LLVM 20.0.0git
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#include "llvm/Transforms/Scalar/Reassociate.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Argument.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
#include <algorithm>
#include <cassert>
#include <utility>
Go to the source code of this file.
Classes | |
class | llvm::reassociate::XorOpnd |
Utility class representing a non-constant Xor-operand. More... | |
Macros | |
#define | DEBUG_TYPE "reassociate" |
Typedefs | |
using | RepeatedValue = std::pair< Value *, uint64_t > |
Functions | |
STATISTIC (NumChanged, "Number of insts reassociated") | |
STATISTIC (NumAnnihil, "Number of expr tree annihilated") | |
STATISTIC (NumFactor, "Number of multiplies factored") | |
static void | PrintOps (Instruction *I, const SmallVectorImpl< ValueEntry > &Ops) |
Print out the expression identified in the Ops list. | |
static bool | hasFPAssociativeFlags (Instruction *I) |
Return true if I is an instruction with the FastMathFlags that are needed for general reassociation set. | |
static BinaryOperator * | isReassociableOp (Value *V, unsigned Opcode) |
Return true if V is an instruction of the specified opcode and if it only has one use. | |
static BinaryOperator * | isReassociableOp (Value *V, unsigned Opcode1, unsigned Opcode2) |
static BinaryOperator * | CreateAdd (Value *S1, Value *S2, const Twine &Name, BasicBlock::iterator InsertBefore, Value *FlagsOp) |
static BinaryOperator * | CreateMul (Value *S1, Value *S2, const Twine &Name, BasicBlock::iterator InsertBefore, Value *FlagsOp) |
static Instruction * | CreateNeg (Value *S1, const Twine &Name, BasicBlock::iterator InsertBefore, Value *FlagsOp) |
static BinaryOperator * | LowerNegateToMultiply (Instruction *Neg) |
Replace 0-X with X*-1. | |
static bool | LinearizeExprTree (Instruction *I, SmallVectorImpl< RepeatedValue > &Ops, ReassociatePass::OrderedSet &ToRedo, reassociate::OverflowTracking &Flags) |
Given an associative binary expression, return the leaf nodes in Ops along with their weights (how many times the leaf occurs). | |
static Value * | NegateValue (Value *V, Instruction *BI, ReassociatePass::OrderedSet &ToRedo) |
Insert instructions before the instruction pointed to by BI, that computes the negative version of the value specified. | |
static bool | isLoadCombineCandidate (Instruction *Or) |
static bool | shouldConvertOrWithNoCommonBitsToAdd (Instruction *Or) |
Return true if it may be profitable to convert this (X|Y) into (X+Y). | |
static BinaryOperator * | convertOrWithNoCommonBitsToAdd (Instruction *Or) |
If we have (X|Y), and iff X and Y have no common bits set, transform this into (X+Y) to allow arithmetics reassociation. | |
static bool | ShouldBreakUpSubtract (Instruction *Sub) |
Return true if we should break up this subtract of X-Y into (X + -Y). | |
static BinaryOperator * | BreakUpSubtract (Instruction *Sub, ReassociatePass::OrderedSet &ToRedo) |
If we have (X-Y), and if either X is an add, or if this is only used by an add, transform this into (X+(0-Y)) to promote better reassociation. | |
static BinaryOperator * | ConvertShiftToMul (Instruction *Shl) |
If this is a shift of a reassociable multiply or is used by one, change this into a multiply by a constant to assist with further reassociation. | |
static unsigned | FindInOperandList (const SmallVectorImpl< ValueEntry > &Ops, unsigned i, Value *X) |
Scan backwards and forwards among values with the same rank as element i to see if X exists. | |
static Value * | EmitAddTreeOfValues (BasicBlock::iterator It, SmallVectorImpl< WeakTrackingVH > &Ops) |
Emit a tree of add instructions, summing Ops together and returning the result. | |
static void | FindSingleUseMultiplyFactors (Value *V, SmallVectorImpl< Value * > &Factors) |
