[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. =]
llvm-svn: 203364
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 770ba82..80f122a 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1590,10 +1590,9 @@
// We can only support instructions that do not define values that are
// live outside of the current basic block.
- for (Value::use_iterator UI = BBI->use_begin(), E = BBI->use_end();
- UI != E; ++UI) {
- Instruction *U = cast<Instruction>(*UI);
- if (U->getParent() != BB || isa<PHINode>(U)) return false;
+ for (User *U : BBI->users()) {
+ Instruction *UI = cast<Instruction>(U);
+ if (UI->getParent() != BB || isa<PHINode>(UI)) return false;
}
// Looks ok, continue checking.
@@ -2016,7 +2015,7 @@
// register pressure or inhibit out-of-order execution.
Instruction *BonusInst = 0;
if (&*FrontIt != Cond &&
- FrontIt->hasOneUse() && *FrontIt->use_begin() == Cond &&
+ FrontIt->hasOneUse() && FrontIt->user_back() == Cond &&
isSafeToSpeculativelyExecute(FrontIt)) {
BonusInst = &*FrontIt;
++FrontIt;
@@ -2095,7 +2094,7 @@
// instructions that are used by the terminator's condition because it
// exposes more merging opportunities.
bool UsedByBranch = (BonusInst && BonusInst->hasOneUse() &&
- *BonusInst->use_begin() == Cond);
+ BonusInst->user_back() == Cond);
if (BonusInst && !UsedByBranch) {
// Collect the values used by the bonus inst
@@ -2689,7 +2688,7 @@
// The use of the icmp has to be in the 'end' block, by the only PHI node in
// the block.
BasicBlock *SuccBlock = BB->getTerminator()->getSuccessor(0);
- PHINode *PHIUse = dyn_cast<PHINode>(ICI->use_back());
+ PHINode *PHIUse = dyn_cast<PHINode>(ICI->user_back());
if (PHIUse == 0 || PHIUse != &SuccBlock->front() ||
isa<PHINode>(++BasicBlock::iterator(PHIUse)))
return false;
@@ -3807,8 +3806,8 @@
// If the result is used to return immediately from the function, we want to
// do that right here.
- if (PHI->hasOneUse() && isa<ReturnInst>(*PHI->use_begin()) &&
- *PHI->use_begin() == CommonDest->getFirstNonPHIOrDbg()) {
+ if (PHI->hasOneUse() && isa<ReturnInst>(*PHI->user_begin()) &&
+ PHI->user_back() == CommonDest->getFirstNonPHIOrDbg()) {
Builder.CreateRet(Result);
ReturnedEarly = true;
break;
@@ -4043,7 +4042,7 @@
if (C->isNullValue()) {
// Only look at the first use, avoid hurting compile time with long uselists
- User *Use = *I->use_begin();
+ User *Use = *I->user_begin();
// Now make sure that there are no instructions in between that can alter
// control flow (eg. calls)