasses(legacy::PassManagerBase &MPM);
>
>
> Added: llvm/trunk/include/llvm/Transforms/IPO/WholeProgramDevirt.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/IPO/WholeProgramDevirt.h?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/IPO/WholeProgramDevirt.h (added)
> +++ llvm/trunk/include/llvm/Transforms/IPO/WholeProgramDevirt.h Tue Feb  9
> 16:50:34 2016
> @@ -0,0 +1,215 @@
> +//===- WholeProgramDevirt.h - Whole-program devirt 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 whole-program devirtualization pass
> +// implementation that may be usefully unit tested.
> +//
>
> +//===----------------------------------------------------------------------===//
> +
> +#ifndef LLVM_TRANSFORMS_IPO_WHOLEPROGRAMDEVIRT_H
> +#define LLVM_TRANSFORMS_IPO_WHOLEPROGRAMDEVIRT_H
> +
> +#include "llvm/ADT/ArrayRef.h"
> +#include "llvm/ADT/DenseMapInfo.h"
> +#include <utility>
> +#include <vector>
> +#include <assert.h>
> +#include <stdint.h>
> +
> +namespace llvm {
> +
> +class Function;
> +class GlobalVariable;
> +
> +namespace wholeprogramdevirt {
> +
> +// A bit vector that keeps track of which bits are used. We use this to
> +// pack constant values compactly before and after each virtual table.
> +struct AccumBitVector {
> +  std::vector<uint8_t> Bytes;
> +
> +  // Bits in BytesUsed[I] are 1 if matching bit in Bytes[I] is used, 0 if
> not.
> +  std::vector<uint8_t> BytesUsed;
> +
> +  std::pair<uint8_t *, uint8_t *> getPtrToData(uint64_t Pos, uint8_t
> Size) {
> +    if (Bytes.size() < Pos + Size) {
> +      Bytes.resize(Pos + Size);
> +      BytesUsed.resize(Pos + Size);
> +    }
> +    return std::make_pair(Bytes.data() + Pos, BytesUsed.data() + Pos);
> +  }
> +
> +  // Set little-endian value Val with size Size at bit position Pos,
> +  // and mark bytes as used.
> +  void setLE(uint64_t Pos, uint64_t Val, uint8_t Size) {
> +    assert(Pos % 8 == 0);
> +    auto DataUsed = getPtrToData(Pos / 8, Size);
> +    for (unsigned I = 0; I != Size; ++I) {
> +      DataUsed.first[I] = Val >> (I * 8);
> +      assert(!DataUsed.second[I]);
> +      DataUsed.second[I] = 0xff;
> +    }
> +  }
> +
> +  // Set big-endian value Val with size Size at bit position Pos,
> +  // and mark bytes as used.
> +  void setBE(uint64_t Pos, uint64_t Val, uint8_t Size) {
> +    assert(Pos % 8 == 0);
> +    auto DataUsed = getPtrToData(Pos / 8, Size);
> +    for (unsigned I = 0; I != Size; ++I) {
> +      DataUsed.first[Size - I - 1] = Val >> (I * 8);
> +      assert(!DataUsed.second[Size - I - 1]);
> +      DataUsed.second[Size - I - 1] = 0xff;
> +    }
> +  }
> +
> +  // Set bit at bit position Pos to b and mark bit as used.
> +  void setBit(uint64_t Pos, bool b) {
> +    auto DataUsed = getPtrToData(Pos / 8, 1);
> +    if (b)
> +      *DataUsed.first |= 1 << (Pos % 8);
> +    assert(!(*DataUsed.second & (1 << Pos % 8)));
> +    *DataUsed.second |= 1 << (Pos % 8);
> +  }
> +};
> +
> +// The bits that will be stored before and after a particular vtable.
> +struct VTableBits {
> +  // The vtable global.
> +  GlobalVariable *GV;
> +
> +  // Cache of the vtable's size in bytes.
> +  uint64_t ObjectSize = 0;
> +
> +  // The bit vector that will be laid out before the vtable. Note that
> these
> +  // bytes are stored in reverse order until the globals are rebuilt.
> This means
> +  // that any values in the array must be stored using the opposite
> endianness
> +  // from the target.
> +  AccumBitVector Before;
> +
> +  // The bit vector that will be laid out after the vtable.
> +  AccumBitVector After;
> +};
> +
> +// Information about an entry in a particular bitset.
> +struct BitSetInfo {
> +  // The VTableBits for the vtable.
> +  VTableBits *Bits;
> +
> +  // The offset in bytes from the start of the vtable (i.e. the address
> point).
> +  uint64_t Offset;
> +
> +  bool operator<(const BitSetInfo &other) const {
> +    return Bits < other.Bits || (Bits == other.Bits && Offset <
> other.Offset);
> +  }
> +};
> +
> +// A virtual call target, i.e. an entry in a particular vtable.
> +struct VirtualCallTarget {
> +  VirtualCallTarget(Function *Fn, const BitSetInfo *BS);
> +
> +  // For testing only.
> +  VirtualCallTarget(const BitSetInfo *BS, bool IsBigEndian)
> +      : Fn(nullptr), BS(BS), IsBigEndian(IsBigEndian) {}
> +
> +  // The function stored in the vtable.
> +  Function *Fn;
> +
> +  // A pointer to the bitset through which the pointer to Fn is accessed.
> +  const BitSetInfo *BS;
> +
> +  // When doing virtual constant propagation, this stores the return
> value for
> +  // the function when passed the currently considered argument list.
> +  uint64_t RetVal;
> +
> +  // Whether the target is big endian.
> +  bool IsBigEndian;
> +
> +  // The minimum byte offset before the address point. This covers the
> bytes in
> +  // the vtable object before the address point (e.g. RTTI, access-to-top,
> +  // vtables for other base classes) and is equal to the offset from the
> start
> +  // of the vtable object to the address point.
> +  uint64_t minBeforeBytes() const { return BS->Offset; }
> +
> +  // The minimum byte offset after the address point. This covers the
> bytes in
> +  // the vtable object after the address point (e.g. the vtable for the
> current
> +  // class and any later base classes) and is equal to the size of the
> vtable
> +  // object minus the offset from the start of the vtable object to the
> address
> +  // point.
> +  uint64_t minAfterBytes() const { return BS->Bits->ObjectSize -
> BS->Offset; }
> +
> +  // The number of bytes allocated (for the vtable plus the byte array)
> before
> +  // the address point.
> +  uint64_t allocatedBeforeBytes() const {
> +    return minBeforeBytes() + BS->Bits->Before.Bytes.size();
> +  }
> +
> +  // The number of bytes allocated (for the vtable plus the byte array)
> after
> +  // the address point.
> +  uint64_t allocatedAfterBytes() const {
> +    return minAfterBytes() + BS->Bits->After.Bytes.size();
> +  }
> +
> +  // Set the bit at position Pos before the address point to RetVal.
> +  void setBeforeBit(uint64_t Pos) {
> +    assert(Pos >= 8 * minBeforeBytes());
> +    BS->Bits->Before.setBit(Pos - 8 * minBeforeBytes(), RetVal);
> +  }
> +
> +  // Set the bit at position Pos after the address point to RetVal.
> +  void setAfterBit(uint64_t Pos) {
> +    assert(Pos >= 8 * minAfterBytes());
> +    BS->Bits->After.setBit(Pos - 8 * minAfterBytes(), RetVal);
> +  }
> +
> +  // Set the bytes at position Pos before the address point to RetVal.
> +  // Because the bytes in Before are stored in reverse order, we use the
> +  // opposite endianness to the target.
> +  void setBeforeBytes(uint64_t Pos, uint8_t Size) {
> +    assert(Pos >= 8 * minBeforeBytes());
> +    if (IsBigEndian)
> +      BS->Bits->Before.setLE(Pos - 8 * minBeforeBytes(), RetVal, Size);
> +    else
> +      BS->Bits->Before.setBE(Pos - 8 * minBeforeBytes(), RetVal, Size);
> +  }
> +
> +  // Set the bytes at position Pos after the address point to RetVal.
> +  void setAfterBytes(uint64_t Pos, uint8_t Size) {
> +    assert(Pos >= 8 * minAfterBytes());
> +    if (IsBigEndian)
> +      BS->Bits->After.setBE(Pos - 8 * minAfterBytes(), RetVal, Size);
> +    else
> +      BS->Bits->After.setLE(Pos - 8 * minAfterBytes(), RetVal, Size);
> +  }
> +};
> +
> +// Find the minimum offset that we may store a value of size Size bits
> at. If
> +// IsAfter is set, look for an offset before the object, otherwise look
> for an
> +// offset after the object.
> +uint64_t findLowestOffset(ArrayRef<VirtualCallTarget> Targets, bool
> IsAfter,
> +                          uint64_t Size);
> +
> +// Set the stored value in each of Targets to VirtualCallTarget::RetVal
> at the
> +// given allocation offset before the vtable address. Stores the computed
> +// byte/bit offset to OffsetByte/OffsetBit.
> +void setBeforeReturnValues(MutableArrayRef<VirtualCallTarget> Targets,
> +                           uint64_t AllocBefore, unsigned BitWidth,
> +                           int64_t &OffsetByte, uint64_t &OffsetBit);
> +
> +// Set the stored value in each of Targets to VirtualCallTarget::RetVal
> at the
> +// given allocation offset after the vtable address. Stores the computed
> +// byte/bit offset to OffsetByte/OffsetBit.
> +void setAfterReturnValues(MutableArrayRef<VirtualCallTarget> Targets,
> +                          uint64_t AllocAfter, unsigned BitWidth,
> +                          int64_t &OffsetByte, uint64_t &OffsetBit);
> +
> +}
> +}
> +
> +#endif
>
> Modified: llvm/trunk/lib/Transforms/IPO/CMakeLists.txt
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/CMakeLists.txt?rev=260312&r1=260311&r2=260312&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/CMakeLists.txt (original)
> +++ llvm/trunk/lib/Transforms/IPO/CMakeLists.txt Tue Feb  9 16:50:34 2016
> @@ -27,6 +27,7 @@ add_llvm_library(LLVMipo
>    SampleProfile.cpp
>    StripDeadPrototypes.cpp
>    StripSymbols.cpp
> +  WholeProgramDevirt.cpp
>
>    ADDITIONAL_HEADER_DIRS
>    ${LLVM_MAIN_INCLUDE_DIR}/llvm/Transforms
>
> Modified: llvm/trunk/lib/Transforms/IPO/IPO.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/IPO.cpp?rev=260312&r1=260311&r2=260312&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/IPO.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/IPO.cpp Tue Feb  9 16:50:34 2016
> @@ -53,6 +53,7 @@ void llvm::initializeIPO(PassRegistry &R
>    initializeEliminateAvailableExternallyPass(Registry);
>    initializeSampleProfileLoaderPass(Registry);
>    initializeFunctionImportPassPass(Registry);
> +  initializeWholeProgramDevirtPass(Registry);
>  }
>
>  void LLVMInitializeIPO(LLVMPassRegistryRef R) {
>
> Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=260312&r1=260311&r2=260312&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Tue Feb  9
> 16:50:34 2016
> @@ -651,6 +651,16 @@ void PassManagerBuilder::addLTOOptimizat
>    PM.add(createJumpThreadingPass());
>  }
>
> +void PassManagerBuilder::addEarlyLTOOptimizationPasses(
> +    legacy::PassManagerBase &PM) {
> +  // Remove unused virtual tables to improve the quality of code
> generated by
> +  // whole-program devirtualization and bitset lowering.
> +  PM.add(createGlobalDCEPass());
> +
> +  // Apply whole-program devirtualization and virtual constant
> propagation.
> +  PM.add(createWholeProgramDevirtPass());
> +}
> +
>  void PassManagerBuilder::addLateLTOOptimizationPasses(
>      legacy::PassManagerBase &PM) {
>    // Delete basic blocks, which optimization passes may have killed.