If V is a single-use multiply, recursively add its operands as factors, otherwise add V to the list of factors. | |
static Value * | OptimizeAndOrXor (unsigned Opcode, SmallVectorImpl< ValueEntry > &Ops) |
Optimize a series of operands to an 'and', 'or', or 'xor' instruction. | |
static Value * | createAndInstr (BasicBlock::iterator InsertBefore, Value *Opnd, const APInt &ConstOpnd) |
Helper function of CombineXorOpnd(). | |
static bool | collectMultiplyFactors (SmallVectorImpl< ValueEntry > &Ops, SmallVectorImpl< Factor > &Factors) |
Build up a vector of value/power pairs factoring a product. | |
static Value * | buildMultiplyTree (IRBuilderBase &Builder, SmallVectorImpl< Value * > &Ops) |
Build a tree of multiplies, computing the product of Ops. | |
static void | getNegatibleInsts (Value *V, SmallVectorImpl< Instruction * > &Candidates) |
Recursively analyze an expression to build a list of instructions that have negative floating-point constant operands. | |
INITIALIZE_PASS (ReassociateLegacyPass, "reassociate", "Reassociate expressions", false, false) FunctionPass *llvm | |
Variables | |
static cl::opt< bool > | UseCSELocalOpt (DEBUG_TYPE "-use-cse-local", cl::desc("Only reorder expressions within a basic block " "when exposing CSE opportunities"), cl::init(true), cl::Hidden) |
#define DEBUG_TYPE "reassociate" |
Definition at line 68 of file Reassociate.cpp.
using RepeatedValue = std::pair<Value *, uint64_t> |
Definition at line 305 of file Reassociate.cpp.
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If we have (X-Y), and if either X is an add, or if this is only used by an add, transform this into (X+(0-Y)) to promote better reassociation.
Definition at line 1007 of file Reassociate.cpp.
References CreateAdd(), llvm::dbgs(), llvm::Instruction::getDebugLoc(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::Constant::getNullValue(), llvm::User::getOperand(), llvm::Value::getType(), LLVM_DEBUG, NegateValue(), llvm::Value::replaceAllUsesWith(), and llvm::User::setOperand().
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Build a tree of multiplies, computing the product of Ops.
Definition at line 1780 of file Reassociate.cpp.
References llvm::SmallVectorTemplateCommon< T, typename >::back(), llvm::IRBuilderBase::CreateFMul(), llvm::IRBuilderBase::CreateMul(), llvm::SmallVectorBase< Size_T >::empty(), llvm::Value::getType(), llvm::Type::isIntOrIntVectorTy(), LHS, llvm::SmallVectorImpl< T >::pop_back_val(), and llvm::SmallVectorBase< Size_T >::size().
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Build up a vector of value/power pairs factoring a product.
Given a series of multiplication operands, build a vector of factors and the powers each is raised to when forming the final product. Sort them in the order of descending power.
(x*x) -> [(x, 2)] ((x*x)*x) -> [(x, 3)]
((((x*y)*x)*y)*x) -> [(x, 3), (y, 2)]
Definition at line 1726 of file Reassociate.cpp.
References assert(), llvm::SmallVectorTemplateCommon< T, typename >::begin(), llvm::SmallVectorImpl< T >::erase(), Idx, LHS, llvm::SmallVectorTemplateBase< T, bool >::push_back(), RHS, llvm::SmallVectorBase< Size_T >::size(), Size, and llvm::stable_sort().
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If we have (X|Y), and iff X and Y have no common bits set, transform this into (X+Y) to allow arithmetics reassociation.
Definition at line 960 of file Reassociate.cpp.
References CreateAdd(), llvm::dbgs(), LLVM_DEBUG, and llvm::Or.
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If this is a shift of a reassociable multiply or is used by one, change this into a multiply by a constant to assist with further reassociation.
Definition at line 1031 of file Reassociate.cpp.
