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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. =]

llvm-svn: 203364
This commit is contained in:
Chandler Carruth
2014-03-09 03:16:01 +00:00
parent c980afc578
commit cdf4788401
100 changed files with 920 additions and 1075 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
llvm/lib/Transforms/Utils/GlobalStatus.cpp
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@@ -35,9 +35,8 @@ bool llvm::isSafeToDestroyConstant(const Constant *C) {
if (isa<GlobalValue>(C))
return false;
for (Value::const_use_iterator UI = C->use_begin(), E = C->use_end(); UI != E;
++UI)
if (const Constant *CU = dyn_cast<Constant>(*UI)) {
for (const User *U : C->users())
if (const Constant *CU = dyn_cast<Constant>(U)) {
if (!isSafeToDestroyConstant(CU))
return false;
} else
@@ -47,10 +46,9 @@ bool llvm::isSafeToDestroyConstant(const Constant *C) {
static bool analyzeGlobalAux(const Value *V, GlobalStatus &GS,
SmallPtrSet<const PHINode *, 16> &PhiUsers) {
for (Value::const_use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;
++UI) {
const User *U = *UI;
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
for (const Use &U : V->uses()) {
const User *UR = U.getUser();
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(UR)) {
GS.HasNonInstructionUser = true;
// If the result of the constantexpr isn't pointer type, then we won't
@@ -60,7 +58,7 @@ static bool analyzeGlobalAux(const Value *V, GlobalStatus &GS,
if (analyzeGlobalAux(CE, GS, PhiUsers))
return true;
} else if (const Instruction *I = dyn_cast<Instruction>(U)) {
} else if (const Instruction *I = dyn_cast<Instruction>(UR)) {
if (!GS.HasMultipleAccessingFunctions) {
const Function *F = I->getParent()->getParent();
if (GS.AccessingFunction == 0)
@@ -150,13 +148,13 @@ static bool analyzeGlobalAux(const Value *V, GlobalStatus &GS,
return true;
GS.StoredType = GlobalStatus::Stored;
} else if (ImmutableCallSite C = I) {
if (!C.isCallee(UI))
if (!C.isCallee(&U))
return true;
GS.IsLoaded = true;
} else {
return true; // Any other non-load instruction might take address!
}
} else if (const Constant *C = dyn_cast<Constant>(U)) {
} else if (const Constant *C = dyn_cast<Constant>(UR)) {
GS.HasNonInstructionUser = true;
// We might have a dead and dangling constant hanging off of here.
if (!isSafeToDestroyConstant(C))