#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/DominatorInternals.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ProfileInfo.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Support/PatternMatch.h"
#include "llvm/Support/ValueHandle.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetData.h"
+#include "llvm/DataLayout.h"
#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Transforms/Utils/AddrModeMatcher.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/BuildLibCalls.h"
+#include "llvm/Transforms/Utils/BypassSlowDivision.h"
#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
using namespace llvm::PatternMatch;
"disable-cgp-branch-opts", cl::Hidden, cl::init(false),
cl::desc("Disable branch optimizations in CodeGenPrepare"));
-// FIXME: Remove this abomination once all of the tests pass without it!
-static cl::opt<bool> DisableDeleteDeadBlocks(
- "disable-cgp-delete-dead-blocks", cl::Hidden, cl::init(false),
- cl::desc("Disable deleting dead blocks in CodeGenPrepare"));
-
static cl::opt<bool> DisableSelectToBranch(
"disable-cgp-select2branch", cl::Hidden, cl::init(false),
cl::desc("Disable select to branch conversion."));
const TargetLibraryInfo *TLInfo;
DominatorTree *DT;
ProfileInfo *PFI;
-
+
/// CurInstIterator - As we scan instructions optimizing them, this is the
/// next instruction to optimize. Xforms that can invalidate this should
/// update it.
}
private:
+ bool EliminateFallThrough(Function &F);
bool EliminateMostlyEmptyBlocks(Function &F);
bool CanMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
void EliminateMostlyEmptyBlock(BasicBlock *BB);
bool MoveExtToFormExtLoad(Instruction *I);
bool OptimizeExtUses(Instruction *I);
bool OptimizeSelectInst(SelectInst *SI);
- bool DupRetToEnableTailCallOpts(ReturnInst *RI);
+ bool DupRetToEnableTailCallOpts(BasicBlock *BB);
bool PlaceDbgValues(Function &F);
};
}
TLInfo = &getAnalysis<TargetLibraryInfo>();
DT = getAnalysisIfAvailable<DominatorTree>();
PFI = getAnalysisIfAvailable<ProfileInfo>();
- OptSize = F.hasFnAttr(Attribute::OptimizeForSize);
+ OptSize = F.getFnAttributes().hasAttribute(Attributes::OptimizeForSize);
+
+ /// This optimization identifies DIV instructions that can be
+ /// profitably bypassed and carried out with a shorter, faster divide.
+ if (TLI && TLI->isSlowDivBypassed()) {
+ const DenseMap<unsigned int, unsigned int> &BypassWidths =
+ TLI->getBypassSlowDivWidths();
+ for (Function::iterator I = F.begin(); I != F.end(); I++)
+ EverMadeChange |= bypassSlowDivision(F, I, BypassWidths);
+ }
- // First pass, eliminate blocks that contain only PHI nodes and an
+ // Eliminate blocks that contain only PHI nodes and an
// unconditional branch.
EverMadeChange |= EliminateMostlyEmptyBlocks(F);
// llvm.dbg.value is far away from the value then iSel may not be able
- // handle it properly. iSel will drop llvm.dbg.value if it can not
+ // handle it properly. iSel will drop llvm.dbg.value if it can not
// find a node corresponding to the value.
EverMadeChange |= PlaceDbgValues(F);
bool MadeChange = true;
while (MadeChange) {
MadeChange = false;
- for (Function::iterator I = F.begin(), E = F.end(); I != E; ) {
+ for (Function::iterator I = F.begin(); I != F.end(); ) {
BasicBlock *BB = I++;
MadeChange |= OptimizeBlock(*BB);
}
WorkList.insert(*II);
}
- if (!DisableDeleteDeadBlocks)
- for (SmallPtrSet<BasicBlock*, 8>::iterator
- I = WorkList.begin(), E = WorkList.end(); I != E; ++I)
- DeleteDeadBlock(*I);
+ for (SmallPtrSet<BasicBlock*, 8>::iterator
+ I = WorkList.begin(), E = WorkList.end(); I != E; ++I)
+ DeleteDeadBlock(*I);
+
+ // Merge pairs of basic blocks with unconditional branches, connected by
+ // a single edge.