References assert(), llvm::BitWidth, llvm::ConstantFoldBinaryInstruction(), llvm::PoisonValue::get(), llvm::Instruction::getDebugLoc(), llvm::Type::getIntegerBitWidth(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::User::getOperand(), llvm::Value::getType(), llvm::Mul, llvm::Value::replaceAllUsesWith(), and llvm::User::setOperand().
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Definition at line 248 of file Reassociate.cpp.
References getFastMathFlags(), Name, S1, and llvm::Instruction::setFastMathFlags().
Referenced by BreakUpSubtract(), convertOrWithNoCommonBitsToAdd(), EmitAddTreeOfValues(), emitTransformedIndex(), and LLVMBuildAdd().
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Helper function of CombineXorOpnd().
It creates a bitwise-and instruction with the given two operands, and return the resulting instruction. There are two special cases: 1) if the constant operand is 0, it will return NULL. 2) if the constant is ~0, the symbolic operand will be returned.
Definition at line 1240 of file Reassociate.cpp.
References llvm::Value::getType(), I, llvm::APInt::isAllOnes(), and llvm::APInt::isZero().
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Definition at line 261 of file Reassociate.cpp.
References getFastMathFlags(), Name, S1, and llvm::Instruction::setFastMathFlags().
Referenced by emitTransformedIndex(), LLVMBuildMul(), and LowerNegateToMultiply().
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Definition at line 274 of file Reassociate.cpp.
References llvm::UnaryOperator::CreateFNegFMF(), llvm::BinaryOperator::CreateNeg(), Name, and S1.
Referenced by LLVMBuildNeg(), and NegateValue().
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Emit a tree of add instructions, summing Ops together and returning the result.
Insert the tree before I.
Definition at line 1088 of file Reassociate.cpp.
References llvm::SmallVectorTemplateCommon< T, typename >::back(), CreateAdd(), EmitAddTreeOfValues(), llvm::SmallVectorImpl< T >::pop_back_val(), and llvm::SmallVectorBase< Size_T >::size().
Referenced by EmitAddTreeOfValues().
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Scan backwards and forwards among values with the same rank as element i to see if X exists.
If X does not exist, return i. This is useful when scanning for 'x' when we see '-x' because they both get the same rank.
Definition at line 1062 of file Reassociate.cpp.
References llvm::SmallVectorBase< Size_T >::size(), and X.
Referenced by OptimizeAndOrXor().
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If V is a single-use multiply, recursively add its operands as factors, otherwise add V to the list of factors.
Ops is the top-level list of add operands we're trying to factor.
Definition at line 1174 of file Reassociate.cpp.
References FindSingleUseMultiplyFactors(), llvm::User::getOperand(), isReassociableOp(), and llvm::SmallVectorTemplateBase< T, bool >::push_back().
Referenced by FindSingleUseMultiplyFactors().
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Recursively analyze an expression to build a list of instructions that have negative floating-point constant operands.
The caller can then transform the list to create positive constants for better reassociation and CSE.
Definition at line 2015 of file Reassociate.cpp.
References llvm::CallingConv::C, llvm::dbgs(), getNegatibleInsts(), I, LLVM_DEBUG, llvm::PatternMatch::m_APFloat(), llvm::PatternMatch::m_Constant(), llvm::PatternMatch::m_Instruction(), llvm::PatternMatch::m_OneUse(), llvm::PatternMatch::match(), and llvm::SmallVectorTemplateBase< T, bool >::push_back().
Referenced by getNegatibleInsts().
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Return true if I is an instruction with the FastMathFlags that are needed for general reassociation set.
This is not the same as testing Instruction::isAssociative() because it includes operations like fsub. (This routine is only intended to be called for floating-point operations.)
Definition at line 156 of file Reassociate.cpp.
Referenced by isReassociableOp(), and LinearizeExprTree().
