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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
lib/Transforms/Utils/SimplifyIndVar.cpp
+10 -13
View File
@@ -285,15 +285,14 @@ Instruction *SimplifyIndvar::splitOverflowIntrinsic(Instruction *IVUser,
// Find a branch guarded by the overflow check.
BranchInst *Branch = 0;
Instruction *AddVal = 0;
for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
UI != E; ++UI) {
if (ExtractValueInst *ExtractInst = dyn_cast<ExtractValueInst>(*UI)) {
for (User *U : II->users()) {
if (ExtractValueInst *ExtractInst = dyn_cast<ExtractValueInst>(U)) {
if (ExtractInst->getNumIndices() != 1)
continue;
if (ExtractInst->getIndices()[0] == 0)
AddVal = ExtractInst;
else if (ExtractInst->getIndices()[0] == 1 && ExtractInst->hasOneUse())
Branch = dyn_cast<BranchInst>(ExtractInst->use_back());
Branch = dyn_cast<BranchInst>(ExtractInst->user_back());
}
}
if (!AddVal || !Branch)
@@ -305,12 +304,11 @@ Instruction *SimplifyIndvar::splitOverflowIntrinsic(Instruction *IVUser,
// Check if all users of the add are provably NSW.
bool AllNSW = true;
for (Value::use_iterator UI = AddVal->use_begin(), E = AddVal->use_end();
UI != E; ++UI) {
if (Instruction *UseInst = dyn_cast<Instruction>(*UI)) {
for (Use &U : AddVal->uses()) {
if (Instruction *UseInst = dyn_cast<Instruction>(U.getUser())) {
BasicBlock *UseBB = UseInst->getParent();
if (PHINode *PHI = dyn_cast<PHINode>(UseInst))
UseBB = PHI->getIncomingBlock(UI);
UseBB = PHI->getIncomingBlock(U);
if (!DT->dominates(ContinueBB, UseBB)) {
AllNSW = false;
break;
@@ -343,16 +341,15 @@ static void pushIVUsers(
SmallPtrSet<Instruction*,16> &Simplified,
SmallVectorImpl< std::pair<Instruction*,Instruction*> > &SimpleIVUsers) {
for (Value::use_iterator UI = Def->use_begin(), E = Def->use_end();
UI != E; ++UI) {
Instruction *User = cast<Instruction>(*UI);
for (User *U : Def->users()) {
Instruction *UI = cast<Instruction>(U);
// Avoid infinite or exponential worklist processing.
// Also ensure unique worklist users.
// If Def is a LoopPhi, it may not be in the Simplified set, so check for
// self edges first.
if (User != Def && Simplified.insert(User))
SimpleIVUsers.push_back(std::make_pair(User, Def));
if (UI != Def && Simplified.insert(UI))
SimpleIVUsers.push_back(std::make_pair(UI, Def));
}
}