> @@ -675,6 +685,9 @@ void PassManagerBuilder::populateLTOPass
>    if (VerifyInput)
>      PM.add(createVerifierPass());
>
> +  if (OptLevel != 0)
> +    addEarlyLTOOptimizationPasses(PM);
> +
>    if (OptLevel > 1)
>      addLTOOptimizationPasses(PM);
>
>
> Added: llvm/trunk/lib/Transforms/IPO/WholeProgramDevirt.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/WholeProgramDevirt.cpp?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/WholeProgramDevirt.cpp (added)
> +++ llvm/trunk/lib/Transforms/IPO/WholeProgramDevirt.cpp Tue Feb  9
> 16:50:34 2016
> @@ -0,0 +1,724 @@
> +//===- WholeProgramDevirt.cpp - Whole program virtual call optimization
> ---===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
>
> +//===----------------------------------------------------------------------===//
> +//
> +// This pass implements whole program optimization of virtual calls in
> cases
> +// where we know (via bitset information) that the list of callee is
> fixed. This
> +// includes the following:
> +// - Single implementation devirtualization: if a virtual call has a
> single
> +//   possible callee, replace all calls with a direct call to that callee.
> +// - Virtual constant propagation: if the virtual function's return type
> is an
> +//   integer <=64 bits and all possible callees are readnone, for each
> class and
> +//   each list of constant arguments: evaluate the function, store the
> return
> +//   value alongside the virtual table, and rewrite each virtual call as
> a load
> +//   from the virtual table.
> +// - Uniform return value optimization: if the conditions for virtual
> constant
> +//   propagation hold and each function returns the same constant value,
> replace
> +//   each virtual call with that constant.
> +// - Unique return value optimization for i1 return values: if the
> conditions
> +//   for virtual constant propagation hold and a single vtable's function
> +//   returns 0, or a single vtable's function returns 1, replace each
> virtual
> +//   call with a comparison of the vptr against that vtable's address.
> +//
>
> +//===----------------------------------------------------------------------===//
> +
> +#include "llvm/Transforms/IPO/WholeProgramDevirt.h"
> +#include "llvm/Transforms/IPO.h"
> +#include "llvm/ADT/DenseSet.h"
> +#include "llvm/ADT/MapVector.h"
> +#include "llvm/IR/CallSite.h"
> +#include "llvm/IR/Constants.h"
> +#include "llvm/IR/DataLayout.h"
> +#include "llvm/IR/IRBuilder.h"
> +#include "llvm/IR/Instructions.h"
> +#include "llvm/IR/Intrinsics.h"
> +#include "llvm/IR/Module.h"
> +#include "llvm/Pass.h"
> +#include "llvm/Support/raw_ostream.h"
> +#include "llvm/Transforms/Utils/Evaluator.h"
> +#include "llvm/Transforms/Utils/Local.h"
> +
> +#include <set>
> +
> +using namespace llvm;
> +using namespace wholeprogramdevirt;
> +
> +#define DEBUG_TYPE "wholeprogramdevirt"
> +
> +// Find the minimum offset that we may store a value of size Size bits
> at. If
> +// IsAfter is set, look for an offset before the object, otherwise look
> for an
> +// offset after the object.
> +uint64_t
> +wholeprogramdevirt::findLowestOffset(ArrayRef<VirtualCallTarget> Targets,
> +                                     bool IsAfter, uint64_t Size) {
> +  // Find a minimum offset taking into account only vtable sizes.
> +  uint64_t MinByte = 0;
> +  for (const VirtualCallTarget &Target : Targets) {
> +    if (IsAfter)
> +      MinByte = std::max(MinByte, Target.minAfterBytes());
> +    else
> +      MinByte = std::max(MinByte, Target.minBeforeBytes());
> +  }
> +
> +  // Build a vector of arrays of bytes covering, for each target, a slice
> of the
> +  // used region (see AccumBitVector::BytesUsed in
> +  // llvm/Transforms/IPO/WholeProgramDevirt.h) starting at MinByte.
> Effectively,
> +  // this aligns the used regions to start at MinByte.
> +  //
> +  // In this example, A, B and C are vtables, # is a byte already
> allocated for
> +  // a virtual function pointer, AAAA... (etc.) are the used regions for
> the
> +  // vtables and Offset(X) is the value computed for the Offset variable
> below
> +  // for X.
> +  //
> +  //                    Offset(A)
> +  //                    |       |
> +  //                            |MinByte
> +  // A: ################AAAAAAAA|AAAAAAAA
> +  // B: ########BBBBBBBBBBBBBBBB|BBBB
> +  // C: ########################|CCCCCCCCCCCCCCCC
> +  //            |   Offset(B)   |
> +  //
> +  // This code produces the slices of A, B and C that appear after the
> divider
> +  // at MinByte.
> +  std::vector<ArrayRef<uint8_t>> Used;
> +  for (const VirtualCallTarget &Target : Targets) {
> +    ArrayRef<uint8_t> VTUsed = IsAfter ? Target.BS->Bits->After.BytesUsed
> +                                       :
> Target.BS->Bits->Before.BytesUsed;
> +    uint64_t Offset = IsAfter ? MinByte - Target.minAfterBytes()
> +                              : MinByte - Target.minBeforeBytes();
> +
> +    // Disregard used regions that are smaller than Offset. These are
> +    // effectively all-free regions that do not need to be checked.
> +    if (VTUsed.size() > Offset)
> +      Used.push_back(VTUsed.slice(Offset));
> +  }
> +
> +  if (Size == 1) {
> +    // Find a free bit in each member of Used.
> +    for (unsigned I = 0;; ++I) {
> +      uint8_t BitsUsed = 0;
> +      for (auto &&B : Used)
> +        if (I < B.size())
> +          BitsUsed |= B[I];
> +      if (BitsUsed != 0xff)
> +        return (MinByte + I) * 8 +
> +               countTrailingZeros(uint8_t(~BitsUsed), ZB_Undefined);
> +    }
> +  } else {
> +    // Find a free (Size/8) byte region in each member of Used.
> +    // FIXME: see if alignment helps.
> +    for (unsigned I = 0;; ++I) {
> +      for (auto &&B : Used) {
> +        unsigned Byte = 0;
> +        while ((I + Byte) < B.size() && Byte < (Size / 8)) {
> +          if (B[I + Byte])
> +            goto NextI;
> +          ++Byte;
> +        }
> +      }
> +      return (MinByte + I) * 8;
> +    NextI:;
> +    }
> +  }
> +}
> +
> +void wholeprogramdevirt::setBeforeReturnValues(
> +    MutableArrayRef<VirtualCallTarget> Targets, uint64_t AllocBefore,
> +    unsigned BitWidth, int64_t &OffsetByte, uint64_t &OffsetBit) {
> +  if (BitWidth == 1)
> +    OffsetByte = -(AllocBefore / 8 + 1);
> +  else
> +    OffsetByte = -((AllocBefore + 7) / 8 + (BitWidth + 7) / 8);
> +  OffsetBit = AllocBefore % 8;
> +
> +  for (VirtualCallTarget &Target : Targets) {
> +    if (BitWidth == 1)
> +      Target.setBeforeBit(AllocBefore);
> +    else
> +      Target.setBeforeBytes(AllocBefore, (BitWidth + 7) / 8);
> +  }
> +}
> +
> +void wholeprogramdevirt::setAfterReturnValues(
> +    MutableArrayRef<VirtualCallTarget> Targets, uint64_t AllocAfter,
> +    unsigned BitWidth, int64_t &OffsetByte, uint64_t &OffsetBit) {
> +  if (BitWidth == 1)
> +    OffsetByte = AllocAfter / 8;
> +  else
> +    OffsetByte = (AllocAfter + 7) / 8;
> +  OffsetBit = AllocAfter % 8;
> +
> +  for (VirtualCallTarget &Target : Targets) {
> +    if (BitWidth == 1)
> +      Target.setAfterBit(AllocAfter);
> +    else
> +      Target.setAfterBytes(AllocAfter, (BitWidth + 7) / 8);
> +  }
> +}
> +
> +VirtualCallTarget::VirtualCallTarget(Function *Fn, const BitSetInfo *BS)
> +    : Fn(Fn), BS(BS),
> +      IsBigEndian(Fn->getParent()->getDataLayout().isBigEndian()) {}
> +
> +namespace {
> +
> +// A slot in a set of virtual tables. The BitSetID identifies the set of
> virtual
> +// tables, and the ByteOffset is the offset in bytes from the address
> point to
> +// the virtual function pointer.
> +struct VTableSlot {
> +  Metadata *BitSetID;
> +  uint64_t ByteOffset;
> +};
> +
> +}
> +
> +template <> struct DenseMapInfo<VTableSlot> {
> +  static VTableSlot getEmptyKey() {
> +    return {DenseMapInfo<Metadata *>::getEmptyKey(),
> +            DenseMapInfo<uint64_t>::getEmptyKey()};
> +  }
> +  static VTableSlot getTombstoneKey() {
> +    return {DenseMapInfo<Metadata *>::getTombstoneKey(),
> +            DenseMapInfo<uint64_t>::getTombstoneKey()};
> +  }
> +  static unsigned getHashValue(const VTableSlot &I) {
> +    return DenseMapInfo<Metadata *>::getHashValue(I.BitSetID) ^
> +           DenseMapInfo<uint64_t>::getHashValue(I.ByteOffset);
> +  }
> +  static bool isEqual(const VTableSlot &LHS,
> +                      const VTableSlot &RHS) {
> +    return LHS.BitSetID == RHS.BitSetID && LHS.ByteOffset ==
> RHS.ByteOffset;
> +  }
> +};
> +
> +namespace {
> +
> +// A virtual call site. VTable is the loaded virtual table pointer, and
> CS is
> +// the indirect virtual call.
> +struct VirtualCallSite {
> +  Value *VTable;
> +  CallSite CS;
> +
> +  void replaceAndErase(Value *New) {
> +    CS->replaceAllUsesWith(New);
> +    if (auto II = dyn_cast<InvokeInst>(CS.getInstruction())) {
> +      BranchInst::Create(II->getNormalDest(), CS.getInstruction());
> +      II->getUnwindDest()->removePredecessor(II->getParent());
> +    }
> +    CS->eraseFromParent();
> +  }
> +};
> +
> +struct DevirtModule {
> +  Module &M;
> +  IntegerType *Int8Ty;
> +  PointerType *Int8PtrTy;
> +  IntegerType *Int32Ty;
> +
> +  MapVector<VTableSlot, std::vector<VirtualCallSite>> CallSlots;
> +
> +  DevirtModule(Module &M)
> +      : M(M), Int8Ty(Type::getInt8Ty(M.getContext())),
> +        Int8PtrTy(Type::getInt8PtrTy(M.getContext())),
> +        Int32Ty(Type::getInt32Ty(M.getContext())) {}
> +  void findLoadCallsAtConstantOffset(Metadata *BitSet, Value *Ptr,
> +                                     uint64_t Offset, Value *VTable);
> +  void findCallsAtConstantOffset(Metadata *BitSet, Value *Ptr, uint64_t
> Offset,
> +                                 Value *VTable);
> +
> +  void buildBitSets(std::vector<VTableBits> &Bits,
> +                    DenseMap<Metadata *, std::set<BitSetInfo>> &BitSets);
> +  bool tryFindVirtualCallTargets(std::vector<VirtualCallTarget>
> &TargetsForSlot,
> +                                 const std::set<BitSetInfo> &BitSetInfos,
> +                                 uint64_t ByteOffset);
> +  bool trySingleImplDevirt(ArrayRef<VirtualCallTarget> TargetsForSlot,
> +                           MutableArrayRef<VirtualCallSite> CallSites);
> +  bool tryEvaluateFunctionsWithArgs(
> +      MutableArrayRef<VirtualCallTarget> TargetsForSlot,
> +      ArrayRef<ConstantInt *> Args);
> +  bool tryUniformRetValOpt(IntegerType *RetType,
> +                           ArrayRef<VirtualCallTarget> TargetsForSlot,
> +                           MutableArrayRef<VirtualCallSite> CallSites);
> +  bool tryUniqueRetValOpt(unsigned BitWidth,
> +                          ArrayRef<VirtualCallTarget> TargetsForSlot,
> +                          MutableArrayRef<VirtualCallSite> CallSites);
> +  bool tryVirtualConstProp(MutableArrayRef<VirtualCallTarget>
> TargetsForSlot,
> +                           ArrayRef<VirtualCallSite> CallSites);
> +
> +  void rebuildGlobal(VTableBits &B);
> +
> +  bool run();
> +};
> +
> +struct WholeProgramDevirt : public ModulePass {
> +  static char ID;
> +  WholeProgramDevirt() : ModulePass(ID) {
> +    initializeWholeProgramDevirtPass(*PassRegistry::getPassRegistry());
> +  }
> +  bool runOnModule(Module &M) { return DevirtModule(M).run(); }
> +};
> +
> +} // anonymous namespace
> +
> +INITIALIZE_PASS(WholeProgramDevirt, "wholeprogramdevirt",
> +                "Whole program devirtualization", false, false)
> +char WholeProgramDevirt::ID = 0;
> +
> +ModulePass *llvm::createWholeProgramDevirtPass() {
> +  return new WholeProgramDevirt;
> +}
> +
> +// Search for virtual calls that call FPtr and add them to CallSlots.