+ if (EverMadeChange || MadeChange)
+ MadeChange |= EliminateFallThrough(F);
if (MadeChange)
ModifiedDT = true;
return EverMadeChange;
}
+/// EliminateFallThrough - Merge basic blocks which are connected
+/// by a single edge, where one of the basic blocks has a single successor
+/// pointing to the other basic block, which has a single predecessor.
+bool CodeGenPrepare::EliminateFallThrough(Function &F) {
+ bool Changed = false;
+ // Scan all of the blocks in the function, except for the entry block.
+ for (Function::iterator I = ++F.begin(), E = F.end(); I != E; ) {
+ BasicBlock *BB = I++;
+ // If the destination block has a single pred, then this is a trivial
+ // edge, just collapse it.
+ BasicBlock *SinglePred = BB->getSinglePredecessor();
+
+ // Don't merge if BB's address is taken.
+ if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
+
+ BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
+ if (Term && !Term->isConditional()) {
+ Changed = true;
+ DEBUG(dbgs() << "To merge:\n"<< *SinglePred << "\n\n\n");
+ // Remember if SinglePred was the entry block of the function.
+ // If so, we will need to move BB back to the entry position.
+ bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
+ MergeBasicBlockIntoOnlyPred(BB, this);
+
+ if (isEntry && BB != &BB->getParent()->getEntryBlock())
+ BB->moveBefore(&BB->getParent()->getEntryBlock());
+
+ // We have erased a block. Update the iterator.
+ I = BB;
+ }
+ }
+ return Changed;
+}
+
/// EliminateMostlyEmptyBlocks - eliminate blocks that contain only PHI nodes,
/// debug info directives, and an unconditional branch. Passes before isel
/// (e.g. LSR/loopsimplify) often split edges in ways that are non-optimal for
if (isEntry && BB != &BB->getParent()->getEntryBlock())
BB->moveBefore(&BB->getParent()->getEntryBlock());
-
+
DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n");
return;
}
bool CodeGenPrepare::OptimizeCallInst(CallInst *CI) {
BasicBlock *BB = CI->getParent();
-
+
// Lower inline assembly if we can.
// If we found an inline asm expession, and if the target knows how to
// lower it to normal LLVM code, do so now.
if (OptimizeInlineAsmInst(CI))
return true;
}
-
+
// Lower all uses of llvm.objectsize.*
IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
if (II && II->getIntrinsicID() == Intrinsic::objectsize) {
bool Min = (cast<ConstantInt>(II->getArgOperand(1))->getZExtValue() == 1);
Type *ReturnTy = CI->getType();
- Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL);
-
+ Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL);
+
// Substituting this can cause recursive simplifications, which can
// invalidate our iterator. Use a WeakVH to hold onto it in case this
// happens.
WeakVH IterHandle(CurInstIterator);
-
- replaceAndRecursivelySimplify(CI, RetVal, TLI ? TLI->getTargetData() : 0,
+
+ replaceAndRecursivelySimplify(CI, RetVal, TLI ? TLI->getDataLayout() : 0,
TLInfo, ModifiedDT ? 0 : DT);
// If the iterator instruction was recursively deleted, start over at the
// From here on out we're working with named functions.
if (CI->getCalledFunction() == 0) return false;
- // We'll need TargetData from here on out.
- const TargetData *TD = TLI ? TLI->getTargetData() : 0;
+ // We'll need DataLayout from here on out.
+ const DataLayout *TD = TLI ? TLI->getDataLayout() : 0;
if (!TD) return false;
-
+
// Lower all default uses of _chk calls. This is very similar
// to what InstCombineCalls does, but here we are only lowering calls
// that have the default "don't know" as the objectsize. Anything else
// should be left alone.
