[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, 1 insertions, 1 deletions

diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index bdb544bef42..97a562e3e5e 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -119,7 +119,7 @@ bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
   // Scan both lists simultaneously until one is exhausted. This limits the
   // search to the shorter list.
   BasicBlock::const_iterator BI = BB->begin(), BE = BB->end();
-  const_use_iterator UI = use_begin(), UE = use_end();
+  const_user_iterator UI = user_begin(), UE = user_end();
   for (; BI != BE && UI != UE; ++BI, ++UI) {
     // Scan basic block: Check if this Value is used by the instruction at BI.
     if (std::find(BI->op_begin(), BI->op_end(), this) != BI->op_end())