#include "llvm/Transforms/Scalar.h"#include "llvm/ADT/STLExtras.h"#include "llvm/ADT/SetVector.h"#include "llvm/ADT/Statistic.h"#include "llvm/Analysis/AliasAnalysis.h"#include "llvm/Analysis/CaptureTracking.h"#include "llvm/Analysis/MemoryBuiltins.h"#include "llvm/Analysis/MemoryDependenceAnalysis.h"#include "llvm/Analysis/ValueTracking.h"#include "llvm/IR/Constants.h"#include "llvm/IR/DataLayout.h"#include "llvm/IR/Dominators.h"#include "llvm/IR/Function.h"#include "llvm/IR/GlobalVariable.h"#include "llvm/IR/Instructions.h"#include "llvm/IR/IntrinsicInst.h"#include "llvm/Pass.h"#include "llvm/Support/Debug.h"#include "llvm/Target/TargetLibraryInfo.h"#include "llvm/Transforms/Utils/Local.h"
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Define Documentation
| #define DEBUG_TYPE "dse" |
Definition at line 40 of file DeadStoreElimination.cpp.
Enumeration Type Documentation
| enum OverwriteResult |
Definition at line 332 of file DeadStoreElimination.cpp.
Function Documentation
| static void DeleteDeadInstruction | ( | Instruction * | I, |
| MemoryDependenceAnalysis & | MD, | ||
| const TargetLibraryInfo * | TLI, | ||
| SmallSetVector< Value *, 16 > * | ValueSet = nullptr |
||
| ) | [static] |
DeleteDeadInstruction - Delete this instruction. Before we do, go through and zero out all the operands of this instruction. If any of them become dead, delete them and the computation tree that feeds them.
If ValueSet is non-null, remove any deleted instructions from it as well.
Definition at line 114 of file DeadStoreElimination.cpp.
References llvm::SmallVectorBase::empty(), llvm::Instruction::eraseFromParent(), llvm::User::getNumOperands(), llvm::User::getOperand(), llvm::isInstructionTriviallyDead(), llvm::SmallVectorImpl< T >::pop_back_val(), llvm::SmallVectorTemplateBase< T, isPodLike< T >::value >::push_back(), llvm::MemoryDependenceAnalysis::removeInstruction(), llvm::User::setOperand(), and llvm::Value::use_empty().
| static void FindUnconditionalPreds | ( | SmallVectorImpl< BasicBlock * > & | Blocks, |
| BasicBlock * | BB, | ||
| DominatorTree * | DT | ||
| ) | [static] |
Find all blocks that will unconditionally lead to the block BB and append them to F.
Definition at line 643 of file DeadStoreElimination.cpp.
References llvm::TerminatorInst::getNumSuccessors(), llvm::BasicBlock::getTerminator(), I, llvm::DominatorTree::isReachableFromEntry(), llvm::pred_begin(), llvm::pred_end(), and llvm::SmallVectorTemplateBase< T, isPodLike >::push_back().
| static AliasAnalysis::Location getLocForRead | ( | Instruction * | Inst, |
| AliasAnalysis & | AA | ||
| ) | [static] |
getLocForRead - Return the location read by the specified "hasMemoryWrite" instruction if any.
Definition at line 236 of file DeadStoreElimination.cpp.
References llvm::AliasAnalysis::getLocationForSource(), llvm::AliasAnalysis::getTargetLibraryInfo(), and hasMemoryWrite().
Referenced by isPossibleSelfRead().
| static AliasAnalysis::Location getLocForWrite | ( | Instruction * | Inst, |
| AliasAnalysis & | AA | ||
| ) | [static] |
getLocForWrite - Return a Location stored to by the specified instruction. If isRemovable returns true, this function and getLocForRead completely describe the memory operations for this instruction.
Definition at line 196 of file DeadStoreElimination.cpp.
References llvm::dyn_cast(), llvm::CallInst::getArgOperand(), llvm::AliasAnalysis::getDataLayout(), llvm::IntrinsicInst::getIntrinsicID(), llvm::AliasAnalysis::getLocation(), llvm::AliasAnalysis::getLocationForDest(), llvm::AArch64CC::MI, llvm::AliasAnalysis::Location::Size, and llvm::AliasAnalysis::UnknownSize.
| static uint64_t getPointerSize | ( | const Value * | V, |
| AliasAnalysis & | AA | ||
| ) | [static] |
Definition at line 324 of file DeadStoreElimination.cpp.
