[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/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
index cb565d0..7add0d5 100644
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -421,14 +421,12 @@
bool IsRead = false;
// We don't need to track IsWritten. If A is written to, return immediately.
- for (Value::use_iterator UI = A->use_begin(), UE = A->use_end();
- UI != UE; ++UI) {
+ for (Use &U : A->uses()) {
if (Count++ >= 20)
return Attribute::None;
- Use *U = &UI.getUse();
- Visited.insert(U);
- Worklist.push_back(U);
+ Visited.insert(&U);
+ Worklist.push_back(&U);
}
while (!Worklist.empty()) {
@@ -443,12 +441,9 @@
case Instruction::Select:
case Instruction::AddrSpaceCast:
// The original value is not read/written via this if the new value isn't.
- for (Instruction::use_iterator UI = I->use_begin(), UE = I->use_end();
- UI != UE; ++UI) {
- Use *U = &UI.getUse();
- if (Visited.insert(U))
- Worklist.push_back(U);
- }
+ for (Use &UU : I->uses())
+ if (Visited.insert(&UU))
+ Worklist.push_back(&UU);
break;
case Instruction::Call: