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fuchsia / third_party / swift / refs/tags/swift-DEVELOPMENT-SNAPSHOT-2016-08-07-a / . / lib / LLVMPasses / LLVMMergeFunctions.cpp
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//===--- LLVMMergeFunctions.cpp - Merge similar functions for swift -------===//
//
// This source file is part of the Swift.org open source project
// Licensed under Apache License v2.0 with Runtime Library Exception
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
// See http://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
//
// This pass looks for similar functions that are mergeable and folds them.
// The implementation is similar to LLVM's MergeFunctions pass. Instead of
// merging identical functions, it merges functions which only differ by a few
// constants in certain instructions.
// Currently this is very Swift specific in the sense that it's intended to
// merge specialized functions which only differ by loading different metadata
// pointers.
// TODO: It could make sense to generalize this pass and move it to LLVM.
//
// This pass should run after LLVM's MergeFunctions pass, because it works best
// if there are no _identical_ functions in the module.
// Note: it would also work for identical functions but could produce more
// code overhead than the LLVM pass.
//
// There is a big TODO: currently there is a large code overlap in this file
// and the LLVM pass, mainly the IR comparison functions. This should be
// factored out into a separate utility and used by both passes.
//
//===----------------------------------------------------------------------===//
#include "swift/LLVMPasses/Passes.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/IR/ValueMap.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <vector>
using namespace llvm;
using namespace swift;
#define DEBUG_TYPE "swift-mergefunc"
STATISTIC(NumSwiftFunctionsMerged, "Number of functions merged");
STATISTIC(NumSwiftThunksWritten, "Number of thunks generated");
static cl::opt<unsigned> NumFunctionsForSanityCheck(
"swiftmergefunc-sanity",
cl::desc("How many functions in module could be used for "
"SwiftMergeFunctions pass sanity check. "
"'0' disables this check. Works only with '-debug' key."),
cl::init(0), cl::Hidden);
static cl::opt<unsigned> FunctionMergeThreshold(
"swiftmergefunc-threshold",
cl::desc("Functions larger than the threshold are considered for merging."
"'0' disables function merging at all."),
cl::init(30), cl::Hidden);
namespace {
// TODO: the following code (GlobalNumberState, FunctionComparator) is copied
// from LLVM's MergeFunctions pass. This code should be shared and not copied.
/// GlobalNumberState assigns an integer to each global value in the program,
/// which is used by the comparison routine to order references to globals. This
/// state must be preserved throughout the pass, because Functions and other
/// globals need to maintain their relative order. Globals are assigned a number
/// when they are first visited. This order is deterministic, and so the
/// assigned numbers are as well. When two functions are merged, neither number
/// is updated. If the symbols are weak, this would be incorrect. If they are
/// strong, then one will be replaced at all references to the other, and so
/// direct callsites will now see one or the other symbol, and no update is
/// necessary. Note that if we were guaranteed unique names, we could just
/// compare those, but this would not work for stripped bitcodes or for those
/// few symbols without a name.
class GlobalNumberState {
struct Config : ValueMapConfig<GlobalValue*> {
enum { FollowRAUW = false };
};
// Each GlobalValue is mapped to an identifier. The Config ensures when RAUW
// occurs, the mapping does not change. Tracking changes is unnecessary, and
// also problematic for weak symbols (which may be overwritten).
typedef ValueMap<GlobalValue *, uint64_t, Config> ValueNumberMap;
ValueNumberMap GlobalNumbers;
// The next unused serial number to assign to a global.
uint64_t NextNumber;
public:
GlobalNumberState() : GlobalNumbers(), NextNumber(0) {}
uint64_t getNumber(GlobalValue* Global) {
ValueNumberMap::iterator MapIter;
bool Inserted;
std::tie(MapIter, Inserted) = GlobalNumbers.insert({Global, NextNumber});
if (Inserted)
NextNumber++;
return MapIter->second;
}
void clear() {
GlobalNumbers.clear();
}
};
/// FunctionComparator - Compares two functions to determine whether or not
/// they will generate machine code with the same behaviour. DataLayout is
/// used if available. The comparator always fails conservatively (erring on the
/// side of claiming that two functions are different).
class FunctionComparator {
public:
FunctionComparator(const Function *F1, const Function *F2,
GlobalNumberState* GN)
: FnL(F1), FnR(F2), GlobalNumbers(GN) {}
/// Test whether the two functions have equivalent behaviour.
int compare();
/// Hash a function. Equivalent functions will have the same hash, and unequal
/// functions will have different hashes with high probability.
typedef uint64_t FunctionHash;
static FunctionHash functionHash(Function &);
private:
/// Test whether two basic blocks have equivalent behaviour.
int cmpBasicBlocks(const BasicBlock *BBL, const BasicBlock *BBR);
/// Constants comparison.
/// Its analog to lexicographical comparison between hypothetical numbers
/// of next format:
/// <bitcastability-trait><raw-bit-contents>
///
/// 1. Bitcastability.
/// Check whether L's type could be losslessly bitcasted to R's type.
/// On this stage method, in case when lossless bitcast is not possible
/// method returns -1 or 1, thus also defining which type is greater in
/// context of bitcastability.
/// Stage 0: If types are equal in terms of cmpTypes, then we can go straight
/// to the contents comparison.
/// If types differ, remember types comparison result and check
/// whether we still can bitcast types.
/// Stage 1: Types that satisfies isFirstClassType conditions are always
/// greater then others.
/// Stage 2: Vector is greater then non-vector.
/// If both types are vectors, then vector with greater bitwidth is
/// greater.
/// If both types are vectors with the same bitwidth, then types
/// are bitcastable, and we can skip other stages, and go to contents
/// comparison.
/// Stage 3: Pointer types are greater than non-pointers. If both types are
/// pointers of the same address space - go to contents comparison.
/// Different address spaces: pointer with greater address space is
/// greater.
/// Stage 4: Types are neither vectors, nor pointers. And they differ.
/// We don't know how to bitcast them. So, we better don't do it,
/// and return types comparison result (so it determines the
/// relationship among constants we don't know how to bitcast).
///
/// Just for clearance, let's see how the set of constants could look
/// on single dimension axis:
///
/// [NFCT], [FCT, "others"], [FCT, pointers], [FCT, vectors]
/// Where: NFCT - Not a FirstClassType
/// FCT - FirstClassTyp:
///
/// 2. Compare raw contents.
/// It ignores types on this stage and only compares bits from L and R.
/// Returns 0, if L and R has equivalent contents.
/// -1 or 1 if values are different.
/// Pretty trivial:
/// 2.1. If contents are numbers, compare numbers.
/// Ints with greater bitwidth are greater. Ints with same bitwidths
/// compared by their contents.
/// 2.2. "And so on". Just to avoid discrepancies with comments
/// perhaps it would be better to read the implementation itself.
/// 3. And again about overall picture. Let's look back at how the ordered set
/// of constants will look like:
/// [NFCT], [FCT, "others"], [FCT, pointers], [FCT, vectors]
///
/// Now look, what could be inside [FCT, "others"], for example:
/// [FCT, "others"] =
/// [
/// [double 0.1], [double 1.23],
/// [i32 1], [i32 2],
/// { double 1.0 }, ; StructTyID, NumElements = 1
/// { i32 1 }, ; StructTyID, NumElements = 1
/// { double 1, i32 1 }, ; StructTyID, NumElements = 2
/// { i32 1, double 1 } ; StructTyID, NumElements = 2
/// ]
///
/// Let's explain the order. Float numbers will be less than integers, just
/// because of cmpType terms: FloatTyID < IntegerTyID.
/// Floats (with same fltSemantics) are sorted according to their value.
/// Then you can see integers, and they are, like floats, which
/// could be easy sorted among each others.
/// The structures. Structures are grouped at the tail, again because of their
/// TypeID: StructTyID > IntegerTyID > FloatTyID.
/// Structures with greater number of elements are greater. Structures with
/// greater elements going first are greater.
/// The same logic with vectors, arrays and other possible complex types.
///
/// Bitcastable constants.
/// Let's assume, that some constant, belongs to some group of
/// "so-called-equal" values with different types, and at the same time
/// belongs to another group of constants with equal types
/// and "really" equal values.
///
/// Now, prove that this is impossible:
///
/// If constant A with type TyA is bitcastable to B with type TyB, then:
/// 1. All constants with equal types to TyA, are bitcastable to B. Since
/// those should be vectors (if TyA is vector), pointers
/// (if TyA is pointer), or else (if TyA equal to TyB), those types should
/// be equal to TyB.
/// 2. All constants with non-equal, but bitcastable types to TyA, are
/// bitcastable to B.
/// Once again, just because we allow it to vectors and pointers only.
/// This statement could be expanded as below:
/// 2.1. All vectors with equal bitwidth to vector A, has equal bitwidth to
/// vector B, and thus bitcastable to B as well.
/// 2.2. All pointers of the same address space, no matter what they point to,
/// bitcastable. So if C is pointer, it could be bitcasted to A and to B.
/// So any constant equal or bitcastable to A is equal or bitcastable to B.
/// QED.
///
/// In another words, for pointers and vectors, we ignore top-level type and
/// look at their particular properties (bit-width for vectors, and
/// address space for pointers).
/// If these properties are equal - compare their contents.
int cmpConstants(const Constant *L, const Constant *R) const;
/// Compares two global values by number. Uses the GlobalNumbersState to
/// identify the same globals across function calls.
int cmpGlobalValues(GlobalValue *L, GlobalValue *R) const;
/// Assign or look up previously assigned numbers for the two values, and
/// return whether the numbers are equal. Numbers are assigned in the order
/// visited.
/// Comparison order:
/// Stage 0: Value that is function itself is always greater then others.
/// If left and right values are references to their functions, then
/// they are equal.
/// Stage 1: Constants are greater than non-constants.
/// If both left and right are constants, then the result of
/// cmpConstants is used as cmpValues result.
/// Stage 2: InlineAsm instances are greater than others. If both left and
/// right are InlineAsm instances, InlineAsm* pointers casted to
/// integers and compared as numbers.
