//
// This pass looks for equivalent functions that are mergable and folds them.
//
-// A hash is computed from the function, based on its type and number of
-// basic blocks.
+// Order relation is defined on set of functions. It was made through
+// special function comparison procedure that returns
+// 0 when functions are equal,
+// -1 when Left function is less than right function, and
+// 1 for opposite case. We need total-ordering, so we need to maintain
+// four properties on the functions set:
+// a <= a (reflexivity)
+// if a <= b and b <= a then a = b (antisymmetry)
+// if a <= b and b <= c then a <= c (transitivity).
+// for all a and b: a <= b or b <= a (totality).
//
-// Once all hashes are computed, we perform an expensive equality comparison
-// on each function pair. This takes n^2/2 comparisons per bucket, so it's
-// important that the hash function be high quality. The equality comparison
-// iterates through each instruction in each basic block.
+// Comparison iterates through each instruction in each basic block.
+// Functions are kept on binary tree. For each new function F we perform
+// lookup in binary tree.
+// In practice it works the following way:
+// -- We define Function* container class with custom "operator<" (FunctionPtr).
+// -- "FunctionPtr" instances are stored in std::set collection, so every
+// std::set::insert operation will give you result in log(N) time.
+//
+// As an optimization, a hash of the function structure is calculated first, and
+// two functions are only compared if they have the same hash. This hash is
+// cheap to compute, and has the property that if function F == G according to
+// the comparison function, then hash(F) == hash(G). This consistency property
+// is critical to ensuring all possible merging opportunities are exploited.
+// Collisions in the hash affect the speed of the pass but not the correctness
+// or determinism of the resulting transformation.
//
// When a match is found the functions are folded. If both functions are
// overridable, we move the functionality into a new internal function and
// the object they belong to. However, as long as it's only used for a lookup
// and call, this is irrelevant, and we'd like to fold such functions.
//
-// * switch from n^2 pair-wise comparisons to an n-way comparison for each
-// bucket.
-//
// * be smarter about bitcasts.
//
// In order to fold functions, we will sometimes add either bitcast instructions
// analysis since the two functions differ where one has a bitcast and the
// other doesn't. We should learn to look through bitcasts.
//
+// * Compare complex types with pointer types inside.
+// * Compare cross-reference cases.
+// * Compare complex expressions.
+//
+// All the three issues above could be described as ability to prove that
+// fA == fB == fC == fE == fF == fG in example below:
+//
+// void fA() {
+// fB();
+// }
+// void fB() {
+// fA();
+// }
+//
+// void fE() {
+// fF();
+// }
+// void fF() {
+// fG();
+// }
+// void fG() {
+// fE();
+// }
+//
+// Simplest cross-reference case (fA <--> fB) was implemented in previous
+// versions of MergeFunctions, though it presented only in two function pairs
+// in test-suite (that counts >50k functions)
+// Though possibility to detect complex cross-referencing (e.g.: A->B->C->D->A)
+// could cover much more cases.
+//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "mergefunc"
#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/STLExtras.h"
-#include "llvm/Constants.h"
-#include "llvm/InlineAsm.h"
-#include "llvm/Instructions.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Module.h"
-#include "llvm/Operator.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/CallSite.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/IRBuilder.h"
-#include "llvm/Support/ValueHandle.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetData.h"
#include <vector>
+
using namespace llvm;
+#define DEBUG_TYPE "mergefunc"
+
STATISTIC(NumFunctionsMerged, "Number of functions merged");
STATISTIC(NumThunksWritten, "Number of thunks generated");
STATISTIC(NumAliasesWritten, "Number of aliases generated");
STATISTIC(NumDoubleWeak, "Number of new functions created");
-/// Creates a hash-code for the function which is the same for any two
-/// functions that will compare equal, without looking at the instructions
-/// inside the function.
-static unsigned profileFunction(const Function *F) {
- const FunctionType *FTy = F->getFunctionType();
-
- FoldingSetNodeID ID;
- ID.AddInteger(F->size());
- ID.AddInteger(F->getCallingConv());
- ID.AddBoolean(F->hasGC());
- ID.AddBoolean(FTy->isVarArg());
- ID.AddInteger(FTy->getReturnType()->getTypeID());
- for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
- ID.AddInteger(FTy->getParamType(i)->getTypeID());
- return ID.ComputeHash();
-}
+static cl::opt<unsigned> NumFunctionsForSanityCheck(
+ "mergefunc-sanity",
+ cl::desc("How many functions in module could be used for "
+ "MergeFunctions pass sanity check. "
+ "'0' disables this check. Works only with '-debug' key."),
+ cl::init(0), cl::Hidden);
namespace {
-/// ComparableFunction - A struct that pairs together functions with a
-/// TargetData so that we can keep them together as elements in the DenseSet.
-class ComparableFunction {
-public:
- static const ComparableFunction EmptyKey;
- static const ComparableFunction TombstoneKey;
- static TargetData * const LookupOnly;
-
- ComparableFunction(Function *Func, TargetData *TD)
- : Func(Func), Hash(profileFunction(Func)), TD(TD) {}
-
- Function *getFunc() const { return Func; }
- unsigned getHash() const { return Hash; }
- TargetData *getTD() const { return TD; }
-
- // Drops AssertingVH reference to the function. Outside of debug mode, this
- // does nothing.