CodeGenPrepareFortifiedLibCalls Simplifier;
- return Simplifier.fold(CI, TD);
+ return Simplifier.fold(CI, TD, TLInfo);
}
/// DupRetToEnableTailCallOpts - Look for opportunities to duplicate return
/// instructions to the predecessor to enable tail call optimizations. The
/// case it is currently looking for is:
+/// @code
/// bb0:
/// %tmp0 = tail call i32 @f0()
/// br label %return
/// return:
/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
/// ret i32 %retval
+/// @endcode
///
/// =>
///
+/// @code
/// bb0:
/// %tmp0 = tail call i32 @f0()
/// ret i32 %tmp0
/// bb2:
/// %tmp2 = tail call i32 @f2()
/// ret i32 %tmp2
-///
-bool CodeGenPrepare::DupRetToEnableTailCallOpts(ReturnInst *RI) {
+/// @endcode
+bool CodeGenPrepare::DupRetToEnableTailCallOpts(BasicBlock *BB) {
if (!TLI)
return false;
- Value *V = RI->getReturnValue();
- PHINode *PN = V ? dyn_cast<PHINode>(V) : NULL;
- if (V && !PN)
+ ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator());
+ if (!RI)
return false;
- BasicBlock *BB = RI->getParent();
+ PHINode *PN = 0;
+ BitCastInst *BCI = 0;
+ Value *V = RI->getReturnValue();
+ if (V) {
+ BCI = dyn_cast<BitCastInst>(V);
+ if (BCI)
+ V = BCI->getOperand(0);
+
+ PN = dyn_cast<PHINode>(V);
+ if (!PN)
+ return false;
+ }
+
if (PN && PN->getParent() != BB)
return false;
// See llvm::isInTailCallPosition().
const Function *F = BB->getParent();
Attributes CallerRetAttr = F->getAttributes().getRetAttributes();
- if ((CallerRetAttr & Attribute::ZExt) || (CallerRetAttr & Attribute::SExt))
+ if (CallerRetAttr.hasAttribute(Attributes::ZExt) ||
+ CallerRetAttr.hasAttribute(Attributes::SExt))
return false;
// Make sure there are no instructions between the PHI and return, or that the
if (PN) {
BasicBlock::iterator BI = BB->begin();
do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
+ if (&*BI == BCI)
+ // Also skip over the bitcast.
+ ++BI;
if (&*BI != RI)
return false;
} else {
// Conservatively require the attributes of the call to match those of the
// return. Ignore noalias because it doesn't affect the call sequence.
Attributes CalleeRetAttr = CS.getAttributes().getRetAttributes();
- if ((CalleeRetAttr ^ CallerRetAttr) & ~Attribute::NoAlias)
+ if (AttrBuilder(CalleeRetAttr).
+ removeAttribute(Attributes::NoAlias) !=
+ AttrBuilder(CallerRetAttr).
+ removeAttribute(Attributes::NoAlias))
continue;
// Make sure the call instruction is followed by an unconditional branch to
}
// If we eliminated all predecessors of the block, delete the block now.
- if (Changed && pred_begin(BB) == pred_end(BB))
+ if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
BB->eraseFromParent();
return Changed;
bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
Type *AccessTy) {
Value *Repl = Addr;
-
- // Try to collapse single-value PHI nodes. This is necessary to undo
+
+ // Try to collapse single-value PHI nodes. This is necessary to undo
// unprofitable PRE transformations.
SmallVector<Value*, 8> worklist;
SmallPtrSet<Value*, 16> Visited;
worklist.push_back(Addr);
-
+
// Use a worklist to iteratively look through PHI nodes, and ensure that
// the addressing mode obtained from the non-PHI roots of the graph
// are equivalent.
while (!worklist.empty()) {
Value *V = worklist.back();
worklist.pop_back();
-
+
// Break use-def graph loops.
if (!Visited.insert(V)) {
Consensus = 0;
break;
}
-
+
// For a PHI node, push all of its incoming values.
if (PHINode *P = dyn_cast<PHINode>(V)) {
for (unsigned i = 0, e = P->getNumIncomingValues(); i != e; ++i)
worklist.push_back(P->getIncomingValue(i));
continue;
}
-
+
// For non-PHIs, determine the addressing mode being computed.
SmallVector<Instruction*, 16> NewAddrModeInsts;
ExtAddrMode NewAddrMode =
}
continue;
}
-
+
Consensus = 0;
break;
}
-
+
// If the addressing mode couldn't be determined, or if multiple different
// ones were determined, bail out now.
if (!Consensus) return false;
-
+
// Check to see if any of the instructions supersumed by this addr mode are
// non-local to I's BB.
bool AnyNonLocal = false;
DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "
<< *MemoryInst);
Type *IntPtrTy =
- TLI->getTargetData()->getIntPtrType(AccessTy->getContext());
+ TLI->getDataLayout()->getIntPtrType(AccessTy->getContext());
Value *Result = 0;
// Use a WeakVH to hold onto it in case this happens.
