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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

52
lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -269,11 +269,11 @@ void IndVarSimplify::HandleFloatingPointIV(Loop *L, PHINode *PN) {
// Check Incr uses. One user is PN and the other user is an exit condition
// used by the conditional terminator.
Value::use_iterator IncrUse = Incr->use_begin();
Value::user_iterator IncrUse = Incr->user_begin();
Instruction *U1 = cast<Instruction>(*IncrUse++);
if (IncrUse == Incr->use_end()) return;
if (IncrUse == Incr->user_end()) return;
Instruction *U2 = cast<Instruction>(*IncrUse++);
if (IncrUse != Incr->use_end()) return;
if (IncrUse != Incr->user_end()) return;
// Find exit condition, which is an fcmp. If it doesn't exist, or if it isn't
// only used by a branch, we can't transform it.
@ -281,10 +281,10 @@ void IndVarSimplify::HandleFloatingPointIV(Loop *L, PHINode *PN) {
if (!Compare)
Compare = dyn_cast<FCmpInst>(U2);
if (Compare == 0 || !Compare->hasOneUse() ||
!isa<BranchInst>(Compare->use_back()))
!isa<BranchInst>(Compare->user_back()))
return;
BranchInst *TheBr = cast<BranchInst>(Compare->use_back());
BranchInst *TheBr = cast<BranchInst>(Compare->user_back());
// We need to verify that the branch actually controls the iteration count
// of the loop. If not, the new IV can overflow and no one will notice.
@ -563,8 +563,8 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L, SCEVExpander &Rewriter) {
unsigned NumHardInternalUses = 0;
unsigned NumSoftExternalUses = 0;
unsigned NumUses = 0;
for (Value::use_iterator IB=Inst->use_begin(), IE=Inst->use_end();
IB!=IE && NumUses<=6 ; ++IB) {
for (auto IB = Inst->user_begin(), IE = Inst->user_end();
IB != IE && NumUses <= 6; ++IB) {
Instruction *UseInstr = cast<Instruction>(*IB);
unsigned Opc = UseInstr->getOpcode();
NumUses++;
@ -576,9 +576,9 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L, SCEVExpander &Rewriter) {
// Do not count the Phi as a use. LCSSA may have inserted
// plenty of trivial ones.
NumUses--;
for (Value::use_iterator PB=UseInstr->use_begin(),
PE=UseInstr->use_end();
PB!=PE && NumUses<=6 ; ++PB, ++NumUses) {
for (auto PB = UseInstr->user_begin(),
PE = UseInstr->user_end();
PB != PE && NumUses <= 6; ++PB, ++NumUses) {
unsigned PhiOpc = cast<Instruction>(*PB)->getOpcode();
if (PhiOpc != Instruction::Call && PhiOpc != Instruction::Ret)
NumSoftExternalUses++;
@ -1018,15 +1018,14 @@ Instruction *WidenIV::WidenIVUse(NarrowIVDefUse DU, SCEVExpander &Rewriter) {
/// pushNarrowIVUsers - Add eligible users of NarrowDef to NarrowIVUsers.
///
void WidenIV::pushNarrowIVUsers(Instruction *NarrowDef, Instruction *WideDef) {
for (Value::use_iterator UI = NarrowDef->use_begin(),
UE = NarrowDef->use_end(); UI != UE; ++UI) {
Instruction *NarrowUse = cast<Instruction>(*UI);
for (User *U : NarrowDef->users()) {
Instruction *NarrowUser = cast<Instruction>(U);
// Handle data flow merges and bizarre phi cycles.
if (!Widened.insert(NarrowUse))
if (!Widened.insert(NarrowUser))
continue;
NarrowIVUsers.push_back(NarrowIVDefUse(NarrowDef, NarrowUse, WideDef));
NarrowIVUsers.push_back(NarrowIVDefUse(NarrowDef, NarrowUser, WideDef));
}
}
@ -1417,15 +1416,11 @@ static bool AlmostDeadIV(PHINode *Phi, BasicBlock *LatchBlock, Value *Cond) {
int LatchIdx = Phi->getBasicBlockIndex(LatchBlock);
Value *IncV = Phi->getIncomingValue(LatchIdx);
for (Value::use_iterator UI = Phi->use_begin(), UE = Phi->use_end();
UI != UE; ++UI) {
if (*UI != Cond && *UI != IncV) return false;
}
for (User *U : Phi->users())
if (U != Cond && U != IncV) return false;
for (Value::use_iterator UI = IncV->use_begin(), UE = IncV->use_end();
UI != UE; ++UI) {
if (*UI != Cond && *UI != Phi) return false;
}
for (User *U : IncV->users())
if (U != Cond && U != Phi) return false;
return true;
}
@ -1755,13 +1750,12 @@ void IndVarSimplify::SinkUnusedInvariants(Loop *L) {
// Determine if there is a use in or before the loop (direct or
// otherwise).
bool UsedInLoop = false;
for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
UI != UE; ++UI) {
User *U = *UI;
BasicBlock *UseBB = cast<Instruction>(U)->getParent();
if (PHINode *P = dyn_cast<PHINode>(U)) {
for (Use &U : I->uses()) {
Instruction *User = cast<Instruction>(U.getUser());
BasicBlock *UseBB = User->getParent();
if (PHINode *P = dyn_cast<PHINode>(User)) {
unsigned i =
PHINode::getIncomingValueNumForOperand(UI.getOperandNo());
PHINode::getIncomingValueNumForOperand(U.getOperandNo());
UseBB = P->getIncomingBlock(i);
}
if (UseBB == Preheader || L->contains(UseBB)) {