- void release() {
- assert(Func &&
- "Attempted to release function twice, or release empty/tombstone!");
- Func = NULL;
- }
-
-private:
- explicit ComparableFunction(unsigned Hash)
- : Func(NULL), Hash(Hash), TD(NULL) {}
-
- AssertingVH<Function> Func;
- unsigned Hash;
- TargetData *TD;
-};
-
-const ComparableFunction ComparableFunction::EmptyKey = ComparableFunction(0);
-const ComparableFunction ComparableFunction::TombstoneKey =
- ComparableFunction(1);
-TargetData *const ComparableFunction::LookupOnly = (TargetData*)(-1);
-
-}
-
-namespace llvm {
- template <>
- struct DenseMapInfo<ComparableFunction> {
- static ComparableFunction getEmptyKey() {
- return ComparableFunction::EmptyKey;
- }
- static ComparableFunction getTombstoneKey() {
- return ComparableFunction::TombstoneKey;
+/// 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;
}
- static unsigned getHashValue(const ComparableFunction &CF) {
- return CF.getHash();
+ void clear() {
+ GlobalNumbers.clear();
}
- static bool isEqual(const ComparableFunction &LHS,
- const ComparableFunction &RHS);
- };
-}
-
-namespace {
+};
/// FunctionComparator - Compares two functions to determine whether or not
-/// they will generate machine code with the same behaviour. TargetData is
+/// 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 TargetData *TD, const Function *F1,
- const Function *F2)
- : F1(F1), F2(F2), TD(TD) {}
+ FunctionComparator(const Function *F1, const Function *F2,
+ GlobalNumberState* GN)
+ : FnL(F1), FnR(F2), GlobalNumbers(GN) {}
/// Test whether the two functions have equivalent behaviour.
- bool compare();
+ 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.
- bool compare(const BasicBlock *BB1, const BasicBlock *BB2);
+ 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.
- bool enumerate(const Value *V1, const Value *V2);
+ /// 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.
- bool isEquivalentOperation(const Instruction *I1,
- const Instruction *I2) const;
+ /// 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;
/// Compare two GEPs for equivalent pointer arithmetic.
- bool isEquivalentGEP(const GEPOperator *GEP1, const GEPOperator *GEP2);
- bool isEquivalentGEP(const GetElementPtrInst *GEP1,
- const GetElementPtrInst *GEP2) {
- return isEquivalentGEP(cast<GEPOperator>(GEP1), cast<GEPOperator>(GEP2));
+ /// 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));
}
- /// Compare two Types, treating all pointer types as equal.
- bool isEquivalentType(const Type *Ty1, const Type *Ty2) const;
+ /// 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;
// The two functions undergoing comparison.
- const Function *F1, *F2;
+ 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;
+};
- const TargetData *TD;
+class FunctionNode {
+ mutable AssertingVH<Function> F;
+ FunctionComparator::FunctionHash Hash;
+public:
+ // Note the hash is recalculated potentially multiple times, but it is cheap.
+ FunctionNode(Function *F)
+ : F(F), Hash(FunctionComparator::functionHash(*F)) {}
+ Function *getFunc() const { return F; }
+ FunctionComparator::FunctionHash getHash() const { return Hash; }
+
+ /// Replace the reference to the function F by the function G, assuming their
+ /// implementations are equal.
+ void replaceBy(Function *G) const {
+ F = G;
+ }
- DenseMap<const Value *, const Value *> id_map;
- DenseSet<const Value *> seen_values;
+ void release() { F = nullptr; }
};
+} // 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;
}
-// Any two pointers in the same address space are equivalent, intptr_t and
-// pointers are equivalent. Otherwise, standard type equivalence rules apply.
-bool FunctionComparator::isEquivalentType(const Type *Ty1,
- const Type *Ty2) const {
- if (Ty1 == Ty2)
- return true;
- if (Ty1->getTypeID() != Ty2->getTypeID()) {
- if (TD) {
- LLVMContext &Ctx = Ty1->getContext();
- if (isa<PointerType>(Ty1) && Ty2 == TD->getIntPtrType(Ctx)) return true;
- if (isa<PointerType>(Ty2) && Ty1 == TD->getIntPtrType(Ctx)) return true;
+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;
}
- return false;
+ 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;
+}
- switch (Ty1->getTypeID()) {
+/// 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:
- case Type::OpaqueTyID:
- case Type::VectorTyID:
- // Ty1 == Ty2 would have returned true earlier.