INITIALIZE_PASS | ( | ReassociateLegacyPass | , |
"reassociate" | , | ||
"Reassociate expressions" | , | ||
false | , | ||
false | |||
) |
Definition at line 2655 of file Reassociate.cpp.
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Definition at line 886 of file Reassociate.cpp.
References llvm::SmallVectorImpl< T >::emplace_back(), llvm::SmallVectorBase< Size_T >::empty(), I, llvm::SmallSet< T, N, C >::insert(), llvm::Or, and llvm::SmallVectorImpl< T >::pop_back_val().
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Return true if V is an instruction of the specified opcode and if it only has one use.
Definition at line 163 of file Reassociate.cpp.
References hasFPAssociativeFlags().
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Definition at line 171 of file Reassociate.cpp.
References hasFPAssociativeFlags().
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Given an associative binary expression, return the leaf nodes in Ops along with their weights (how many times the leaf occurs).
The original expression is the same as (Ops[0].first op Ops[0].first op ... Ops[0].first) <- Ops[0].second times op (Ops[1].first op Ops[1].first op ... Ops[1].first) <- Ops[1].second times op ... op (Ops[N].first op Ops[N].first op ... Ops[N].first) <- Ops[N].second times
Note that the values Ops[0].first, ..., Ops[N].first are all distinct.
This routine may modify the function, in which case it returns 'true'. The changes it makes may well be destructive, changing the value computed by 'I' to something completely different. Thus if the routine returns 'true' then you MUST either replace I with a new expression computed from the Ops array, or use RewriteExprTree to put the values back in.
A leaf node is either not a binary operation of the same kind as the root node 'I' (i.e. is not a binary operator at all, or is, but with a different opcode), or is the same kind of binary operator but has a use which either does not belong to the expression, or does belong to the expression but is a leaf node. Every leaf node has at least one use that is a non-leaf node of the expression, while for non-leaf nodes (except for the root 'I') every use is a non-leaf node of the expression.
For example: expression graph node names
+ | I / \ | + + | A, B / \ / \ | * + * | C, D, E / \ / \ / \ | + * | F, G
The leaf nodes are C, E, F and G. The Ops array will contain (maybe not in that order) (C, 1), (E, 1), (F, 2), (G, 2).
The expression is maximal: if some instruction is a binary operator of the same kind as 'I', and all of its uses are non-leaf nodes of the expression, then the instruction also belongs to the expression, is not a leaf node of it, and its operands also belong to the expression (but may be leaf nodes).
NOTE: This routine will set operands of non-leaf non-root nodes to undef in order to ensure that every non-root node in the expression has exactly one use by a non-leaf node of the expression. This destruction means that the caller MUST either replace 'I' with a new expression or use something like RewriteExprTree to put the values back in if the routine indicates that it made a change by returning 'true'.
In the above example either the right operand of A or the left operand of B will be replaced by undef. If it is B's operand then this gives:
+ | I / \ | + + | A, B - operand of B replaced with undef / \ \ | * + * | C, D, E / \ / \ / \ | + * | F, G
Note that such undef operands can only be reached by passing through 'I'. For example, if you visit operands recursively starting from a leaf node then you will never see such an undef operand unless you get back to 'I', which requires passing through a phi node.
Note that this routine may also mutate binary operators of the wrong type that have all uses inside the expression (i.e. only used by non-leaf nodes of the expression) if it can turn them into binary operators of the right type and thus make the expression bigger.
Definition at line 380 of file Reassociate.cpp.
References assert(), llvm::SmallPtrSetImpl< PtrType >::count(), llvm::dbgs(), DL, llvm::SmallVectorImpl< T >::emplace_back(), llvm::SmallVectorBase< Size_T >::empty(), llvm::ConstantExpr::getBinOpIdentity(), getOpcode(), hasFPAssociativeFlags(), I, llvm::SetVector< T, Vector, Set, N >::insert(), llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::isKnownNonNegative(), llvm::isKnownNonZero(), isReassociableOp(), LLVM_DEBUG, LowerNegateToMultiply(), llvm::PatternMatch::m_FNeg(), llvm::PatternMatch::m_Instruction(), llvm::PatternMatch::m_Neg(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::Mul, llvm::SmallVectorImpl< T >::pop_back_val(), and llvm::SmallVectorTemplateBase< T, bool >::push_back().
