llvm/lib/Transforms/InstCombine/InstCombineWorklist.h
Chandler Carruth 36b699f2b1 [C++11] Add range based accessors for the Use-Def chain of a Value.
This requires a number of steps.
1) Move value_use_iterator into the Value class as an implementation
   detail
2) Change it to actually be a *Use* iterator rather than a *User*
   iterator.
3) Add an adaptor which is a User iterator that always looks through the
   Use to the User.
4) Wrap these in Value::use_iterator and Value::user_iterator typedefs.
5) Add the range adaptors as Value::uses() and Value::users().
6) Update *all* of the callers to correctly distinguish between whether
   they wanted a use_iterator (and to explicitly dig out the User when
   needed), or a user_iterator which makes the Use itself totally
   opaque.

Because #6 requires churning essentially everything that walked the
Use-Def chains, I went ahead and added all of the range adaptors and
switched them to range-based loops where appropriate. Also because the
renaming requires at least churning every line of code, it didn't make
any sense to split these up into multiple commits -- all of which would
touch all of the same lies of code.

The result is still not quite optimal. The Value::use_iterator is a nice
regular iterator, but Value::user_iterator is an iterator over User*s
rather than over the User objects themselves. As a consequence, it fits
a bit awkwardly into the range-based world and it has the weird
extra-dereferencing 'operator->' that so many of our iterators have.
I think this could be fixed by providing something which transforms
a range of T&s into a range of T*s, but that *can* be separated into
another patch, and it isn't yet 100% clear whether this is the right
move.

However, this change gets us most of the benefit and cleans up
a substantial amount of code around Use and User. =]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203364 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-09 03:16:01 +00:00

105 lines
3.2 KiB
C++

//===- InstCombineWorklist.h - Worklist for InstCombine pass ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef INSTCOMBINE_WORKLIST_H
#define INSTCOMBINE_WORKLIST_H
#define DEBUG_TYPE "instcombine"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/Instruction.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
namespace llvm {
/// InstCombineWorklist - This is the worklist management logic for
/// InstCombine.
class LLVM_LIBRARY_VISIBILITY InstCombineWorklist {
SmallVector<Instruction*, 256> Worklist;
DenseMap<Instruction*, unsigned> WorklistMap;
void operator=(const InstCombineWorklist&RHS) LLVM_DELETED_FUNCTION;
InstCombineWorklist(const InstCombineWorklist&) LLVM_DELETED_FUNCTION;
public:
InstCombineWorklist() {}
bool isEmpty() const { return Worklist.empty(); }
/// Add - Add the specified instruction to the worklist if it isn't already
/// in it.
void Add(Instruction *I) {
if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) {
DEBUG(dbgs() << "IC: ADD: " << *I << '\n');
Worklist.push_back(I);
}
}
void AddValue(Value *V) {
if (Instruction *I = dyn_cast<Instruction>(V))
Add(I);
}
/// AddInitialGroup - Add the specified batch of stuff in reverse order.
/// which should only be done when the worklist is empty and when the group
/// has no duplicates.
void AddInitialGroup(Instruction *const *List, unsigned NumEntries) {
assert(Worklist.empty() && "Worklist must be empty to add initial group");
Worklist.reserve(NumEntries+16);
WorklistMap.resize(NumEntries);
DEBUG(dbgs() << "IC: ADDING: " << NumEntries << " instrs to worklist\n");
for (unsigned Idx = 0; NumEntries; --NumEntries) {
Instruction *I = List[NumEntries-1];
WorklistMap.insert(std::make_pair(I, Idx++));
Worklist.push_back(I);
}
}
// Remove - remove I from the worklist if it exists.
void Remove(Instruction *I) {
DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
if (It == WorklistMap.end()) return; // Not in worklist.
// Don't bother moving everything down, just null out the slot.
Worklist[It->second] = 0;
WorklistMap.erase(It);
}
Instruction *RemoveOne() {
Instruction *I = Worklist.pop_back_val();
WorklistMap.erase(I);
return I;
}
/// AddUsersToWorkList - When an instruction is simplified, add all users of
/// the instruction to the work lists because they might get more simplified
/// now.
///
void AddUsersToWorkList(Instruction &I) {
for (User *U : I.users())
Add(cast<Instruction>(U));
}
/// Zap - check that the worklist is empty and nuke the backing store for
/// the map if it is large.
void Zap() {
assert(WorklistMap.empty() && "Worklist empty, but map not?");
// Do an explicit clear, this shrinks the map if needed.
WorklistMap.clear();
}
};
} // end namespace llvm.
#endif