> +void DevirtModule::findCallsAtConstantOffset(Metadata *BitSet, Value
> *FPtr,
> +                                             uint64_t Offset, Value
> *VTable) {
> +  for (const Use &U : FPtr->uses()) {
> +    Value *User = U.getUser();
> +    if (isa<BitCastInst>(User)) {
> +      findCallsAtConstantOffset(BitSet, User, Offset, VTable);
> +    } else if (auto CI = dyn_cast<CallInst>(User)) {
> +      CallSlots[{BitSet, Offset}].push_back({VTable, CI});
> +    } else if (auto II = dyn_cast<InvokeInst>(User)) {
> +      CallSlots[{BitSet, Offset}].push_back({VTable, II});
> +    }
> +  }
> +}
> +
> +// Search for virtual calls that load from VPtr and add them to CallSlots.
> +void DevirtModule::findLoadCallsAtConstantOffset(Metadata *BitSet, Value
> *VPtr,
> +                                                 uint64_t Offset,
> +                                                 Value *VTable) {
> +  for (const Use &U : VPtr->uses()) {
> +    Value *User = U.getUser();
> +    if (isa<BitCastInst>(User)) {
> +      findLoadCallsAtConstantOffset(BitSet, User, Offset, VTable);
> +    } else if (isa<LoadInst>(User)) {
> +      findCallsAtConstantOffset(BitSet, User, Offset, VTable);
> +    } else if (auto GEP = dyn_cast<GetElementPtrInst>(User)) {
> +      // Take into account the GEP offset.
> +      if (VPtr == GEP->getPointerOperand() &&
> GEP->hasAllConstantIndices()) {
> +        SmallVector<Value *, 8> Indices(GEP->op_begin() + 1,
> GEP->op_end());
> +        uint64_t GEPOffset = M.getDataLayout().getIndexedOffsetInType(
> +            GEP->getSourceElementType(), Indices);
> +        findLoadCallsAtConstantOffset(BitSet, User, Offset + GEPOffset,
> VTable);
> +      }
> +    }
> +  }
> +}
> +
> +void DevirtModule::buildBitSets(
> +    std::vector<VTableBits> &Bits,
> +    DenseMap<Metadata *, std::set<BitSetInfo>> &BitSets) {
> +  NamedMDNode *BitSetNM = M.getNamedMetadata("llvm.bitsets");
> +  if (!BitSetNM)
> +    return;
> +
> +  DenseMap<GlobalVariable *, VTableBits *> GVToBits;
> +  Bits.reserve(BitSetNM->getNumOperands());
> +  for (auto Op : BitSetNM->operands()) {
> +    auto OpConstMD =
> dyn_cast_or_null<ConstantAsMetadata>(Op->getOperand(1));
> +    if (!OpConstMD)
> +      continue;
> +    auto BitSetID = Op->getOperand(0).get();
> +
> +    Constant *OpConst = OpConstMD->getValue();
> +    if (auto GA = dyn_cast<GlobalAlias>(OpConst))
> +      OpConst = GA->getAliasee();
> +    auto OpGlobal = dyn_cast<GlobalVariable>(OpConst);
> +    if (!OpGlobal)
> +      continue;
> +
> +    uint64_t Offset =
> +        cast<ConstantInt>(
> +            cast<ConstantAsMetadata>(Op->getOperand(2))->getValue())
> +            ->getZExtValue();
> +
> +    VTableBits *&BitsPtr = GVToBits[OpGlobal];
> +    if (!BitsPtr) {
> +      Bits.emplace_back();
> +      Bits.back().GV = OpGlobal;
> +      Bits.back().ObjectSize = M.getDataLayout().getTypeAllocSize(
> +          OpGlobal->getInitializer()->getType());
> +      BitsPtr = &Bits.back();
> +    }
> +    BitSets[BitSetID].insert({BitsPtr, Offset});
> +  }
> +}
> +
> +bool DevirtModule::tryFindVirtualCallTargets(
> +    std::vector<VirtualCallTarget> &TargetsForSlot,
> +    const std::set<BitSetInfo> &BitSetInfos, uint64_t ByteOffset) {
> +  for (const BitSetInfo &BS : BitSetInfos) {
> +    if (!BS.Bits->GV->isConstant())
> +      return false;
> +
> +    auto Init = dyn_cast<ConstantArray>(BS.Bits->GV->getInitializer());
> +    if (!Init)
> +      return false;
> +    ArrayType *VTableTy = Init->getType();
> +
> +    uint64_t ElemSize =
> +        M.getDataLayout().getTypeAllocSize(VTableTy->getElementType());
> +    uint64_t GlobalSlotOffset = BS.Offset + ByteOffset;
> +    if (GlobalSlotOffset % ElemSize != 0)
> +      return false;
> +
> +    unsigned Op = GlobalSlotOffset / ElemSize;
> +    if (Op >= Init->getNumOperands())
> +      return false;
> +
> +    auto Fn =
> dyn_cast<Function>(Init->getOperand(Op)->stripPointerCasts());
> +    if (!Fn)
> +      return false;
> +
> +    // We can disregard __cxa_pure_virtual as a possible call target, as
> +    // calls to pure virtuals are UB.
> +    if (Fn->getName() == "__cxa_pure_virtual")
> +      continue;
> +
> +    TargetsForSlot.push_back({Fn, &BS});
> +  }
> +
> +  // Give up if we couldn't find any targets.
> +  return !TargetsForSlot.empty();
> +}
> +
> +bool DevirtModule::trySingleImplDevirt(
> +    ArrayRef<VirtualCallTarget> TargetsForSlot,
> +    MutableArrayRef<VirtualCallSite> CallSites) {
> +  // See if the program contains a single implementation of this virtual
> +  // function.
> +  Function *TheFn = TargetsForSlot[0].Fn;
> +  for (auto &&Target : TargetsForSlot)
> +    if (TheFn != Target.Fn)
> +      return false;
> +
> +  // If so, update each call site to call that implementation directly.
> +  for (auto &&VCallSite : CallSites) {
> +    VCallSite.CS.setCalledFunction(ConstantExpr::getBitCast(
> +        TheFn, VCallSite.CS.getCalledValue()->getType()));
> +  }
> +  return true;
> +}
> +
> +bool DevirtModule::tryEvaluateFunctionsWithArgs(
> +    MutableArrayRef<VirtualCallTarget> TargetsForSlot,
> +    ArrayRef<ConstantInt *> Args) {
> +  // Evaluate each function and store the result in each target's RetVal
> +  // field.
> +  for (VirtualCallTarget &Target : TargetsForSlot) {
> +    if (Target.Fn->arg_size() != Args.size() + 1)
> +      return false;
> +    for (unsigned I = 0; I != Args.size(); ++I)
> +      if (Target.Fn->getFunctionType()->getParamType(I + 1) !=
> +          Args[I]->getType())
> +        return false;
> +
> +    Evaluator Eval(M.getDataLayout(), nullptr);
> +    SmallVector<Constant *, 2> EvalArgs;
> +    EvalArgs.push_back(
> +
> Constant::getNullValue(Target.Fn->getFunctionType()->getParamType(0)));
> +    EvalArgs.insert(EvalArgs.end(), Args.begin(), Args.end());
> +    Constant *RetVal;
> +    if (!Eval.EvaluateFunction(Target.Fn, RetVal, EvalArgs) ||
> +        !isa<ConstantInt>(RetVal))
> +      return false;
> +    Target.RetVal = cast<ConstantInt>(RetVal)->getZExtValue();
> +  }
> +  return true;
> +}
> +
> +bool DevirtModule::tryUniformRetValOpt(
> +    IntegerType *RetType, ArrayRef<VirtualCallTarget> TargetsForSlot,
> +    MutableArrayRef<VirtualCallSite> CallSites) {
> +  // Uniform return value optimization. If all functions return the same
> +  // constant, replace all calls with that constant.
> +  uint64_t TheRetVal = TargetsForSlot[0].RetVal;
> +  for (const VirtualCallTarget &Target : TargetsForSlot)
> +    if (Target.RetVal != TheRetVal)
> +      return false;
> +
> +  auto TheRetValConst = ConstantInt::get(RetType, TheRetVal);
> +  for (auto Call : CallSites)
> +    Call.replaceAndErase(TheRetValConst);
> +  return true;
> +}
> +
> +bool DevirtModule::tryUniqueRetValOpt(
> +    unsigned BitWidth, ArrayRef<VirtualCallTarget> TargetsForSlot,
> +    MutableArrayRef<VirtualCallSite> CallSites) {
> +  // IsOne controls whether we look for a 0 or a 1.
> +  auto tryUniqueRetValOptFor = [&](bool IsOne) {
> +    const BitSetInfo *UniqueBitSet = 0;
> +    for (const VirtualCallTarget &Target : TargetsForSlot) {
> +      if (Target.RetVal == IsOne ? 1 : 0) {
> +        if (UniqueBitSet)
> +          return false;
> +        UniqueBitSet = Target.BS;
> +      }
> +    }
> +
> +    // We should have found a unique bit set or bailed out by now. We
> already
> +    // checked for a uniform return value in tryUniformRetValOpt.
> +    assert(UniqueBitSet);
> +
> +    // Replace each call with the comparison.
> +    for (auto &&Call : CallSites) {
> +      IRBuilder<> B(Call.CS.getInstruction());
> +      Value *OneAddr = B.CreateBitCast(UniqueBitSet->Bits->GV, Int8PtrTy);
> +      OneAddr = B.CreateConstGEP1_64(OneAddr, UniqueBitSet->Offset);
> +      Value *Cmp = B.CreateICmp(IsOne ? ICmpInst::ICMP_EQ :
> ICmpInst::ICMP_NE,
> +                                Call.VTable, OneAddr);
> +      Call.replaceAndErase(Cmp);
> +    }
> +    return true;
> +  };
> +
> +  if (BitWidth == 1) {
> +    if (tryUniqueRetValOptFor(true))
> +      return true;
> +    if (tryUniqueRetValOptFor(false))
> +      return true;
> +  }
> +  return false;
> +}
> +
> +bool DevirtModule::tryVirtualConstProp(
> +    MutableArrayRef<VirtualCallTarget> TargetsForSlot,
> +    ArrayRef<VirtualCallSite> CallSites) {
> +  // This only works if the function returns an integer.