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Replace 0-X with X*-1.
Definition at line 287 of file Reassociate.cpp.
References assert(), CreateMul(), llvm::Constant::getAllOnesValue(), llvm::Instruction::getDebugLoc(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::Constant::getNullValue(), llvm::User::getOperand(), llvm::Value::getType(), llvm::Type::isIntOrIntVectorTy(), llvm::Value::replaceAllUsesWith(), llvm::Instruction::setDebugLoc(), llvm::User::setOperand(), and llvm::Value::takeName().
Referenced by LinearizeExprTree().
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Insert instructions before the instruction pointed to by BI, that computes the negative version of the value specified.
The negative version of the value is returned, and BI is left pointing at the instruction that should be processed next by the reassociation pass. Also add intermediate instructions to the redo list that are modified while pushing the negates through adds. These will be revisited to see if additional opportunities have been exposed.
Definition at line 776 of file Reassociate.cpp.
References llvm::Instruction::andIRFlags(), llvm::CallingConv::C, llvm::ConstantFoldUnaryOpOperand(), CreateNeg(), DL, llvm::Instruction::dropLocation(), llvm::Instruction::getDataLayout(), llvm::Function::getEntryBlock(), llvm::BasicBlock::getFirstNonPHIOrDbg(), llvm::Instruction::getFunction(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::ConstantExpr::getNeg(), llvm::Instruction::getOpcode(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), I, llvm::SetVector< T, Vector, Set, N >::insert(), isReassociableOp(), llvm::PatternMatch::m_BinOp(), llvm::PatternMatch::m_Constant(), llvm::PatternMatch::m_FNeg(), llvm::PatternMatch::m_Neg(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::Instruction::moveBefore(), NegateValue(), llvm::Instruction::setHasNoSignedWrap(), and llvm::Instruction::setHasNoUnsignedWrap().
Referenced by BreakUpSubtract(), and NegateValue().
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Optimize a series of operands to an 'and', 'or', or 'xor' instruction.
This optimizes based on identities. If it can be reduced to a single Value, it is returned, otherwise the Ops list is mutated as necessary.
Definition at line 1190 of file Reassociate.cpp.
References assert(), llvm::SmallVectorTemplateCommon< T, typename >::begin(), llvm::SmallVectorImpl< T >::erase(), FindInOperandList(), llvm::Constant::getAllOnesValue(), llvm::Constant::getNullValue(), llvm::PatternMatch::m_Not(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::SmallVectorBase< Size_T >::size(), and X.
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Print out the expression identified in the Ops list.
Definition at line 82 of file Reassociate.cpp.
References llvm::dbgs(), llvm::Instruction::getOpcodeName(), I, and llvm::SmallVectorBase< Size_T >::size().
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Return true if we should break up this subtract of X-Y into (X + -Y).
Definition at line 977 of file Reassociate.cpp.
References llvm::User::getOperand(), llvm::Value::hasOneUse(), isReassociableOp(), llvm::PatternMatch::m_FNeg(), llvm::PatternMatch::m_Neg(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), and llvm::Instruction::user_back().
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Return true if it may be profitable to convert this (X|Y) into (X+Y).
Definition at line 936 of file Reassociate.cpp.
References llvm::any_of(), isInteresting(), isReassociableOp(), and llvm::Or.
STATISTIC | ( | NumAnnihil | , |
"Number of expr tree annihilated" | |||
) |
STATISTIC | ( | NumChanged | , |
"Number of insts reassociated" | |||
) |
STATISTIC | ( | NumFactor | , |
"Number of multiplies factored" | |||
) |
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