/// Stage 3: For all other cases we compare order we meet these values in
/// their functions. If right value was met first during scanning,
/// then left value is greater.
/// In another words, we compare serial numbers, for more details
/// see comments for sn_mapL and sn_mapR.
int cmpValues(const Value *L, const Value *R) const;
/// Compare two Instructions for equivalence, similar to
/// Instruction::isSameOperationAs but with modifications to the type
/// comparison.
/// Stages are listed in "most significant stage first" order:
/// On each stage below, we do comparison between some left and right
/// operation parts. If parts are non-equal, we assign parts comparison
/// result to the operation comparison result and exit from method.
/// Otherwise we proceed to the next stage.
/// Stages:
/// 1. Operations opcodes. Compared as numbers.
/// 2. Number of operands.
/// 3. Operation types. Compared with cmpType method.
/// 4. Compare operation subclass optional data as stream of bytes:
/// just convert it to integers and call cmpNumbers.
/// 5. Compare in operation operand types with cmpType in
/// most significant operand first order.
/// 6. Last stage. Check operations for some specific attributes.
/// For example, for Load it would be:
/// 6.1.Load: volatile (as boolean flag)
/// 6.2.Load: alignment (as integer numbers)
/// 6.3.Load: synch-scope (as integer numbers)
/// 6.4.Load: range metadata (as integer numbers)
/// On this stage its better to see the code, since its not more than 10-15
/// strings for particular instruction, and could change sometimes.
int cmpOperations(const Instruction *L, const Instruction *R) const;
int cmpOperands(const Instruction *L, const Instruction *R, unsigned opIdx);
/// Compare two GEPs for equivalent pointer arithmetic.
/// Parts to be compared for each comparison stage,
/// most significant stage first:
/// 1. Address space. As numbers.
/// 2. Constant offset, (using GEPOperator::accumulateConstantOffset method).
/// 3. Pointer operand type (using cmpType method).
/// 4. Number of operands.
/// 5. Compare operands, using cmpValues method.
int cmpGEPs(const GEPOperator *GEPL, const GEPOperator *GEPR);
int cmpGEPs(const GetElementPtrInst *GEPL, const GetElementPtrInst *GEPR) {
return cmpGEPs(cast<GEPOperator>(GEPL), cast<GEPOperator>(GEPR));
}
/// cmpType - compares two types,
/// defines total ordering among the types set.
///
/// Return values:
/// 0 if types are equal,
/// -1 if Left is less than Right,
/// +1 if Left is greater than Right.
///
/// Description:
/// Comparison is broken onto stages. Like in lexicographical comparison
/// stage coming first has higher priority.
/// On each explanation stage keep in mind total ordering properties.
///
/// 0. Before comparison we coerce pointer types of 0 address space to
/// integer.
/// We also don't bother with same type at left and right, so
/// just return 0 in this case.
///
/// 1. If types are of different kind (different type IDs).
/// Return result of type IDs comparison, treating them as numbers.
/// 2. If types are integers, check that they have the same width. If they
/// are vectors, check that they have the same count and subtype.
/// 3. Types have the same ID, so check whether they are one of:
/// * Void
/// * Float
/// * Double
/// * X86_FP80
/// * FP128
/// * PPC_FP128
/// * Label
/// * Metadata
/// We can treat these types as equal whenever their IDs are same.
/// 4. If Left and Right are pointers, return result of address space
/// comparison (numbers comparison). We can treat pointer types of same
/// address space as equal.
/// 5. If types are complex.
/// Then both Left and Right are to be expanded and their element types will
/// be checked with the same way. If we get Res != 0 on some stage, return it.
/// Otherwise return 0.
/// 6. For all other cases put llvm_unreachable.
int cmpTypes(Type *TyL, Type *TyR) const;
int cmpNumbers(uint64_t L, uint64_t R) const;
int cmpAPInts(const APInt &L, const APInt &R) const;
int cmpAPFloats(const APFloat &L, const APFloat &R) const;
int cmpInlineAsm(const InlineAsm *L, const InlineAsm *R) const;
int cmpMem(StringRef L, StringRef R) const;
int cmpAttrs(const AttributeSet L, const AttributeSet R) const;
int cmpRangeMetadata(const MDNode* L, const MDNode* R) const;
int cmpOperandBundlesSchema(const Instruction *L, const Instruction *R) const;
// The two functions undergoing comparison.
const Function *FnL, *FnR;
/// Assign serial numbers to values from left function, and values from
/// right function.
/// Explanation:
/// Being comparing functions we need to compare values we meet at left and
/// right sides.
/// Its easy to sort things out for external values. It just should be
/// the same value at left and right.
/// But for local values (those were introduced inside function body)
/// we have to ensure they were introduced at exactly the same place,
/// and plays the same role.
/// Let's assign serial number to each value when we meet it first time.
/// Values that were met at same place will be with same serial numbers.
/// In this case it would be good to explain few points about values assigned
/// to BBs and other ways of implementation (see below).
///
/// 1. Safety of BB reordering.
/// It's safe to change the order of BasicBlocks in function.
/// Relationship with other functions and serial numbering will not be
/// changed in this case.
/// As follows from FunctionComparator::compare(), we do CFG walk: we start
/// from the entry, and then take each terminator. So it doesn't matter how in
/// fact BBs are ordered in function. And since cmpValues are called during
/// this walk, the numbering depends only on how BBs located inside the CFG.
/// So the answer is - yes. We will get the same numbering.
///
/// 2. Impossibility to use dominance properties of values.
/// If we compare two instruction operands: first is usage of local
/// variable AL from function FL, and second is usage of local variable AR
/// from FR, we could compare their origins and check whether they are
/// defined at the same place.
/// But, we are still not able to compare operands of PHI nodes, since those
/// could be operands from further BBs we didn't scan yet.
/// So it's impossible to use dominance properties in general.
mutable DenseMap<const Value *, int> sn_mapL, sn_mapR;
// The global state we will use
GlobalNumberState* GlobalNumbers;
};
} // end anonymous namespace
int FunctionComparator::cmpNumbers(uint64_t L, uint64_t R) const {
if (L < R) return -1;
if (L > R) return 1;
return 0;
}
int FunctionComparator::cmpAPInts(const APInt &L, const APInt &R) const {
if (int Res = cmpNumbers(L.getBitWidth(), R.getBitWidth()))
return Res;
if (L.ugt(R)) return 1;
if (R.ugt(L)) return -1;
return 0;
}
int FunctionComparator::cmpAPFloats(const APFloat &L, const APFloat &R) const {
// Floats are ordered first by semantics (i.e. float, double, half, etc.),
// then by value interpreted as a bitstring (aka APInt).
const fltSemantics &SL = L.getSemantics(), &SR = R.getSemantics();
if (int Res = cmpNumbers(APFloat::semanticsPrecision(SL),
APFloat::semanticsPrecision(SR)))
return Res;
if (int Res = cmpNumbers(APFloat::semanticsMaxExponent(SL),
APFloat::semanticsMaxExponent(SR)))
return Res;
if (int Res = cmpNumbers(APFloat::semanticsMinExponent(SL),
APFloat::semanticsMinExponent(SR)))
return Res;
if (int Res = cmpNumbers(APFloat::semanticsSizeInBits(SL),
APFloat::semanticsSizeInBits(SR)))
return Res;
return cmpAPInts(L.bitcastToAPInt(), R.bitcastToAPInt());
}
int FunctionComparator::cmpMem(StringRef L, StringRef R) const {
// Prevent heavy comparison, compare sizes first.
if (int Res = cmpNumbers(L.size(), R.size()))
return Res;
// Compare strings lexicographically only when it is necessary: only when
// strings are equal in size.
return L.compare(R);
}
int FunctionComparator::cmpAttrs(const AttributeSet L,
const AttributeSet R) const {
if (int Res = cmpNumbers(L.getNumSlots(), R.getNumSlots()))
return Res;
for (unsigned i = 0, e = L.getNumSlots(); i != e; ++i) {
AttributeSet::iterator LI = L.begin(i), LE = L.end(i), RI = R.begin(i),
RE = R.end(i);
for (; LI != LE && RI != RE; ++LI, ++RI) {
Attribute LA = *LI;
Attribute RA = *RI;
if (LA < RA)
return -1;
if (RA < LA)
return 1;
}
if (LI != LE)
return 1;
if (RI != RE)
return -1;
}
return 0;
}
int FunctionComparator::cmpRangeMetadata(const MDNode* L,
const MDNode* R) const {
if (L == R)
return 0;
if (!L)
return -1;
if (!R)
return 1;
// Range metadata is a sequence of numbers. Make sure they are the same
// sequence.
// TODO: Note that as this is metadata, it is possible to drop and/or merge
// this data when considering functions to merge. Thus this comparison would
// return 0 (i.e. equivalent), but merging would become more complicated
// because the ranges would need to be combined. It is not likely that
// functions differ ONLY in this metadata if they are actually the same
// function semantically.
if (int Res = cmpNumbers(L->getNumOperands(), R->getNumOperands()))
return Res;
for (size_t I = 0; I < L->getNumOperands(); ++I) {
ConstantInt* LLow = mdconst::extract<ConstantInt>(L->getOperand(I));
ConstantInt* RLow = mdconst::extract<ConstantInt>(R->getOperand(I));
if (int Res = cmpAPInts(LLow->getValue(), RLow->getValue()))
return Res;
}
return 0;
}
int FunctionComparator::cmpOperandBundlesSchema(const Instruction *L,
const Instruction *R) const {
ImmutableCallSite LCS(L);
ImmutableCallSite RCS(R);
assert(LCS && RCS && "Must be calls or invokes!");
assert(LCS.isCall() == RCS.isCall() && "Can't compare otherwise!");
if (int Res =
cmpNumbers(LCS.getNumOperandBundles(), RCS.getNumOperandBundles()))
return Res;
for (unsigned i = 0, e = LCS.getNumOperandBundles(); i != e; ++i) {
auto OBL = LCS.getOperandBundleAt(i);
auto OBR = RCS.getOperandBundleAt(i);
if (int Res = OBL.getTagName().compare(OBR.getTagName()))
return Res;
if (int Res = cmpNumbers(OBL.Inputs.size(), OBR.Inputs.size()))
return Res;
}
return 0;
}
/// Constants comparison:
/// 1. Check whether type of L constant could be losslessly bitcasted to R
/// type.
