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swift-mirror/lib/LLVMPasses/LLVMMergeFunctions.cpp
Erik Eckstein f0022a5aac Add an LLVM pass to merge similar functions. 
It's like LLVM's MergeFunctions pass, except that it can also merge functions which differ by some constants.
The intention is to merge specialized functions which only differ by metadata lookups. But it can also merge other types of functions.
It gives ~7% code size reducation for the stdlib.

There are still some open TODOs, e.g. to share common code with LLVM's MergeFunctions pass (currently much code is just copied).
2016-05-11 09:46:46 -07:00

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//===- LLVMMergeFunctions.cpp - Merge similar functions for swift ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass looks for similar functions that are mergable 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 a floats,
/// 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);
/// Compares two global values by number. Uses the GlobalNumbersState to
/// identify the same gobals across function calls.
int cmpGlobalValues(GlobalValue *L, GlobalValue *R);
/// 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);
/// 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.
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 unioned. 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) {
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 endiness 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) {
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());
}
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) {
// 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 functions'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;
SmallVector<FunctionEntry *, 8> FuncsInCallCycleToMerge;
// 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);
// Containes 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<false> &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<false> 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<false> Builder(CI);
FunctionType *NewFuncTy = New->getFunctionType();
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();
}
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