Index: include/llvm/Transforms/Utils/FunctionComparator.h =================================================================== --- include/llvm/Transforms/Utils/FunctionComparator.h +++ include/llvm/Transforms/Utils/FunctionComparator.h @@ -0,0 +1,364 @@ +//===- FunctionComparator.h - Function Comparator ---------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file defines the FunctionComparator and GlobalNumberState classes which +// are used by the MergeFunctions pass for comparing functions. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_TRANSFORMS_UTILS_FUNCTIONCOMPARATOR_H +#define LLVM_TRANSFORMS_UTILS_FUNCTIONCOMPARATOR_H + +#include "llvm/IR/Function.h" +#include "llvm/IR/ValueMap.h" +#include "llvm/IR/Operator.h" +#include "llvm/Support/AtomicOrdering.h" + +namespace llvm { + +/// 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 { + 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 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 &); + +protected: + + /// Start the comparison. + void beginCompare() { + sn_mapL.clear(); + sn_mapR.clear(); + } + + /// Compares the signature and other general attributes of the two functions. + int compareSignature(); + + /// Test whether two basic blocks have equivalent behaviour. + int cmpBasicBlocks(const BasicBlock *BBL, const BasicBlock *BBR) const; + + /// Constants comparison. + /// Its analog to lexicographical comparison between hypothetical numbers + /// of next format: + /// + /// + /// 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) const; + + /// Compares two global values by number. Uses the GlobalNumbersState to + /// identify the same gobals across function calls. + int cmpGlobalValues(GlobalValue *L, GlobalValue *R) const; + + /// Assign or look up previously assigned numbers for the two values, and + /// return whether the numbers are equal. Numbers are assigned in the order + /// visited. + /// Comparison order: + /// Stage 0: Value that is function itself is always greater then others. + /// If left and right values are references to their functions, then + /// they are equal. + /// Stage 1: Constants are greater than non-constants. + /// If both left and right are constants, then the result of + /// cmpConstants is used as cmpValues result. + /// Stage 2: InlineAsm instances are greater than others. If both left and + /// right are InlineAsm instances, InlineAsm* pointers casted to + /// integers and compared as numbers. + /// Stage 3: For all other cases we compare order we meet these values in + /// their functions. If right value was met first during scanning, + /// then left value is greater. + /// In another words, we compare serial numbers, for more details + /// see comments for sn_mapL and sn_mapR. + int cmpValues(const Value *L, const Value *R) const; + + /// Compare two Instructions for equivalence, similar to + /// Instruction::isSameOperationAs. + /// + /// 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: ordering (as underlying enum class value) + /// 6.4.Load: synch-scope (as integer numbers) + /// 6.5.Load: range metadata (as integer ranges) + /// On this stage its better to see the code, since its not more than 10-15 + /// strings for particular instruction, and could change sometimes. + /// + /// Sets \p needToCmpOperands to true if the operands of the instructions + /// still must be compared afterwards. In this case it's already guaranteed + /// that both instructions have the same number of operands. + int cmpOperations(const Instruction *L, const Instruction *R, + bool &needToCmpOperands) const; + + /// 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) const; + int cmpGEPs(const GetElementPtrInst *GEPL, + const GetElementPtrInst *GEPR) const { + return cmpGEPs(cast(GEPL), cast(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 cmpOrderings(AtomicOrdering L, AtomicOrdering R) const; + int cmpAPInts(const APInt &L, const APInt &R) const; + int cmpAPFloats(const APFloat &L, const APFloat &R) const; + int cmpInlineAsm(const InlineAsm *L, const InlineAsm *R) const; + int cmpMem(StringRef L, StringRef R) const; + int cmpAttrs(const AttributeSet L, const AttributeSet R) const; + int cmpRangeMetadata(const MDNode *L, const MDNode *R) const; + int cmpOperandBundlesSchema(const Instruction *L, const Instruction *R) const; + + // The two functions undergoing comparison. + const Function *FnL, *FnR; + + /// Assign serial numbers to values from left function, and values from + /// right function. + /// Explanation: + /// Being comparing functions we need to compare values we meet at left and + /// right sides. + /// Its easy to sort things out for external values. It just should be + /// the same value at left and right. + /// But for local values (those were introduced inside function body) + /// we have to ensure they were introduced at exactly the same place, + /// and plays the same role. + /// Let's assign serial number to each value when we meet it first time. + /// Values that were met at same place will be with same serial numbers. + /// In this case it would be good to explain few points about values assigned + /// to BBs and other ways of implementation (see below). + /// + /// 1. Safety of BB reordering. + /// It's safe to change the order of BasicBlocks in function. + /// Relationship with other functions and serial numbering will not be + /// changed in this case. + /// As follows from FunctionComparator::compare(), we do CFG walk: we start + /// from the entry, and then take each terminator. So it doesn't matter how in + /// fact BBs are ordered in function. And since cmpValues are called during + /// this