/// 2. Compare constant contents.
/// For more details see declaration comments.
int FunctionComparator::cmpConstants(const Constant *L,
const Constant *R) const {
Type *TyL = L->getType();
Type *TyR = R->getType();
// Check whether types are bitcastable. This part is just re-factored
// Type::canLosslesslyBitCastTo method, but instead of returning true/false,
// we also pack into result which type is "less" for us.
int TypesRes = cmpTypes(TyL, TyR);
if (TypesRes != 0) {
// Types are different, but check whether we can bitcast them.
if (!TyL->isFirstClassType()) {
if (TyR->isFirstClassType())
return -1;
// Neither TyL nor TyR are values of first class type. Return the result
// of comparing the types
return TypesRes;
}
if (!TyR->isFirstClassType()) {
if (TyL->isFirstClassType())
return 1;
return TypesRes;
}
// Vector -> Vector conversions are always lossless if the two vector types
// have the same size, otherwise not.
unsigned TyLWidth = 0;
unsigned TyRWidth = 0;
if (auto *VecTyL = dyn_cast<VectorType>(TyL))
TyLWidth = VecTyL->getBitWidth();
if (auto *VecTyR = dyn_cast<VectorType>(TyR))
TyRWidth = VecTyR->getBitWidth();
if (TyLWidth != TyRWidth)
return cmpNumbers(TyLWidth, TyRWidth);
// Zero bit-width means neither TyL nor TyR are vectors.
if (!TyLWidth) {
PointerType *PTyL = dyn_cast<PointerType>(TyL);
PointerType *PTyR = dyn_cast<PointerType>(TyR);
if (PTyL && PTyR) {
unsigned AddrSpaceL = PTyL->getAddressSpace();
unsigned AddrSpaceR = PTyR->getAddressSpace();
if (int Res = cmpNumbers(AddrSpaceL, AddrSpaceR))
return Res;
}
if (PTyL)
return 1;
if (PTyR)
return -1;
// TyL and TyR aren't vectors, nor pointers. We don't know how to
// bitcast them.
return TypesRes;
}
}
// OK, types are bitcastable, now check constant contents.
if (L->isNullValue() && R->isNullValue())
return TypesRes;
if (L->isNullValue() && !R->isNullValue())
return 1;
if (!L->isNullValue() && R->isNullValue())
return -1;
auto GlobalValueL = const_cast<GlobalValue*>(dyn_cast<GlobalValue>(L));
auto GlobalValueR = const_cast<GlobalValue*>(dyn_cast<GlobalValue>(R));
if (GlobalValueL && GlobalValueR) {
return cmpGlobalValues(GlobalValueL, GlobalValueR);
}
if (int Res = cmpNumbers(L->getValueID(), R->getValueID()))
return Res;
if (const auto *SeqL = dyn_cast<ConstantDataSequential>(L)) {
const auto *SeqR = cast<ConstantDataSequential>(R);
// This handles ConstantDataArray and ConstantDataVector. Note that we
// compare the two raw data arrays, which might differ depending on the host
// endianness. This isn't a problem though, because the endianness of a
// module will affect the order of the constants, but this order is the same
// for a given input module and host platform.
return cmpMem(SeqL->getRawDataValues(), SeqR->getRawDataValues());
}
switch (L->getValueID()) {
case Value::UndefValueVal:
case Value::ConstantTokenNoneVal:
return TypesRes;
case Value::ConstantIntVal: {
const APInt &LInt = cast<ConstantInt>(L)->getValue();
const APInt &RInt = cast<ConstantInt>(R)->getValue();
return cmpAPInts(LInt, RInt);
}
case Value::ConstantFPVal: {
const APFloat &LAPF = cast<ConstantFP>(L)->getValueAPF();
const APFloat &RAPF = cast<ConstantFP>(R)->getValueAPF();
return cmpAPFloats(LAPF, RAPF);
}
case Value::ConstantArrayVal: {
const ConstantArray *LA = cast<ConstantArray>(L);
const ConstantArray *RA = cast<ConstantArray>(R);
uint64_t NumElementsL = cast<ArrayType>(TyL)->getNumElements();
uint64_t NumElementsR = cast<ArrayType>(TyR)->getNumElements();
if (int Res = cmpNumbers(NumElementsL, NumElementsR))
return Res;
for (uint64_t i = 0; i < NumElementsL; ++i) {
if (int Res = cmpConstants(cast<Constant>(LA->getOperand(i)),
cast<Constant>(RA->getOperand(i))))
return Res;
}
return 0;
}
case Value::ConstantStructVal: {
const ConstantStruct *LS = cast<ConstantStruct>(L);
const ConstantStruct *RS = cast<ConstantStruct>(R);
unsigned NumElementsL = cast<StructType>(TyL)->getNumElements();
unsigned NumElementsR = cast<StructType>(TyR)->getNumElements();
if (int Res = cmpNumbers(NumElementsL, NumElementsR))
return Res;
for (unsigned i = 0; i != NumElementsL; ++i) {
if (int Res = cmpConstants(cast<Constant>(LS->getOperand(i)),
cast<Constant>(RS->getOperand(i))))
return Res;
}
return 0;
}
case Value::ConstantVectorVal: {
const ConstantVector *LV = cast<ConstantVector>(L);
const ConstantVector *RV = cast<ConstantVector>(R);
unsigned NumElementsL = cast<VectorType>(TyL)->getNumElements();
unsigned NumElementsR = cast<VectorType>(TyR)->getNumElements();
if (int Res = cmpNumbers(NumElementsL, NumElementsR))
return Res;
for (uint64_t i = 0; i < NumElementsL; ++i) {
if (int Res = cmpConstants(cast<Constant>(LV->getOperand(i)),
cast<Constant>(RV->getOperand(i))))
return Res;
}
return 0;
}
case Value::ConstantExprVal: {
const ConstantExpr *LE = cast<ConstantExpr>(L);
const ConstantExpr *RE = cast<ConstantExpr>(R);
unsigned NumOperandsL = LE->getNumOperands();
unsigned NumOperandsR = RE->getNumOperands();
if (int Res = cmpNumbers(NumOperandsL, NumOperandsR))
return Res;
for (unsigned i = 0; i < NumOperandsL; ++i) {
if (int Res = cmpConstants(cast<Constant>(LE->getOperand(i)),
cast<Constant>(RE->getOperand(i))))
return Res;
}
return 0;
}
case Value::BlockAddressVal: {
const BlockAddress *LBA = cast<BlockAddress>(L);
const BlockAddress *RBA = cast<BlockAddress>(R);
if (int Res = cmpValues(LBA->getFunction(), RBA->getFunction()))
return Res;
if (LBA->getFunction() == RBA->getFunction()) {
// They are BBs in the same function. Order by which comes first in the
// BB order of the function. This order is deterministic.
Function* F = LBA->getFunction();
BasicBlock *LBB = LBA->getBasicBlock();
BasicBlock *RBB = RBA->getBasicBlock();
if (LBB == RBB)
return 0;
for (BasicBlock &BB : F->getBasicBlockList()) {
if (&BB == LBB) {
assert(&BB != RBB);
return -1;
}
if (&BB == RBB)
return 1;
}
llvm_unreachable("Basic Block Address does not point to a basic block in "
"its function.");
return -1;
} else {
// cmpValues said the functions are the same. So because they aren't
// literally the same pointer, they must respectively be the left and
// right functions.
assert(LBA->getFunction() == FnL && RBA->getFunction() == FnR);
// cmpValues will tell us if these are equivalent BasicBlocks, in the
// context of their respective functions.
return cmpValues(LBA->getBasicBlock(), RBA->getBasicBlock());
}
}
default: // Unknown constant, abort.
DEBUG(dbgs() << "Looking at valueID " << L->getValueID() << "\n");
llvm_unreachable("Constant ValueID not recognized.");
return -1;
}
}
int FunctionComparator::cmpGlobalValues(GlobalValue *L, GlobalValue *R) const {
return cmpNumbers(GlobalNumbers->getNumber(L), GlobalNumbers->getNumber(R));
}
/// cmpType - compares two types,
/// defines total ordering among the types set.
/// See method declaration comments for more details.
int FunctionComparator::cmpTypes(Type *TyL, Type *TyR) const {
PointerType *PTyL = dyn_cast<PointerType>(TyL);
PointerType *PTyR = dyn_cast<PointerType>(TyR);
const DataLayout &DL = FnL->getParent()->getDataLayout();
if (PTyL && PTyL->getAddressSpace() == 0)
TyL = DL.getIntPtrType(TyL);
if (PTyR && PTyR->getAddressSpace() == 0)
TyR = DL.getIntPtrType(TyR);
if (TyL == TyR)
return 0;
if (int Res = cmpNumbers(TyL->getTypeID(), TyR->getTypeID()))
return Res;
switch (TyL->getTypeID()) {
default:
llvm_unreachable("Unknown type!");
// Fall through in Release mode.
case Type::IntegerTyID:
return cmpNumbers(cast<IntegerType>(TyL)->getBitWidth(),
cast<IntegerType>(TyR)->getBitWidth());
case Type::VectorTyID: {
VectorType *VTyL = cast<VectorType>(TyL), *VTyR = cast<VectorType>(TyR);
if (int Res = cmpNumbers(VTyL->getNumElements(), VTyR->getNumElements()))
return Res;
return cmpTypes(VTyL->getElementType(), VTyR->getElementType());
}
// TyL == TyR would have returned true earlier, because types are uniqued.
