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[LCSSA] Use range for loops; NFC

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llvm-svn: 251248
This commit is contained in:
Sanjoy Das 2015-10-25 19:08:32 +00:00
parent 8a425d054a
commit d668744358
1 changed files with 21 additions and 28 deletions
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49
lib/Transforms/Utils/LCSSA.cpp
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@ -104,10 +104,7 @@ static bool processInstruction(Loop &L, Instruction &Inst, DominatorTree &DT,
// Insert the LCSSA phi's into all of the exit blocks dominated by the
// value, and add them to the Phi's map.
for (SmallVectorImpl<BasicBlock *>::const_iterator BBI = ExitBlocks.begin(),
BBE = ExitBlocks.end();
BBI != BBE; ++BBI) {
BasicBlock *ExitBB = *BBI;
for (BasicBlock *ExitBB : ExitBlocks) {
if (!DT.dominates(DomNode, DT.getNode(ExitBB)))
continue;
@ -151,26 +148,26 @@ static bool processInstruction(Loop &L, Instruction &Inst, DominatorTree &DT,
// Rewrite all uses outside the loop in terms of the new PHIs we just
// inserted.
for (unsigned i = 0, e = UsesToRewrite.size(); i != e; ++i) {
for (Use *UseToRewrite : UsesToRewrite) {
// If this use is in an exit block, rewrite to use the newly inserted PHI.
// This is required for correctness because SSAUpdate doesn't handle uses in
// the same block. It assumes the PHI we inserted is at the end of the
// block.
Instruction *User = cast<Instruction>(UsesToRewrite[i]->getUser());
Instruction *User = cast<Instruction>(UseToRewrite->getUser());
BasicBlock *UserBB = User->getParent();
if (PHINode *PN = dyn_cast<PHINode>(User))
UserBB = PN->getIncomingBlock(*UsesToRewrite[i]);
UserBB = PN->getIncomingBlock(*UseToRewrite);
if (isa<PHINode>(UserBB->begin()) && isExitBlock(UserBB, ExitBlocks)) {
// Tell the VHs that the uses changed. This updates SCEV's caches.
if (UsesToRewrite[i]->get()->hasValueHandle())
ValueHandleBase::ValueIsRAUWd(*UsesToRewrite[i], &UserBB->front());
UsesToRewrite[i]->set(&UserBB->front());
if (UseToRewrite->get()->hasValueHandle())
ValueHandleBase::ValueIsRAUWd(*UseToRewrite, &UserBB->front());
UseToRewrite->set(&UserBB->front());
continue;
}
// Otherwise, do full PHI insertion.
SSAUpdate.RewriteUse(*UsesToRewrite[i]);
SSAUpdate.RewriteUse(*UseToRewrite);
}
// Post process PHI instructions that were inserted into another disjoint loop
@ -193,10 +190,9 @@ static bool processInstruction(Loop &L, Instruction &Inst, DominatorTree &DT,
}
// Remove PHI nodes that did not have any uses rewritten.
for (unsigned i = 0, e = AddedPHIs.size(); i != e; ++i) {
if (AddedPHIs[i]->use_empty())
AddedPHIs[i]->eraseFromParent();
}
for (PHINode *PN : AddedPHIs)
if (PN->use_empty())
PN->eraseFromParent();
return true;
}
@ -208,8 +204,8 @@ blockDominatesAnExit(BasicBlock *BB,
DominatorTree &DT,
const SmallVectorImpl<BasicBlock *> &ExitBlocks) {
DomTreeNode *DomNode = DT.getNode(BB);
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
if (DT.dominates(DomNode, DT.getNode(ExitBlocks[i])))
for (BasicBlock *ExitBB : ExitBlocks)
if (DT.dominates(DomNode, DT.getNode(ExitBB)))
return true;
return false;
@ -230,25 +226,22 @@ bool llvm::formLCSSA(Loop &L, DominatorTree &DT, LoopInfo *LI,
// Look at all the instructions in the loop, checking to see if they have uses
// outside the loop. If so, rewrite those uses.
for (Loop::block_iterator BBI = L.block_begin(), BBE = L.block_end();
BBI != BBE; ++BBI) {
BasicBlock *BB = *BBI;
for (BasicBlock *BB : L.blocks()) {
// For large loops, avoid use-scanning by using dominance information: In
// particular, if a block does not dominate any of the loop exits, then none
// of the values defined in the block could be used outside the loop.
if (!blockDominatesAnExit(BB, DT, ExitBlocks))
continue;
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
for (Instruction &I : *BB) {
// Reject two common cases fast: instructions with no uses (like stores)
// and instructions with one use that is in the same block as this.
if (I->use_empty() ||
(I->hasOneUse() && I->user_back()->getParent() == BB &&
!isa<PHINode>(I->user_back())))
if (I.use_empty() ||
(I.hasOneUse() && I.user_back()->getParent() == BB &&
!isa<PHINode>(I.user_back())))
continue;
Changed |= processInstruction(L, *I, DT, ExitBlocks, PredCache, LI);
Changed |= processInstruction(L, I, DT, ExitBlocks, PredCache, LI);
}
}
@ -269,8 +262,8 @@ bool llvm::formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI,
bool Changed = false;
// Recurse depth-first through inner loops.
for (Loop::iterator I = L.begin(), E = L.end(); I != E; ++I)
Changed |= formLCSSARecursively(**I, DT, LI, SE);
for (Loop *L : L.getSubLoops())
Changed |= formLCSSARecursively(*L, DT, LI, SE);
Changed |= formLCSSA(L, DT, LI, SE);
return Changed;