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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
Download Patch File Download Diff File Expand all files Collapse all files

21
lib/Transforms/InstCombine/InstructionCombining.cpp
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@ -641,10 +641,9 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
// uses into the PHI.
if (!PN->hasOneUse()) {
// Walk the use list for the instruction, comparing them to I.
for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
UI != E; ++UI) {
Instruction *User = cast<Instruction>(*UI);
if (User != &I && !I.isIdenticalTo(User))
for (User *U : PN->users()) {
Instruction *UI = cast<Instruction>(U);
if (UI != &I && !I.isIdenticalTo(UI))
return 0;
}
// Otherwise, we can replace *all* users with the new PHI we form.
@ -759,8 +758,7 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
}
}
for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
UI != E; ) {
for (auto UI = PN->user_begin(), E = PN->user_end(); UI != E;) {
Instruction *User = cast<Instruction>(*UI++);
if (User == &I) continue;
ReplaceInstUsesWith(*User, NewPN);
@ -1080,7 +1078,7 @@ Value *InstCombiner::Descale(Value *Val, APInt Scale, bool &NoSignedWrap) {
// Move up one level in the expression.
assert(Ancestor->hasOneUse() && "Drilled down when more than one use!");
Ancestor = Ancestor->use_back();
Ancestor = Ancestor->user_back();
} while (1);
}
@ -1425,9 +1423,8 @@ isAllocSiteRemovable(Instruction *AI, SmallVectorImpl<WeakVH> &Users,
do {
Instruction *PI = Worklist.pop_back_val();
for (Value::use_iterator UI = PI->use_begin(), UE = PI->use_end(); UI != UE;
++UI) {
Instruction *I = cast<Instruction>(*UI);
for (User *U : PI->users()) {
Instruction *I = cast<Instruction>(U);
switch (I->getOpcode()) {
default:
// Give up the moment we see something we can't handle.
@ -2404,12 +2401,12 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
// See if we can trivially sink this instruction to a successor basic block.
if (I->hasOneUse()) {
BasicBlock *BB = I->getParent();
Instruction *UserInst = cast<Instruction>(I->use_back());
Instruction *UserInst = cast<Instruction>(*I->user_begin());
BasicBlock *UserParent;
// Get the block the use occurs in.
if (PHINode *PN = dyn_cast<PHINode>(UserInst))
UserParent = PN->getIncomingBlock(I->use_begin().getUse());
UserParent = PN->getIncomingBlock(*I->use_begin());
else
UserParent = UserInst->getParent();