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[C++11] Add range based accessors for the Use-Def chain of a Value.

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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
This commit is contained in:
Chandler Carruth
2014-03-09 03:16:01 +00:00
parent b033b03c23
commit 36b699f2b1
100 changed files with 920 additions and 1075 deletions
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14
lib/Transforms/Utils/InlineFunction.cpp
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@@ -401,9 +401,8 @@ static Value *HandleByValArgument(Value *Arg, Instruction *TheCall,
// isUsedByLifetimeMarker - Check whether this Value is used by a lifetime
// intrinsic.
static bool isUsedByLifetimeMarker(Value *V) {
for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;
++UI) {
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI)) {
for (User *U : V->users()) {
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U)) {
switch (II->getIntrinsicID()) {
default: break;
case Intrinsic::lifetime_start:
@@ -423,11 +422,10 @@ static bool hasLifetimeMarkers(AllocaInst *AI) {
return isUsedByLifetimeMarker(AI);
// Do a scan to find all the casts to i8*.
for (Value::use_iterator I = AI->use_begin(), E = AI->use_end(); I != E;
++I) {
if (I->getType() != Int8PtrTy) continue;
if (I->stripPointerCasts() != AI) continue;
if (isUsedByLifetimeMarker(*I))
for (User *U : AI->users()) {
if (U->getType() != Int8PtrTy) continue;
if (U->stripPointerCasts() != AI) continue;
if (isUsedByLifetimeMarker(U))
return true;
}
return false;