> +  auto RetType =
> dyn_cast<IntegerType>(TargetsForSlot[0].Fn->getReturnType());
> +  if (!RetType)
> +    return false;
> +  unsigned BitWidth = RetType->getBitWidth();
> +  if (BitWidth > 64)
> +    return false;
> +
> +  // Make sure that each function does not access memory, takes at least
> one
> +  // argument, does not use its first argument (which we assume is
> 'this'),
> +  // and has the same return type.
> +  for (VirtualCallTarget &Target : TargetsForSlot) {
> +    if (!Target.Fn->doesNotAccessMemory() || Target.Fn->arg_empty() ||
> +        !Target.Fn->arg_begin()->use_empty() ||
> +        Target.Fn->getReturnType() != RetType)
> +      return false;
> +  }
> +
> +  // Group call sites by the list of constant arguments they pass.
> +  // The comparator ensures deterministic ordering.
> +  struct ByAPIntValue {
> +    bool operator()(const std::vector<ConstantInt *> &A,
> +                    const std::vector<ConstantInt *> &B) const {
> +      return std::lexicographical_compare(
> +          A.begin(), A.end(), B.begin(), B.end(),
> +          [](ConstantInt *AI, ConstantInt *BI) {
> +            return AI->getValue().ult(BI->getValue());
> +          });
> +    }
> +  };
> +  std::map<std::vector<ConstantInt *>, std::vector<VirtualCallSite>,
> +           ByAPIntValue>
> +      VCallSitesByConstantArg;
> +  for (auto &&VCallSite : CallSites) {
> +    std::vector<ConstantInt *> Args;
> +    if (VCallSite.CS.getType() != RetType)
> +      continue;
> +    for (auto &&Arg :
> +         make_range(VCallSite.CS.arg_begin() + 1,
> VCallSite.CS.arg_end())) {
> +      if (!isa<ConstantInt>(Arg))
> +        break;
> +      Args.push_back(cast<ConstantInt>(&Arg));
> +    }
> +    if (Args.size() + 1 != VCallSite.CS.arg_size())
> +      continue;
> +
> +    VCallSitesByConstantArg[Args].push_back(VCallSite);
> +  }
> +
> +  for (auto &&CSByConstantArg : VCallSitesByConstantArg) {
> +    if (!tryEvaluateFunctionsWithArgs(TargetsForSlot,
> CSByConstantArg.first))
> +      continue;
> +
> +    if (tryUniformRetValOpt(RetType, TargetsForSlot,
> CSByConstantArg.second))
> +      continue;
> +
> +    if (tryUniqueRetValOpt(BitWidth, TargetsForSlot,
> CSByConstantArg.second))
> +      continue;
> +
> +    // Find an allocation offset in bits in all vtables in the bitset.
> +    uint64_t AllocBefore =
> +        findLowestOffset(TargetsForSlot, /*IsAfter=*/false, BitWidth);
> +    uint64_t AllocAfter =
> +        findLowestOffset(TargetsForSlot, /*IsAfter=*/true, BitWidth);
> +
> +    // Calculate the total amount of padding needed to store a value at
> both
> +    // ends of the object.
> +    uint64_t TotalPaddingBefore = 0, TotalPaddingAfter = 0;
> +    for (auto &&Target : TargetsForSlot) {
> +      TotalPaddingBefore += std::max<int64_t>(
> +          (AllocBefore + 7) / 8 - Target.allocatedBeforeBytes() - 1, 0);
> +      TotalPaddingAfter += std::max<int64_t>(
> +          (AllocAfter + 7) / 8 - Target.allocatedAfterBytes() - 1, 0);
> +    }
> +
> +    // If the amount of padding is too large, give up.
> +    // FIXME: do something smarter here.
> +    if (std::min(TotalPaddingBefore, TotalPaddingAfter) > 128)
> +      continue;
> +
> +    // Calculate the offset to the value as a (possibly negative) byte
> offset
> +    // and (if applicable) a bit offset, and store the values in the
> targets.
> +    int64_t OffsetByte;
> +    uint64_t OffsetBit;
> +    if (TotalPaddingBefore <= TotalPaddingAfter)
> +      setBeforeReturnValues(TargetsForSlot, AllocBefore, BitWidth,
> OffsetByte,
> +                            OffsetBit);
> +    else
> +      setAfterReturnValues(TargetsForSlot, AllocAfter, BitWidth,
> OffsetByte,
> +                           OffsetBit);
> +
> +    // Rewrite each call to a load from OffsetByte/OffsetBit.
> +    for (auto Call : CSByConstantArg.second) {
> +      IRBuilder<> B(Call.CS.getInstruction());
> +      Value *Addr = B.CreateConstGEP1_64(Call.VTable, OffsetByte);
> +      if (BitWidth == 1) {
> +        Value *Bits = B.CreateLoad(Addr);
> +        Value *Bit = ConstantInt::get(Int8Ty, 1 << OffsetBit);
> +        Value *BitsAndBit = B.CreateAnd(Bits, Bit);
> +        auto IsBitSet = B.CreateICmpNE(BitsAndBit,
> ConstantInt::get(Int8Ty, 0));
> +        Call.replaceAndErase(IsBitSet);
> +      } else {
> +        Value *ValAddr = B.CreateBitCast(Addr, RetType->getPointerTo());
> +        Value *Val = B.CreateLoad(RetType, ValAddr);
> +        Call.replaceAndErase(Val);
> +      }
> +    }
> +  }
> +  return true;
> +}
> +
> +void DevirtModule::rebuildGlobal(VTableBits &B) {
> +  if (B.Before.Bytes.empty() && B.After.Bytes.empty())
> +    return;
> +
> +  // Align each byte array to pointer width.
> +  unsigned PointerSize = M.getDataLayout().getPointerSize();
> +  B.Before.Bytes.resize(alignTo(B.Before.Bytes.size(), PointerSize));
> +  B.After.Bytes.resize(alignTo(B.After.Bytes.size(), PointerSize));
> +
> +  // Before was stored in reverse order; flip it now.
> +  for (size_t I = 0, Size = B.Before.Bytes.size(); I != Size / 2; ++I)
> +    std::swap(B.Before.Bytes[I], B.Before.Bytes[Size - 1 - I]);
> +
> +  // Build an anonymous global containing the before bytes, followed by
> the
> +  // original initializer, followed by the after bytes.
> +  auto NewInit = ConstantStruct::getAnon(
> +      {ConstantDataArray::get(M.getContext(), B.Before.Bytes),
> +       B.GV->getInitializer(),
> +       ConstantDataArray::get(M.getContext(), B.After.Bytes)});
> +  auto NewGV =
> +      new GlobalVariable(M, NewInit->getType(), B.GV->isConstant(),
> +                         GlobalVariable::PrivateLinkage, NewInit, "",
> B.GV);
> +  NewGV->setSection(B.GV->getSection());
> +  NewGV->setComdat(B.GV->getComdat());
> +
> +  // Build an alias named after the original global, pointing at the
> second
> +  // element (the original initializer).
> +  auto Alias = GlobalAlias::create(
> +      B.GV->getInitializer()->getType(), 0, B.GV->getLinkage(), "",
> +      ConstantExpr::getGetElementPtr(
> +          NewInit->getType(), NewGV,
> +          ArrayRef<Constant *>{ConstantInt::get(Int32Ty, 0),
> +                               ConstantInt::get(Int32Ty, 1)}),
> +      &M);
> +  Alias->setVisibility(B.GV->getVisibility());
> +  Alias->takeName(B.GV);
> +
> +  B.GV->replaceAllUsesWith(Alias);
> +  B.GV->eraseFromParent();
> +}
> +
> +bool DevirtModule::run() {
> +  Function *BitSetTestFunc =
> +      M.getFunction(Intrinsic::getName(Intrinsic::bitset_test));
> +  if (!BitSetTestFunc || BitSetTestFunc->use_empty())
> +    return false;
> +
> +  Function *AssumeFunc =
> M.getFunction(Intrinsic::getName(Intrinsic::assume));
> +  if (!AssumeFunc || AssumeFunc->use_empty())
> +    return false;
> +
> +  // Find all virtual calls via a virtual table pointer %p under an
> assumption
> +  // of the form llvm.assume(llvm.bitset.test(%p, %md)). This indicates
> that %p
> +  // points to a vtable in the bitset %md. Group calls by (bitset,
> offset) pair
> +  // (effectively the identity of the virtual function) and store to
> CallSlots.
> +  DenseSet<Value *> SeenPtrs;
> +  for (auto I = BitSetTestFunc->use_begin(), E =
> BitSetTestFunc->use_end();
> +       I != E;) {
> +    auto CI = dyn_cast<CallInst>(I->getUser());
> +    ++I;
> +    if (!CI)
> +      continue;
> +
> +    // Find llvm.assume intrinsics for this llvm.bitset.test call.
> +    SmallVector<CallInst *, 1> Assumes;
> +    for (const Use &CIU : CI->uses()) {
> +      auto AssumeCI = dyn_cast<CallInst>(CIU.getUser());
> +      if (AssumeCI && AssumeCI->getCalledValue() == AssumeFunc)
> +        Assumes.push_back(AssumeCI);
> +    }
> +
> +    // If we found any, search for virtual calls based on %p and add them
> to
> +    // CallSlots.
> +    if (!Assumes.empty()) {
> +      Metadata *BitSet =
> +          cast<MetadataAsValue>(CI->getArgOperand(1))->getMetadata();
> +      Value *Ptr = CI->getArgOperand(0)->stripPointerCasts();
> +      if (SeenPtrs.insert(Ptr).second)
> +        findLoadCallsAtConstantOffset(BitSet, Ptr, 0,
> CI->getArgOperand(0));
> +    }
> +
> +    // We no longer need the assumes or the bitset test.
> +    for (auto Assume : Assumes)
> +      Assume->eraseFromParent();
> +    // We can't use RecursivelyDeleteTriviallyDeadInstructions here
> because we
> +    // may use the vtable argument later.
> +    if (CI->use_empty())
> +      CI->eraseFromParent();
> +  }
> +
> +  // Rebuild llvm.bitsets metadata into a map for easy lookup.
> +  std::vector<VTableBits> Bits;
> +  DenseMap<Metadata *, std::set<BitSetInfo>> BitSets;
> +  buildBitSets(Bits, BitSets);
> +  if (BitSets.empty())
> +    return true;
> +
> +  // For each (bitset, offset) pair:
> +  bool DidVirtualConstProp = false;
> +  for (auto &S : CallSlots) {
> +    // Search each of the vtables in the bitset for the virtual function
> +    // implementation at offset S.first.ByteOffset, and add to
> TargetsForSlot.
> +    std::vector<VirtualCallTarget> TargetsForSlot;
> +    if (!tryFindVirtualCallTargets(TargetsForSlot,
> BitSets[S.first.BitSetID],
> +                                   S.first.ByteOffset))
> +      continue;
> +
> +    if (trySingleImplDevirt(TargetsForSlot, S.second))
> +      continue;
> +
> +    DidVirtualConstProp |= tryVirtualConstProp(TargetsForSlot, S.second);
> +  }
> +
> +  // Rebuild each global we touched as part of virtual constant
> propagation to
> +  // include the before and after bytes.