- return false;
-
+ 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::PPC_FP128TyID:
case Type::LabelTyID:
case Type::MetadataTyID:
- return true;
+ case Type::TokenTyID:
+ return 0;
case Type::PointerTyID: {
- const PointerType *PTy1 = cast<PointerType>(Ty1);
- const PointerType *PTy2 = cast<PointerType>(Ty2);
- return PTy1->getAddressSpace() == PTy2->getAddressSpace();
+ assert(PTyL && PTyR && "Both types must be pointers here.");
+ return cmpNumbers(PTyL->getAddressSpace(), PTyR->getAddressSpace());
}
case Type::StructTyID: {
- const StructType *STy1 = cast<StructType>(Ty1);
- const StructType *STy2 = cast<StructType>(Ty2);
- if (STy1->getNumElements() != STy2->getNumElements())
- return false;
+ StructType *STyL = cast<StructType>(TyL);
+ StructType *STyR = cast<StructType>(TyR);
+ if (STyL->getNumElements() != STyR->getNumElements())
+ return cmpNumbers(STyL->getNumElements(), STyR->getNumElements());
- if (STy1->isPacked() != STy2->isPacked())
- return false;
+ if (STyL->isPacked() != STyR->isPacked())
+ return cmpNumbers(STyL->isPacked(), STyR->isPacked());
- for (unsigned i = 0, e = STy1->getNumElements(); i != e; ++i) {
- if (!isEquivalentType(STy1->getElementType(i), STy2->getElementType(i)))
- return false;
+ for (unsigned i = 0, e = STyL->getNumElements(); i != e; ++i) {
+ if (int Res = cmpTypes(STyL->getElementType(i), STyR->getElementType(i)))
+ return Res;
}
- return true;
+ return 0;
}
case Type::FunctionTyID: {
- const FunctionType *FTy1 = cast<FunctionType>(Ty1);
- const FunctionType *FTy2 = cast<FunctionType>(Ty2);
- if (FTy1->getNumParams() != FTy2->getNumParams() ||
- FTy1->isVarArg() != FTy2->isVarArg())
- return false;
+ FunctionType *FTyL = cast<FunctionType>(TyL);
+ FunctionType *FTyR = cast<FunctionType>(TyR);
+ if (FTyL->getNumParams() != FTyR->getNumParams())
+ return cmpNumbers(FTyL->getNumParams(), FTyR->getNumParams());
- if (!isEquivalentType(FTy1->getReturnType(), FTy2->getReturnType()))
- return false;
+ 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 = FTy1->getNumParams(); i != e; ++i) {
- if (!isEquivalentType(FTy1->getParamType(i), FTy2->getParamType(i)))
- return false;
+ for (unsigned i = 0, e = FTyL->getNumParams(); i != e; ++i) {
+ if (int Res = cmpTypes(FTyL->getParamType(i), FTyR->getParamType(i)))
+ return Res;
}
- return true;
+ return 0;
}
case Type::ArrayTyID: {
- const ArrayType *ATy1 = cast<ArrayType>(Ty1);
- const ArrayType *ATy2 = cast<ArrayType>(Ty2);
- return ATy1->getNumElements() == ATy2->getNumElements() &&
- isEquivalentType(ATy1->getElementType(), ATy2->getElementType());
+ 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.
-bool FunctionComparator::isEquivalentOperation(const Instruction *I1,
- const Instruction *I2) const {
+// 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 (I1->getOpcode() != I2->getOpcode() ||
- I1->getNumOperands() != I2->getNumOperands() ||
- !isEquivalentType(I1->getType(), I2->getType()) ||
- !I1->hasSameSubclassOptionalData(I2))
- return false;
+ 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 = I1->getNumOperands(); i != e; ++i)
- if (!isEquivalentType(I1->getOperand(i)->getType(),
- I2->getOperand(i)->getType()))
- return false;
+ 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>(I1))
- return LI->isVolatile() == cast<LoadInst>(I2)->isVolatile() &&
- LI->getAlignment() == cast<LoadInst>(I2)->getAlignment();
- if (const StoreInst *SI = dyn_cast<StoreInst>(I1))
- return SI->isVolatile() == cast<StoreInst>(I2)->isVolatile() &&
- SI->getAlignment() == cast<StoreInst>(I2)->getAlignment();
- if (const CmpInst *CI = dyn_cast<CmpInst>(I1))
- return CI->getPredicate() == cast<CmpInst>(I2)->getPredicate();
- if (const CallInst *CI = dyn_cast<CallInst>(I1))
- return CI->getCallingConv() == cast<CallInst>(I2)->getCallingConv() &&
- CI->getAttributes() == cast<CallInst>(I2)->getAttributes();
- if (const InvokeInst *CI = dyn_cast<InvokeInst>(I1))
- return CI->getCallingConv() == cast<InvokeInst>(I2)->getCallingConv() &&
- CI->getAttributes() == cast<InvokeInst>(I2)->getAttributes();
- if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(I1)) {
- if (IVI->getNumIndices() != cast<InsertValueInst>(I2)->getNumIndices())
- return false;
- for (unsigned i = 0, e = IVI->getNumIndices(); i != e; ++i)
- if (IVI->idx_begin()[i] != cast<InsertValueInst>(I2)->idx_begin()[i])
- return false;
- return true;
+ 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 ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I1)) {
- if (EVI->getNumIndices() != cast<ExtractValueInst>(I2)->getNumIndices())
- return false;
- for (unsigned i = 0, e = EVI->getNumIndices(); i != e; ++i)
- if (EVI->idx_begin()[i] != cast<ExtractValueInst>(I2)->idx_begin()[i])
- return false;
- return true;
+ 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;
+ return cmpRangeMetadata(
+ CI->getMetadata(LLVMContext::MD_range),
+ cast<CallInst>(R)->getMetadata(LLVMContext::MD_range));
+ }
+ if (const InvokeInst *CI = dyn_cast<InvokeInst>(L)) {
+ if (int Res = cmpNumbers(CI->getCallingConv(),
+ cast<InvokeInst>(R)->getCallingConv()))
+ return Res;
+ if (int Res =
+ cmpAttrs(CI->getAttributes(), cast<InvokeInst>(R)->getAttributes()))
+ return Res;
+ return cmpRangeMetadata(
+ CI->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());
}
- return true;
+ 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.
-bool FunctionComparator::isEquivalentGEP(const GEPOperator *GEP1,
- const GEPOperator *GEP2) {
- // When we have target data, we can reduce the GEP down to the value in bytes
- // added to the address.
- if (TD && GEP1->hasAllConstantIndices() && GEP2->hasAllConstantIndices()) {
- SmallVector<Value *, 8> Indices1(GEP1->idx_begin(), GEP1->idx_end());
- SmallVector<Value *, 8> Indices2(GEP2->idx_begin(), GEP2->idx_end());
- uint64_t Offset1 = TD->getIndexedOffset(GEP1->getPointerOperandType(),
- Indices1.data(), Indices1.size());
- uint64_t Offset2 = TD->getIndexedOffset(GEP2->getPointerOperandType(),
- Indices2.data(), Indices2.size());
- return Offset1 == Offset2;
- }
-
- if (GEP1->getPointerOperand()->getType() !=
- GEP2->getPointerOperand()->getType())
- return false;
+// Read method declaration comments for more details.
+int FunctionComparator::cmpGEPs(const GEPOperator *GEPL,
+ const GEPOperator *GEPR) {
- if (GEP1->getNumOperands() != GEP2->getNumOperands())
- return false;
+ unsigned int ASL = GEPL->getPointerAddressSpace();
+ unsigned int ASR = GEPR->getPointerAddressSpace();
- for (unsigned i = 0, e = GEP1->getNumOperands(); i != e; ++i) {
- if (!enumerate(GEP1->getOperand(i), GEP2->getOperand(i)))
- return false;
+ 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 true;
+ 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.
-bool FunctionComparator::enumerate(const Value *V1, const Value *V2) {
- // Check for function @f1 referring to itself and function @f2 referring to
- // itself, or referring to each other, or both referring to either of them.
- // They're all equivalent if the two functions are otherwise equivalent.
- if (V1 == F1 && V2 == F2)
- return true;
- if (V1 == F2 && V2 == F1)
- return true;
-
- if (const Constant *C1 = dyn_cast<Constant>(V1)) {
- if (V1 == V2) return true;
- const Constant *C2 = dyn_cast<Constant>(V2);
- if (!C2) return false;
- // TODO: constant expressions with GEP or references to F1 or F2.
- if (C1->isNullValue() && C2->isNullValue() &&
- isEquivalentType(C1->getType(), C2->getType()))
- return true;
- // Try bitcasting C2 to C1's type. If the bitcast is legal and returns C1
- // then they must have equal bit patterns.
- return C1->getType()->canLosslesslyBitCastTo(C2->getType()) &&
- C1 == ConstantExpr::getBitCast(const_cast<Constant*>(C2), C1->getType());
- }
-
- if (isa<InlineAsm>(V1) || isa<InlineAsm>(V2))
- return V1 == V2;
-
- // Check that V1 maps to V2. If we find a value that V1 maps to then we simply
- // check whether it's equal to V2. When there is no mapping then we need to
- // ensure that V2 isn't already equivalent to something else. For this
- // purpose, we track the V2 values in a set.
-
- const Value *&map_elem = id_map[V1];
- if (map_elem)
- return map_elem == V2;
- if (!seen_values.insert(V2).second)
- return false;
- map_elem = V2;
- return true;
+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;
}
-// Test whether two basic blocks have equivalent behaviour.
-bool FunctionComparator::compare(const BasicBlock *BB1, const BasicBlock *BB2) {
- BasicBlock::const_iterator F1I = BB1->begin(), F1E = BB1->end();
- BasicBlock::const_iterator F2I = BB2->begin(), F2E = BB2->end();
+/// 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;
+ }
- do {
- if (!enumerate(F1I, F2I))
- return false;
+ 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 (const GetElementPtrInst *GEP1 = dyn_cast<GetElementPtrInst>(F1I)) {
- const GetElementPtrInst *GEP2 = dyn_cast<GetElementPtrInst>(F2I);
- if (!GEP2)
- return false;
+ if (ConstL)
+ return 1;
+ if (ConstR)
+ return -1;
- if (!enumerate(GEP1->getPointerOperand(), GEP2->getPointerOperand()))
- return false;
+ const InlineAsm *InlineAsmL = dyn_cast<InlineAsm>(L);
+ const InlineAsm *InlineAsmR = dyn_cast<InlineAsm>(R);
- if (!isEquivalentGEP(GEP1, GEP2))
- return false;
- } else {
- if (!isEquivalentOperation(F1I, F2I))
- return false;
+ if (InlineAsmL && InlineAsmR)
+ return cmpInlineAsm(InlineAsmL, InlineAsmR);
+ if (InlineAsmL)
+ return 1;
+ if (InlineAsmR)
+ return -1;
- assert(F1I->getNumOperands() == F2I->getNumOperands());
- for (unsigned i = 0, e = F1I->getNumOperands(); i != e; ++i) {
- Value *OpF1 = F1I->getOperand(i);
- Value *OpF2 = F2I->getOperand(i);
+ auto LeftSN = sn_mapL.insert(std::make_pair(L, sn_mapL.size())),
+ RightSN = sn_mapR.insert(std::make_pair(R, sn_mapR.size()));
- if (!enumerate(OpF1, OpF2))
- return false;
+ return cmpNumbers(LeftSN.first->second, RightSN.first->second);
+}
+// 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();
- if (OpF1->getValueID() != OpF2->getValueID() ||
- !isEquivalentType(OpF1->getType(), OpF2->getType()))
- return false;
+ 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) {
+ Value *OpL = InstL->getOperand(i);
+ Value *OpR = InstR->getOperand(i);
+ if (int Res = cmpValues(OpL, OpR))
+ return Res;
+ // cmpValues should ensure this is true.
+ assert(cmpTypes(OpL->getType(), OpR->getType()) == 0);
}
}
- ++F1I, ++F2I;
- } while (F1I != F1E && F2I != F2E);
+ ++InstL, ++InstR;
+ } while (InstL != InstLE && InstR != InstRE);
- return F1I == F1E && F2I == F2E;
+ if (InstL != InstLE && InstR == InstRE)
+ return 1;
+ if (InstL == InstLE && InstR != InstRE)
+ return -1;
+ return 0;
}
// Test whether the two functions have equivalent behaviour.