case Type::VoidTyID:
case Type::FloatTyID:
case Type::DoubleTyID:
case Type::X86_FP80TyID:
case Type::FP128TyID:
case Type::PPC_FP128TyID:
case Type::LabelTyID:
case Type::MetadataTyID:
case Type::TokenTyID:
return 0;
case Type::PointerTyID: {
assert(PTyL && PTyR && "Both types must be pointers here.");
return cmpNumbers(PTyL->getAddressSpace(), PTyR->getAddressSpace());
}
case Type::StructTyID: {
StructType *STyL = cast<StructType>(TyL);
StructType *STyR = cast<StructType>(TyR);
if (STyL->getNumElements() != STyR->getNumElements())
return cmpNumbers(STyL->getNumElements(), STyR->getNumElements());
if (STyL->isPacked() != STyR->isPacked())
return cmpNumbers(STyL->isPacked(), STyR->isPacked());
for (unsigned i = 0, e = STyL->getNumElements(); i != e; ++i) {
if (int Res = cmpTypes(STyL->getElementType(i), STyR->getElementType(i)))
return Res;
}
return 0;
}
case Type::FunctionTyID: {
FunctionType *FTyL = cast<FunctionType>(TyL);
FunctionType *FTyR = cast<FunctionType>(TyR);
if (FTyL->getNumParams() != FTyR->getNumParams())
return cmpNumbers(FTyL->getNumParams(), FTyR->getNumParams());
if (FTyL->isVarArg() != FTyR->isVarArg())
return cmpNumbers(FTyL->isVarArg(), FTyR->isVarArg());
if (int Res = cmpTypes(FTyL->getReturnType(), FTyR->getReturnType()))
return Res;
for (unsigned i = 0, e = FTyL->getNumParams(); i != e; ++i) {
if (int Res = cmpTypes(FTyL->getParamType(i), FTyR->getParamType(i)))
return Res;
}
return 0;
}
case Type::ArrayTyID: {
ArrayType *ATyL = cast<ArrayType>(TyL);
ArrayType *ATyR = cast<ArrayType>(TyR);
if (ATyL->getNumElements() != ATyR->getNumElements())
return cmpNumbers(ATyL->getNumElements(), ATyR->getNumElements());
return cmpTypes(ATyL->getElementType(), ATyR->getElementType());
}
}
}
// Determine whether the two operations are the same except that pointer-to-A
// and pointer-to-B are equivalent. This should be kept in sync with
// Instruction::isSameOperationAs.
// Read method declaration comments for more details.
int FunctionComparator::cmpOperations(const Instruction *L,
const Instruction *R) const {
// Differences from Instruction::isSameOperationAs:
// * replace type comparison with calls to isEquivalentType.
// * we test for I->hasSameSubclassOptionalData (nuw/nsw/tail) at the top
// * because of the above, we don't test for the tail bit on calls later on
if (int Res = cmpNumbers(L->getOpcode(), R->getOpcode()))
return Res;
if (int Res = cmpNumbers(L->getNumOperands(), R->getNumOperands()))
return Res;
if (int Res = cmpTypes(L->getType(), R->getType()))
return Res;
if (int Res = cmpNumbers(L->getRawSubclassOptionalData(),
R->getRawSubclassOptionalData()))
return Res;
if (const AllocaInst *AI = dyn_cast<AllocaInst>(L)) {
if (int Res = cmpTypes(AI->getAllocatedType(),
cast<AllocaInst>(R)->getAllocatedType()))
return Res;
if (int Res =
cmpNumbers(AI->getAlignment(), cast<AllocaInst>(R)->getAlignment()))
return Res;
}
// We have two instructions of identical opcode and #operands. Check to see
// if all operands are the same type
for (unsigned i = 0, e = L->getNumOperands(); i != e; ++i) {
if (int Res =
cmpTypes(L->getOperand(i)->getType(), R->getOperand(i)->getType()))
return Res;
}
// Check special state that is a part of some instructions.
if (const LoadInst *LI = dyn_cast<LoadInst>(L)) {
if (int Res = cmpNumbers(LI->isVolatile(), cast<LoadInst>(R)->isVolatile()))
return Res;
if (int Res =
cmpNumbers(LI->getAlignment(), cast<LoadInst>(R)->getAlignment()))
return Res;
if (int Res =
cmpNumbers(LI->getOrdering(), cast<LoadInst>(R)->getOrdering()))
return Res;
if (int Res =
cmpNumbers(LI->getSynchScope(), cast<LoadInst>(R)->getSynchScope()))
return Res;
return cmpRangeMetadata(LI->getMetadata(LLVMContext::MD_range),
cast<LoadInst>(R)->getMetadata(LLVMContext::MD_range));
}
if (const StoreInst *SI = dyn_cast<StoreInst>(L)) {
if (int Res =
cmpNumbers(SI->isVolatile(), cast<StoreInst>(R)->isVolatile()))
return Res;
if (int Res =
cmpNumbers(SI->getAlignment(), cast<StoreInst>(R)->getAlignment()))
return Res;
if (int Res =
cmpNumbers(SI->getOrdering(), cast<StoreInst>(R)->getOrdering()))
return Res;
return cmpNumbers(SI->getSynchScope(), cast<StoreInst>(R)->getSynchScope());
}
if (const CmpInst *CI = dyn_cast<CmpInst>(L))
return cmpNumbers(CI->getPredicate(), cast<CmpInst>(R)->getPredicate());
if (const CallInst *CI = dyn_cast<CallInst>(L)) {
if (int Res = cmpNumbers(CI->getCallingConv(),
cast<CallInst>(R)->getCallingConv()))
return Res;
if (int Res =
cmpAttrs(CI->getAttributes(), cast<CallInst>(R)->getAttributes()))
return Res;
if (int Res = cmpOperandBundlesSchema(CI, R))
return Res;
return cmpRangeMetadata(
CI->getMetadata(LLVMContext::MD_range),
cast<CallInst>(R)->getMetadata(LLVMContext::MD_range));
}
if (const InvokeInst *II = dyn_cast<InvokeInst>(L)) {
if (int Res = cmpNumbers(II->getCallingConv(),
cast<InvokeInst>(R)->getCallingConv()))
return Res;
if (int Res =
cmpAttrs(II->getAttributes(), cast<InvokeInst>(R)->getAttributes()))
return Res;
if (int Res = cmpOperandBundlesSchema(II, R))
return Res;
return cmpRangeMetadata(
II->getMetadata(LLVMContext::MD_range),
cast<InvokeInst>(R)->getMetadata(LLVMContext::MD_range));
}
if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(L)) {
ArrayRef<unsigned> LIndices = IVI->getIndices();
ArrayRef<unsigned> RIndices = cast<InsertValueInst>(R)->getIndices();
if (int Res = cmpNumbers(LIndices.size(), RIndices.size()))
return Res;
for (size_t i = 0, e = LIndices.size(); i != e; ++i) {
if (int Res = cmpNumbers(LIndices[i], RIndices[i]))
return Res;
}
}
if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(L)) {
ArrayRef<unsigned> LIndices = EVI->getIndices();
ArrayRef<unsigned> RIndices = cast<ExtractValueInst>(R)->getIndices();
if (int Res = cmpNumbers(LIndices.size(), RIndices.size()))
return Res;
for (size_t i = 0, e = LIndices.size(); i != e; ++i) {
if (int Res = cmpNumbers(LIndices[i], RIndices[i]))
return Res;
}
}
if (const FenceInst *FI = dyn_cast<FenceInst>(L)) {
if (int Res =
cmpNumbers(FI->getOrdering(), cast<FenceInst>(R)->getOrdering()))
return Res;
return cmpNumbers(FI->getSynchScope(), cast<FenceInst>(R)->getSynchScope());
}
if (const AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(L)) {
if (int Res = cmpNumbers(CXI->isVolatile(),
cast<AtomicCmpXchgInst>(R)->isVolatile()))
return Res;
if (int Res = cmpNumbers(CXI->isWeak(),
cast<AtomicCmpXchgInst>(R)->isWeak()))
return Res;
if (int Res = cmpNumbers(CXI->getSuccessOrdering(),
cast<AtomicCmpXchgInst>(R)->getSuccessOrdering()))
return Res;
if (int Res = cmpNumbers(CXI->getFailureOrdering(),
cast<AtomicCmpXchgInst>(R)->getFailureOrdering()))
return Res;
return cmpNumbers(CXI->getSynchScope(),
cast<AtomicCmpXchgInst>(R)->getSynchScope());
}
if (const AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(L)) {
if (int Res = cmpNumbers(RMWI->getOperation(),
cast<AtomicRMWInst>(R)->getOperation()))
return Res;
if (int Res = cmpNumbers(RMWI->isVolatile(),
cast<AtomicRMWInst>(R)->isVolatile()))
return Res;
if (int Res = cmpNumbers(RMWI->getOrdering(),
cast<AtomicRMWInst>(R)->getOrdering()))
return Res;
return cmpNumbers(RMWI->getSynchScope(),
cast<AtomicRMWInst>(R)->getSynchScope());
}
if (const PHINode *PNL = dyn_cast<PHINode>(L)) {
const PHINode *PNR = cast<PHINode>(R);
// Ensure that in addition to the incoming values being identical
// (checked by the caller of this function), the incoming blocks
// are also identical.
for (unsigned i = 0, e = PNL->getNumIncomingValues(); i != e; ++i) {
if (int Res =
cmpValues(PNL->getIncomingBlock(i), PNR->getIncomingBlock(i)))
return Res;
}
}
return 0;
}
// Determine whether two GEP operations perform the same underlying arithmetic.