> +  if (DidVirtualConstProp)
> +    for (VTableBits &B : Bits)
> +      rebuildGlobal(B);
> +
> +  return true;
> +}
>
> Added:
> llvm/trunk/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll
> (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll
> Tue Feb  9 16:50:34 2016
> @@ -0,0 +1,64 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt = global [2 x i8*] [i8* zeroinitializer, i8* bitcast (void (i8*)* @vf
> to i8*)]
> +
> +define void @vf(i8* %this) {
> +  ret void
> +}
> +
> +; CHECK: define void @unaligned
> +define void @unaligned(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr i8, i8* %vtablei8, i32 1
> +  %fptrptr_casted = bitcast i8* %fptrptr to i8**
> +  %fptr = load i8*, i8** %fptrptr_casted
> +  %fptr_casted = bitcast i8* %fptr to void (i8*)*
> +  ; CHECK: call void %
> +  call void %fptr_casted(i8* %obj)
> +  ret void
> +}
> +
> +; CHECK: define void @outofbounds
> +define void @outofbounds(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr i8, i8* %vtablei8, i32 16
> +  %fptrptr_casted = bitcast i8* %fptrptr to i8**
> +  %fptr = load i8*, i8** %fptrptr_casted
> +  %fptr_casted = bitcast i8* %fptr to void (i8*)*
> +  ; CHECK: call void %
> +  call void %fptr_casted(i8* %obj)
> +  ret void
> +}
> +
> +; CHECK: define void @nonfunction
> +define void @nonfunction(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr i8, i8* %vtablei8, i32 0
> +  %fptrptr_casted = bitcast i8* %fptrptr to i8**
> +  %fptr = load i8*, i8** %fptrptr_casted
> +  %fptr_casted = bitcast i8* %fptr to void (i8*)*
> +  ; CHECK: call void %
> +  call void %fptr_casted(i8* %obj)
> +  ret void
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [2 x i8*]* @vt, i32 0}
> +!llvm.bitsets = !{!0}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/constant-arg.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/constant-arg.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/constant-arg.ll (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/constant-arg.ll Tue Feb
> 9 16:50:34 2016
> @@ -0,0 +1,79 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> +; CHECK: private constant { [8 x i8], [1 x i8*], [0 x i8] } { [8 x i8]
> c"\00\00\00\00\00\00\00\01", [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf1 to
> i8*)], [0 x i8] zeroinitializer }
> +; CHECK: private constant { [8 x i8], [1 x i8*], [0 x i8] } { [8 x i8]
> c"\00\00\00\00\00\00\00\02", [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf2 to
> i8*)], [0 x i8] zeroinitializer }
> +; CHECK: private constant { [8 x i8], [1 x i8*], [0 x i8] } { [8 x i8]
> c"\00\00\00\00\00\00\00\01", [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf4 to
> i8*)], [0 x i8] zeroinitializer }
> +; CHECK: private constant { [8 x i8], [1 x i8*], [0 x i8] } { [8 x i8]
> c"\00\00\00\00\00\00\00\02", [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf8 to
> i8*)], [0 x i8] zeroinitializer }
> +
> + at vt1 = constant [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf1 to i8*)]
> + at vt2 = constant [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf2 to i8*)]
> + at vt4 = constant [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf4 to i8*)]
> + at vt8 = constant [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf8 to i8*)]
> +
> +define i1 @vf1(i8* %this, i32 %arg) readnone {
> +  %and = and i32 %arg, 1
> +  %cmp = icmp ne i32 %and, 0
> +  ret i1 %cmp
> +}
> +
> +define i1 @vf2(i8* %this, i32 %arg) readnone {
> +  %and = and i32 %arg, 2
> +  %cmp = icmp ne i32 %and, 0
> +  ret i1 %cmp
> +}
> +
> +define i1 @vf4(i8* %this, i32 %arg) readnone {
> +  %and = and i32 %arg, 4
> +  %cmp = icmp ne i32 %and, 0
> +  ret i1 %cmp
> +}
> +
> +define i1 @vf8(i8* %this, i32 %arg) readnone {
> +  %and = and i32 %arg, 8
> +  %cmp = icmp ne i32 %and, 0
> +  ret i1 %cmp
> +}
> +
> +; CHECK: define i1 @call1
> +define i1 @call1(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i1 (i8*, i32)*
> +  ; CHECK: getelementptr {{.*}} -1
> +  ; CHECK: and {{.*}}, 1
> +  %result = call i1 %fptr_casted(i8* %obj, i32 5)
> +  ret i1 %result
> +}
> +
> +; CHECK: define i1 @call2
> +define i1 @call2(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i1 (i8*, i32)*
> +  ; CHECK: getelementptr {{.*}} -1
> +  ; CHECK: and {{.*}}, 2
> +  %result = call i1 %fptr_casted(i8* %obj, i32 10)
> +  ret i1 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
> +!2 = !{!"bitset", [1 x i8*]* @vt4, i32 0}
> +!3 = !{!"bitset", [1 x i8*]* @vt8, i32 0}
> +!llvm.bitsets = !{!0, !1, !2, !3}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/devirt-single-impl.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/devirt-single-impl.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/devirt-single-impl.ll
> (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/devirt-single-impl.ll
> Tue Feb  9 16:50:34 2016
> @@ -0,0 +1,33 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt1 = constant [1 x i8*] [i8* bitcast (void (i8*)* @vf to i8*)]
> + at vt2 = constant [1 x i8*] [i8* bitcast (void (i8*)* @vf to i8*)]
> +
> +define void @vf(i8* %this) {
> +  ret void
> +}
> +
> +; CHECK: define void @call
> +define void @call(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to void (i8*)*
> +  ; CHECK: call void @vf(
> +  call void %fptr_casted(i8* %obj)
> +  ret void
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
> +!llvm.bitsets = !{!0, !1}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/non-array-vtable.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/non-array-vtable.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/non-array-vtable.ll
> (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/non-array-vtable.ll Tue
> Feb  9 16:50:34 2016
> @@ -0,0 +1,31 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt = constant i8* bitcast (void (i8*)* @vf to i8*)
> +
> +define void @vf(i8* %this) {
> +  ret void
> +}
> +
> +; CHECK: define void @call
> +define void @call(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to void (i8*)*
> +  ; CHECK: call void %
> +  call void %fptr_casted(i8* %obj)
> +  ret void
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", i8** @vt, i32 0}
> +!llvm.bitsets = !{!0}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll
> (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll
> Tue Feb  9 16:50:34 2016
> @@ -0,0 +1,31 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt = global [1 x i8*] [i8* bitcast (void (i8*)* @vf to i8*)]
> +
> +define void @vf(i8* %this) {
> +  ret void
> +}
> +
> +; CHECK: define void @call
> +define void @call(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to void (i8*)*
> +  ; CHECK: call void %
> +  call void %fptr_casted(i8* %obj)
> +  ret void
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt, i32 0}
> +!llvm.bitsets = !{!0}
>
> Added:
> llvm/trunk/test/Transforms/WholeProgramDevirt/uniform-retval-invoke.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/uniform-retval-invoke.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/uniform-retval-invoke.ll
> (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/uniform-retval-invoke.ll
> Tue Feb  9 16:50:34 2016
> @@ -0,0 +1,45 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt1 = constant [1 x i8*] [i8* bitcast (i32 (i8*)* @vf1 to i8*)]
> + at vt2 = constant [1 x i8*] [i8* bitcast (i32 (i8*)* @vf2 to i8*)]
> +
> +define i32 @vf1(i8* %this) readnone {
> +  ret i32 123
> +}
> +
> +define i32 @vf2(i8* %this) readnone {
> +  ret i32 123
> +}
> +
> +; CHECK: define i32 @call
> +define i32 @call(i8* %obj) personality i8* undef {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i32 (i8*)*
> +  ; CHECK: br label %[[RET:[0-9A-Za-z]*]]
> +  %result = invoke i32 %fptr_casted(i8* %obj) to label %ret unwind label
> %unwind
> +
> +unwind:
> +  %x = landingpad i32 cleanup
> +  unreachable
> +
> +ret:
> +  ; CHECK: [[RET]]:
> +  ; CHECK-NEXT: ret i32 123
> +  ret i32 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
> +!llvm.bitsets = !{!0, !1}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/uniform-retval.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/uniform-retval.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/uniform-retval.ll (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/uniform-retval.ll Tue
> Feb  9 16:50:34 2016
> @@ -0,0 +1,38 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt1 = constant [1 x i8*] [i8* bitcast (i32 (i8*)* @vf1 to i8*)]
> + at vt2 = constant [1 x i8*] [i8* bitcast (i32 (i8*)* @vf2 to i8*)]
> +
> +define i32 @vf1(i8* %this) readnone {
> +  ret i32 123
> +}
> +
> +define i32 @vf2(i8* %this) readnone {
> +  ret i32 123
> +}
> +
> +; CHECK: define i32 @call
> +define i32 @call(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i32 (i8*)*
> +  %result = call i32 %fptr_casted(i8* %obj)
> +  ; CHECK-NOT: call
> +  ; CHECK: ret i32 123
> +  ret i32 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
> +!llvm.bitsets = !{!0, !1}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/unique-retval.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/unique-retval.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/unique-retval.ll (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/unique-retval.ll Tue
> Feb  9 16:50:34 2016
> @@ -0,0 +1,61 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt1 = constant [1 x i8*] [i8* bitcast (i1 (i8*)* @vf0 to i8*)]
> + at vt2 = constant [1 x i8*] [i8* bitcast (i1 (i8*)* @vf0 to i8*)]
> + at vt3 = constant [1 x i8*] [i8* bitcast (i1 (i8*)* @vf1 to i8*)]
> + at vt4 = constant [1 x i8*] [i8* bitcast (i1 (i8*)* @vf1 to i8*)]
> +
> +define i1 @vf0(i8* %this) readnone {
> +  ret i1 0
> +}
> +
> +define i1 @vf1(i8* %this) readnone {
> +  ret i1 1
> +}
> +
> +; CHECK: define i1 @call1
> +define i1 @call1(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  ; CHECK: [[VT1:%[^ ]*]] = bitcast [1 x i8*]* {{.*}} to i8*
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset1")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i1 (i8*)*
> +  ; CHECK: [[RES1:%[^ ]*]] = icmp eq i8* [[VT1]], bitcast ([1 x i8*]*
> @vt3 to i8*)
> +  %result = call i1 %fptr_casted(i8* %obj)
> +  ; CHECK: ret i1 [[RES1]]
> +  ret i1 %result