-bool FunctionComparator::compare() {
- // We need to recheck everything, but check the things that weren't included
- // in the hash first.
+int FunctionComparator::compare() {
+ sn_mapL.clear();
+ sn_mapR.clear();
- if (F1->getAttributes() != F2->getAttributes())
- return false;
+ if (int Res = cmpAttrs(FnL->getAttributes(), FnR->getAttributes()))
+ return Res;
- if (F1->hasGC() != F2->hasGC())
- return false;
+ if (int Res = cmpNumbers(FnL->hasGC(), FnR->hasGC()))
+ return Res;
- if (F1->hasGC() && F1->getGC() != F2->getGC())
- return false;
+ if (FnL->hasGC()) {
+ if (int Res = cmpMem(FnL->getGC(), FnR->getGC()))
+ return Res;
+ }
- if (F1->hasSection() != F2->hasSection())
- return false;
+ if (int Res = cmpNumbers(FnL->hasSection(), FnR->hasSection()))
+ return Res;
- if (F1->hasSection() && F1->getSection() != F2->getSection())
- return false;
+ if (FnL->hasSection()) {
+ if (int Res = cmpMem(FnL->getSection(), FnR->getSection()))
+ return Res;
+ }
- if (F1->isVarArg() != F2->isVarArg())
- return false;
+ 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 (F1->getCallingConv() != F2->getCallingConv())
- return false;
+ if (int Res = cmpNumbers(FnL->getCallingConv(), FnR->getCallingConv()))
+ return Res;
- if (!isEquivalentType(F1->getFunctionType(), F2->getFunctionType()))
- return false;
+ if (int Res = cmpTypes(FnL->getFunctionType(), FnR->getFunctionType()))
+ return Res;
- assert(F1->arg_size() == F2->arg_size() &&
+ 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 f1i = F1->arg_begin(),
- f2i = F2->arg_begin(), f1e = F1->arg_end(); f1i != f1e; ++f1i, ++f2i) {
- if (!enumerate(f1i, f2i))
+ 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!");
}
// linked list is immaterial. Our walk starts at the entry block for both
// functions, then takes each block from each terminator in order. As an
// artifact, this also means that unreachable blocks are ignored.
- SmallVector<const BasicBlock *, 8> F1BBs, F2BBs;
+ SmallVector<const BasicBlock *, 8> FnLBBs, FnRBBs;
SmallSet<const BasicBlock *, 128> VisitedBBs; // in terms of F1.
- F1BBs.push_back(&F1->getEntryBlock());
- F2BBs.push_back(&F2->getEntryBlock());
+ FnLBBs.push_back(&FnL->getEntryBlock());
+ FnRBBs.push_back(&FnR->getEntryBlock());
- VisitedBBs.insert(F1BBs[0]);
- while (!F1BBs.empty()) {
- const BasicBlock *F1BB = F1BBs.pop_back_val();
- const BasicBlock *F2BB = F2BBs.pop_back_val();
+ VisitedBBs.insert(FnLBBs[0]);
+ while (!FnLBBs.empty()) {
+ const BasicBlock *BBL = FnLBBs.pop_back_val();
+ const BasicBlock *BBR = FnRBBs.pop_back_val();
- if (!enumerate(F1BB, F2BB) || !compare(F1BB, F2BB))
- return false;
+ if (int Res = cmpValues(BBL, BBR))
+ return Res;
+
+ if (int Res = cmpBasicBlocks(BBL, BBR))
+ return Res;
- const TerminatorInst *F1TI = F1BB->getTerminator();
- const TerminatorInst *F2TI = F2BB->getTerminator();
+ const TerminatorInst *TermL = BBL->getTerminator();
+ const TerminatorInst *TermR = BBR->getTerminator();
- assert(F1TI->getNumSuccessors() == F2TI->getNumSuccessors());
- for (unsigned i = 0, e = F1TI->getNumSuccessors(); i != e; ++i) {
- if (!VisitedBBs.insert(F1TI->getSuccessor(i)))
+ assert(TermL->getNumSuccessors() == TermR->getNumSuccessors());
+ for (unsigned i = 0, e = TermL->getNumSuccessors(); i != e; ++i) {
+ if (!VisitedBBs.insert(TermL->getSuccessor(i)).second)
continue;
- F1BBs.push_back(F1TI->getSuccessor(i));
- F2BBs.push_back(F2TI->getSuccessor(i));
+ FnLBBs.push_back(TermL->getSuccessor(i));
+ FnRBBs.push_back(TermR->getSuccessor(i));
}
}
- return true;
+ return 0;
}
+// 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; }
+};
+
+// 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 {
/// MergeFunctions finds functions which will generate identical machine code,
public:
static char ID;
MergeFunctions()
- : ModulePass(ID), HasGlobalAliases(false) {
+ : ModulePass(ID), FnTree(FunctionNodeCmp(&GlobalNumbers)), FNodesInTree(),
+ HasGlobalAliases(false) {
initializeMergeFunctionsPass(*PassRegistry::getPassRegistry());
}
- bool runOnModule(Module &M);
+ bool runOnModule(Module &M) override;
private:
- typedef DenseSet<ComparableFunction> FnSetType;
+ // 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 FunctionNode &LHS, const FunctionNode &RHS) const {
+ // Order first by hashes, then full function comparison.