walk, the numbering depends only on how BBs located inside the CFG. + /// So the answer is - yes. We will get the same numbering. + /// + /// 2. Impossibility to use dominance properties of values. + /// If we compare two instruction operands: first is usage of local + /// variable AL from function FL, and second is usage of local variable AR + /// from FR, we could compare their origins and check whether they are + /// defined at the same place. + /// But, we are still not able to compare operands of PHI nodes, since those + /// could be operands from further BBs we didn't scan yet. + /// So it's impossible to use dominance properties in general. + mutable DenseMap sn_mapL, sn_mapR; + + // The global state we will use + GlobalNumberState* GlobalNumbers; +}; + +} + +#endif // LLVM_TRANSFORMS_UTILS_FUNCTIONCOMPARATOR_H Index: lib/Transforms/IPO/MergeFunctions.cpp =================================================================== --- lib/Transforms/IPO/MergeFunctions.cpp +++ lib/Transforms/IPO/MergeFunctions.cpp @@ -97,11 +97,9 @@ #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" @@ -110,6 +108,7 @@ #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Transforms/IPO.h" +#include "llvm/Transforms/Utils/FunctionComparator.h" #include using namespace llvm; @@ -130,328 +129,6 @@ namespace { -/// 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 { - 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 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) const; - - /// Constants comparison. - /// Its analog to lexicographical comparison between hypothetical numbers - /// of next format: - /// - /// - /// 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) const; - - /// Compares two global values by number. Uses the GlobalNumbersState to - /// identify the same gobals across function calls. - int cmpGlobalValues(GlobalValue *L, GlobalValue *R) const; - - /// Assign or look up previously assigned numbers for the two values, and - /// return whether the numbers are equal. Numbers are assigned in the order - /// visited. - /// Comparison order: - /// Stage 0: Value that is function itself is always greater then others. - /// If left and right values are references to their functions, then - /// they are equal. - /// Stage 1: Constants are greater than non-constants. - /// If both left and right are constants, then the result of - /// cmpConstants is used as cmpValues result. - /// Stage 2: InlineAsm instances are greater than others. If both left and - /// right are InlineAsm instances, InlineAsm* pointers casted to - /// integers and compared as numbers. - /// Stage 3: For all other cases we compare order we meet these values in - /// their functions. If right value was met first during scanning, - /// then left value is greater. - /// In another words, we compare serial numbers, for more details - /// see comments for sn_mapL and sn_mapR. - int cmpValues(const Value *L, const Value *R) const; - - /// Compare two Instructions for equivalence, similar to - /// Instruction::isSameOperationAs. - /// - /// 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: ordering (as underlying enum class value) - /// 6.4.Load: synch-scope (as integer numbers) - /// 6.5.Load: range metadata (as integer ranges) - /// 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. - /// 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) const; - int cmpGEPs(const GetElementPtrInst *GEPL, - const GetElementPtrInst *GEPR) const { - return cmpGEPs(cast(GEPL), cast(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 cmpOrderings(AtomicOrdering L, AtomicOrdering R) const; - int cmpAPInts(const APInt &L, const APInt &R) const; - int cmpAPFloats(const APFloat &L, const APFloat &R) const; - int cmpInlineAsm(const InlineAsm *L, const InlineAsm *R) const; - int cmpMem(StringRef L, StringRef R) const; - int cmpAttrs(const AttributeSet L, const AttributeSet R) const; - int cmpRangeMetadata(const MDNode *L, const MDNode *R) const; - int cmpOperandBundlesSchema(const Instruction *L, const Instruction *R) const; - - // The two functions undergoing comparison. - const Function *FnL, *FnR; - - /// Assign serial numbers to values from left function, and values from - /// right function. - /// Explanation: - /// Being comparing functions we need to compare values we meet at left and - /// right sides. - /// Its easy to sort things out for external values. It just should be - /// the same value at left and right. - /// But for local values (those were introduced inside function body) - /// we have to ensure they were introduced at exactly the same place, - /// and plays the same role. - /// Let's assign serial number to each value when we meet it first time. - /// Values that were met at same place will be with same serial numbers. - /// In this case it would be good to explain few points about values assigned - /// to BBs and other ways of implementation (see below). - /// - /// 1. Safety of BB reordering. - /// It's safe to change the order of BasicBlocks in function. - /// Relationship with other functions and serial numbering will not be - /// changed in this case. - /// As follows from FunctionComparator::compare(), we do CFG walk: we start - /// from the entry, and then take each terminator. So it doesn't matter how in - /// fact BBs are ordered in function. And since cmpValues are called during - /// this walk, the numbering depends only on how BBs located inside the CFG. - /// So the answer is - yes. We will get the same numbering. - /// - /// 2. Impossibility to use dominance properties of values. - /// If we compare two instruction operands: first is usage