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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
lib/Transforms/IPO/DeadArgumentElimination.cpp
+19 -24
View File
@@ -144,7 +144,7 @@ namespace {
private:
Liveness MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses);
Liveness SurveyUse(Value::const_use_iterator U, UseVector &MaybeLiveUses,
Liveness SurveyUse(const Use *U, UseVector &MaybeLiveUses,
unsigned RetValNum = 0);
Liveness SurveyUses(const Value *V, UseVector &MaybeLiveUses);
@@ -260,7 +260,7 @@ bool DAE::DeleteDeadVarargs(Function &Fn) {
// to pass in a smaller number of arguments into the new function.
//
std::vector<Value*> Args;
for (Value::use_iterator I = Fn.use_begin(), E = Fn.use_end(); I != E; ) {
for (Value::user_iterator I = Fn.user_begin(), E = Fn.user_end(); I != E; ) {
CallSite CS(*I++);
if (!CS)
continue;
@@ -382,10 +382,9 @@ bool DAE::RemoveDeadArgumentsFromCallers(Function &Fn)
bool Changed = false;
for (Function::use_iterator I = Fn.use_begin(), E = Fn.use_end();
I != E; ++I) {
CallSite CS(*I);
if (!CS || !CS.isCallee(I))
for (Use &U : Fn.uses()) {
CallSite CS(U.getUser());
if (!CS || !CS.isCallee(&U))
continue;
// Now go through all unused args and replace them with "undef".
@@ -436,9 +435,9 @@ DAE::Liveness DAE::MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses) {
/// RetValNum is the return value number to use when this use is used in a
/// return instruction. This is used in the recursion, you should always leave
/// it at 0.
DAE::Liveness DAE::SurveyUse(Value::const_use_iterator U,
DAE::Liveness DAE::SurveyUse(const Use *U,
UseVector &MaybeLiveUses, unsigned RetValNum) {
const User *V = *U;
const User *V = U->getUser();
if (const ReturnInst *RI = dyn_cast<ReturnInst>(V)) {
// The value is returned from a function. It's only live when the
// function's return value is live. We use RetValNum here, for the case
@@ -449,7 +448,7 @@ DAE::Liveness DAE::SurveyUse(Value::const_use_iterator U,
return MarkIfNotLive(Use, MaybeLiveUses);
}
if (const InsertValueInst *IV = dyn_cast<InsertValueInst>(V)) {
if (U.getOperandNo() != InsertValueInst::getAggregateOperandIndex()
if (U->getOperandNo() != InsertValueInst::getAggregateOperandIndex()
&& IV->hasIndices())
// The use we are examining is inserted into an aggregate. Our liveness
// depends on all uses of that aggregate, but if it is used as a return
@@ -460,9 +459,8 @@ DAE::Liveness DAE::SurveyUse(Value::const_use_iterator U,
// we don't change RetValNum, but do survey all our uses.
Liveness Result = MaybeLive;
for (Value::const_use_iterator I = IV->use_begin(),
E = V->use_end(); I != E; ++I) {
Result = SurveyUse(I, MaybeLiveUses, RetValNum);
for (const Use &UU : IV->uses()) {
Result = SurveyUse(&UU, MaybeLiveUses, RetValNum);
if (Result == Live)
break;
}
@@ -485,7 +483,7 @@ DAE::Liveness DAE::SurveyUse(Value::const_use_iterator U,
return Live;
assert(CS.getArgument(ArgNo)
== CS->getOperand(U.getOperandNo())
== CS->getOperand(U->getOperandNo())
&& "Argument is not where we expected it");
// Value passed to a normal call. It's only live when the corresponding
@@ -508,9 +506,8 @@ DAE::Liveness DAE::SurveyUses(const Value *V, UseVector &MaybeLiveUses) {
// Assume it's dead (which will only hold if there are no uses at all..).
Liveness Result = MaybeLive;
// Check each use.
for (Value::const_use_iterator I = V->use_begin(),
E = V->use_end(); I != E; ++I) {
Result = SurveyUse(I, MaybeLiveUses);
for (const Use &U : V->uses()) {
Result = SurveyUse(&U, MaybeLiveUses);
if (Result == Live)
break;
}
@@ -564,12 +561,11 @@ void DAE::SurveyFunction(const Function &F) {
unsigned NumLiveRetVals = 0;
Type *STy = dyn_cast<StructType>(F.getReturnType());
// Loop all uses of the function.
for (Value::const_use_iterator I = F.use_begin(), E = F.use_end();
I != E; ++I) {
for (const Use &U : F.uses()) {
// If the function is PASSED IN as an argument, its address has been
// taken.
ImmutableCallSite CS(*I);
if (!CS || !CS.isCallee(I)) {
ImmutableCallSite CS(U.getUser());
if (!CS || !CS.isCallee(&U)) {
MarkLive(F);
return;
}
@@ -588,9 +584,8 @@ void DAE::SurveyFunction(const Function &F) {
if (NumLiveRetVals != RetCount) {
if (STy) {
// Check all uses of the return value.
for (Value::const_use_iterator I = TheCall->use_begin(),
E = TheCall->use_end(); I != E; ++I) {
const ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(*I);
for (const User *U : TheCall->users()) {
const ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(U);
if (Ext && Ext->hasIndices()) {
// This use uses a part of our return value, survey the uses of
// that part and store the results for this index only.
@@ -893,7 +888,7 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
//
std::vector<Value*> Args;
while (!F->use_empty()) {
CallSite CS(F->use_back());
CallSite CS(F->user_back());
Instruction *Call = CS.getInstruction();
AttributesVec.clear();