+ if (LHS.getHash() != RHS.getHash())
+ return LHS.getHash() < RHS.getHash();
+ FunctionComparator FCmp(LHS.getFunc(), RHS.getFunc(), GlobalNumbers);
+ return FCmp.compare() == -1;
+ }
+ };
+ typedef std::set<FunctionNode, FunctionNodeCmp> FnTreeType;
+
+ GlobalNumberState GlobalNumbers;
/// A work queue of functions that may have been modified and should be
/// analyzed again.
std::vector<WeakVH> Deferred;
- /// Insert a ComparableFunction into the FnSet, or merge it away if it's
+ /// 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);
+
+ /// Insert a ComparableFunction into the FnTree, or merge it away if it's
/// equal to one that's already present.
- bool insert(ComparableFunction &NewF);
+ bool insert(Function *NewFunction);
- /// Remove a Function from the FnSet and queue it up for a second sweep of
+ /// Remove a Function from the FnTree and queue it up for a second sweep of
/// analysis.
void remove(Function *F);
- /// Find the functions that use this Value and remove them from FnSet and
+ /// Find the functions that use this Value and remove them from FnTree and
/// queue the functions.
void removeUsers(Value *V);
/// Replace G with an alias to F. Deletes G.
void writeAlias(Function *F, Function *G);
- /// The set of all distinct functions. Use the insert() and remove() methods
- /// to modify it.
- FnSetType FnSet;
+ /// Replace function F with function G in the function tree.
+ void replaceFunctionInTree(const FunctionNode &FN, Function *G);
- /// TargetData for more accurate GEP comparisons. May be NULL.
- TargetData *TD;
+ /// 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;
+ // Map functions to the iterators of the FunctionNode which contains them
+ // in the FnTree. This must be updated carefully whenever the FnTree is
+ // modified, i.e. in insert(), remove(), and replaceFunctionInTree(), to avoid
+ // dangling iterators into FnTree. The invariant that preserves this is that
+ // there is exactly one mapping F -> FN for each FunctionNode FN in FnTree.
+ ValueMap<Function*, FnTreeType::iterator> FNodesInTree;
/// Whether or not the target supports global aliases.
bool HasGlobalAliases;
};
-} // end anonymous namespace
+} // end anonymous namespace
char MergeFunctions::ID = 0;
INITIALIZE_PASS(MergeFunctions, "mergefunc", "Merge Functions", false, false)
return new MergeFunctions();
}
+bool MergeFunctions::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;
+}
+
bool MergeFunctions::runOnModule(Module &M) {
bool Changed = false;
- TD = getAnalysisIfAvailable<TargetData>();
- for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
- if (!I->isDeclaration() && !I->hasAvailableExternallyLinkage())
- Deferred.push_back(WeakVH(I));
+ // 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 (!Func.isDeclaration() && !Func.hasAvailableExternallyLinkage()) {
+ HashedFuncs.push_back({FunctionComparator::functionHash(Func), &Func});
+ }
}
- FnSet.resize(Deferred.size());
+ 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;
+ });
+
+ auto S = HashedFuncs.begin();
+ for (auto I = HashedFuncs.begin(), IE = HashedFuncs.end(); I != IE; ++I) {
+ // 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(I->second));
+ }
+ }
+
do {
std::vector<WeakVH> Worklist;
Deferred.swap(Worklist);
+ DEBUG(doSanityCheck(Worklist));
+
DEBUG(dbgs() << "size of module: " << M.size() << '\n');
DEBUG(dbgs() << "size of worklist: " << Worklist.size() << '\n');
Function *F = cast<Function>(*I);
if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
!F->mayBeOverridden()) {
- ComparableFunction CF = ComparableFunction(F, TD);
- Changed |= insert(CF);
+ Changed |= insert(F);
}
}
Function *F = cast<Function>(*I);
if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage() &&
F->mayBeOverridden()) {
- ComparableFunction CF = ComparableFunction(F, TD);
- Changed |= insert(CF);
+ Changed |= insert(F);
}
}
- DEBUG(dbgs() << "size of FnSet: " << FnSet.size() << '\n');
+ DEBUG(dbgs() << "size of FnTree: " << FnTree.size() << '\n');
} while (!Deferred.empty());
- FnSet.clear();
+ FnTree.clear();
+ GlobalNumbers.clear();
return Changed;
}
-bool DenseMapInfo<ComparableFunction>::isEqual(const ComparableFunction &LHS,
- const ComparableFunction &RHS) {
- if (LHS.getFunc() == RHS.getFunc() &&
- LHS.getHash() == RHS.getHash())
- return true;
- if (!LHS.getFunc() || !RHS.getFunc())
- return false;
-
- // One of these is a special "underlying pointer comparison only" object.
- if (LHS.getTD() == ComparableFunction::LookupOnly ||
- RHS.getTD() == ComparableFunction::LookupOnly)
- return false;
-
- assert(LHS.getTD() == RHS.getTD() &&
- "Comparing functions for different targets");
-
- return FunctionComparator(LHS.getTD(), LHS.getFunc(),
- RHS.getFunc()).compare();
-}
-
// Replace direct callers of Old with New.
void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
Constant *BitcastNew = ConstantExpr::getBitCast(New, Old->getType());
- for (Value::use_iterator UI = Old->use_begin(), UE = Old->use_end();
- UI != UE;) {
- Value::use_iterator TheIter = UI;
+ for (auto UI = Old->use_begin(), UE = Old->use_end(); UI != UE;) {
+ Use *U = &*UI;
++UI;
- CallSite CS(*TheIter);
- if (CS && CS.isCallee(TheIter)) {
+ CallSite CS(U->getUser());
+ if (CS && CS.isCallee(U)) {
+ // Transfer the called function's attributes to the call site. Due to the
+ // bitcast we will 'lose' ABI changing attributes because the 'called
+ // function' is no longer a Function* but the bitcast. Code that looks up
+ // the attributes from the called function will fail.
