[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

1 files changed, 7 insertions, 8 deletions

diff --git a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
index 3f473a96b0..8a662aaac2 100644
--- a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -607,10 +607,10 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
         }
         NewF->getBasicBlockList().splice(NewF->begin(), F.getBasicBlockList());
 
-        for (Function::use_iterator ui = F.use_begin(), ue = F.use_end();
-             ui != ue;) {
-          BlockAddress *BA = dyn_cast<BlockAddress>(ui.getUse().getUser());
-          ++ui;
+        for (Function::user_iterator UI = F.user_begin(), UE = F.user_end();
+             UI != UE;) {
+          BlockAddress *BA = dyn_cast<BlockAddress>(*UI);
+          ++UI;
           if (BA) {
             BA->replaceAllUsesWith(
                 BlockAddress::get(NewF, BA->getBasicBlock()));
@@ -1105,12 +1105,11 @@ void DFSanVisitor::visitInsertValueInst(InsertValueInst &I) {
 
 void DFSanVisitor::visitAllocaInst(AllocaInst &I) {
   bool AllLoadsStores = true;
-  for (Instruction::use_iterator i = I.use_begin(), e = I.use_end(); i != e;
-       ++i) {
-    if (isa<LoadInst>(*i))
+  for (User *U : I.users()) {
+    if (isa<LoadInst>(U))
       continue;
 
-    if (StoreInst *SI = dyn_cast<StoreInst>(*i)) {
+    if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
       if (SI->getPointerOperand() == &I)
         continue;
     }