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[C++11] Add range based accessors for the Use-Def chain of a Value.

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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
This commit is contained in:
Chandler Carruth
2014-03-09 03:16:01 +00:00
parent b033b03c23
commit 36b699f2b1
100 changed files with 920 additions and 1075 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
lib/Transforms/Scalar/LoopStrengthReduce.cpp
View File

@ -722,13 +722,12 @@ static bool isHighCostExpansion(const SCEV *S,
// multiplication already generates this expression.
if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Mul->getOperand(1))) {
Value *UVal = U->getValue();
for (Value::use_iterator UI = UVal->use_begin(), UE = UVal->use_end();
UI != UE; ++UI) {
for (User *UR : UVal->users()) {
// If U is a constant, it may be used by a ConstantExpr.
Instruction *User = dyn_cast<Instruction>(*UI);
if (User && User->getOpcode() == Instruction::Mul
&& SE.isSCEVable(User->getType())) {
return SE.getSCEV(User) == Mul;
Instruction *UI = dyn_cast<Instruction>(UR);
if (UI && UI->getOpcode() == Instruction::Mul &&
SE.isSCEVable(UI->getType())) {
return SE.getSCEV(UI) == Mul;
}
}
}
@ -2635,9 +2634,8 @@ void LSRInstance::ChainInstruction(Instruction *UserInst, Instruction *IVOper,
// they will eventually be used be the current chain, or can be computed
// from one of the chain increments. To be more precise we could
// transitively follow its user and only add leaf IV users to the set.
for (Value::use_iterator UseIter = IVOper->use_begin(),
UseEnd = IVOper->use_end(); UseIter != UseEnd; ++UseIter) {
Instruction *OtherUse = dyn_cast<Instruction>(*UseIter);
for (User *U : IVOper->users()) {
Instruction *OtherUse = dyn_cast<Instruction>(U);
if (!OtherUse)
continue;
// Uses in the chain will no longer be uses if the chain is formed.
@ -3048,18 +3046,17 @@ LSRInstance::CollectLoopInvariantFixupsAndFormulae() {
else if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
Worklist.push_back(D->getLHS());
Worklist.push_back(D->getRHS());
} else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
if (!Inserted.insert(U)) continue;
const Value *V = U->getValue();
} else if (const SCEVUnknown *US = dyn_cast<SCEVUnknown>(S)) {
if (!Inserted.insert(US)) continue;
const Value *V = US->getValue();
if (const Instruction *Inst = dyn_cast<Instruction>(V)) {
// Look for instructions defined outside the loop.
if (L->contains(Inst)) continue;
} else if (isa<UndefValue>(V))
// Undef doesn't have a live range, so it doesn't matter.
continue;
for (Value::const_use_iterator UI = V->use_begin(), UE = V->use_end();
UI != UE; ++UI) {
const Instruction *UserInst = dyn_cast<Instruction>(*UI);
for (const Use &U : V->uses()) {
const Instruction *UserInst = dyn_cast<Instruction>(U.getUser());
// Ignore non-instructions.
if (!UserInst)
continue;
@ -3071,7 +3068,7 @@ LSRInstance::CollectLoopInvariantFixupsAndFormulae() {
const BasicBlock *UseBB = !isa<PHINode>(UserInst) ?
UserInst->getParent() :
cast<PHINode>(UserInst)->getIncomingBlock(
PHINode::getIncomingValueNumForOperand(UI.getOperandNo()));
PHINode::getIncomingValueNumForOperand(U.getOperandNo()));
if (!DT.dominates(L->getHeader(), UseBB))
continue;
// Ignore uses which are part of other SCEV expressions, to avoid
@ -3081,7 +3078,7 @@ LSRInstance::CollectLoopInvariantFixupsAndFormulae() {
// If the user is a no-op, look through to its uses.
if (!isa<SCEVUnknown>(UserS))
continue;
if (UserS == U) {
if (UserS == US) {
Worklist.push_back(
SE.getUnknown(const_cast<Instruction *>(UserInst)));
continue;
@ -3089,7 +3086,7 @@ LSRInstance::CollectLoopInvariantFixupsAndFormulae() {
}
// Ignore icmp instructions which are already being analyzed.
if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UserInst)) {
unsigned OtherIdx = !UI.getOperandNo();
unsigned OtherIdx = !U.getOperandNo();
Value *OtherOp = const_cast<Value *>(ICI->getOperand(OtherIdx));
if (SE.hasComputableLoopEvolution(SE.getSCEV(OtherOp), L))
continue;
@ -3097,7 +3094,7 @@ LSRInstance::CollectLoopInvariantFixupsAndFormulae() {
LSRFixup &LF = getNewFixup();
LF.UserInst = const_cast<Instruction *>(UserInst);
LF.OperandValToReplace = UI.getUse();
LF.OperandValToReplace = U;
std::pair<size_t, int64_t> P = getUse(S, LSRUse::Basic, 0);
LF.LUIdx = P.first;
LF.Offset = P.second;
@ -3107,7 +3104,7 @@ LSRInstance::CollectLoopInvariantFixupsAndFormulae() {
SE.getTypeSizeInBits(LU.WidestFixupType) <
SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))
LU.WidestFixupType = LF.OperandValToReplace->getType();
InsertSupplementalFormula(U, LU, LF.LUIdx);
InsertSupplementalFormula(US, LU, LF.LUIdx);
CountRegisters(LU.Formulae.back(), Uses.size() - 1);
break;
}