+
+ // FIXME: This is not actually true, at least not anymore. The callsite
+ // will always have the same ABI affecting attributes as the callee,
+ // because otherwise the original input has UB. Note that Old and New
+ // always have matching ABI, so no attributes need to be changed.
+ // Transferring other attributes may help other optimizations, but that
+ // should be done uniformly and not in this ad-hoc way.
+ auto &Context = New->getContext();
+ auto NewFuncAttrs = New->getAttributes();
+ auto CallSiteAttrs = CS.getAttributes();
+
+ CallSiteAttrs = CallSiteAttrs.addAttributes(
+ Context, AttributeSet::ReturnIndex, NewFuncAttrs.getRetAttributes());
+
+ for (unsigned argIdx = 0; argIdx < CS.arg_size(); argIdx++) {
+ AttributeSet Attrs = NewFuncAttrs.getParamAttributes(argIdx);
+ if (Attrs.getNumSlots())
+ CallSiteAttrs = CallSiteAttrs.addAttributes(Context, argIdx, Attrs);
+ }
+
+ CS.setAttributes(CallSiteAttrs);
+
remove(CS.getInstruction()->getParent()->getParent());
- TheIter.getUse().set(BitcastNew);
+ U->set(BitcastNew);
}
}
}
writeThunk(F, G);
}
+// 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 G with a simple tail call to bitcast(F). Also replace direct uses
// of G with bitcast(F). Deletes G.
void MergeFunctions::writeThunk(Function *F, Function *G) {
SmallVector<Value *, 16> Args;
unsigned i = 0;
- const FunctionType *FFTy = F->getFunctionType();
- for (Function::arg_iterator AI = NewG->arg_begin(), AE = NewG->arg_end();
- AI != AE; ++AI) {
- Args.push_back(Builder.CreateBitCast(AI, FFTy->getParamType(i)));
+ FunctionType *FFTy = F->getFunctionType();
+ for (Argument & AI : NewG->args()) {
+ Args.push_back(createCast(Builder, &AI, FFTy->getParamType(i)));
++i;
}
- CallInst *CI = Builder.CreateCall(F, Args.begin(), Args.end());
+ CallInst *CI = Builder.CreateCall(F, Args);
CI->setTailCall();
CI->setCallingConv(F->getCallingConv());
+ CI->setAttributes(F->getAttributes());
if (NewG->getReturnType()->isVoidTy()) {
Builder.CreateRetVoid();
} else {
- Builder.CreateRet(Builder.CreateBitCast(CI, NewG->getReturnType()));
+ Builder.CreateRet(createCast(Builder, CI, NewG->getReturnType()));
}
NewG->copyAttributesFrom(G);
// Replace G with an alias to F and delete G.
void MergeFunctions::writeAlias(Function *F, Function *G) {
- Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
- GlobalAlias *GA = new GlobalAlias(G->getType(), G->getLinkage(), "",
- BitcastF, G->getParent());
+ auto *GA = GlobalAlias::create(G->getLinkage(), "", F);
F->setAlignment(std::max(F->getAlignment(), G->getAlignment()));
GA->takeName(G);
GA->setVisibility(G->getVisibility());
if (F->mayBeOverridden()) {
assert(G->mayBeOverridden());
- if (HasGlobalAliases) {
- // Make them both thunks to the same internal function.
- Function *H = Function::Create(F->getFunctionType(), F->getLinkage(), "",
- F->getParent());
- H->copyAttributesFrom(F);
- H->takeName(F);
- removeUsers(F);
- F->replaceAllUsesWith(H);
+ // Make them both thunks to the same internal function.
+ Function *H = Function::Create(F->getFunctionType(), F->getLinkage(), "",
+ F->getParent());
+ H->copyAttributesFrom(F);
+ H->takeName(F);
+ removeUsers(F);
+ F->replaceAllUsesWith(H);
- unsigned MaxAlignment = std::max(G->getAlignment(), H->getAlignment());
+ unsigned MaxAlignment = std::max(G->getAlignment(), H->getAlignment());
+ if (HasGlobalAliases) {
writeAlias(F, G);
writeAlias(F, H);
-
- F->setAlignment(MaxAlignment);
- F->setLinkage(GlobalValue::PrivateLinkage);
} else {
- // We can't merge them. Instead, pick one and update all direct callers
- // to call it and hope that we improve the instruction cache hit rate.
- replaceDirectCallers(G, F);
+ writeThunk(F, G);
+ writeThunk(F, H);
}
+ F->setAlignment(MaxAlignment);
+ F->setLinkage(GlobalValue::PrivateLinkage);
++NumDoubleWeak;
} else {
writeThunkOrAlias(F, G);
++NumFunctionsMerged;
}
-// Insert a ComparableFunction into the FnSet, or merge it away if equal to one
+/// Replace function F by function G.
+void MergeFunctions::replaceFunctionInTree(const FunctionNode &FN,
+ Function *G) {
+ Function *F = FN.getFunc();
+ assert(FunctionComparator(F, G, &GlobalNumbers).compare() == 0 &&
+ "The two functions must be equal");
+
+ auto I = FNodesInTree.find(F);
+ assert(I != FNodesInTree.end() && "F should be in FNodesInTree");
+ assert(FNodesInTree.count(G) == 0 && "FNodesInTree should not contain G");
+
+ FnTreeType::iterator IterToFNInFnTree = I->second;
+ assert(&(*IterToFNInFnTree) == &FN && "F should map to FN in FNodesInTree.");
+ // Remove F -> FN and insert G -> FN
+ FNodesInTree.erase(I);
+ FNodesInTree.insert({G, IterToFNInFnTree});
+ // Replace F with G in FN, which is stored inside the FnTree.