> +}
> +
> +; CHECK: define i1 @call2
> +define i1 @call2(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  ; CHECK: [[VT2:%[^ ]*]] = bitcast [1 x i8*]* {{.*}} to i8*
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset2")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i1 (i8*)*
> +  ; CHECK: [[RES1:%[^ ]*]] = icmp ne i8* [[VT1]], bitcast ([1 x i8*]*
> @vt2 to i8*)
> +  %result = call i1 %fptr_casted(i8* %obj)
> +  ret i1 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset1", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset1", [1 x i8*]* @vt2, i32 0}
> +!2 = !{!"bitset1", [1 x i8*]* @vt3, i32 0}
> +!3 = !{!"bitset2", [1 x i8*]* @vt2, i32 0}
> +!4 = !{!"bitset2", [1 x i8*]* @vt3, i32 0}
> +!5 = !{!"bitset2", [1 x i8*]* @vt4, i32 0}
> +!llvm.bitsets = !{!0, !1, !2, !3, !4, !5}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-accesses-memory.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-accesses-memory.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-accesses-memory.ll
> (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-accesses-memory.ll
> Tue Feb  9 16:50:34 2016
> @@ -0,0 +1,37 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt1 = global [1 x i8*] [i8* bitcast (i32 (i8*, i32)* @vf1 to i8*)]
> + at vt2 = global [1 x i8*] [i8* bitcast (i32 (i8*, i32)* @vf2 to i8*)]
> +
> +define i32 @vf1(i8* %this, i32 %arg) {
> +  ret i32 %arg
> +}
> +
> +define i32 @vf2(i8* %this, i32 %arg) {
> +  ret i32 %arg
> +}
> +
> +; CHECK: define i32 @call
> +define i32 @call(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i32 (i8*, i32)*
> +  ; CHECK: call i32 %
> +  %result = call i32 %fptr_casted(i8* %obj, i32 1)
> +  ret i32 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
> +!llvm.bitsets = !{!0}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-no-this.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-no-this.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-no-this.ll (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-no-this.ll Tue Feb
> 9 16:50:34 2016
> @@ -0,0 +1,37 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt1 = global [1 x i8*] [i8* bitcast (i32 ()* @vf1 to i8*)]
> + at vt2 = global [1 x i8*] [i8* bitcast (i32 ()* @vf2 to i8*)]
> +
> +define i32 @vf1() readnone {
> +  ret i32 1
> +}
> +
> +define i32 @vf2() readnone {
> +  ret i32 2
> +}
> +
> +; CHECK: define i32 @call
> +define i32 @call(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i32 ()*
> +  ; CHECK: call i32 %
> +  %result = call i32 %fptr_casted()
> +  ret i32 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
> +!llvm.bitsets = !{!0}
>
> Added:
> llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-non-constant-arg.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-non-constant-arg.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-non-constant-arg.ll
> (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-non-constant-arg.ll
> Tue Feb  9 16:50:34 2016
> @@ -0,0 +1,37 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt1 = global [1 x i8*] [i8* bitcast (i32 (i8*, i32)* @vf1 to i8*)]
> + at vt2 = global [1 x i8*] [i8* bitcast (i32 (i8*, i32)* @vf2 to i8*)]
> +
> +define i32 @vf1(i8* %this, i32 %arg) readnone {
> +  ret i32 %arg
> +}
> +
> +define i32 @vf2(i8* %this, i32 %arg) readnone {
> +  ret i32 %arg
> +}
> +
> +; CHECK: define void @call
> +define void @call(i8* %obj, i32 %arg) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i32 (i8*, i32)*
> +  ; CHECK: call i32 %
> +  %result = call i32 %fptr_casted(i8* %obj, i32 %arg)
> +  ret void
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
> +!llvm.bitsets = !{!0}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-too-wide-ints.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-too-wide-ints.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-too-wide-ints.ll
> (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-too-wide-ints.ll Tue
> Feb  9 16:50:34 2016
> @@ -0,0 +1,37 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt1 = global [1 x i8*] [i8* bitcast (i128 (i8*, i128)* @vf1 to i8*)]
> + at vt2 = global [1 x i8*] [i8* bitcast (i128 (i8*, i128)* @vf2 to i8*)]
> +
> +define i128 @vf1(i8* %this, i128 %arg) readnone {
> +  ret i128 %arg
> +}
> +
> +define i128 @vf2(i8* %this, i128 %arg) readnone {
> +  ret i128 %arg
> +}
> +
> +; CHECK: define i128 @call
> +define i128 @call(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i128 (i8*, i128)*
> +  ; CHECK: call i128 %
> +  %result = call i128 %fptr_casted(i8* %obj, i128 1)
> +  ret i128 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
> +!llvm.bitsets = !{!0}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-type-mismatch.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-type-mismatch.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-type-mismatch.ll
> (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-type-mismatch.ll Tue
> Feb  9 16:50:34 2016
> @@ -0,0 +1,67 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt1 = global [1 x i8*] [i8* bitcast (i32 (i8*, i32)* @vf1 to i8*)]
> + at vt2 = global [1 x i8*] [i8* bitcast (i32 (i8*, i32)* @vf2 to i8*)]
> +
> +define i32 @vf1(i8* %this, i32 %arg) readnone {
> +  ret i32 %arg
> +}
> +
> +define i32 @vf2(i8* %this, i32 %arg) readnone {
> +  ret i32 %arg
> +}
> +
> +; CHECK: define i32 @bad_arg_type
> +define i32 @bad_arg_type(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i32 (i8*, i64)*
> +  ; CHECK: call i32 %
> +  %result = call i32 %fptr_casted(i8* %obj, i64 1)
> +  ret i32 %result
> +}
> +
> +; CHECK: define i32 @bad_arg_count
> +define i32 @bad_arg_count(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i32 (i8*, i64, i64)*
> +  ; CHECK: call i32 %
> +  %result = call i32 %fptr_casted(i8* %obj, i64 1, i64 2)
> +  ret i32 %result
> +}
> +
> +; CHECK: define i64 @bad_return_type
> +define i64 @bad_return_type(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i64 (i8*, i32)*
> +  ; CHECK: call i64 %
> +  %result = call i64 %fptr_casted(i8* %obj, i32 1)
> +  ret i64 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
> +!llvm.bitsets = !{!0}
>
> Added: llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-uses-this.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-uses-this.ll?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-uses-this.ll (added)
> +++ llvm/trunk/test/Transforms/WholeProgramDevirt/vcp-uses-this.ll Tue
> Feb  9 16:50:34 2016
> @@ -0,0 +1,39 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at vt1 = global [1 x i8*] [i8* bitcast (i32 (i8*)* @vf1 to i8*)]
> + at vt2 = global [1 x i8*] [i8* bitcast (i32 (i8*)* @vf2 to i8*)]
> +
> +define i32 @vf1(i8* %this) readnone {
> +  %this_int = ptrtoint i8* %this to i32
> +  ret i32 %this_int
> +}
> +
> +define i32 @vf2(i8* %this) readnone {
> +  %this_int = ptrtoint i8* %this to i32
> +  ret i32 %this_int
> +}
> +
> +; CHECK: define i32 @call
> +define i32 @call(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [1 x i8*]**
> +  %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
> +  %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i32 (i8*)*
> +  ; CHECK: call i32 %
> +  %result = call i32 %fptr_casted(i8* %obj)
> +  ret i32 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
> +!llvm.bitsets = !{!0}
>
> Added:
> llvm/trunk/test/Transforms/WholeProgramDevirt/virtual-const-prop-begin.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/virtual-const-prop-begin.ll?rev=260312&view=auto
>
> ==============================================================================
> ---
> llvm/trunk/test/Transforms/WholeProgramDevirt/virtual-const-prop-begin.ll
> (added)
> +++
> llvm/trunk/test/Transforms/WholeProgramDevirt/virtual-const-prop-begin.ll
> Tue Feb  9 16:50:34 2016
> @@ -0,0 +1,137 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> +; CHECK: [[VT1DATA:@[^ ]*]] = private constant { [8 x i8], [3 x i8*], [0
> x i8] } { [8 x i8] c"\00\00\00\01\01\00\00\00", [3 x i8*] [i8* bitcast (i1
> (i8*)* @vf0i1 to i8*), i8* bitcast (i1 (i8*)* @vf1i1 to i8*), i8* bitcast
> (i32 (i8*)* @vf1i32 to i8*)], [0 x i8] zeroinitializer }, section "vt1sec"
> + at vt1 = constant [3 x i8*] [
> +i8* bitcast (i1 (i8*)* @vf0i1 to i8*),
> +i8* bitcast (i1 (i8*)* @vf1i1 to i8*),
> +i8* bitcast (i32 (i8*)* @vf1i32 to i8*)
> +], section "vt1sec"
> +
> +; CHECK: [[VT2DATA:@[^ ]*]] = private constant { [8 x i8], [3 x i8*], [0
> x i8] } { [8 x i8] c"\00\00\00\02\02\00\00\00", [3 x i8*] [i8* bitcast (i1
> (i8*)* @vf1i1 to i8*), i8* bitcast (i1 (i8*)* @vf0i1 to i8*), i8* bitcast
> (i32 (i8*)* @vf2i32 to i8*)], [0 x i8] zeroinitializer }{{$}}
> + at vt2 = constant [3 x i8*] [
> +i8* bitcast (i1 (i8*)* @vf1i1 to i8*),
> +i8* bitcast (i1 (i8*)* @vf0i1 to i8*),
> +i8* bitcast (i32 (i8*)* @vf2i32 to i8*)
> +]
> +
> +; CHECK: [[VT3DATA:@[^ ]*]] = private constant { [8 x i8], [3 x i8*], [0
> x i8] } { [8 x i8] c"\00\00\00\01\03\00\00\00", [3 x i8*] [i8* bitcast (i1
> (i8*)* @vf0i1 to i8*), i8* bitcast (i1 (i8*)* @vf1i1 to i8*), i8* bitcast
> (i32 (i8*)* @vf3i32 to i8*)], [0 x i8] zeroinitializer }{{$}}
> + at vt3 = constant [3 x i8*] [
> +i8* bitcast (i1 (i8*)* @vf0i1 to i8*),
> +i8* bitcast (i1 (i8*)* @vf1i1 to i8*),
> +i8* bitcast (i32 (i8*)* @vf3i32 to i8*)
> +]
> +
> +; CHECK: [[VT4DATA:@[^ ]*]] = private constant { [8 x i8], [3 x i8*], [0
> x i8] } { [8 x i8] c"\00\00\00\02\04\00\00\00", [3 x i8*] [i8* bitcast (i1
> (i8*)* @vf1i1 to i8*), i8* bitcast (i1 (i8*)* @vf0i1 to i8*), i8* bitcast
> (i32 (i8*)* @vf4i32 to i8*)], [0 x i8] zeroinitializer }{{$}}
> + at vt4 = constant [3 x i8*] [
> +i8* bitcast (i1 (i8*)* @vf1i1 to i8*),
> +i8* bitcast (i1 (i8*)* @vf0i1 to i8*),
> +i8* bitcast (i32 (i8*)* @vf4i32 to i8*)
> +]
> +
> + at vt5 = constant [3 x i8*] [
> +i8* bitcast (void ()* @__cxa_pure_virtual to i8*),
> +i8* bitcast (void ()* @__cxa_pure_virtual to i8*),
> +i8* bitcast (void ()* @__cxa_pure_virtual to i8*)
> +]
> +
> +; CHECK: @vt1 = alias [3 x i8*], getelementptr inbounds ({ [8 x i8], [3 x
> i8*], [0 x i8] }, { [8 x i8], [3 x i8*], [0 x i8] }* [[VT1DATA]], i32 0,
> i32 1)
> +; CHECK: @vt2 = alias [3 x i8*], getelementptr inbounds ({ [8 x i8], [3 x