// Read method declaration comments for more details.
int FunctionComparator::cmpGEPs(const GEPOperator *GEPL,
const GEPOperator *GEPR) {
unsigned int ASL = GEPL->getPointerAddressSpace();
unsigned int ASR = GEPR->getPointerAddressSpace();
if (int Res = cmpNumbers(ASL, ASR))
return Res;
// When we have target data, we can reduce the GEP down to the value in bytes
// added to the address.
const DataLayout &DL = FnL->getParent()->getDataLayout();
unsigned BitWidth = DL.getPointerSizeInBits(ASL);
APInt OffsetL(BitWidth, 0), OffsetR(BitWidth, 0);
if (GEPL->accumulateConstantOffset(DL, OffsetL) &&
GEPR->accumulateConstantOffset(DL, OffsetR))
return cmpAPInts(OffsetL, OffsetR);
if (int Res = cmpTypes(GEPL->getSourceElementType(),
GEPR->getSourceElementType()))
return Res;
if (int Res = cmpNumbers(GEPL->getNumOperands(), GEPR->getNumOperands()))
return Res;
for (unsigned i = 0, e = GEPL->getNumOperands(); i != e; ++i) {
if (int Res = cmpValues(GEPL->getOperand(i), GEPR->getOperand(i)))
return Res;
}
return 0;
}
int FunctionComparator::cmpInlineAsm(const InlineAsm *L,
const InlineAsm *R) const {
// InlineAsm's are uniqued. If they are the same pointer, obviously they are
// the same, otherwise compare the fields.
if (L == R)
return 0;
if (int Res = cmpTypes(L->getFunctionType(), R->getFunctionType()))
return Res;
if (int Res = cmpMem(L->getAsmString(), R->getAsmString()))
return Res;
if (int Res = cmpMem(L->getConstraintString(), R->getConstraintString()))
return Res;
if (int Res = cmpNumbers(L->hasSideEffects(), R->hasSideEffects()))
return Res;
if (int Res = cmpNumbers(L->isAlignStack(), R->isAlignStack()))
return Res;
if (int Res = cmpNumbers(L->getDialect(), R->getDialect()))
return Res;
llvm_unreachable("InlineAsm blocks were not uniqued.");
return 0;
}
/// Compare two values used by the two functions under pair-wise comparison. If
/// this is the first time the values are seen, they're added to the mapping so
/// that we will detect mismatches on next use.
/// See comments in declaration for more details.
int FunctionComparator::cmpValues(const Value *L, const Value *R) const {
// Catch self-reference case.
if (L == FnL) {
if (R == FnR)
return 0;
return -1;
}
if (R == FnR) {
if (L == FnL)
return 0;
return 1;
}
const Constant *ConstL = dyn_cast<Constant>(L);
const Constant *ConstR = dyn_cast<Constant>(R);
if (ConstL && ConstR) {
if (L == R)
return 0;
return cmpConstants(ConstL, ConstR);
}
if (ConstL)
return 1;
if (ConstR)
return -1;
const InlineAsm *InlineAsmL = dyn_cast<InlineAsm>(L);
const InlineAsm *InlineAsmR = dyn_cast<InlineAsm>(R);
if (InlineAsmL && InlineAsmR)
return cmpInlineAsm(InlineAsmL, InlineAsmR);
if (InlineAsmL)
return 1;
if (InlineAsmR)
return -1;
auto LeftSN = sn_mapL.insert(std::make_pair(L, sn_mapL.size())),
RightSN = sn_mapR.insert(std::make_pair(R, sn_mapR.size()));
return cmpNumbers(LeftSN.first->second, RightSN.first->second);
}
static bool isEligibleForConstantSharing(const Instruction *I) {
switch (I->getOpcode()) {
case Instruction::Load:
case Instruction::Store:
case Instruction::Call:
return true;
default:
return false;
}
}
int FunctionComparator::cmpOperands(const Instruction *L, const Instruction *R,
unsigned opIdx) {
Value *OpL = L->getOperand(opIdx);
Value *OpR = R->getOperand(opIdx);
int Res = cmpValues(OpL, OpR);
if (Res == 0)
return Res;
if (!isa<Constant>(OpL) || !isa<Constant>(OpR))
return Res;
if (!isEligibleForConstantSharing(L))
return Res;
if (const CallInst *CL = dyn_cast<CallInst>(L)) {
if (CL->isInlineAsm())
return Res;
if (Function *CalleeL = CL->getCalledFunction()) {
if (CalleeL->isIntrinsic())
return Res;
}
const CallInst *CR = cast<CallInst>(R);
if (CR->isInlineAsm())
return Res;
if (Function *CalleeR = CR->getCalledFunction()) {
if (CalleeR->isIntrinsic())
return Res;
}
}
if (cmpTypes(OpL->getType(), OpR->getType()))
return Res;
return 0;
}
// Test whether two basic blocks have equivalent behaviour.
int FunctionComparator::cmpBasicBlocks(const BasicBlock *BBL,
const BasicBlock *BBR) {
BasicBlock::const_iterator InstL = BBL->begin(), InstLE = BBL->end();
BasicBlock::const_iterator InstR = BBR->begin(), InstRE = BBR->end();
do {
if (int Res = cmpValues(&*InstL, &*InstR))
return Res;
const GetElementPtrInst *GEPL = dyn_cast<GetElementPtrInst>(InstL);
const GetElementPtrInst *GEPR = dyn_cast<GetElementPtrInst>(InstR);
if (GEPL && !GEPR)
return 1;
if (GEPR && !GEPL)
return -1;
if (GEPL && GEPR) {
if (int Res =
cmpValues(GEPL->getPointerOperand(), GEPR->getPointerOperand()))
return Res;
if (int Res = cmpGEPs(GEPL, GEPR))
return Res;
} else {
if (int Res = cmpOperations(&*InstL, &*InstR))
return Res;
assert(InstL->getNumOperands() == InstR->getNumOperands());
for (unsigned i = 0, e = InstL->getNumOperands(); i != e; ++i) {
if (int Res = cmpOperands(&*InstL, &*InstR, i))
return Res;
// cmpValues should ensure this is true.
assert(cmpTypes(InstL->getOperand(i)->getType(),
InstR->getOperand(i)->getType()) == 0);
}
}
++InstL, ++InstR;
} while (InstL != InstLE && InstR != InstRE);
if (InstL != InstLE && InstR == InstRE)
return 1;
if (InstL == InstLE && InstR != InstRE)
return -1;
return 0;
}
// Test whether the two functions have equivalent behaviour.
int FunctionComparator::compare() {
sn_mapL.clear();
sn_mapR.clear();
if (int Res = cmpAttrs(FnL->getAttributes(), FnR->getAttributes()))
return Res;
if (int Res = cmpNumbers(FnL->hasGC(), FnR->hasGC()))
return Res;
if (FnL->hasGC()) {
if (int Res = cmpMem(FnL->getGC(), FnR->getGC()))
return Res;
}
if (int Res = cmpNumbers(FnL->hasSection(), FnR->hasSection()))
return Res;
if (FnL->hasSection()) {
if (int Res = cmpMem(FnL->getSection(), FnR->getSection()))
return Res;
}
if (int Res = cmpNumbers(FnL->isVarArg(), FnR->isVarArg()))
return Res;
// TODO: if it's internal and only used in direct calls, we could handle this
// case too.
if (int Res = cmpNumbers(FnL->getCallingConv(), FnR->getCallingConv()))
return Res;
if (int Res = cmpTypes(FnL->getFunctionType(), FnR->getFunctionType()))
return Res;
assert(FnL->arg_size() == FnR->arg_size() &&
"Identically typed functions have different numbers of args!");
// Visit the arguments so that they get enumerated in the order they're
// passed in.
for (Function::const_arg_iterator ArgLI = FnL->arg_begin(),
ArgRI = FnR->arg_begin(),
ArgLE = FnL->arg_end();
ArgLI != ArgLE; ++ArgLI, ++ArgRI) {
if (cmpValues(&*ArgLI, &*ArgRI) != 0)
llvm_unreachable("Arguments repeat!");
}
Function::const_iterator LIter = FnL->begin(), LEnd = FnL->end();
Function::const_iterator RIter = FnR->begin(), REnd = FnR->end();
do {
const BasicBlock *BBL = &*LIter;
const BasicBlock *BBR = &*RIter;
if (int Res = cmpValues(BBL, BBR))
return Res;
if (int Res = cmpBasicBlocks(BBL, BBR))
return Res;
++LIter, ++RIter;
} while (LIter != LEnd && RIter != REnd);
return 0;
}
namespace {
// Accumulate the hash of a sequence of 64-bit integers. This is similar to a
// hash of a sequence of 64bit ints, but the entire input does not need to be
// available at once. This interface is necessary for functionHash because it
// needs to accumulate the hash as the structure of the function is traversed
// without saving these values to an intermediate buffer. This form of hashing
// is not often needed, as usually the object to hash is just read from a
// buffer.
class HashAccumulator64 {
uint64_t Hash;
public:
// Initialize to random constant, so the state isn't zero.
HashAccumulator64() { Hash = 0x6acaa36bef8325c5ULL; }
void add(uint64_t V) {
Hash = llvm::hashing::detail::hash_16_bytes(Hash, V);
}
// No finishing is required, because the entire hash value is used.
uint64_t getHash() { return Hash; }
};
} // end anonymous namespace
// A function hash is calculated by considering only the number of arguments and
// whether a function is varargs, the order of basic blocks (given by the
// successors of each basic block in depth first order), and the order of
// opcodes of each instruction within each of these basic blocks. This mirrors
// the strategy compare() uses to compare functions by walking the BBs in depth
// first order and comparing each instruction in sequence. Because this hash
// does not look at the operands, it is insensitive to things such as the
// target of calls and the constants used in the function, which makes it useful
// when possibly merging functions which are the same modulo constants and call
// targets.
FunctionComparator::FunctionHash FunctionComparator::functionHash(Function &F) {
HashAccumulator64 H;
H.add(F.isVarArg());
H.add(F.arg_size());
SmallVector<const BasicBlock *, 8> BBs;
SmallSet<const BasicBlock *, 16> VisitedBBs;
// Walk the blocks in the same order as FunctionComparator::cmpBasicBlocks(),
// accumulating the hash of the function "structure." (BB and opcode sequence)
BBs.push_back(&F.getEntryBlock());
VisitedBBs.insert(BBs[0]);
while (!BBs.empty()) {
const BasicBlock *BB = BBs.pop_back_val();
// This random value acts as a block header, as otherwise the partition of
// opcodes into BBs wouldn't affect the hash, only the order of the opcodes
H.add(45798);
for (auto &Inst : *BB) {
H.add(Inst.getOpcode());
}
const TerminatorInst *Term = BB->getTerminator();
for (unsigned i = 0, e = Term->getNumSuccessors(); i != e; ++i) {
if (!VisitedBBs.insert(Term->getSuccessor(i)).second)
continue;
BBs.push_back(Term->getSuccessor(i));
}
}
return H.getHash();
}
namespace {
/// SwiftMergeFunctions finds functions which only differ by constants in
/// certain instructions, e.g. resulting from specialized functions of layout
/// compatible types.
