Make makeLoopInvariant report whether it made any changes or not,
and use this to simplify more code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75722 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopDeletion.cpp b/lib/Transforms/Scalar/LoopDeletion.cpp
index 38d0b39..525d03f 100644
--- a/lib/Transforms/Scalar/LoopDeletion.cpp
+++ b/lib/Transforms/Scalar/LoopDeletion.cpp
@@ -38,9 +38,9 @@
bool SingleDominatingExit(Loop* L,
SmallVector<BasicBlock*, 4>& exitingBlocks);
bool IsLoopDead(Loop* L, SmallVector<BasicBlock*, 4>& exitingBlocks,
- SmallVector<BasicBlock*, 4>& exitBlocks);
- bool IsLoopInvariantInst(Instruction *I, Loop* L);
-
+ SmallVector<BasicBlock*, 4>& exitBlocks,
+ bool &Changed, BasicBlock *Preheader);
+
virtual void getAnalysisUsage(AnalysisUsage& AU) const {
AU.addRequired<ScalarEvolution>();
AU.addRequired<DominatorTree>();
@@ -84,32 +84,13 @@
return DT.dominates(exitingBlocks[0], latch);
}
-/// IsLoopInvariantInst - Checks if an instruction is invariant with respect to
-/// a loop, which is defined as being true if all of its operands are defined
-/// outside of the loop. These instructions can be hoisted out of the loop
-/// if their results are needed. This could be made more aggressive by
-/// recursively checking the operands for invariance, but it's not clear that
-/// it's worth it.
-bool LoopDeletion::IsLoopInvariantInst(Instruction *I, Loop* L) {
- // PHI nodes are not loop invariant if defined in the loop.
- if (isa<PHINode>(I) && L->contains(I->getParent()))
- return false;
-
- // The instruction is loop invariant if all of its operands are loop-invariant
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (!L->isLoopInvariant(I->getOperand(i)))
- return false;
-
- // If we got this far, the instruction is loop invariant!
- return true;
-}
-
/// IsLoopDead - Determined if a loop is dead. This assumes that we've already
/// checked for unique exit and exiting blocks, and that the code is in LCSSA
/// form.
bool LoopDeletion::IsLoopDead(Loop* L,
SmallVector<BasicBlock*, 4>& exitingBlocks,
- SmallVector<BasicBlock*, 4>& exitBlocks) {
+ SmallVector<BasicBlock*, 4>& exitBlocks,
+ bool &Changed, BasicBlock *Preheader) {
BasicBlock* exitingBlock = exitingBlocks[0];
BasicBlock* exitBlock = exitBlocks[0];
@@ -122,7 +103,7 @@
while (PHINode* P = dyn_cast<PHINode>(BI)) {
Value* incoming = P->getIncomingValueForBlock(exitingBlock);
if (Instruction* I = dyn_cast<Instruction>(incoming))
- if (!IsLoopInvariantInst(I, L))
+ if (!L->makeLoopInvariant(I, Changed, Preheader->getTerminator()))
return false;
BI++;
@@ -181,15 +162,16 @@
return false;
// Finally, we have to check that the loop really is dead.
- if (!IsLoopDead(L, exitingBlocks, exitBlocks))
- return false;
+ bool Changed = false;
+ if (!IsLoopDead(L, exitingBlocks, exitBlocks, Changed, preheader))
+ return Changed;
// Don't remove loops for which we can't solve the trip count.
// They could be infinite, in which case we'd be changing program behavior.
ScalarEvolution& SE = getAnalysis<ScalarEvolution>();
const SCEV *S = SE.getBackedgeTakenCount(L);
if (isa<SCEVCouldNotCompute>(S))
- return false;
+ return Changed;
// Now that we know the removal is safe, remove the loop by changing the
// branch from the preheader to go to the single exit block.
@@ -205,17 +187,6 @@
// to determine what it needs to clean up.
SE.forgetLoopBackedgeTakenCount(L);
- // Move simple loop-invariant expressions out of the loop, since they
- // might be needed by the exit phis.
- for (Loop::block_iterator LI = L->block_begin(), LE = L->block_end();
- LI != LE; ++LI)
- for (BasicBlock::iterator BI = (*LI)->begin(), BE = (*LI)->end();
- BI != BE; ) {
- Instruction* I = BI++;
- if (!I->use_empty() && IsLoopInvariantInst(I, L))
- I->moveBefore(preheader->getTerminator());
- }
-
// Connect the preheader directly to the exit block.
TerminatorInst* TI = preheader->getTerminator();
TI->replaceUsesOfWith(L->getHeader(), exitBlock);
@@ -273,8 +244,9 @@
// The last step is to inform the loop pass manager that we've
// eliminated this loop.
LPM.deleteLoopFromQueue(L);
+ Changed = true;
NumDeleted++;
- return true;
+ return Changed;
}
diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index f5061b5..daf1841 100644
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -168,13 +168,10 @@
if (isa<Constant>(Cond)) return 0;
// TODO: Handle: br (VARIANT|INVARIANT).
- if (L->isLoopInvariant(Cond)) return Cond;
// Hoist simple values out.
- if (L->makeLoopInvariant(Cond)) {
- Changed = true;
+ if (L->makeLoopInvariant(Cond, Changed))
return Cond;
- }
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Cond))
if (BO->getOpcode() == Instruction::And ||
diff --git a/lib/Transforms/Utils/LoopSimplify.cpp b/lib/Transforms/Utils/LoopSimplify.cpp
index cfdfcb0..81fa4f9 100644
--- a/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/lib/Transforms/Utils/LoopSimplify.cpp
@@ -93,7 +93,7 @@
BasicBlock *RewriteLoopExitBlock(Loop *L, BasicBlock *Exit);
BasicBlock *InsertPreheaderForLoop(Loop *L);
Loop *SeparateNestedLoop(Loop *L);
- void InsertUniqueBackedgeBlock(Loop *L);
+ void InsertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader);
void PlaceSplitBlockCarefully(BasicBlock *NewBB,
SmallVectorImpl<BasicBlock*> &SplitPreds,
Loop *L);
@@ -244,7 +244,7 @@
// If we either couldn't, or didn't want to, identify nesting of the loops,
// insert a new block that all backedges target, then make it jump to the
// loop header.
- InsertUniqueBackedgeBlock(L);
+ InsertUniqueBackedgeBlock(L, Preheader);
NumInserted++;
Changed = true;
}
@@ -288,9 +288,8 @@
Instruction *Inst = I++;
if (Inst == CI)
continue;
- if (!L->makeLoopInvariant(Inst, Preheader->getTerminator())) {
+ if (!L->makeLoopInvariant(Inst, Changed, Preheader->getTerminator())) {
AllInvariant = false;
- Changed = true;
break;
}
}
@@ -574,11 +573,10 @@
/// backedges to target a new basic block and have that block branch to the loop
/// header. This ensures that loops have exactly one backedge.
///
-void LoopSimplify::InsertUniqueBackedgeBlock(Loop *L) {
+void LoopSimplify::InsertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader) {
assert(L->getNumBackEdges() > 1 && "Must have > 1 backedge!");
// Get information about the loop
- BasicBlock *Preheader = L->getLoopPreheader();
BasicBlock *Header = L->getHeader();
Function *F = Header->getParent();