[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

1 files changed, 6 insertions, 9 deletions

diff --git a/llvm/lib/Analysis/PHITransAddr.cpp b/llvm/lib/Analysis/PHITransAddr.cpp
index 866f82a..ad3685a 100644
--- a/llvm/lib/Analysis/PHITransAddr.cpp
+++ b/llvm/lib/Analysis/PHITransAddr.cpp
@@ -202,9 +202,8 @@ Value *PHITransAddr::PHITranslateSubExpr(Value *V, BasicBlock *CurBB,
 
     // Otherwise we have to see if a casted version of the incoming pointer
     // is available.  If so, we can use it, otherwise we have to fail.
-    for (Value::use_iterator UI = PHIIn->use_begin(), E = PHIIn->use_end();
-         UI != E; ++UI) {
-      if (CastInst *CastI = dyn_cast<CastInst>(*UI))
+    for (User *U : PHIIn->users()) {
+      if (CastInst *CastI = dyn_cast<CastInst>(U))
         if (CastI->getOpcode() == Cast->getOpcode() &&
             CastI->getType() == Cast->getType() &&
             (!DT || DT->dominates(CastI->getParent(), PredBB)))
@@ -238,9 +237,8 @@ Value *PHITransAddr::PHITranslateSubExpr(Value *V, BasicBlock *CurBB,
 
     // Scan to see if we have this GEP available.
     Value *APHIOp = GEPOps[0];
-    for (Value::use_iterator UI = APHIOp->use_begin(), E = APHIOp->use_end();
-         UI != E; ++UI) {
-      if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI))
+    for (User *U : APHIOp->users()) {
+      if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U))
         if (GEPI->getType() == GEP->getType() &&
             GEPI->getNumOperands() == GEPOps.size() &&
             GEPI->getParent()->getParent() == CurBB->getParent() &&
@@ -297,9 +295,8 @@ Value *PHITransAddr::PHITranslateSubExpr(Value *V, BasicBlock *CurBB,
       return Inst;
 
     // Otherwise, see if we have this add available somewhere.
-    for (Value::use_iterator UI = LHS->use_begin(), E = LHS->use_end();
-         UI != E; ++UI) {
-      if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*UI))
+    for (User *U : LHS->users()) {
+      if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U))
         if (BO->getOpcode() == Instruction::Add &&
             BO->getOperand(0) == LHS && BO->getOperand(1) == RHS &&
             BO->getParent()->getParent() == CurBB->getParent() &&