#define DEBUG_TYPE "loop-unswitch"
#include "llvm/Transforms/Scalar.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Function.h"
-#include "llvm/Instructions.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/CodeMetrics.h"
+#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/ScalarEvolution.h"
-#include "llvm/Transforms/Utils/Cloning.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/STLExtras.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/Local.h"
#include <algorithm>
#include <map>
#include <set>
loopPreheader = currentLoop->getLoopPreheader();
}
- /// HasIndirectBrsInPreds - Returns true if there are predecessors, that are
- /// terminated with indirect branch instruction.
- bool HasIndirectBrsInPreds(const SmallVectorImpl<BasicBlock *> &ExitBlocks);
-
/// Split all of the edges from inside the loop to their exit blocks.
/// Update the appropriate Phi nodes as we do so.
void SplitExitEdges(Loop *L, const SmallVector<BasicBlock *, 8> &ExitBlocks);
bool UnswitchIfProfitable(Value *LoopCond, Constant *Val);
void UnswitchTrivialCondition(Loop *L, Value *Cond, Constant *Val,
BasicBlock *ExitBlock);
- bool UnswitchNontrivialCondition(Value *LIC, Constant *OnVal, Loop *L);
+ void UnswitchNontrivialCondition(Value *LIC, Constant *OnVal, Loop *L);
void RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
Constant *Val, bool isEqual);
if (!loopPreheader)
return false;
+ // Loops with indirectbr cannot be cloned.
+ if (!currentLoop->isSafeToClone())
+ return false;
+
+ // Without dedicated exits, splitting the exit edge may fail.
+ if (!currentLoop->hasDedicatedExits())
+ return false;
+
LLVMContext &Context = loopHeader->getContext();
// Probably we reach the quota of branches for this loop. If so
/// LoopCond == Val to simplify the loop. If we decide that this is profitable,
/// unswitch the loop, reprocess the pieces, then return true.
bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val) {
-
Function *F = loopHeader->getParent();
-
Constant *CondVal = 0;
BasicBlock *ExitBlock = 0;
+
if (IsTrivialUnswitchCondition(LoopCond, &CondVal, &ExitBlock)) {
// If the condition is trivial, always unswitch. There is no code growth
// for this case.
// Check to see if it would be profitable to unswitch current loop.
// Do not do non-trivial unswitch while optimizing for size.
- if (OptimizeForSize || F->hasFnAttr(Attribute::OptimizeForSize))
+ if (OptimizeForSize ||
+ F->getFnAttributes().hasAttribute(Attributes::OptimizeForSize))
return false;
- return UnswitchNontrivialCondition(LoopCond, Val, currentLoop);
+ UnswitchNontrivialCondition(LoopCond, Val, currentLoop);
+ return true;
}
/// CloneLoop - Recursively clone the specified loop and all of its children,
// If either edge is critical, split it. This helps preserve LoopSimplify
// form for enclosing loops.
- SplitCriticalEdge(BI, 0, this);
- SplitCriticalEdge(BI, 1, this);
+ SplitCriticalEdge(BI, 0, this, false, false, true);
+ SplitCriticalEdge(BI, 1, this, false, false, true);
}
/// UnswitchTrivialCondition - Given a loop that has a trivial unswitchable
++NumTrivial;
}
-/// HasIndirectBrsInPreds - Returns true if there are predecessors, that are
-/// terminated with indirect branch instruction.
-bool LoopUnswitch::HasIndirectBrsInPreds(
- const SmallVectorImpl<BasicBlock *> &ExitBlocks){
-
- for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
- const BasicBlock *ExitBlock = ExitBlocks[i];
- for (const_pred_iterator p = pred_begin(ExitBlock), e = pred_end(ExitBlock);
- p != e; ++p) {
- // Cannot split an edge from an IndirectBrInst
- if (isa<IndirectBrInst>((*p)->getTerminator()))
- return true;
-
- }
- }
- return false;
-}
-
/// SplitExitEdges - Split all of the edges from inside the loop to their exit
/// blocks. Update the appropriate Phi nodes as we do so.
void LoopUnswitch::SplitExitEdges(Loop *L,
/// UnswitchNontrivialCondition - We determined that the loop is profitable
/// to unswitch when LIC equal Val. Split it into loop versions and test the
/// condition outside of either loop. Return the loops created as Out1/Out2.
-bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
+void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
Loop *L) {
Function *F = loopHeader->getParent();
DEBUG(dbgs() << "loop-unswitch: Unswitching loop %"
SmallVector<BasicBlock*, 8> ExitBlocks;
L->getUniqueExitBlocks(ExitBlocks);
- if (HasIndirectBrsInPreds(ExitBlocks))
- return false;
// Split all of the edges from inside the loop to their exit blocks. Update
// the appropriate Phi nodes as we do so.
if (!LoopProcessWorklist.empty() && LoopProcessWorklist.back() == NewLoop &&
LICHandle && !isa<Constant>(LICHandle))
RewriteLoopBodyWithConditionConstant(NewLoop, LICHandle, Val, true);
-
- return true;
}
/// RemoveFromWorklist - Remove all instances of I from the worklist vector
/// specified.
static void RemoveFromWorklist(Instruction *I,
std::vector<Instruction*> &Worklist) {
- std::vector<Instruction*>::iterator WI = std::find(Worklist.begin(),
- Worklist.end(), I);
- while (WI != Worklist.end()) {
- unsigned Offset = WI-Worklist.begin();
- Worklist.erase(WI);
- WI = std::find(Worklist.begin()+Offset, Worklist.end(), I);
- }
+
+ Worklist.erase(std::remove(Worklist.begin(), Worklist.end(), I),
+ Worklist.end());
}
/// ReplaceUsesOfWith - When we find that I really equals V, remove I from the
// See if instruction simplification can hack this up. This is common for
// things like "select false, X, Y" after unswitching made the condition be
- // 'false'.
- if (Value *V = SimplifyInstruction(I, 0, 0, DT))
+ // 'false'. TODO: update the domtree properly so we can pass it here.
+ if (Value *V = SimplifyInstruction(I))
if (LI->replacementPreservesLCSSAForm(I, V)) {
ReplaceUsesOfWith(I, V, Worklist, L, LPM);
continue;
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