of local - /// variable AL from function FL, and second is usage of local variable AR - /// from FR, we could compare their origins and check whether they are - /// defined at the same place. - /// But, we are still not able to compare operands of PHI nodes, since those - /// could be operands from further BBs we didn't scan yet. - /// So it's impossible to use dominance properties in general. - mutable DenseMap sn_mapL, sn_mapR; - - // The global state we will use - GlobalNumberState* GlobalNumbers; -}; - class FunctionNode { mutable AssertingVH F; FunctionComparator::FunctionHash Hash; @@ -470,899 +147,6 @@ 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::cmpOrderings(AtomicOrdering L, AtomicOrdering R) const { - if ((int)L < (int)R) return -1; - if ((int)L > (int)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(L->getOperand(I)); - ConstantInt *RLow = mdconst::extract(R->getOperand(I)); - if (int Res = cmpAPInts(LLow->getValue(), RLow->getValue())) - return Res; - } - return 0; -} - -int FunctionComparator::cmpOperandBundlesSchema(const Instruction *L, - const Instruction *R) const { - ImmutableCallSite LCS(L); - ImmutableCallSite RCS(R); - - assert(LCS && RCS && "Must be calls or invokes!"); - assert(LCS.isCall() == RCS.isCall() && "Can't compare otherwise!"); - - if (int Res = - cmpNumbers(LCS.getNumOperandBundles(), RCS.getNumOperandBundles())) - return Res; - - for (unsigned i = 0, e = LCS.getNumOperandBundles(); i != e; ++i) { - auto OBL = LCS.getOperandBundleAt(i); - auto OBR = RCS.getOperandBundleAt(i); - - if (int Res = OBL.getTagName().compare(OBR.getTagName())) - return Res; - - if (int Res = cmpNumbers(OBL.Inputs.size(), OBR.Inputs.size())) - return Res; - } - - return 0; -} - -/// Constants comparison: -/// 1. Check whether type of L constant could be losslessly bitcasted to R -/// type. -/// 2. Compare constant contents. -/// For more details see declaration comments. -int FunctionComparator::cmpConstants(const Constant *L, - const Constant *R) const { - - Type *TyL = L->getType(); - Type *TyR = R->getType(); - - // Check whether types are bitcastable. This part is just re-factored - // Type::canLosslesslyBitCastTo method, but instead of returning true/false, - // we also pack into result which type is "less" for us. - int TypesRes = cmpTypes(TyL, TyR); - if (TypesRes != 0) { - // Types are different, but check whether we can bitcast them. - if (!TyL->isFirstClassType()) { - if (TyR->isFirstClassType()) - return -1; - // Neither TyL nor TyR are values of first class type. Return the result - // of comparing the types - return TypesRes; - } - if (!TyR->isFirstClassType()) { - if (TyL->isFirstClassType()) - return 1; - return TypesRes; - } - - // Vector -> Vector conversions are always lossless if the two vector types - // have the same size, otherwise not. - unsigned TyLWidth = 0; - unsigned TyRWidth = 0; - - if (auto *VecTyL = dyn_cast(TyL)) - TyLWidth = VecTyL->getBitWidth(); - if (auto *VecTyR = dyn_cast(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(TyL); - PointerType *PTyR = dyn_cast(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(dyn_cast(L)); - auto GlobalValueR = const_cast(dyn_cast(R)); - if (GlobalValueL && GlobalValueR) { - return cmpGlobalValues(GlobalValueL, GlobalValueR); - } - - if (int Res = cmpNumbers(L->getValueID(), R->getValueID())) - return Res; - - if (const auto *SeqL = dyn_cast(L)) { - const auto *SeqR = cast(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(L)->getValue(); - const APInt &RInt = cast(R)->getValue(); - return cmpAPInts(LInt, RInt); - } - case Value::ConstantFPVal: { - const APFloat &LAPF = cast(L)->getValueAPF(); - const APFloat &RAPF = cast(R)->getValueAPF(); - return cmpAPFloats(LAPF, RAPF); - } - case Value::ConstantArrayVal: { - const ConstantArray *LA = cast(L); - const ConstantArray *RA = cast(R); - uint64_t NumElementsL = cast(TyL)->getNumElements(); - uint64_t NumElementsR = cast(TyR)->getNumElements(); - if (int Res = cmpNumbers(NumElementsL, NumElementsR)) - return Res; - for (uint64_t i = 0; i < NumElementsL; ++i) { - if (int Res = cmpConstants(cast(LA->getOperand(i)), - cast(RA->getOperand(i)))) - return Res; - } - return 0; - } - case Value::ConstantStructVal: { - const ConstantStruct *LS = cast(L); - const ConstantStruct *RS = cast(R); - unsigned NumElementsL = cast(TyL)->getNumElements(); - unsigned NumElementsR = cast(TyR)->getNumElements(); - if (int Res = cmpNumbers(NumElementsL, NumElementsR)) - return Res; - for (unsigned i = 0; i != NumElementsL; ++i) { - if (int Res = cmpConstants(cast(LS->getOperand(i)), - cast(RS->getOperand(i)))) - return Res; - } - return 0; - } - case Value::ConstantVectorVal: { - const ConstantVector *LV = cast(L); - const ConstantVector *RV = cast(R); - unsigned NumElementsL = cast(TyL)->getNumElements(); - unsigned NumElementsR = cast(TyR)->getNumElements(); - if (int Res = cmpNumbers(NumElementsL, NumElementsR)) - return Res; - for (uint64_t i = 0; i < NumElementsL; ++i) { - if (int Res = cmpConstants(cast(LV->getOperand(i)), - cast(RV->getOperand(i)))) - return Res; - } - return 0; - } - case Value::ConstantExprVal: { - const ConstantExpr *LE = cast(L); - const ConstantExpr *RE = cast(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(LE->getOperand(i)), - cast(RE->getOperand(i)))) - return Res; - } - return 0; - } - case Value::BlockAddressVal: { - const BlockAddress *LBA = cast(L); - const BlockAddress *RBA = cast(R); - if (int Res = cmpValues(LBA->getFunction(), RBA->getFunction())) - return Res; - if (LBA->getFunction() == RBA->getFunction()) { - // They are BBs in the same function. Order by