+ FN.replaceBy(G);
+}
+
+// Insert a ComparableFunction into the FnTree, or merge it away if equal to one
// that was already inserted.
-bool MergeFunctions::insert(ComparableFunction &NewF) {
- std::pair<FnSetType::iterator, bool> Result = FnSet.insert(NewF);
+bool MergeFunctions::insert(Function *NewFunction) {
+ std::pair<FnTreeType::iterator, bool> Result =
+ FnTree.insert(FunctionNode(NewFunction));
+
if (Result.second) {
- DEBUG(dbgs() << "Inserting as unique: " << NewF.getFunc()->getName() << '\n');
+ assert(FNodesInTree.count(NewFunction) == 0);
+ FNodesInTree.insert({NewFunction, Result.first});
+ DEBUG(dbgs() << "Inserting as unique: " << NewFunction->getName() << '\n');
return false;
}
- const ComparableFunction &OldF = *Result.first;
+ const FunctionNode &OldF = *Result.first;
+
+ // Don't merge tiny functions, since it can just end up making the function
+ // larger.
+ // FIXME: Should still merge them if they are unnamed_addr and produce an
+ // alias.
+ if (NewFunction->size() == 1) {
+ if (NewFunction->front().size() <= 2) {
+ DEBUG(dbgs() << NewFunction->getName()
+ << " is to small to bother merging\n");
+ return false;
+ }
+ }
+
+ // Impose a total order (by name) on the replacement of functions. This is
+ // important when operating on more than one module independently to prevent
+ // cycles of thunks calling each other when the modules are linked together.
+ //
+ // When one function is weak and the other is strong there is an order imposed
+ // already. We process strong functions before weak functions.
+ if ((OldF.getFunc()->mayBeOverridden() && NewFunction->mayBeOverridden()) ||
+ (!OldF.getFunc()->mayBeOverridden() && !NewFunction->mayBeOverridden()))
+ if (OldF.getFunc()->getName() > NewFunction->getName()) {
+ // Swap the two functions.
+ Function *F = OldF.getFunc();
+ replaceFunctionInTree(*Result.first, NewFunction);
+ NewFunction = F;
+ assert(OldF.getFunc() != F && "Must have swapped the functions.");
+ }
// Never thunk a strong function to a weak function.
- assert(!OldF.getFunc()->mayBeOverridden() ||
- NewF.getFunc()->mayBeOverridden());
+ assert(!OldF.getFunc()->mayBeOverridden() || NewFunction->mayBeOverridden());
- DEBUG(dbgs() << " " << OldF.getFunc()->getName() << " == "
- << NewF.getFunc()->getName() << '\n');
+ DEBUG(dbgs() << " " << OldF.getFunc()->getName()
+ << " == " << NewFunction->getName() << '\n');
- Function *DeleteF = NewF.getFunc();
- NewF.release();
+ Function *DeleteF = NewFunction;
mergeTwoFunctions(OldF.getFunc(), DeleteF);
return true;
}
-// Remove a function from FnSet. If it was already in FnSet, add it to Deferred
-// so that we'll look at it in the next round.
+// Remove a function from FnTree. If it was already in FnTree, add
+// it to Deferred so that we'll look at it in the next round.
void MergeFunctions::remove(Function *F) {
- // We need to make sure we remove F, not a function "equal" to F per the
- // function equality comparator.
- //
- // The special "lookup only" ComparableFunction bypasses the expensive
- // function comparison in favour of a pointer comparison on the underlying
- // Function*'s.
- ComparableFunction CF = ComparableFunction(F, ComparableFunction::LookupOnly);
- if (FnSet.erase(CF)) {
- DEBUG(dbgs() << "Removed " << F->getName() << " from set and deferred it.\n");
- Deferred.push_back(F);
+ auto I = FNodesInTree.find(F);
+ if (I != FNodesInTree.end()) {
+ DEBUG(dbgs() << "Deferred " << F->getName()<< ".\n");
+ FnTree.erase(I->second);
+ // I->second has been invalidated, remove it from the FNodesInTree map to
+ // preserve the invariant.
+ FNodesInTree.erase(I);
+ Deferred.emplace_back(F);
}
}
void MergeFunctions::removeUsers(Value *V) {
std::vector<Value *> Worklist;
Worklist.push_back(V);
+ SmallSet<Value*, 8> Visited;
+ Visited.insert(V);
while (!Worklist.empty()) {
Value *V = Worklist.back();
Worklist.pop_back();
- for (Value::use_iterator UI = V->use_begin(), UE = V->use_end();
- UI != UE; ++UI) {
- Use &U = UI.getUse();
- if (Instruction *I = dyn_cast<Instruction>(U.getUser())) {
+ for (User *U : V->users()) {
+ if (Instruction *I = dyn_cast<Instruction>(U)) {
remove(I->getParent()->getParent());
- } else if (isa<GlobalValue>(U.getUser())) {
+ } else if (isa<GlobalValue>(U)) {
// do nothing
- } else if (Constant *C = dyn_cast<Constant>(U.getUser())) {
- for (Value::use_iterator CUI = C->use_begin(), CUE = C->use_end();
- CUI != CUE; ++CUI)
- Worklist.push_back(*CUI);
+ } else if (Constant *C = dyn_cast<Constant>(U)) {
+ for (User *UU : C->users()) {
+ if (!Visited.insert(UU).second)
+ Worklist.push_back(UU);
+ }
}
}
}
projects / oota-llvm.git / blobdiff