/// Such functions are merged by replacing the differing constants by a
/// parameter. The original functions are replaced by thunks which call the
/// merged function with the specific argument constants.
///
class SwiftMergeFunctions : public ModulePass {
public:
static char ID;
SwiftMergeFunctions()
: ModulePass(ID), FnTree(FunctionNodeCmp(&GlobalNumbers)) {
}
bool runOnModule(Module &M) override;
private:
enum {
/// The maximum number of parameters added to a merged functions. This
/// roughly corresponds to the number of differing constants.
maxAddedParams = 4
};
struct FunctionEntry;
/// Describes the set of functions which are considered as "equivalent" (i.e.
/// only differing by some constants).
struct EquivalenceClass {
/// The single-linked list of all functions which are a member of this
/// equivalence class.
FunctionEntry *First;
/// A very cheap hash, used to early exit if functions do not match.
FunctionComparator::FunctionHash Hash;
public:
// Note the hash is recalculated potentially multiple times, but it is cheap.
EquivalenceClass(FunctionEntry *First)
: First(First), Hash(FunctionComparator::functionHash(*First->F)) {
assert(!First->Next);
}
};
/// The function comparison operator is provided here so that FunctionNodes do
/// not need to become larger with another pointer.
class FunctionNodeCmp {
GlobalNumberState* GlobalNumbers;
public:
FunctionNodeCmp(GlobalNumberState* GN) : GlobalNumbers(GN) {}
bool operator()(const EquivalenceClass &LHS, const EquivalenceClass &RHS) const {
// Order first by hashes, then full function comparison.
if (LHS.Hash != RHS.Hash)
return LHS.Hash < RHS.Hash;
FunctionComparator FCmp(LHS.First->F, RHS.First->F, GlobalNumbers);
return FCmp.compare() == -1;
}
};
typedef std::set<EquivalenceClass, FunctionNodeCmp> FnTreeType;
///
struct FunctionEntry {
FunctionEntry(Function *F, FnTreeType::iterator I) :
F(F), Next(nullptr), numUnhandledCallees(0), TreeIter(I),
isMerged(false) { }
/// Back-link to the function.
AssertingVH<Function> F;
/// The next function in its equivalence class.
FunctionEntry *Next;
/// The number of not-yet merged callees. Used to process the merging in
/// bottom-up call order.
/// This is only valid in the first entry of an equivalence class. The
/// counts of all functions in an equivalence class are accumulated in the
/// first entry.
int numUnhandledCallees;
/// The iterator of the function's equivalence class in the FnTree.
/// It's FnTree.end() if the function is not in an equivalence class.
FnTreeType::iterator TreeIter;
/// True if this function is already a thunk, calling the merged function.
bool isMerged;
};
/// Describes an operator of a specific instruction.
struct OpLocation {
Instruction *I;
unsigned OpIndex;
};
/// Information for a function. Used during merging.
struct FunctionInfo {
FunctionInfo(Function *F) : F(F), CurrentInst(nullptr), NumParamsNeeded(0) {
}
void init() {
CurrentInst = &*F->begin()->begin();
NumParamsNeeded = 0;
}
/// Advances the current instruction to the next instruction.
void nextInst() {
assert(CurrentInst);
if (isa<TerminatorInst>(CurrentInst)) {
auto BlockIter = std::next(CurrentInst->getParent()->getIterator());
if (BlockIter == F->end()) {
CurrentInst = nullptr;
return;
}
CurrentInst = &*BlockIter->begin();
return;
}
CurrentInst = &*std::next(CurrentInst->getIterator());
}
Function *F;
/// The current instruction while iterating over all instructions.
Instruction *CurrentInst;
/// Roughly the number of parameters needed if this function would be
/// merged with the first function of the equivalence class.
int NumParamsNeeded;
};
typedef SmallVector<FunctionInfo, 8> FunctionInfos;
/// Describes a parameter which we create to parameterize the merged function.
struct ParamInfo {
/// The value of the parameter for all the functions in the equivalence
/// class.
SmallVector<Constant *, 8> Values;
/// All uses of the parameter in the merged function.
SmallVector<OpLocation, 16> Uses;
/// Checks if this parameter can be used to describe an operand in all
/// functions of the equivalence class. Returns true if all values match
/// the specific instruction operands in all functions.
bool matches(const FunctionInfos &FInfos, unsigned OpIdx) const {
unsigned NumFuncs = FInfos.size();
assert(Values.size() == NumFuncs);
for (unsigned Idx = 0; Idx < NumFuncs; ++Idx) {
const FunctionInfo &FI = FInfos[Idx];
Constant *C = cast<Constant>(FI.CurrentInst->getOperand(OpIdx));
if (Values[Idx] != C)
return false;
}
return true;
}
};
typedef SmallVector<ParamInfo, maxAddedParams> ParamInfos;
GlobalNumberState GlobalNumbers;
/// A work queue of functions that may have been modified and should be
/// analyzed again.
std::vector<WeakVH> Deferred;
/// The set of all distinct functions. Use the insert() and remove() methods
/// to modify it. The map allows efficient lookup and deferring of Functions.
FnTreeType FnTree;
ValueMap<Function*, FunctionEntry *> FuncEntries;
FunctionEntry *getEntry(Function *F) const {
return FuncEntries.lookup(F);
}
bool isInEquivalenceClass(FunctionEntry *FE) const {
if (FE->TreeIter != FnTree.end()) {
return true;
}
assert(!FE->Next);
assert(FE->numUnhandledCallees == 0);
return false;
}
/// Checks the rules of order relation introduced among functions set.
/// Returns true, if sanity check has been passed, and false if failed.
bool doSanityCheck(std::vector<WeakVH> &Worklist);
/// Updates the numUnhandledCallees of all user functions of the equivalence
/// class containing \p FE by \p Delta.
void updateUnhandledCalleeCount(FunctionEntry *FE, int Delta);
bool tryMergeEquivalenceClass(FunctionEntry *FirstInClass);
FunctionInfo removeFuncWithMostParams(FunctionInfos &FInfos);
bool deriveParams(ParamInfos &Params, FunctionInfos &FInfos);
bool constsDiffer(const FunctionInfos &FInfos, unsigned OpIdx);
bool tryMapToParameter(FunctionInfos &FInfos, unsigned OpIdx,
ParamInfos &Params);
void mergeWithParams(const FunctionInfos &FInfos, ParamInfos &Params);
void removeEquivalenceClassFromTree(FunctionEntry *FE);
void writeThunk(Function *ToFunc, Function *Thunk,
const ParamInfos &Params, unsigned FuncIdx);
/// Replace all direct calls of Old with calls of New. Will bitcast New if
/// necessary to make types match.
bool replaceDirectCallers(Function *Old, Function *New,
const ParamInfos &Params, unsigned FuncIdx);
};
} // end anonymous namespace
char SwiftMergeFunctions::ID = 0;
INITIALIZE_PASS_BEGIN(SwiftMergeFunctions,
"swift-merge-functions", "Swift merge function pass",
false, false)
INITIALIZE_PASS_END(SwiftMergeFunctions,
"swift-merge-functions", "Swift merge function pass",
false, false)
llvm::ModulePass *swift::createSwiftMergeFunctionsPass() {
initializeSwiftMergeFunctionsPass(*llvm::PassRegistry::getPassRegistry());
return new SwiftMergeFunctions();
}
bool SwiftMergeFunctions::doSanityCheck(std::vector<WeakVH> &Worklist) {
if (const unsigned Max = NumFunctionsForSanityCheck) {
unsigned TripleNumber = 0;
bool Valid = true;
dbgs() << "MERGEFUNC-SANITY: Started for first " << Max << " functions.\n";
unsigned i = 0;
for (std::vector<WeakVH>::iterator I = Worklist.begin(), E = Worklist.end();
I != E && i < Max; ++I, ++i) {
unsigned j = i;
for (std::vector<WeakVH>::iterator J = I; J != E && j < Max; ++J, ++j) {
Function *F1 = cast<Function>(*I);
Function *F2 = cast<Function>(*J);
int Res1 = FunctionComparator(F1, F2, &GlobalNumbers).compare();
int Res2 = FunctionComparator(F2, F1, &GlobalNumbers).compare();
// If F1 <= F2, then F2 >= F1, otherwise report failure.
if (Res1 != -Res2) {
dbgs() << "MERGEFUNC-SANITY: Non-symmetric; triple: " << TripleNumber
<< "\n";
F1->dump();
F2->dump();
Valid = false;
}
if (Res1 == 0)
continue;
unsigned k = j;
for (std::vector<WeakVH>::iterator K = J; K != E && k < Max;
++k, ++K, ++TripleNumber) {
if (K == J)
continue;
Function *F3 = cast<Function>(*K);
int Res3 = FunctionComparator(F1, F3, &GlobalNumbers).compare();
int Res4 = FunctionComparator(F2, F3, &GlobalNumbers).compare();
bool Transitive = true;
if (Res1 != 0 && Res1 == Res4) {
// F1 > F2, F2 > F3 => F1 > F3
Transitive = Res3 == Res1;
} else if (Res3 != 0 && Res3 == -Res4) {
// F1 > F3, F3 > F2 => F1 > F2
Transitive = Res3 == Res1;
} else if (Res4 != 0 && -Res3 == Res4) {
// F2 > F3, F3 > F1 => F2 > F1
Transitive = Res4 == -Res1;
}
if (!Transitive) {
dbgs() << "MERGEFUNC-SANITY: Non-transitive; triple: "
<< TripleNumber << "\n";
dbgs() << "Res1, Res3, Res4: " << Res1 << ", " << Res3 << ", "
<< Res4 << "\n";
F1->dump();
F2->dump();
F3->dump();
Valid = false;
}
}
}
}
dbgs() << "MERGEFUNC-SANITY: " << (Valid ? "Passed." : "Failed.") << "\n";
return Valid;
}
return true;
}
/// Returns true if function \p F is eligible for merging.
