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Factor out part of LICM::sink into a helper function.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211678 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evgeniy Stepanov 2014-06-25 09:17:21 +00:00
parent 9316a78fdd
commit 97c856a612
1 changed files with 41 additions and 28 deletions
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69
lib/Transforms/Scalar/LICM.cpp
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@ -192,6 +192,14 @@ namespace {
SmallVectorImpl<BasicBlock*> &ExitBlocks,
SmallVectorImpl<Instruction*> &InsertPts,
PredIteratorCache &PIC);
/// \brief Create a copy of the instruction in the exit block and patch up
/// SSA.
/// PN is a user of I in ExitBlock that can be used to get the number and
/// list of predecessors fast.
Instruction *CloneInstructionInExitBlock(Instruction &I,
BasicBlock &ExitBlock,
PHINode &PN);
};
}
@ -531,6 +539,35 @@ bool LICM::isNotUsedInLoop(Instruction &I) {
return true;
}
Instruction *LICM::CloneInstructionInExitBlock(Instruction &I,
BasicBlock &ExitBlock,
PHINode &PN) {
Instruction *New = I.clone();
ExitBlock.getInstList().insert(ExitBlock.getFirstInsertionPt(), New);
if (!I.getName().empty()) New->setName(I.getName() + ".le");
// Build LCSSA PHI nodes for any in-loop operands. Note that this is
// particularly cheap because we can rip off the PHI node that we're
// replacing for the number and blocks of the predecessors.
// OPT: If this shows up in a profile, we can instead finish sinking all
// invariant instructions, and then walk their operands to re-establish
// LCSSA. That will eliminate creating PHI nodes just to nuke them when
// sinking bottom-up.
for (User::op_iterator OI = New->op_begin(), OE = New->op_end(); OI != OE;
++OI)
if (Instruction *OInst = dyn_cast<Instruction>(*OI))
if (Loop *OLoop = LI->getLoopFor(OInst->getParent()))
if (!OLoop->contains(&PN)) {
PHINode *OpPN =
PHINode::Create(OInst->getType(), PN.getNumIncomingValues(),
OInst->getName() + ".lcssa", ExitBlock.begin());
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
OpPN->addIncoming(OInst, PN.getIncomingBlock(i));
*OI = OpPN;
}
return New;
}
/// sink - When an instruction is found to only be used outside of the loop,
/// this function moves it to the exit blocks and patches up SSA form as needed.
/// This method is guaranteed to remove the original instruction from its
@ -566,35 +603,11 @@ void LICM::sink(Instruction &I) {
Instruction *New;
auto It = SunkCopies.find(ExitBlock);
if (It != SunkCopies.end()) {
if (It != SunkCopies.end())
New = It->second;
} else {
New = I.clone();
SunkCopies[ExitBlock] = New;
ExitBlock->getInstList().insert(ExitBlock->getFirstInsertionPt(), New);
if (!I.getName().empty())
New->setName(I.getName() + ".le");
// Build LCSSA PHI nodes for any in-loop operands. Note that this is
// particularly cheap because we can rip off the PHI node that we're
// replacing for the number and blocks of the predecessors.
// OPT: If this shows up in a profile, we can instead finish sinking all
// invariant instructions, and then walk their operands to re-establish
// LCSSA. That will eliminate creating PHI nodes just to nuke them when
// sinking bottom-up.
for (User::op_iterator OI = New->op_begin(), OE = New->op_end(); OI != OE;
++OI)
if (Instruction *OInst = dyn_cast<Instruction>(*OI))
if (Loop *OLoop = LI->getLoopFor(OInst->getParent()))
if (!OLoop->contains(PN)) {
PHINode *OpPN = PHINode::Create(
OInst->getType(), PN->getNumIncomingValues(),
OInst->getName() + ".lcssa", ExitBlock->begin());
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
OpPN->addIncoming(OInst, PN->getIncomingBlock(i));
*OI = OpPN;
}
}
else
New = SunkCopies[ExitBlock] =
CloneInstructionInExitBlock(I, *ExitBlock, *PN);
PN->replaceAllUsesWith(New);
PN->eraseFromParent();