which comes first in the - // BB order of the function. This order is deterministic. - Function* F = LBA->getFunction(); - BasicBlock *LBB = LBA->getBasicBlock(); - BasicBlock *RBB = RBA->getBasicBlock(); - if (LBB == RBB) - return 0; - for(BasicBlock &BB : F->getBasicBlockList()) { - if (&BB == LBB) { - assert(&BB != RBB); - return -1; - } - if (&BB == RBB) - return 1; - } - llvm_unreachable("Basic Block Address does not point to a basic block in " - "its function."); - return -1; - } else { - // cmpValues said the functions are the same. So because they aren't - // literally the same pointer, they must respectively be the left and - // right functions. - assert(LBA->getFunction() == FnL && RBA->getFunction() == FnR); - // cmpValues will tell us if these are equivalent BasicBlocks, in the - // context of their respective functions. - return cmpValues(LBA->getBasicBlock(), RBA->getBasicBlock()); - } - } - default: // Unknown constant, abort. - DEBUG(dbgs() << "Looking at valueID " << L->getValueID() << "\n"); - llvm_unreachable("Constant ValueID not recognized."); - return -1; - } -} - -int FunctionComparator::cmpGlobalValues(GlobalValue *L, GlobalValue *R) const { - return cmpNumbers(GlobalNumbers->getNumber(L), GlobalNumbers->getNumber(R)); -} - -/// cmpType - compares two types, -/// defines total ordering among the types set. -/// See method declaration comments for more details. -int FunctionComparator::cmpTypes(Type *TyL, Type *TyR) const { - PointerType *PTyL = dyn_cast(TyL); - PointerType *PTyR = dyn_cast(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. - LLVM_FALLTHROUGH; - case Type::IntegerTyID: - return cmpNumbers(cast(TyL)->getBitWidth(), - cast(TyR)->getBitWidth()); - case Type::VectorTyID: { - VectorType *VTyL = cast(TyL), *VTyR = cast(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(TyL); - StructType *STyR = cast(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(TyL); - FunctionType *FTyR = cast(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(TyL); - ArrayType *ATyR = cast(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 cmpTypes. - // * we test for I->getRawSubclassOptionalData (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; - - // 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 AllocaInst *AI = dyn_cast(L)) { - if (int Res = cmpTypes(AI->getAllocatedType(), - cast(R)->getAllocatedType())) - return Res; - return cmpNumbers(AI->getAlignment(), cast(R)->getAlignment()); - } - if (const LoadInst *LI = dyn_cast(L)) { - if (int Res = cmpNumbers(LI->isVolatile(), cast(R)->isVolatile())) - return Res; - if (int Res = - cmpNumbers(LI->getAlignment(), cast(R)->getAlignment())) - return Res; - if (int Res = - cmpOrderings(LI->getOrdering(), cast(R)->getOrdering())) - return Res; - if (int Res = - cmpNumbers(LI->getSynchScope(), cast(R)->getSynchScope())) - return Res; - return cmpRangeMetadata(LI->getMetadata(LLVMContext::MD_range), - cast(R)->getMetadata(LLVMContext::MD_range)); - } - if (const StoreInst *SI = dyn_cast(L)) { - if (int Res = - cmpNumbers(SI->isVolatile(), cast(R)->isVolatile())) - return Res; - if (int Res = - cmpNumbers(SI->getAlignment(), cast(R)->getAlignment())) - return Res; - if (int Res = - cmpOrderings(SI->getOrdering(), cast(R)->getOrdering())) - return Res; - return cmpNumbers(SI->getSynchScope(), cast(R)->getSynchScope()); - } - if (const CmpInst *CI = dyn_cast(L)) - return cmpNumbers(CI->getPredicate(), cast(R)->getPredicate()); - if (const CallInst *CI = dyn_cast(L)) { - if (int Res = cmpNumbers(CI->getCallingConv(), - cast(R)->getCallingConv())) - return Res; - if (int Res = - cmpAttrs(CI->getAttributes(), cast(R)->getAttributes())) - return Res; - if (int Res = cmpOperandBundlesSchema(CI, R)) - return Res; - return cmpRangeMetadata( - CI->getMetadata(LLVMContext::MD_range), - cast(R)->getMetadata(LLVMContext::MD_range)); - } - if (const InvokeInst *II = dyn_cast(L)) { - if (int Res = cmpNumbers(II->getCallingConv(), - cast(R)->getCallingConv())) - return Res; - if (int Res = - cmpAttrs(II->getAttributes(), cast(R)->getAttributes())) - return Res; - if (int Res = cmpOperandBundlesSchema(II, R)) - return Res; - return cmpRangeMetadata( - II->getMetadata(LLVMContext::MD_range), - cast(R)->getMetadata(LLVMContext::MD_range)); - } - if (const InsertValueInst *IVI = dyn_cast(L)) { - ArrayRef LIndices = IVI->getIndices(); - ArrayRef RIndices = cast(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; - } - return 0; - } - if (const ExtractValueInst *EVI = dyn_cast(L)) { - ArrayRef LIndices = EVI->getIndices(); - ArrayRef RIndices = cast(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(L)) { - if (int Res = - cmpOrderings(FI->getOrdering(), cast(R)->getOrdering())) - return Res; - return cmpNumbers(FI->getSynchScope(), cast(R)->getSynchScope()); - } - if (const AtomicCmpXchgInst *CXI = dyn_cast(L)) { - if (int Res = cmpNumbers(CXI->isVolatile(), - cast(R)->isVolatile())) - return Res; - if (int Res = cmpNumbers(CXI->isWeak(), - cast(R)->isWeak())) - return Res; - if (int Res = - cmpOrderings(CXI->getSuccessOrdering(), - cast(R)->getSuccessOrdering())) - return Res; - if (int Res = - cmpOrderings(CXI->getFailureOrdering(), - cast(R)->getFailureOrdering())) - return Res; - return cmpNumbers(CXI->getSynchScope(), - cast(R)->getSynchScope()); - } - if (const AtomicRMWInst *RMWI = dyn_cast(L)) { - if (int Res = cmpNumbers(RMWI->getOperation(), - cast(R)->getOperation())) - return Res; - if (int Res = cmpNumbers(RMWI->isVolatile(), - cast(R)->isVolatile())) - return Res; - if (int Res = cmpOrderings(RMWI->getOrdering(), - cast(R)->getOrdering())) - return Res; - return