References llvm::AliasAnalysis::getDataLayout(), llvm::getObjectSize(), llvm::AliasAnalysis::getTargetLibraryInfo(), and llvm::AliasAnalysis::UnknownSize.
Referenced by isOverwrite(), and llvm::MSP430TargetLowering::LowerRETURNADDR().
| static Value* getStoredPointerOperand | ( | Instruction * | I | ) | [static] |
getStoredPointerOperand - Return the pointer that is being written to.
Definition at line 304 of file DeadStoreElimination.cpp.
References llvm::CallSiteBase< FunTy, ValTy, UserTy, InstrTy, CallTy, InvokeTy, IterTy >::getArgument(), I, llvm_unreachable, and llvm::AArch64CC::MI.
| static bool hasMemoryWrite | ( | Instruction * | I, |
| const TargetLibraryInfo * | TLI | ||
| ) | [static] |
hasMemoryWrite - Does this instruction write some memory? This only returns true for things that we can analyze with other helpers below.
Definition at line 154 of file DeadStoreElimination.cpp.
References llvm::Value::getName(), llvm::TargetLibraryInfo::getName(), llvm::TargetLibraryInfo::has(), llvm::LibFunc::memcpy, llvm::LibFunc::memmove, llvm::LibFunc::memset, llvm::LibFunc::strcat, llvm::LibFunc::strcpy, llvm::LibFunc::strncat, and llvm::LibFunc::strncpy.
Referenced by getLocForRead().
| static OverwriteResult isOverwrite | ( | const AliasAnalysis::Location & | Later, |
| const AliasAnalysis::Location & | Earlier, | ||
| AliasAnalysis & | AA, | ||
| int64_t & | EarlierOff, | ||
| int64_t & | LaterOff | ||
| ) | [static] |
isOverwrite - Return 'OverwriteComplete' if a store to the 'Later' location completely overwrites a store to the 'Earlier' location. 'OverwriteEnd' if the end of the 'Earlier' location is completely overwritten by 'Later', or 'OverwriteUnknown' if nothing can be determined
Definition at line 344 of file DeadStoreElimination.cpp.
References llvm::AliasAnalysis::getDataLayout(), llvm::GetPointerBaseWithConstantOffset(), getPointerSize(), llvm::Value::getType(), llvm::GetUnderlyingObject(), llvm::AliasAnalysis::Location::Ptr, llvm::AliasAnalysis::Location::Size, llvm::Value::stripPointerCasts(), and llvm::AliasAnalysis::UnknownSize.
| static bool isPossibleSelfRead | ( | Instruction * | Inst, |
| const AliasAnalysis::Location & | InstStoreLoc, | ||
| Instruction * | DepWrite, | ||
| AliasAnalysis & | AA | ||
| ) | [static] |
isPossibleSelfRead - If 'Inst' might be a self read (i.e. a noop copy of a memory region into an identical pointer) then it doesn't actually make its input dead in the traditional sense. Consider this case:
memcpy(A <- B) memcpy(A <- A)
In this case, the second store to A does not make the first store to A dead. The usual situation isn't an explicit A<-A store like this (which can be trivially removed) but a case where two pointers may alias.
This function detects when it is unsafe to remove a dependent instruction because the DSE inducing instruction may be a self-read.
Definition at line 459 of file DeadStoreElimination.cpp.
References getLocForRead(), llvm::AliasAnalysis::isMustAlias(), llvm::AliasAnalysis::isNoAlias(), and llvm::AliasAnalysis::Location::Ptr.
| static bool isRemovable | ( | Instruction * | I | ) | [static] |
isRemovable - If the value of this instruction and the memory it writes to is unused, may we delete this instruction?
Definition at line 250 of file DeadStoreElimination.cpp.
References llvm_unreachable, llvm::LibFunc::memcpy, llvm::LibFunc::memmove, and llvm::LibFunc::memset.
| static bool isShortenable | ( | Instruction * | I | ) | [static] |
isShortenable - Returns true if this instruction can be safely shortened in length.
Definition at line 283 of file DeadStoreElimination.cpp.
References llvm::LibFunc::memcpy, and llvm::LibFunc::memset.
| STATISTIC | ( | NumFastStores | , |
| "Number of stores deleted" | |||
| ) |
| STATISTIC | ( | NumFastOther | , |
| "Number of other instrs removed" | |||
| ) |
1.7.6.1