> i8*], [0 x i8] }, { [8 x i8], [3 x i8*], [0 x i8] }* [[VT2DATA]], i32 0,
> i32 1)
> +; CHECK: @vt3 = alias [3 x i8*], getelementptr inbounds ({ [8 x i8], [3 x
> i8*], [0 x i8] }, { [8 x i8], [3 x i8*], [0 x i8] }* [[VT3DATA]], i32 0,
> i32 1)
> +; CHECK: @vt4 = alias [3 x i8*], getelementptr inbounds ({ [8 x i8], [3 x
> i8*], [0 x i8] }, { [8 x i8], [3 x i8*], [0 x i8] }* [[VT4DATA]], i32 0,
> i32 1)
> +
> +define i1 @vf0i1(i8* %this) readnone {
> +  ret i1 0
> +}
> +
> +define i1 @vf1i1(i8* %this) readnone {
> +  ret i1 1
> +}
> +
> +define i32 @vf1i32(i8* %this) readnone {
> +  ret i32 1
> +}
> +
> +define i32 @vf2i32(i8* %this) readnone {
> +  ret i32 2
> +}
> +
> +define i32 @vf3i32(i8* %this) readnone {
> +  ret i32 3
> +}
> +
> +define i32 @vf4i32(i8* %this) readnone {
> +  ret i32 4
> +}
> +
> +; CHECK: define i1 @call1(
> +define i1 @call1(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [3 x i8*]**
> +  %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
> +  ; CHECK: [[VT1:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
> +  %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [3 x i8*], [3 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i1 (i8*)*
> +  ; CHECK: [[VTGEP1:%[^ ]*]] = getelementptr i8, i8* [[VT1]], i64 -5
> +  ; CHECK: [[VTLOAD1:%[^ ]*]] = load i8, i8* [[VTGEP1]]
> +  ; CHECK: [[VTAND1:%[^ ]*]] = and i8 [[VTLOAD1]], 2
> +  ; CHECK: [[VTCMP1:%[^ ]*]] = icmp ne i8 [[VTAND1]], 0
> +  %result = call i1 %fptr_casted(i8* %obj)
> +  ; CHECK: ret i1 [[VTCMP1]]
> +  ret i1 %result
> +}
> +
> +; CHECK: define i1 @call2(
> +define i1 @call2(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [3 x i8*]**
> +  %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
> +  ; CHECK: [[VT2:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
> +  %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [3 x i8*], [3 x i8*]* %vtable, i32 0, i32 1
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i1 (i8*)*
> +  ; CHECK: [[VTGEP2:%[^ ]*]] = getelementptr i8, i8* [[VT2]], i64 -5
> +  ; CHECK: [[VTLOAD2:%[^ ]*]] = load i8, i8* [[VTGEP2]]
> +  ; CHECK: [[VTAND2:%[^ ]*]] = and i8 [[VTLOAD2]], 1
> +  ; CHECK: [[VTCMP2:%[^ ]*]] = icmp ne i8 [[VTAND2]], 0
> +  %result = call i1 %fptr_casted(i8* %obj)
> +  ; CHECK: ret i1 [[VTCMP2]]
> +  ret i1 %result
> +}
> +
> +; CHECK: define i32 @call3(
> +define i32 @call3(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [3 x i8*]**
> +  %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
> +  ; CHECK: [[VT3:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
> +  %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [3 x i8*], [3 x i8*]* %vtable, i32 0, i32 2
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i32 (i8*)*
> +  ; CHECK: [[VTGEP3:%[^ ]*]] = getelementptr i8, i8* [[VT3]], i64 -4
> +  ; CHECK: [[VTBC3:%[^ ]*]] = bitcast i8* [[VTGEP3]] to i32*
> +  ; CHECK: [[VTLOAD3:%[^ ]*]] = load i32, i32* [[VTBC3]]
> +  %result = call i32 %fptr_casted(i8* %obj)
> +  ; CHECK: ret i32 [[VTLOAD3]]
> +  ret i32 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +declare void @__cxa_pure_virtual()
> +
> +!0 = !{!"bitset", [3 x i8*]* @vt1, i32 0}
> +!1 = !{!"bitset", [3 x i8*]* @vt2, i32 0}
> +!2 = !{!"bitset", [3 x i8*]* @vt3, i32 0}
> +!3 = !{!"bitset", [3 x i8*]* @vt4, i32 0}
> +!4 = !{!"bitset", [3 x i8*]* @vt5, i32 0}
> +!llvm.bitsets = !{!0, !1, !2, !3, !4}
>
> Added:
> llvm/trunk/test/Transforms/WholeProgramDevirt/virtual-const-prop-end.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/WholeProgramDevirt/virtual-const-prop-end.ll?rev=260312&view=auto
>
> ==============================================================================
> ---
> llvm/trunk/test/Transforms/WholeProgramDevirt/virtual-const-prop-end.ll
> (added)
> +++
> llvm/trunk/test/Transforms/WholeProgramDevirt/virtual-const-prop-end.ll Tue
> Feb  9 16:50:34 2016
> @@ -0,0 +1,131 @@
> +; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
> +
> +target datalayout = "e-p:64:64"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> +; CHECK: [[VT1DATA:@[^ ]*]] = private constant { [0 x i8], [4 x i8*], [8
> x i8] } { [0 x i8] zeroinitializer, [4 x i8*] [i8* null, i8* bitcast (i1
> (i8*)* @vf0i1 to i8*), i8* bitcast (i1 (i8*)* @vf1i1 to i8*), i8* bitcast
> (i32 (i8*)* @vf1i32 to i8*)], [8 x i8] c"\01\00\00\00\01\00\00\00" }
> + at vt1 = constant [4 x i8*] [
> +i8* null,
> +i8* bitcast (i1 (i8*)* @vf0i1 to i8*),
> +i8* bitcast (i1 (i8*)* @vf1i1 to i8*),
> +i8* bitcast (i32 (i8*)* @vf1i32 to i8*)
> +]
> +
> +; CHECK: [[VT2DATA:@[^ ]*]] = private constant { [0 x i8], [3 x i8*], [8
> x i8] } { [0 x i8] zeroinitializer, [3 x i8*] [i8* bitcast (i1 (i8*)*
> @vf1i1 to i8*), i8* bitcast (i1 (i8*)* @vf0i1 to i8*), i8* bitcast (i32
> (i8*)* @vf2i32 to i8*)], [8 x i8] c"\02\00\00\00\02\00\00\00" }
> + at vt2 = constant [3 x i8*] [
> +i8* bitcast (i1 (i8*)* @vf1i1 to i8*),
> +i8* bitcast (i1 (i8*)* @vf0i1 to i8*),
> +i8* bitcast (i32 (i8*)* @vf2i32 to i8*)
> +]
> +
> +; CHECK: [[VT3DATA:@[^ ]*]] = private constant { [0 x i8], [4 x i8*], [8
> x i8] } { [0 x i8] zeroinitializer, [4 x i8*] [i8* null, i8* bitcast (i1
> (i8*)* @vf0i1 to i8*), i8* bitcast (i1 (i8*)* @vf1i1 to i8*), i8* bitcast
> (i32 (i8*)* @vf3i32 to i8*)], [8 x i8] c"\03\00\00\00\01\00\00\00" }
> + at vt3 = constant [4 x i8*] [
> +i8* null,
> +i8* bitcast (i1 (i8*)* @vf0i1 to i8*),
> +i8* bitcast (i1 (i8*)* @vf1i1 to i8*),
> +i8* bitcast (i32 (i8*)* @vf3i32 to i8*)
> +]
> +
> +; CHECK: [[VT4DATA:@[^ ]*]] = private constant { [0 x i8], [3 x i8*], [8
> x i8] } { [0 x i8] zeroinitializer, [3 x i8*] [i8* bitcast (i1 (i8*)*
> @vf1i1 to i8*), i8* bitcast (i1 (i8*)* @vf0i1 to i8*), i8* bitcast (i32
> (i8*)* @vf4i32 to i8*)], [8 x i8] c"\04\00\00\00\02\00\00\00" }
> + at vt4 = constant [3 x i8*] [
> +i8* bitcast (i1 (i8*)* @vf1i1 to i8*),
> +i8* bitcast (i1 (i8*)* @vf0i1 to i8*),
> +i8* bitcast (i32 (i8*)* @vf4i32 to i8*)
> +]
> +
> +; CHECK: @vt1 = alias [4 x i8*], getelementptr inbounds ({ [0 x i8], [4 x
> i8*], [8 x i8] }, { [0 x i8], [4 x i8*], [8 x i8] }* [[VT1DATA]], i32 0,
> i32 1)
> +; CHECK: @vt2 = alias [3 x i8*], getelementptr inbounds ({ [0 x i8], [3 x
> i8*], [8 x i8] }, { [0 x i8], [3 x i8*], [8 x i8] }* [[VT2DATA]], i32 0,
> i32 1)
> +; CHECK: @vt3 = alias [4 x i8*], getelementptr inbounds ({ [0 x i8], [4 x
> i8*], [8 x i8] }, { [0 x i8], [4 x i8*], [8 x i8] }* [[VT3DATA]], i32 0,
> i32 1)
> +; CHECK: @vt4 = alias [3 x i8*], getelementptr inbounds ({ [0 x i8], [3 x
> i8*], [8 x i8] }, { [0 x i8], [3 x i8*], [8 x i8] }* [[VT4DATA]], i32 0,
> i32 1)
> +
> +define i1 @vf0i1(i8* %this) readnone {
> +  ret i1 0
> +}
> +
> +define i1 @vf1i1(i8* %this) readnone {
> +  ret i1 1
> +}
> +
> +define i32 @vf1i32(i8* %this) readnone {
> +  ret i32 1
> +}
> +
> +define i32 @vf2i32(i8* %this) readnone {
> +  ret i32 2
> +}
> +
> +define i32 @vf3i32(i8* %this) readnone {
> +  ret i32 3
> +}
> +
> +define i32 @vf4i32(i8* %this) readnone {
> +  ret i32 4
> +}
> +
> +; CHECK: define i1 @call1(
> +define i1 @call1(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [3 x i8*]**
> +  %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
> +  ; CHECK: [[VT1:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
> +  %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [3 x i8*], [3 x i8*]* %vtable, i32 0, i32 0
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i1 (i8*)*
> +  ; CHECK: [[VTGEP1:%[^ ]*]] = getelementptr i8, i8* [[VT1]], i64 28
> +  ; CHECK: [[VTLOAD1:%[^ ]*]] = load i8, i8* [[VTGEP1]]
> +  ; CHECK: [[VTAND1:%[^ ]*]] = and i8 [[VTLOAD1]], 2
> +  ; CHECK: [[VTCMP1:%[^ ]*]] = icmp ne i8 [[VTAND1]], 0
> +  %result = call i1 %fptr_casted(i8* %obj)
> +  ; CHECK: ret i1 [[VTCMP1]]
> +  ret i1 %result
> +}
> +
> +; CHECK: define i1 @call2(
> +define i1 @call2(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [3 x i8*]**
> +  %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
> +  ; CHECK: [[VT2:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
> +  %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [3 x i8*], [3 x i8*]* %vtable, i32 0, i32 1
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i1 (i8*)*
> +  ; CHECK: [[VTGEP2:%[^ ]*]] = getelementptr i8, i8* [[VT2]], i64 28
> +  ; CHECK: [[VTLOAD2:%[^ ]*]] = load i8, i8* [[VTGEP2]]
> +  ; CHECK: [[VTAND2:%[^ ]*]] = and i8 [[VTLOAD2]], 1
> +  ; CHECK: [[VTCMP2:%[^ ]*]] = icmp ne i8 [[VTAND2]], 0
> +  %result = call i1 %fptr_casted(i8* %obj)
> +  ; CHECK: ret i1 [[VTCMP2]]
> +  ret i1 %result
> +}
> +
> +; CHECK: define i32 @call3(
> +define i32 @call3(i8* %obj) {
> +  %vtableptr = bitcast i8* %obj to [3 x i8*]**
> +  %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
> +  ; CHECK: [[VT3:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
> +  %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
> +  %p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
> +  call void @llvm.assume(i1 %p)
> +  %fptrptr = getelementptr [3 x i8*], [3 x i8*]* %vtable, i32 0, i32 2
> +  %fptr = load i8*, i8** %fptrptr
> +  %fptr_casted = bitcast i8* %fptr to i32 (i8*)*
> +  ; CHECK: [[VTGEP3:%[^ ]*]] = getelementptr i8, i8* [[VT3]], i64 24
> +  ; CHECK: [[VTBC3:%[^ ]*]] = bitcast i8* [[VTGEP3]] to i32*
> +  ; CHECK: [[VTLOAD3:%[^ ]*]] = load i32, i32* [[VTBC3]]
> +  %result = call i32 %fptr_casted(i8* %obj)
> +  ; CHECK: ret i32 [[VTLOAD3]]
> +  ret i32 %result
> +}
> +
> +declare i1 @llvm.bitset.test(i8*, metadata)
> +declare void @llvm.assume(i1)
> +
> +!0 = !{!"bitset", [4 x i8*]* @vt1, i32 8}
> +!1 = !{!"bitset", [3 x i8*]* @vt2, i32 0}
> +!2 = !{!"bitset", [4 x i8*]* @vt3, i32 8}
> +!3 = !{!"bitset", [3 x i8*]* @vt4, i32 0}
> +!llvm.bitsets = !{!0, !1, !2, !3}
>
> Modified: llvm/trunk/test/tools/gold/X86/disable-verify.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/gold/X86/disable-verify.ll?rev=260312&r1=260311&r2=260312&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/tools/gold/X86/disable-verify.ll (original)
> +++ llvm/trunk/test/tools/gold/X86/disable-verify.ll Tue Feb  9 16:50:34
> 2016
> @@ -14,7 +14,7 @@ target triple = "x86_64-unknown-linux-gn
>
>  ; -disable-verify should disable output verification from the optimization
>  ; pipeline.
