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[LICM] Remove unneeded tracking of whether changes were made. NFC. 

"Changed" doesn't actually change within the loop, so there's
no reason to keep track of it - we always return false during
analysis and true after the transformation is made.

llvm-svn: 290735
This commit is contained in:
Michael Kuperstein 2016-12-30 00:43:22 +00:00
parent 62b98c3977
commit 4a86a1921a
1 changed files with 7 additions and 9 deletions
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16
llvm/lib/Transforms/Scalar/LICM.cpp
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@ -946,7 +946,6 @@ bool llvm::promoteLoopAccessesToScalars(
// Check that all of the pointers in the alias set have the same type. We
// cannot (yet) promote a memory location that is loaded and stored in
// different sizes. While we are at it, collect alignment and AA info.
bool Changed = false;
for (const auto &ASI : AS) {
Value *ASIV = ASI.getValue();
PointerMustAliases.insert(ASIV);
@ -955,7 +954,7 @@ bool llvm::promoteLoopAccessesToScalars(
// cannot (yet) promote a memory location that is loaded and stored in
// different sizes.
if (SomePtr->getType() != ASIV->getType())
return Changed;
return false;
for (User *U : ASIV->users()) {
// Ignore instructions that are outside the loop.
@ -968,7 +967,7 @@ bool llvm::promoteLoopAccessesToScalars(
if (const LoadInst *Load = dyn_cast<LoadInst>(UI)) {
assert(!Load->isVolatile() && "AST broken");
if (!Load->isSimple())
return Changed;
return false;
if (!DereferenceableInPH)
DereferenceableInPH = isSafeToExecuteUnconditionally(
@ -980,7 +979,7 @@ bool llvm::promoteLoopAccessesToScalars(
continue;
assert(!Store->isVolatile() && "AST broken");
if (!Store->isSimple())
return Changed;
return false;
// If the store is guaranteed to execute, both properties are satisfied.
// We may want to check if a store is guaranteed to execute even if we
@ -1009,7 +1008,7 @@ bool llvm::promoteLoopAccessesToScalars(
Preheader->getTerminator(), DT);
}
} else
return Changed; // Not a load or store.
return false; // Not a load or store.
// Merge the AA tags.
if (LoopUses.empty()) {
@ -1026,7 +1025,7 @@ bool llvm::promoteLoopAccessesToScalars(
// If we couldn't prove we can hoist the load, bail.
if (!DereferenceableInPH)
return Changed;
return false;
// We know we can hoist the load, but don't have a guaranteed store.
// Check whether the location is thread-local. If it is, then we can insert
@ -1040,12 +1039,11 @@ bool llvm::promoteLoopAccessesToScalars(
// If we've still failed to prove we can sink the store, give up.
if (!SafeToInsertStore)
return Changed;
return false;
// Otherwise, this is safe to promote, lets do it!
DEBUG(dbgs() << "LICM: Promoting value stored to in loop: " << *SomePtr
<< '\n');
Changed = true;
++NumPromoted;
// Grab a debug location for the inserted loads/stores; given that the
@ -1078,7 +1076,7 @@ bool llvm::promoteLoopAccessesToScalars(
if (PreheaderLoad->use_empty())
PreheaderLoad->eraseFromParent();
return Changed;
return true;
}
/// Returns an owning pointer to an alias set which incorporates aliasing info