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author | Andrew Trick <atrick@apple.com> | 2012-06-26 04:11:38 +0000 |
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committer | Andrew Trick <atrick@apple.com> | 2012-06-26 04:11:38 +0000 |
commit | c9b1e25493b393013b28e5d457f2fb2845a4dd9f (patch) | |
tree | c1193bd83841e829e703beeb00c1fe6415de5f05 /lib | |
parent | 5ac3f96c0e4a1f6b8253aabf74fe30b0439e9bdf (diff) | |
download | llvm-c9b1e25493b393013b28e5d457f2fb2845a4dd9f.tar.gz llvm-c9b1e25493b393013b28e5d457f2fb2845a4dd9f.tar.bz2 llvm-c9b1e25493b393013b28e5d457f2fb2845a4dd9f.tar.xz |
Enable the new LoopInfo algorithm by default.
The primary advantage is that loop optimizations will be applied in a
stable order. This helps debugging and unit test creation. It is also
a better overall implementation without pathologically bad performance
on deep functions.
On large functions (llvm-stress --size=200000 | opt -loops)
Before: 0.1263s
After: 0.0225s
On deep functions (after tweaking llvm-stress, thanks Nadav):
Before: 0.2281s
After: 0.0227s
See r158790 for more comments.
The loop tree is now consistently generated in forward order, but loop
passes are applied in reverse order over the program. If we have a
loop optimization that prefers forward order, that can easily be
achieved by adding a different type of LoopPassManager.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159183 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r-- | lib/Analysis/LoopInfo.cpp | 9 | ||||
-rw-r--r-- | lib/Analysis/LoopPass.cpp | 10 | ||||
-rw-r--r-- | lib/CodeGen/MachineLoopInfo.cpp | 10 |
3 files changed, 9 insertions, 20 deletions
diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp index c5e5bbe266..20c33a3d9d 100644 --- a/lib/Analysis/LoopInfo.cpp +++ b/lib/Analysis/LoopInfo.cpp @@ -44,10 +44,6 @@ static cl::opt<bool,true> VerifyLoopInfoX("verify-loop-info", cl::location(VerifyLoopInfo), cl::desc("Verify loop info (time consuming)")); -static cl::opt<bool> -StableLoopInfo("stable-loops", cl::Hidden, cl::init(false), - cl::desc("Compute a stable loop tree.")); - char LoopInfo::ID = 0; INITIALIZE_PASS_BEGIN(LoopInfo, "loops", "Natural Loop Information", true, true) INITIALIZE_PASS_DEPENDENCY(DominatorTree) @@ -516,10 +512,7 @@ Loop *UnloopUpdater::getNearestLoop(BasicBlock *BB, Loop *BBLoop) { // bool LoopInfo::runOnFunction(Function &) { releaseMemory(); - if (StableLoopInfo) - LI.Analyze(getAnalysis<DominatorTree>().getBase()); - else - LI.Calculate(getAnalysis<DominatorTree>().getBase()); // Update + LI.Analyze(getAnalysis<DominatorTree>().getBase()); return false; } diff --git a/lib/Analysis/LoopPass.cpp b/lib/Analysis/LoopPass.cpp index aba700ac5c..1540112fe1 100644 --- a/lib/Analysis/LoopPass.cpp +++ b/lib/Analysis/LoopPass.cpp @@ -162,7 +162,7 @@ void LPPassManager::deleteSimpleAnalysisValue(Value *V, Loop *L) { // Recurse through all subloops and all loops into LQ. static void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) { LQ.push_back(L); - for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) + for (Loop::reverse_iterator I = L->rbegin(), E = L->rend(); I != E; ++I) addLoopIntoQueue(*I, LQ); } @@ -183,8 +183,12 @@ bool LPPassManager::runOnFunction(Function &F) { // Collect inherited analysis from Module level pass manager. populateInheritedAnalysis(TPM->activeStack); - // Populate Loop Queue - for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) + // Populate the loop queue in reverse program order. There is no clear need to + // process sibling loops in either forward or reverse order. There may be some + // advantage in deleting uses in a later loop before optimizing the + // definitions in an earlier loop. If we find a clear reason to process in + // forward order, then a forward variant of LoopPassManager should be created. + for (LoopInfo::reverse_iterator I = LI->rbegin(), E = LI->rend(); I != E; ++I) addLoopIntoQueue(*I, LQ); if (LQ.empty()) // No loops, skip calling finalizers diff --git a/lib/CodeGen/MachineLoopInfo.cpp b/lib/CodeGen/MachineLoopInfo.cpp index b7298e48ee..9f3829e3c0 100644 --- a/lib/CodeGen/MachineLoopInfo.cpp +++ b/lib/CodeGen/MachineLoopInfo.cpp @@ -18,7 +18,6 @@ #include "llvm/CodeGen/MachineDominators.h" #include "llvm/CodeGen/Passes.h" #include "llvm/Analysis/LoopInfoImpl.h" -#include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" using namespace llvm; @@ -26,10 +25,6 @@ using namespace llvm; template class llvm::LoopBase<MachineBasicBlock, MachineLoop>; template class llvm::LoopInfoBase<MachineBasicBlock, MachineLoop>; -static cl::opt<bool> -StableLoopInfo("stable-machine-loops", cl::Hidden, cl::init(false), - cl::desc("Compute a stable loop tree.")); - char MachineLoopInfo::ID = 0; INITIALIZE_PASS_BEGIN(MachineLoopInfo, "machine-loops", "Machine Natural Loop Construction", true, true) @@ -41,10 +36,7 @@ char &llvm::MachineLoopInfoID = MachineLoopInfo::ID; bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) { releaseMemory(); - if (StableLoopInfo) - LI.Analyze(getAnalysis<MachineDominatorTree>().getBase()); - else - LI.Calculate(getAnalysis<MachineDominatorTree>().getBase()); // Update + LI.Analyze(getAnalysis<MachineDominatorTree>().getBase()); return false; } |