cmpNumbers(RMWI->getSynchScope(), - cast(R)->getSynchScope()); - } - if (const PHINode *PNL = dyn_cast(L)) { - const PHINode *PNR = cast(R); - // Ensure that in addition to the incoming values being identical - // (checked by the caller of this function), the incoming blocks - // are also identical. - for (unsigned i = 0, e = PNL->getNumIncomingValues(); i != e; ++i) { - if (int Res = - cmpValues(PNL->getIncomingBlock(i), PNR->getIncomingBlock(i))) - return Res; - } - } - return 0; -} - -// Determine whether two GEP operations perform the same underlying arithmetic. -// Read method declaration comments for more details. -int FunctionComparator::cmpGEPs(const GEPOperator *GEPL, - const GEPOperator *GEPR) const { - - unsigned int ASL = GEPL->getPointerAddressSpace(); - unsigned int ASR = GEPR->getPointerAddressSpace(); - - if (int Res = cmpNumbers(ASL, ASR)) - return Res; - - // When we have target data, we can reduce the GEP down to the value in bytes - // added to the address. - const DataLayout &DL = FnL->getParent()->getDataLayout(); - unsigned BitWidth = DL.getPointerSizeInBits(ASL); - APInt OffsetL(BitWidth, 0), OffsetR(BitWidth, 0); - if (GEPL->accumulateConstantOffset(DL, OffsetL) && - GEPR->accumulateConstantOffset(DL, OffsetR)) - return cmpAPInts(OffsetL, OffsetR); - if (int Res = cmpTypes(GEPL->getSourceElementType(), - GEPR->getSourceElementType())) - return Res; - - if (int Res = cmpNumbers(GEPL->getNumOperands(), GEPR->getNumOperands())) - return Res; - - for (unsigned i = 0, e = GEPL->getNumOperands(); i != e; ++i) { - if (int Res = cmpValues(GEPL->getOperand(i), GEPR->getOperand(i))) - return Res; - } - - return 0; -} - -int FunctionComparator::cmpInlineAsm(const InlineAsm *L, - const InlineAsm *R) const { - // InlineAsm's are uniqued. If they are the same pointer, obviously they are - // the same, otherwise compare the fields. - if (L == R) - return 0; - if (int Res = cmpTypes(L->getFunctionType(), R->getFunctionType())) - return Res; - if (int Res = cmpMem(L->getAsmString(), R->getAsmString())) - return Res; - if (int Res = cmpMem(L->getConstraintString(), R->getConstraintString())) - return Res; - if (int Res = cmpNumbers(L->hasSideEffects(), R->hasSideEffects())) - return Res; - if (int Res = cmpNumbers(L->isAlignStack(), R->isAlignStack())) - return Res; - if (int Res = cmpNumbers(L->getDialect(), R->getDialect())) - return Res; - llvm_unreachable("InlineAsm blocks were not uniqued."); - return 0; -} - -/// Compare two values used by the two functions under pair-wise comparison. If -/// this is the first time the values are seen, they're added to the mapping so -/// that we will detect mismatches on next use. -/// See comments in declaration for more details. -int FunctionComparator::cmpValues(const Value *L, const Value *R) const { - // Catch self-reference case. - if (L == FnL) { - if (R == FnR) - return 0; - return -1; - } - if (R == FnR) { - if (L == FnL) - return 0; - return 1; - } - - const Constant *ConstL = dyn_cast(L); - const Constant *ConstR = dyn_cast(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(L); - const InlineAsm *InlineAsmR = dyn_cast(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); -} -// Test whether two basic blocks have equivalent behaviour. -int FunctionComparator::cmpBasicBlocks(const BasicBlock *BBL, - const BasicBlock *BBR) const { - 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(InstL); - const GetElementPtrInst *GEPR = dyn_cast(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); - } - } - - ++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!"); - } - - // We do a CFG-ordered walk since the actual ordering of the blocks in the - // 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 FnLBBs, FnRBBs; - SmallPtrSet VisitedBBs; // in terms of F1. - - FnLBBs.push_back(&FnL->getEntryBlock()); - FnRBBs.push_back(&FnR->getEntryBlock()); - - VisitedBBs.insert(FnLBBs[0]); - while (!FnLBBs.empty()) { - const BasicBlock *BBL = FnLBBs.pop_back_val(); - const BasicBlock *BBR = FnRBBs.pop_back_val(); - - if (int Res = cmpValues(BBL, BBR)) - return Res; - - if (int Res = cmpBasicBlocks(BBL, BBR)) - return Res; - - const TerminatorInst *TermL = BBL->getTerminator(); - const TerminatorInst *TermR = BBR->getTerminator(); - - assert(TermL->getNumSuccessors() == TermR->getNumSuccessors()); - for (unsigned i = 0, e = TermL->getNumSuccessors(); i != e; ++i) { - if (!VisitedBBs.insert(TermL->getSuccessor(i)).second) - continue; - - FnLBBs.push_back(TermL->getSuccessor(i)); - FnRBBs.push_back(TermR->getSuccessor(i)); - } - } - 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 BBs; - SmallSet 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, /// by considering all pointer types to be equivalent. Once identified, Index: lib/Transforms/Utils/CMakeLists.txt =================================================================== --- lib/Transforms/Utils/CMakeLists.txt +++ lib/Transforms/Utils/CMakeLists.txt @@ -13,6 +13,7 @@ DemoteRegToStack.cpp Evaluator.cpp FlattenCFG.cpp + FunctionComparator.cpp FunctionImportUtils.cpp GlobalStatus.cpp InlineFunction.cpp Index: lib/Transforms/Utils/FunctionComparator.cpp =================================================================== --- lib/Transforms/Utils/FunctionComparator.cpp +++ lib/Transforms/Utils/FunctionComparator.cpp @@ -0,0 +1,922 @@ +//===- FunctionComparator.h - Function Comparator -------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the FunctionComparator and GlobalNumberState classes +// which are used by the MergeFunctions pass for comparing functions. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Transforms/Utils/FunctionComparator.h" +#include "llvm/ADT/SmallSet.h" +#include "llvm/IR/CallSite.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/InlineAsm.h" +#include "llvm/IR/Module.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" + +using namespace llvm; + +#define DEBUG_TYPE "functioncomparator" + +int FunctionComparator::cmpNumbers(uint64_t L, uint64_t R) const { + if (L < R) return -1; + if (L > R) return 1; + return 0; +} + +int FunctionComparator::cmpOrderings(AtomicOrdering L, AtomicOrdering R) const { + if ((int)L < (int)R) return -1; + if ((int)L > (int)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(L->getOperand(I)); + ConstantInt *RLow = mdconst::extract(R->getOperand(I)); + if (int Res = cmpAPInts(LLow->getValue(), RLow->getValue())) + return Res; + } + return 0; +} + +int FunctionComparator::cmpOperandBundlesSchema(const Instruction *L, + const Instruction *R) const { + ImmutableCallSite LCS(L); + ImmutableCallSite RCS(R); + + assert(LCS && RCS && "Must be calls or invokes!"); + assert(LCS.isCall() == RCS.isCall() && "Can't compare otherwise!"); + + if (int Res = + cmpNumbers(LCS.getNumOperandBundles(), RCS.getNumOperandBundles())) + return Res; + + for (unsigned i = 0, e = LCS.getNumOperandBundles(); i != e; ++i) { + auto OBL = LCS.getOperandBundleAt(i); + auto OBR = RCS.getOperandBundleAt(i); + + if (int Res = OBL.getTagName().compare(OBR.getTagName())) + return Res; + + if (int Res = cmpNumbers(OBL.Inputs.size(), OBR.Inputs.size())) + return Res; + } + + return 0; +} + +/// Constants comparison: +/// 1. Check whether type of L constant could be losslessly bitcasted to R +/// type. +/// 2. Compare constant contents. +/// For more details see declaration comments. +int FunctionComparator::cmpConstants(const Constant *L, + const Constant *R) const { + + Type *TyL = L->getType(); + Type *TyR = R->getType(); + + // Check whether types are bitcastable. This part is just re-factored + // Type::canLosslesslyBitCastTo method, but instead of returning true/false, + // we also pack into result which type is "less" for us. + int TypesRes = cmpTypes(TyL, TyR); + if (TypesRes != 0) { + // Types are different, but check whether we can bitcast them. + if (!TyL->isFirstClassType()) { + if (TyR->isFirstClassType()) + return -1; + // Neither TyL nor TyR are values of first class type. Return the result + // of comparing the types + return TypesRes; + } + if (!TyR->isFirstClassType()) { + if (TyL->isFirstClassType()) + return 1; + return TypesRes; + } + + // Vector -> Vector conversions are always lossless if the two vector types + // have the same size, otherwise not. + unsigned TyLWidth = 0; + unsigned TyRWidth = 0; + + if (auto *VecTyL = dyn_cast(TyL)) + TyLWidth = VecTyL->getBitWidth(); + if (auto *VecTyR = dyn_cast(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(TyL); + PointerType *PTyR = dyn_cast(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(dyn_cast(L)); + auto GlobalValueR = const_cast(dyn_cast(R)); + if (GlobalValueL && GlobalValueR) { + return cmpGlobalValues(GlobalValueL, GlobalValueR); + } + + if (int Res = cmpNumbers(L->getValueID(), R->getValueID())) + return Res; + + if (const auto *SeqL = dyn_cast(L)) { + const auto *SeqR = cast(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(L)->getValue(); + const APInt &RInt = cast(R)->getValue(); + return cmpAPInts(LInt, RInt); + } + case Value::ConstantFPVal: { + const APFloat &LAPF = cast(L)->getValueAPF(); + const APFloat &RAPF = cast(R)->getValueAPF(); + return cmpAPFloats(LAPF, RAPF); + } + case Value::ConstantArrayVal: { + const ConstantArray *LA = cast(L); + const ConstantArray *RA = cast(R); + uint64_t NumElementsL = cast(TyL)->getNumElements(); + uint64_t NumElementsR = cast(TyR)->getNumElements(); + if (int Res = cmpNumbers(NumElementsL, NumElementsR)) + return Res; + for (uint64_t i = 0; i < NumElementsL; ++i) { + if (int Res = cmpConstants(cast(LA->getOperand(i)), + cast(RA->getOperand(i)))) + return Res; + } + return 0; + } + case Value::ConstantStructVal: { + const ConstantStruct *LS = cast(L); + const ConstantStruct *RS = cast(R); + unsigned NumElementsL = cast(TyL)->getNumElements(); + unsigned NumElementsR = cast(TyR)->getNumElements(); + if (int Res = cmpNumbers(NumElementsL, NumElementsR)) + return Res; + for (unsigned i = 0; i != NumElementsL; ++i) { + if (int Res = cmpConstants(cast(LS->getOperand(i)), + cast(RS->getOperand(i)))) + return Res; + } + return 0; + } + case Value::ConstantVectorVal: { + const ConstantVector *LV = cast(L); + const ConstantVector *RV = cast(R); + unsigned NumElementsL = cast(TyL)->getNumElements(); + unsigned NumElementsR = cast(TyR)->getNumElements(); + if (int Res = cmpNumbers(NumElementsL, NumElementsR)) + return Res; + for (uint64_t i = 0; i < NumElementsL; ++i) { + if (int Res = cmpConstants(cast(LV->getOperand(i)), + cast(RV->getOperand(i)))) + return Res; + } + return 0; + } + case Value::ConstantExprVal: { + const ConstantExpr *LE = cast(L); + const ConstantExpr *RE = cast(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(LE->getOperand(i)), + cast(RE->getOperand(i)))) + return Res; + } + return 0; + } + case Value::BlockAddressVal: { + const BlockAddress *LBA = cast(L); + const BlockAddress *RBA = cast(R); + if (int Res = cmpValues(LBA->getFunction(), RBA->getFunction())) + return Res; + if (LBA->getFunction() == RBA->getFunction()) { + // They are BBs in the same function. Order by which comes first in the + // BB order of the function. This order is deterministic. + Function* F = LBA->getFunction(); + BasicBlock *LBB = LBA->getBasicBlock(); + BasicBlock *RBB = RBA->getBasicBlock(); + if (LBB == RBB) + return 0; + for(BasicBlock &BB : F->getBasicBlockList()) { + if (&BB == LBB) { + assert(&BB != RBB); + return -1; + } + if (&BB == RBB) + return 1; + } + llvm_unreachable("Basic Block Address does not point to a basic block in " + "its function."); + return -1; + } else { + // cmpValues said the functions are the same. So because they aren't + // literally the same pointer, they must respectively be the left and + // right functions. + assert(LBA->getFunction() == FnL && RBA->getFunction() == FnR); + // cmpValues will tell us if these are equivalent BasicBlocks, in the + // context of their respective functions. + return cmpValues(LBA->getBasicBlock(), RBA->getBasicBlock()); + } + } + default: // Unknown constant, abort. + DEBUG(dbgs() << "Looking at valueID " << L->getValueID() << "\n"); + llvm_unreachable("Constant ValueID not recognized."); + return -1; + } +} + +int FunctionComparator::cmpGlobalValues(GlobalValue *L, GlobalValue *R) const { + return cmpNumbers(GlobalNumbers->getNumber(L), GlobalNumbers->getNumber(R)); +} + +/// cmpType - compares two types, +/// defines total ordering among the types set. +/// See method declaration comments for more details. +int FunctionComparator::cmpTypes(Type *TyL, Type *TyR) const { + PointerType *PTyL = dyn_cast(TyL); + PointerType *PTyR = dyn_cast(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. + LLVM_FALLTHROUGH; + case Type::IntegerTyID: + return cmpNumbers(cast(TyL)->getBitWidth(), + cast(TyR)->getBitWidth()); + case Type::VectorTyID: { + VectorType *VTyL = cast(TyL), *VTyR = cast(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(TyL); + StructType *STyR = cast(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(TyL); + FunctionType *FTyR = cast(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(TyL); + ArrayType *ATyR = cast(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, + bool &needToCmpOperands) const { + needToCmpOperands = true; + if (int Res = cmpValues(L, R)) + return Res; + + // Differences from Instruction::isSameOperationAs: + // * replace type comparison with calls to cmpTypes. + // * we test for I->getRawSubclassOptionalData (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 (const GetElementPtrInst *GEPL = dyn_cast(L)) { + needToCmpOperands = false; + const GetElementPtrInst *GEPR = cast(R); + if (int Res = + cmpValues(GEPL->getPointerOperand(), GEPR->getPointerOperand())) + return Res; + return cmpGEPs(GEPL, GEPR); + } + + 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; + + // 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 AllocaInst *AI = dyn_cast(L)) { + if (int Res = cmpTypes(AI->getAllocatedType(), + cast(R)->getAllocatedType())) + return Res; + return cmpNumbers(AI->getAlignment(), cast(R)->getAlignment()); + } + if (const LoadInst *LI = dyn_cast(L)) { + if (int Res = cmpNumbers(LI->isVolatile(), cast(R)->isVolatile())) + return Res; + if (int Res = + cmpNumbers(LI->getAlignment(), cast(R)->getAlignment())) + return Res; + if (int Res = + cmpOrderings(LI->getOrdering(), cast(R)->getOrdering())) + return Res; + if (int Res = + cmpNumbers(LI->getSynchScope(), cast(R)->getSynchScope())) + return Res; + return cmpRangeMetadata(LI->getMetadata(LLVMContext::MD_range), + cast(R)->getMetadata(LLVMContext::MD_range)); + } + if (const StoreInst *SI = dyn_cast(L)) { + if (int Res = + cmpNumbers(SI->isVolatile(), cast(R)->isVolatile())) + return Res; + if (int Res = + cmpNumbers(SI->getAlignment(), cast(R)->getAlignment())) + return Res; + if (int Res = + cmpOrderings(SI->getOrdering(), cast(R)->getOrdering())) + return Res; + return cmpNumbers(SI->getSynchScope(), cast(R)->getSynchScope()); + } + if (const CmpInst *CI = dyn_cast(L)) + return cmpNumbers(CI->getPredicate(), cast(R)->getPredicate()); + if (const CallInst *CI = dyn_cast(L)) { + if (int Res = cmpNumbers(CI->getCallingConv(), + cast(R)->getCallingConv())) + return Res; + if (int Res = + cmpAttrs(CI->getAttributes(), cast(R)->getAttributes())) + return Res; + if (int Res = cmpOperandBundlesSchema(CI, R)) + return Res; + return cmpRangeMetadata( + CI->getMetadata(LLVMContext::MD_range), + cast(R)->getMetadata(LLVMContext::MD_range)); + } + if (const InvokeInst *II = dyn_cast(L)) { + if (int Res = cmpNumbers(II->getCallingConv(), + cast(R)->getCallingConv())) + return Res; + if (int Res = + cmpAttrs(II->getAttributes(), cast(R)->getAttributes())) + return Res; + if (int Res = cmpOperandBundlesSchema(II, R)) + return Res; + return cmpRangeMetadata( + II->getMetadata(LLVMContext::MD_range), + cast(R)->getMetadata(LLVMContext::MD_range)); + } + if (const InsertValueInst *IVI = dyn_cast(L)) { + ArrayRef LIndices = IVI->getIndices(); + ArrayRef RIndices = cast(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; + } + return 0; + } + if (const ExtractValueInst *EVI = dyn_cast(L)) { + ArrayRef LIndices = EVI->getIndices(); + ArrayRef RIndices = cast(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(L)) { + if (int Res = + cmpOrderings(FI->getOrdering(), cast(R)->getOrdering())) + return Res; + return cmpNumbers(FI->getSynchScope(), cast(R)->getSynchScope()); + } + if (const AtomicCmpXchgInst *CXI = dyn_cast(L)) { + if (int Res = cmpNumbers(CXI->isVolatile(), + cast(R)->isVolatile())) + return Res; + if (int Res = cmpNumbers(CXI->isWeak(), + cast(R)->isWeak())) + return Res; + if (int Res = + cmpOrderings(CXI->getSuccessOrdering(), + cast(R)->getSuccessOrdering())) + return Res; + if (int Res = + cmpOrderings(CXI->getFailureOrdering(), + cast(R)->getFailureOrdering())) + return Res; + return cmpNumbers(CXI->getSynchScope(), + cast(R)->getSynchScope()); + } + if (const AtomicRMWInst *RMWI = dyn_cast(L)) { + if (int Res = cmpNumbers(RMWI->getOperation(), + cast(R)->getOperation())) + return Res; + if (int Res = cmpNumbers(RMWI->isVolatile(), + cast(R)->isVolatile())) + return Res; + if (int Res = cmpOrderings(RMWI->getOrdering(), + cast(R)->getOrdering())) + return Res; + return cmpNumbers(RMWI->getSynchScope(), + cast(R)->getSynchScope()); + } + if (const PHINode *PNL = dyn_cast(L)) { + const PHINode *PNR = cast(R); + // Ensure that in addition to the incoming values being identical + // (checked by the caller of this function), the incoming blocks + // are also identical. + for (unsigned i = 0, e = PNL->getNumIncomingValues(); i != e; ++i) { + if (int Res = + cmpValues(PNL->getIncomingBlock(i), PNR->getIncomingBlock(i))) + return Res; + } + } + return 0; +} + +// Determine whether two GEP operations perform the same underlying arithmetic. +// Read method declaration comments for more details. +int FunctionComparator::cmpGEPs(const GEPOperator *GEPL, + const GEPOperator *GEPR) const { + + unsigned int ASL = GEPL->getPointerAddressSpace(); + unsigned int ASR = GEPR->getPointerAddressSpace(); + + if (int Res = cmpNumbers(ASL, ASR)) + return Res; + + // When we have target data, we can reduce the GEP down to the value in bytes + // added to the address. + const DataLayout &DL = FnL->getParent()->getDataLayout(); + unsigned BitWidth = DL.getPointerSizeInBits(ASL); + APInt OffsetL(BitWidth, 0), OffsetR(BitWidth, 0); + if (GEPL->accumulateConstantOffset(DL, OffsetL) && + GEPR->accumulateConstantOffset(DL, OffsetR)) + return cmpAPInts(OffsetL, OffsetR); + if (int Res = cmpTypes(GEPL->getSourceElementType(), + GEPR->getSourceElementType())) + return Res; + + if (int Res = cmpNumbers(GEPL->getNumOperands(), GEPR->getNumOperands())) + return Res; + + for (unsigned i = 0, e = GEPL->getNumOperands(); i != e; ++i) { + if (int Res = cmpValues(GEPL->getOperand(i), GEPR->getOperand(i))) + return Res; + } + + return 0; +} + +int FunctionComparator::cmpInlineAsm(const InlineAsm *L, + const InlineAsm *R) const { + // InlineAsm's are uniqued. If they are the same pointer, obviously they are + // the same, otherwise compare the fields. + if (L == R) + return 0; + if (int Res = cmpTypes(L->getFunctionType(), R->getFunctionType())) + return Res; + if (int Res = cmpMem(L->getAsmString(), R->getAsmString())) + return Res; + if (int Res = cmpMem(L->getConstraintString(), R->getConstraintString())) + return Res; + if (int Res = cmpNumbers(L->hasSideEffects(), R->hasSideEffects())) + return Res; + if (int Res = cmpNumbers(L->isAlignStack(), R->isAlignStack())) + return Res; + if (int Res = cmpNumbers(L->getDialect(), R->getDialect())) + return Res; + llvm_unreachable("InlineAsm blocks were not uniqued."); + return 0; +} + +/// Compare two values used by the two functions under pair-wise comparison. If +/// this is the first time the values are seen, they're added to the mapping so +/// that we will detect mismatches on next use. +/// See comments in declaration for more details. +int FunctionComparator::cmpValues(const Value *L, const Value *R) const { + // Catch self-reference case. + if (L == FnL) { + if (R == FnR) + return 0; + return -1; + } + if (R == FnR) { + if (L == FnL) + return 0; + return 1; + } + + const Constant *ConstL = dyn_cast(L); + const Constant *ConstR = dyn_cast(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(L); + const InlineAsm *InlineAsmR = dyn_cast(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); +} + +// Test whether two basic blocks have equivalent behaviour. +int FunctionComparator::cmpBasicBlocks(const BasicBlock *BBL, + const BasicBlock *BBR) const { + BasicBlock::const_iterator InstL = BBL->begin(), InstLE = BBL->end(); + BasicBlock::const_iterator InstR = BBR->begin(), InstRE = BBR->end(); + + do { + bool needToCmpOperands = true; + if (int Res = cmpOperations(&*InstL, &*InstR, needToCmpOperands)) + return Res; + if (needToCmpOperands) { + 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); + } + } + + ++InstL; + ++InstR; + } while (InstL != InstLE && InstR != InstRE); + + if (InstL != InstLE && InstR == InstRE) + return 1; + if (InstL == InstLE && InstR != InstRE) + return -1; + return 0; +} + +int FunctionComparator::compareSignature() { + 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!"); + } + return 0; +} + +// Test whether the two functions have equivalent behaviour. +int FunctionComparator::compare() { + beginCompare(); + + if (int Res = compareSignature()) + return Res; + + // We do a CFG-ordered walk since the actual ordering of the blocks in the + // 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 FnLBBs, FnRBBs; + SmallPtrSet VisitedBBs; // in terms of F1. + + FnLBBs.push_back(&FnL->getEntryBlock()); + FnRBBs.push_back(&FnR->getEntryBlock()); + + VisitedBBs.insert(FnLBBs[0]); + while (!FnLBBs.empty()) { + const BasicBlock *BBL = FnLBBs.pop_back_val(); + const BasicBlock *BBR = FnRBBs.pop_back_val(); + + if (int Res = cmpValues(BBL, BBR)) + return Res; + + if (int Res = cmpBasicBlocks(BBL, BBR)) + return Res; + + const TerminatorInst *TermL = BBL->getTerminator(); + const TerminatorInst *TermR = BBR->getTerminator(); + + assert(TermL->getNumSuccessors() == TermR->getNumSuccessors()); + for (unsigned i = 0, e = TermL->getNumSuccessors(); i != e; ++i) { + if (!VisitedBBs.insert(TermL->getSuccessor(i)).second) + continue; + + FnLBBs.push_back(TermL->getSuccessor(i)); + FnRBBs.push_back(TermR->getSuccessor(i)); + } + } + 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 BBs; + SmallSet 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(); +} + +