static bool isEligibleFunction(Function *F) {
if (F->isDeclaration())
return false;
if (F->hasAvailableExternallyLinkage())
return false;
if (F->getFunctionType()->isVarArg())
return false;
unsigned Benefit = 0;
// We don't want to merge very small functions, because the overhead of
// adding creating thunks and/or adding parameters to the call sites
// outweighs the benefit.
for (BasicBlock &BB : *F) {
for (Instruction &I : BB) {
if (CallSite CS = CallSite(&I)) {
Function *Callee = CS.getCalledFunction();
if (!Callee || !Callee->isIntrinsic()) {
Benefit += 5;
continue;
}
}
Benefit += 1;
}
}
if (Benefit < FunctionMergeThreshold)
return false;
return true;
}
bool SwiftMergeFunctions::runOnModule(Module &M) {
if (FunctionMergeThreshold == 0)
return false;
bool Changed = false;
// All functions in the module, ordered by hash. Functions with a unique
// hash value are easily eliminated.
std::vector<std::pair<FunctionComparator::FunctionHash, Function *>>
HashedFuncs;
for (Function &Func : M) {
if (isEligibleFunction(&Func)) {
HashedFuncs.push_back({FunctionComparator::functionHash(Func), &Func});
}
}
std::stable_sort(
HashedFuncs.begin(), HashedFuncs.end(),
[](const std::pair<FunctionComparator::FunctionHash, Function *> &a,
const std::pair<FunctionComparator::FunctionHash, Function *> &b) {
return a.first < b.first;
});
std::vector<FunctionEntry> FuncEntryStorage;
FuncEntryStorage.reserve(HashedFuncs.size());
auto S = HashedFuncs.begin();
for (auto I = HashedFuncs.begin(), IE = HashedFuncs.end(); I != IE; ++I) {
Function *F = I->second;
FuncEntryStorage.push_back(FunctionEntry(F, FnTree.end()));
FunctionEntry &FE = FuncEntryStorage.back();
FuncEntries[F] = &FE;
// If the hash value matches the previous value or the next one, we must
// consider merging it. Otherwise it is dropped and never considered again.
if ((I != S && std::prev(I)->first == I->first) ||
(std::next(I) != IE && std::next(I)->first == I->first) ) {
Deferred.push_back(WeakVH(F));
}
}
do {
std::vector<WeakVH> Worklist;
Deferred.swap(Worklist);
DEBUG(dbgs() << "======\nbuild tree: worklist-size=" << Worklist.size() <<
'\n');
DEBUG(doSanityCheck(Worklist));
SmallVector<FunctionEntry *, 8> FuncsToMerge;
// Insert all candidates into the Worklist.
for (std::vector<WeakVH>::iterator I = Worklist.begin(),
E = Worklist.end(); I != E; ++I) {
if (!*I) continue;
Function *F = cast<Function>(*I);
FunctionEntry *FE = getEntry(F);
assert(!isInEquivalenceClass(FE));
std::pair<FnTreeType::iterator, bool> Result = FnTree.insert(FE);
FE->TreeIter = Result.first;
const EquivalenceClass &Eq = *Result.first;
if (Result.second) {
assert(Eq.First == FE);
DEBUG(dbgs() << " new in tree: " << F->getName() << '\n');
} else {
assert(Eq.First != FE);
DEBUG(dbgs() << " add to existing: " << F->getName() << '\n');
// Add the function to the existing equivalence class.
FE->Next = Eq.First->Next;
Eq.First->Next = FE;
// Schedule for merging if the function's equivalence class reaches the
// size of 2.
if (!FE->Next)
FuncsToMerge.push_back(Eq.First);
}
}
DEBUG(dbgs() << "merge functions: tree-size=" << FnTree.size() << '\n');
// Figure out the leaf functions. We want to do the merging in bottom-up
// call order. This ensures that we don't parameterize on callee function
// names if we don't have to (because the callee may be merged).
// Note that "leaf functions" refer to the sub-call-graph of functions which
// are in the FnTree.
for (FunctionEntry *ToMerge : FuncsToMerge) {
assert(isInEquivalenceClass(ToMerge));
updateUnhandledCalleeCount(ToMerge, 1);
}
// Check if there are any leaf functions at all.
bool LeafFound = false;
for (FunctionEntry *ToMerge : FuncsToMerge) {
if (ToMerge->numUnhandledCallees == 0)
LeafFound = true;
}
for (FunctionEntry *ToMerge : FuncsToMerge) {
if (isInEquivalenceClass(ToMerge)) {
// Only merge leaf functions (or all functions if all functions are in
// a call cycle).
if (ToMerge->numUnhandledCallees == 0 || !LeafFound) {
updateUnhandledCalleeCount(ToMerge, -1);
Changed |= tryMergeEquivalenceClass(ToMerge);
} else {
// Non-leaf functions (i.e. functions in a call cycle) may become
// leaf functions in the next iteration.
removeEquivalenceClassFromTree(ToMerge);
}
}
}
} while (!Deferred.empty());
FnTree.clear();
GlobalNumbers.clear();
FuncEntries.clear();
return Changed;
}
void SwiftMergeFunctions::updateUnhandledCalleeCount(FunctionEntry *FE,
int Delta) {
// Iterate over all functions of FE's equivalence class.
do {
for (Use &U : FE->F->uses()) {
if (Instruction *I = dyn_cast<Instruction>(U.getUser())) {
FunctionEntry *CallerFE = getEntry(I->getFunction());
if (CallerFE && CallerFE->TreeIter != FnTree.end()) {
// Accumulate the count in the first entry of the equivalence class.
FunctionEntry *Head = CallerFE->TreeIter->First;
Head->numUnhandledCallees += Delta;
}
}
}
FE = FE->Next;
} while (FE);
}
bool SwiftMergeFunctions::tryMergeEquivalenceClass(FunctionEntry *FirstInClass) {
// Build the FInfos vector from all functions in the equivalence class.
FunctionInfos FInfos;
FunctionEntry *FE = FirstInClass;
do {
FInfos.push_back(FunctionInfo(FE->F));
FE->isMerged = true;
FE = FE->Next;
} while (FE);
assert(FInfos.size() >= 2);
// Merged or not: in any case we remove the equivalence class from the FnTree.
removeEquivalenceClassFromTree(FirstInClass);
// Contains functions which differ too much from the first function (i.e.
// would need too many parameters).
FunctionInfos Removed;
bool Changed = false;
int Try = 0;
// We need multiple tries if there are some functions in FInfos which differ
// too much from the first function in FInfos. But we limit the number of
// tries to a small number, because this is quadratic.
while (FInfos.size() >= 2 && Try++ < 4) {
ParamInfos Params;
bool Merged = deriveParams(Params, FInfos);
if (Merged) {
mergeWithParams(FInfos, Params);
Changed = true;
} else {
// We ran out of parameters. Remove the function from the set which
// differs most from the first function.
Removed.push_back(removeFuncWithMostParams(FInfos));
}
if (Merged || FInfos.size() < 2) {
// Try again with the functions which were removed from the original set.
FInfos.swap(Removed);
Removed.clear();
}
}
return Changed;
}
/// Remove the function from \p FInfos which needs the most parameters. Add the
/// removed function to
SwiftMergeFunctions::FunctionInfo SwiftMergeFunctions::
removeFuncWithMostParams(FunctionInfos &FInfos) {
FunctionInfos::iterator MaxIter = FInfos.end();
for (auto Iter = FInfos.begin(), End = FInfos.end(); Iter != End; ++Iter) {
if (MaxIter == FInfos.end() ||
Iter->NumParamsNeeded > MaxIter->NumParamsNeeded) {
MaxIter = Iter;
}
}
FunctionInfo Removed = *MaxIter;
FInfos.erase(MaxIter);
return Removed;
}
/// Finds the set of parameters which are required to merge the functions in
/// \p FInfos.
/// Returns true on success, i.e. the functions in \p FInfos can be merged with
/// the parameters returned in \p Params.
bool SwiftMergeFunctions::deriveParams(ParamInfos &Params,
FunctionInfos &FInfos) {
for (FunctionInfo &FI : FInfos)
FI.init();
FunctionInfo &FirstFI = FInfos.front();
// Iterate over all instructions synchronously in all functions.
do {
if (isEligibleForConstantSharing(FirstFI.CurrentInst)) {
for (unsigned OpIdx = 0, NumOps = FirstFI.CurrentInst->getNumOperands();
OpIdx != NumOps; ++OpIdx) {
if (constsDiffer(FInfos, OpIdx)) {
// This instruction has operands which differ in at least some
// functions. So we need to parameterize it.
if (!tryMapToParameter(FInfos, OpIdx, Params)) {
// We ran out of parameters.
return false;
}
}
}
}
// Go to the next instruction in all functions.
for (FunctionInfo &FI : FInfos)
FI.nextInst();
} while (FirstFI.CurrentInst);
return true;
}
/// Returns true if the \p OpIdx's constant operand in the current instruction
/// does differ in any of the functions in \p FInfos.
bool SwiftMergeFunctions::constsDiffer(const FunctionInfos &FInfos,
unsigned OpIdx) {
Constant *CommonConst = nullptr;
for (const FunctionInfo &FI : FInfos) {
Value *Op = FI.CurrentInst->getOperand(OpIdx);
if (Constant *C = dyn_cast<Constant>(Op)) {
if (!CommonConst) {
CommonConst = C;
} else if (C != CommonConst) {
return true;
}
}
}
return false;
}
/// Create a new parameter for differing operands or try to reuse an existing
/// parameter.
/// Returns true if a parameter could be created or found without exceeding the
/// maximum number of parameters.
bool SwiftMergeFunctions::tryMapToParameter(FunctionInfos &FInfos,
unsigned OpIdx, ParamInfos &Params) {
ParamInfo *Matching = nullptr;
// Try to find an existing parameter which exactly matches the differing
// operands of the current instruction.
for (ParamInfo &PI : Params) {
if (PI.matches(FInfos, OpIdx)) {
Matching = &PI;
break;
}
}
if (!Matching) {
// We need a new parameter.
// Check if we are within the limit.
if (Params.size() >= maxAddedParams)
return false;
Params.resize(Params.size() + 1);
Matching = &Params.back();
// Store the constant values into the new parameter.