WeakVH IterHandle(CurInstIterator);
BasicBlock *BB = CurInstIterator->getParent();
-
- RecursivelyDeleteTriviallyDeadInstructions(Repl);
+
+ RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
if (IterHandle != CurInstIterator) {
// If the iterator instruction was recursively deleted, start over at the
// This address is now available for reassignment, so erase the table
// entry; we don't want to match some completely different instruction.
SunkAddrs[Addr] = 0;
- }
+ }
}
++NumMemoryInsts;
return true;
bool CodeGenPrepare::OptimizeInlineAsmInst(CallInst *CS) {
bool MadeChange = false;
- TargetLowering::AsmOperandInfoVector
+ TargetLowering::AsmOperandInfoVector
TargetConstraints = TLI->ParseConstraints(CS);
unsigned ArgNo = 0;
for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
-
+
// Compute the constraint code and ConstraintType to use.
TLI->ComputeConstraintToUse(OpInfo, SDValue());
}
+/// If we have a SelectInst that will likely profit from branch prediction,
+/// turn it into a branch.
bool CodeGenPrepare::OptimizeSelectInst(SelectInst *SI) {
- // If we have a SelectInst that will likely profit from branch prediction,
- // turn it into a branch.
- if (DisableSelectToBranch || OptSize || !TLI->isPredictableSelectExpensive())
- return false;
+ bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1);
- if (!SI->getCondition()->getType()->isIntegerTy(1) ||
- !isFormingBranchFromSelectProfitable(SI))
+ // Can we convert the 'select' to CF ?
+ if (DisableSelectToBranch || OptSize || !TLI || VectorCond)
return false;
+ TargetLowering::SelectSupportKind SelectKind;
+ if (VectorCond)
+ SelectKind = TargetLowering::VectorMaskSelect;
+ else if (SI->getType()->isVectorTy())
+ SelectKind = TargetLowering::ScalarCondVectorVal;
+ else
+ SelectKind = TargetLowering::ScalarValSelect;
+
+ // Do we have efficient codegen support for this kind of 'selects' ?
+ if (TLI->isSelectSupported(SelectKind)) {
+ // We have efficient codegen support for the select instruction.
+ // Check if it is profitable to keep this 'select'.
+ if (!TLI->isPredictableSelectExpensive() ||
+ !isFormingBranchFromSelectProfitable(SI))
+ return false;
+ }
+
ModifiedDT = true;
// First, we split the block containing the select into 2 blocks.
}
return false;
}
-
+
if (CastInst *CI = dyn_cast<CastInst>(I)) {
// If the source of the cast is a constant, then this should have
// already been constant folded. The only reason NOT to constant fold
}
return false;
}
-
+
if (CmpInst *CI = dyn_cast<CmpInst>(I))
return OptimizeCmpExpression(CI);
-
+
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
if (TLI)
return OptimizeMemoryInst(I, I->getOperand(0), LI->getType());
return false;
}
-
+
if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
if (TLI)
return OptimizeMemoryInst(I, SI->getOperand(1),
SI->getOperand(0)->getType());
return false;
}
-
+
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
if (GEPI->hasAllZeroIndices()) {
/// The GEP operand must be a pointer, so must its result -> BitCast
}
return false;
}
-
+
if (CallInst *CI = dyn_cast<CallInst>(I))
return OptimizeCallInst(CI);
- if (ReturnInst *RI = dyn_cast<ReturnInst>(I))
- return DupRetToEnableTailCallOpts(RI);
-
if (SelectInst *SI = dyn_cast<SelectInst>(I))
return OptimizeSelectInst(SI);
bool MadeChange = false;
CurInstIterator = BB.begin();
- for (BasicBlock::iterator E = BB.end(); CurInstIterator != E; )
+ while (CurInstIterator != BB.end())
MadeChange |= OptimizeInst(CurInstIterator++);
+ MadeChange |= DupRetToEnableTailCallOpts(&BB);
+
return MadeChange;
}
// llvm.dbg.value is far away from the value then iSel may not be able
-// handle it properly. iSel will drop llvm.dbg.value if it can not
+// handle it properly. iSel will drop llvm.dbg.value if it can not
// find a node corresponding to the value.
bool CodeGenPrepare::PlaceDbgValues(Function &F) {
bool MadeChange = false;
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