> -; CHECK: Pass Arguments: {{.*}} -verify -forceattrs
> +; CHECK: Pass Arguments: {{.*}} -verify -
>  ; CHECK-NOT: -verify
>
>  ; VERIFY: Pass Arguments: {{.*}} -verify {{.*}} -verify
>
> Modified: llvm/trunk/unittests/Transforms/IPO/CMakeLists.txt
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Transforms/IPO/CMakeLists.txt?rev=260312&r1=260311&r2=260312&view=diff
>
> ==============================================================================
> --- llvm/trunk/unittests/Transforms/IPO/CMakeLists.txt (original)
> +++ llvm/trunk/unittests/Transforms/IPO/CMakeLists.txt Tue Feb  9 16:50:34
> 2016
> @@ -6,4 +6,5 @@ set(LLVM_LINK_COMPONENTS
>
>  add_llvm_unittest(IPOTests
>    LowerBitSets.cpp
> +  WholeProgramDevirt.cpp
>    )
>
> Added: llvm/trunk/unittests/Transforms/IPO/WholeProgramDevirt.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Transforms/IPO/WholeProgramDevirt.cpp?rev=260312&view=auto
>
> ==============================================================================
> --- llvm/trunk/unittests/Transforms/IPO/WholeProgramDevirt.cpp (added)
> +++ llvm/trunk/unittests/Transforms/IPO/WholeProgramDevirt.cpp Tue Feb  9
> 16:50:34 2016
> @@ -0,0 +1,164 @@
> +//===- WholeProgramDevirt.cpp - Unit tests for whole-program devirt
> -------===//
> +//
> +//                     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/WholeProgramDevirt.h"
> +#include "gtest/gtest.h"
> +
> +using namespace llvm;
> +using namespace wholeprogramdevirt;
> +
> +TEST(WholeProgramDevirt, findLowestOffset) {
> +  VTableBits VT1;
> +  VT1.ObjectSize = 8;
> +  VT1.Before.BytesUsed = {1 << 0};
> +  VT1.After.BytesUsed = {1 << 1};
> +
> +  VTableBits VT2;
> +  VT2.ObjectSize = 8;
> +  VT2.Before.BytesUsed = {1 << 1};
> +  VT2.After.BytesUsed = {1 << 0};
> +
> +  BitSetInfo BS1{&VT1, 0};
> +  BitSetInfo BS2{&VT2, 0};
> +  VirtualCallTarget Targets[] = {
> +    {&BS1, /*IsBigEndian=*/false},
> +    {&BS2, /*IsBigEndian=*/false},
> +  };
> +
> +  EXPECT_EQ(2ull, findLowestOffset(Targets, /*IsAfter=*/false, 1));
> +  EXPECT_EQ(66ull, findLowestOffset(Targets, /*IsAfter=*/true, 1));
> +
> +  EXPECT_EQ(8ull, findLowestOffset(Targets, /*IsAfter=*/false, 8));
> +  EXPECT_EQ(72ull, findLowestOffset(Targets, /*IsAfter=*/true, 8));
> +
> +  BS1.Offset = 4;
> +  EXPECT_EQ(33ull, findLowestOffset(Targets, /*IsAfter=*/false, 1));
> +  EXPECT_EQ(65ull, findLowestOffset(Targets, /*IsAfter=*/true, 1));
> +
> +  EXPECT_EQ(40ull, findLowestOffset(Targets, /*IsAfter=*/false, 8));
> +  EXPECT_EQ(72ull, findLowestOffset(Targets, /*IsAfter=*/true, 8));
> +
> +  BS1.Offset = 8;
> +  BS2.Offset = 8;
> +  EXPECT_EQ(66ull, findLowestOffset(Targets, /*IsAfter=*/false, 1));
> +  EXPECT_EQ(2ull, findLowestOffset(Targets, /*IsAfter=*/true, 1));
> +
> +  EXPECT_EQ(72ull, findLowestOffset(Targets, /*IsAfter=*/false, 8));
> +  EXPECT_EQ(8ull, findLowestOffset(Targets, /*IsAfter=*/true, 8));
> +
> +  VT1.After.BytesUsed = {0xff, 0, 0, 0, 0xff};
> +  VT2.After.BytesUsed = {0xff, 1, 0, 0, 0};
> +  EXPECT_EQ(16ull, findLowestOffset(Targets, /*IsAfter=*/true, 16));
> +  EXPECT_EQ(40ull, findLowestOffset(Targets, /*IsAfter=*/true, 32));
> +}
> +
> +TEST(WholeProgramDevirt, setReturnValues) {
> +  VTableBits VT1;
> +  VT1.ObjectSize = 8;
> +
> +  VTableBits VT2;
> +  VT2.ObjectSize = 8;
> +
> +  BitSetInfo BS1{&VT1, 0};
> +  BitSetInfo BS2{&VT2, 0};
> +  VirtualCallTarget Targets[] = {
> +    {&BS1, /*IsBigEndian=*/false},
> +    {&BS2, /*IsBigEndian=*/false},
> +  };
> +
> +  BS1.Offset = 4;
> +  BS2.Offset = 4;
> +
> +  int64_t OffsetByte;
> +  uint64_t OffsetBit;
> +
> +  Targets[0].RetVal = 1;
> +  Targets[1].RetVal = 0;
> +  setBeforeReturnValues(Targets, 32, 1, OffsetByte, OffsetBit);
> +  EXPECT_EQ(-5ll, OffsetByte);
> +  EXPECT_EQ(0ull, OffsetBit);
> +  EXPECT_EQ(std::vector<uint8_t>{1}, VT1.Before.Bytes);
> +  EXPECT_EQ(std::vector<uint8_t>{1}, VT1.Before.BytesUsed);
> +  EXPECT_EQ(std::vector<uint8_t>{0}, VT2.Before.Bytes);
> +  EXPECT_EQ(std::vector<uint8_t>{1}, VT2.Before.BytesUsed);
> +
> +  Targets[0].RetVal = 0;
> +  Targets[1].RetVal = 1;
> +  setBeforeReturnValues(Targets, 39, 1, OffsetByte, OffsetBit);
> +  EXPECT_EQ(-5ll, OffsetByte);
> +  EXPECT_EQ(7ull, OffsetBit);
> +  EXPECT_EQ(std::vector<uint8_t>{1}, VT1.Before.Bytes);
> +  EXPECT_EQ(std::vector<uint8_t>{0x81}, VT1.Before.BytesUsed);
> +  EXPECT_EQ(std::vector<uint8_t>{0x80}, VT2.Before.Bytes);
> +  EXPECT_EQ(std::vector<uint8_t>{0x81}, VT2.Before.BytesUsed);
> +
> +  Targets[0].RetVal = 12;
> +  Targets[1].RetVal = 34;
> +  setBeforeReturnValues(Targets, 40, 8, OffsetByte, OffsetBit);
> +  EXPECT_EQ(-6ll, OffsetByte);
> +  EXPECT_EQ(0ull, OffsetBit);
> +  EXPECT_EQ((std::vector<uint8_t>{1, 12}), VT1.Before.Bytes);
> +  EXPECT_EQ((std::vector<uint8_t>{0x81, 0xff}), VT1.Before.BytesUsed);
> +  EXPECT_EQ((std::vector<uint8_t>{0x80, 34}), VT2.Before.Bytes);
> +  EXPECT_EQ((std::vector<uint8_t>{0x81, 0xff}), VT2.Before.BytesUsed);
> +
> +  Targets[0].RetVal = 56;
> +  Targets[1].RetVal = 78;
> +  setBeforeReturnValues(Targets, 48, 16, OffsetByte, OffsetBit);
> +  EXPECT_EQ(-8ll, OffsetByte);
> +  EXPECT_EQ(0ull, OffsetBit);
> +  EXPECT_EQ((std::vector<uint8_t>{1, 12, 0, 56}), VT1.Before.Bytes);
> +  EXPECT_EQ((std::vector<uint8_t>{0x81, 0xff, 0xff, 0xff}),
> +            VT1.Before.BytesUsed);
> +  EXPECT_EQ((std::vector<uint8_t>{0x80, 34, 0, 78}), VT2.Before.Bytes);
> +  EXPECT_EQ((std::vector<uint8_t>{0x81, 0xff, 0xff, 0xff}),
> +            VT2.Before.BytesUsed);
> +
> +  Targets[0].RetVal = 1;
> +  Targets[1].RetVal = 0;
> +  setAfterReturnValues(Targets, 32, 1, OffsetByte, OffsetBit);
> +  EXPECT_EQ(4ll, OffsetByte);
> +  EXPECT_EQ(0ull, OffsetBit);
> +  EXPECT_EQ(std::vector<uint8_t>{1}, VT1.After.Bytes);
> +  EXPECT_EQ(std::vector<uint8_t>{1}, VT1.After.BytesUsed);
> +  EXPECT_EQ(std::vector<uint8_t>{0}, VT2.After.Bytes);
> +  EXPECT_EQ(std::vector<uint8_t>{1}, VT2.After.BytesUsed);
> +
> +  Targets[0].RetVal = 0;
> +  Targets[1].RetVal = 1;
> +  setAfterReturnValues(Targets, 39, 1, OffsetByte, OffsetBit);
> +  EXPECT_EQ(4ll, OffsetByte);
> +  EXPECT_EQ(7ull, OffsetBit);
> +  EXPECT_EQ(std::vector<uint8_t>{1}, VT1.After.Bytes);
> +  EXPECT_EQ(std::vector<uint8_t>{0x81}, VT1.After.BytesUsed);
> +  EXPECT_EQ(std::vector<uint8_t>{0x80}, VT2.After.Bytes);
> +  EXPECT_EQ(std::vector<uint8_t>{0x81}, VT2.After.BytesUsed);
> +
> +  Targets[0].RetVal = 12;
> +  Targets[1].RetVal = 34;
> +  setAfterReturnValues(Targets, 40, 8, OffsetByte, OffsetBit);
> +  EXPECT_EQ(5ll, OffsetByte);
> +  EXPECT_EQ(0ull, OffsetBit);
> +  EXPECT_EQ((std::vector<uint8_t>{1, 12}), VT1.After.Bytes);
> +  EXPECT_EQ((std::vector<uint8_t>{0x81, 0xff}), VT1.After.BytesUsed);
> +  EXPECT_EQ((std::vector<uint8_t>{0x80, 34}), VT2.After.Bytes);
> +  EXPECT_EQ((std::vector<uint8_t>{0x81, 0xff}), VT2.After.BytesUsed);
> +
> +  Targets[0].RetVal = 56;
> +  Targets[1].RetVal = 78;
> +  setAfterReturnValues(Targets, 48, 16, OffsetByte, OffsetBit);
> +  EXPECT_EQ(6ll, OffsetByte);
> +  EXPECT_EQ(0ull, OffsetBit);
> +  EXPECT_EQ((std::vector<uint8_t>{1, 12, 56, 0}), VT1.After.Bytes);
> +  EXPECT_EQ((std::vector<uint8_t>{0x81, 0xff, 0xff, 0xff}),
> +            VT1.After.BytesUsed);
> +  EXPECT_EQ((std::vector<uint8_t>{0x80, 34, 78, 0}), VT2.After.Bytes);
> +  EXPECT_EQ((std::vector<uint8_t>{0x81, 0xff, 0xff, 0xff}),
> +            VT2.After.BytesUsed);
> +}
>
>
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