Constant *FirstC = cast<Constant>(FInfos[0].CurrentInst->getOperand(OpIdx));
for (FunctionInfo &FI : FInfos) {
Constant *C = cast<Constant>(FI.CurrentInst->getOperand(OpIdx));
Matching->Values.push_back(C);
if (C != FirstC)
FI.NumParamsNeeded += 1;
}
}
/// Remember where the parameter is needed when we build our merged function.
Matching->Uses.push_back({FInfos[0].CurrentInst, OpIdx});
return true;
}
/// Merge all functions in \p FInfos by creating thunks which call the single
/// merged function with additional parameters.
void SwiftMergeFunctions::mergeWithParams(const FunctionInfos &FInfos,
ParamInfos &Params) {
// We reuse the body of the first function for the new merged function.
Function *FirstF = FInfos.front().F;
// Build the type for the merged function. This will be the type of the
// original function (FirstF) but with the additional parameter which are
// needed to parameterize the merged function.
FunctionType *OrigTy = FirstF->getFunctionType();
SmallVector<Type *, 8> ParamTypes(OrigTy->param_begin(), OrigTy->param_end());
for (const ParamInfo &PI : Params) {
ParamTypes.push_back(PI.Values[0]->getType());
}
FunctionType *funcType =
FunctionType::get(OrigTy->getReturnType(), ParamTypes, false);
// Create the new function.
// TODO: Use a better name than just adding a suffix. Ideally it would be
// a name which can be demangled in a meaningful way.
Function *NewFunction = Function::Create(funcType,
FirstF->getLinkage(),
FirstF->getName() + "_merged");
NewFunction->copyAttributesFrom(FirstF);
NewFunction->setLinkage(GlobalValue::InternalLinkage);
// Insert the new function after the last function in the equivalence class.
FirstF->getParent()->getFunctionList().insert(
std::next(FInfos[1].F->getIterator()), NewFunction);
DEBUG(dbgs() << " Merge into " << NewFunction->getName() << '\n');
// Move the body of FirstF into the NewFunction.
NewFunction->getBasicBlockList().splice(NewFunction->begin(),
FirstF->getBasicBlockList());
auto NewArgIter = NewFunction->arg_begin();
for (Argument &OrigArg : FirstF->args()) {
Argument &NewArg = *NewArgIter++;
OrigArg.replaceAllUsesWith(&NewArg);
}
// Replace all differing operands with a parameter.
for (const ParamInfo &PI : Params) {
Argument *NewArg = &*NewArgIter++;
for (const OpLocation &OL : PI.Uses) {
OL.I->setOperand(OL.OpIndex, NewArg);
}
ParamTypes.push_back(PI.Values[0]->getType());
}
for (unsigned FIdx = 0, NumFuncs = FInfos.size(); FIdx < NumFuncs; ++FIdx) {
Function *OrigFunc = FInfos[FIdx].F;
if (replaceDirectCallers(OrigFunc, NewFunction, Params, FIdx)) {
// We could replace all uses (and the function is not externally visible),
// so we can delete the original function.
auto Iter = FuncEntries.find(OrigFunc);
assert(Iter != FuncEntries.end());
assert(!isInEquivalenceClass(&*Iter->second));
Iter->second->F = nullptr;
FuncEntries.erase(Iter);
OrigFunc->eraseFromParent();
} else {
// Otherwise we need a thunk which calls the merged function.
writeThunk(NewFunction, OrigFunc, Params, FIdx);
}
++NumSwiftFunctionsMerged;
}
}
/// Remove all functions of \p FE's equivalence class from FnTree. Add them to
/// Deferred so that we'll look at them in the next round.
void SwiftMergeFunctions::removeEquivalenceClassFromTree(FunctionEntry *FE) {
if (!isInEquivalenceClass(FE))
return;
FnTreeType::iterator Iter = FE->TreeIter;
FunctionEntry *Unlink = Iter->First;
Unlink->numUnhandledCallees = 0;
while (Unlink) {
DEBUG(dbgs() << " remove from tree: " << Unlink->F->getName() << '\n');
if (!Unlink->isMerged)
Deferred.emplace_back(Unlink->F);
Unlink->TreeIter = FnTree.end();
assert(Unlink->numUnhandledCallees == 0);
FunctionEntry *NextEntry = Unlink->Next;
Unlink->Next = nullptr;
Unlink = NextEntry;
}
FnTree.erase(Iter);
}
// Helper for writeThunk,
// Selects proper bitcast operation,
// but a bit simpler then CastInst::getCastOpcode.
static Value *createCast(IRBuilder<> &Builder, Value *V, Type *DestTy) {
Type *SrcTy = V->getType();
if (SrcTy->isStructTy()) {
assert(DestTy->isStructTy());
assert(SrcTy->getStructNumElements() == DestTy->getStructNumElements());
Value *Result = UndefValue::get(DestTy);
for (unsigned int I = 0, E = SrcTy->getStructNumElements(); I < E; ++I) {
Value *Element = createCast(
Builder, Builder.CreateExtractValue(V, makeArrayRef(I)),
DestTy->getStructElementType(I));
Result =
Builder.CreateInsertValue(Result, Element, makeArrayRef(I));
}
return Result;
}
assert(!DestTy->isStructTy());
if (SrcTy->isIntegerTy() && DestTy->isPointerTy())
return Builder.CreateIntToPtr(V, DestTy);
else if (SrcTy->isPointerTy() && DestTy->isIntegerTy())
return Builder.CreatePtrToInt(V, DestTy);
else
return Builder.CreateBitCast(V, DestTy);
}
/// Replace \p Thunk with a simple tail call to \p ToFunc. Also add parameters
/// to the call to \p ToFunc, which are defined by the FuncIdx's value in
/// \p Params.
void SwiftMergeFunctions::writeThunk(Function *ToFunc, Function *Thunk,
const ParamInfos &Params,
unsigned FuncIdx) {
// Delete the existing content of Thunk.
Thunk->dropAllReferences();
BasicBlock *BB = BasicBlock::Create(Thunk->getContext(), "", Thunk);
IRBuilder<> Builder(BB);
SmallVector<Value *, 16> Args;
unsigned ParamIdx = 0;
FunctionType *ToFuncTy = ToFunc->getFunctionType();
// Add arguments which are passed through Thunk.
for (Argument & AI : Thunk->args()) {
Args.push_back(createCast(Builder, &AI, ToFuncTy->getParamType(ParamIdx)));
++ParamIdx;
}
// Add new arguments defined by Params.
for (const ParamInfo &PI : Params) {
assert(ParamIdx < ToFuncTy->getNumParams());
Args.push_back(createCast(Builder, PI.Values[FuncIdx],
ToFuncTy->getParamType(ParamIdx)));
++ParamIdx;
}
CallInst *CI = Builder.CreateCall(ToFunc, Args);
CI->setTailCall();
CI->setCallingConv(ToFunc->getCallingConv());
CI->setAttributes(ToFunc->getAttributes());
if (Thunk->getReturnType()->isVoidTy()) {
Builder.CreateRetVoid();
} else {
Builder.CreateRet(createCast(Builder, CI, Thunk->getReturnType()));
}
DEBUG(dbgs() << " writeThunk: " << Thunk->getName() << '\n');
++NumSwiftThunksWritten;
}
/// Replace direct callers of Old with New. Also add parameters to the call to
/// \p New, which are defined by the FuncIdx's value in \p Params.
bool SwiftMergeFunctions::replaceDirectCallers(Function *Old, Function *New,
const ParamInfos &Params, unsigned FuncIdx) {
bool AllReplaced = true;
SmallVector<CallInst *, 8> Callers;
for (Use &U : Old->uses()) {
Instruction *I = dyn_cast<Instruction>(U.getUser());
if (!I) {
AllReplaced = false;
continue;
}
FunctionEntry *FE = getEntry(I->getFunction());
if (FE)
removeEquivalenceClassFromTree(FE);
CallInst *CI = dyn_cast<CallInst>(I);
if (!CI || CI->getCalledValue() != Old) {
AllReplaced = false;
continue;
}
Callers.push_back(CI);
}
if (!AllReplaced)
return false;
for (CallInst *CI : Callers) {
auto &Context = New->getContext();
auto NewFuncAttrs = New->getAttributes();
auto CallSiteAttrs = CI->getAttributes();
CallSiteAttrs = CallSiteAttrs.addAttributes(
Context, AttributeSet::ReturnIndex, NewFuncAttrs.getRetAttributes());
SmallVector<Type *, 8> OldParamTypes;
SmallVector<Value *, 16> NewArgs;
IRBuilder<> Builder(CI);
FunctionType *NewFuncTy = New->getFunctionType();
(void) NewFuncTy;
unsigned ParamIdx = 0;
// Add the existing parameters.
for (Value *OldArg : CI->arg_operands()) {
AttributeSet Attrs = NewFuncAttrs.getParamAttributes(ParamIdx);
if (Attrs.getNumSlots())
CallSiteAttrs = CallSiteAttrs.addAttributes(Context, ParamIdx, Attrs);
NewArgs.push_back(OldArg);
OldParamTypes.push_back(OldArg->getType());
++ParamIdx;
}
// Add the new parameters.
for (const ParamInfo &PI : Params) {
assert(ParamIdx < NewFuncTy->getNumParams());
NewArgs.push_back(PI.Values[FuncIdx]);
OldParamTypes.push_back(PI.Values[FuncIdx]->getType());
++ParamIdx;
}
auto *FType = FunctionType::get(Old->getFunctionType()->getReturnType(),
OldParamTypes, false);
auto *FPtrType = PointerType::get(FType,
cast<PointerType>(New->getType())->getAddressSpace());
Value *Callee = ConstantExpr::getBitCast(New, FPtrType);
CallInst *NewCI = Builder.CreateCall(Callee, NewArgs);
NewCI->setCallingConv(CI->getCallingConv());
NewCI->setAttributes(CallSiteAttrs);
CI->replaceAllUsesWith(NewCI);
CI->eraseFromParent();
}
return Old->hasLocalLinkage();
}