[llvm-commits] [llvm] r61181 - /llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
Dale Johannesen
dalej at apple.com
Wed Dec 17 17:23:42 PST 2008
Author: johannes
Date: Wed Dec 17 19:23:41 2008
New Revision: 61181
URL: http://llvm.org/viewvc/llvm-project?rev=61181&view=rev
Log:
Revert previous patch, appears to break bootstrap.
Modified:
llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=61181&r1=61180&r2=61181&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Wed Dec 17 19:23:41 2008
@@ -508,22 +508,14 @@
if (isa<PHINode>(User) && Processed.count(User))
continue;
- // Descend recursively, but not into PHI nodes outside the current loop.
- // It's important to see the entire expression outside the loop to get
- // choices that depend on addressing mode use right, although we won't
- // consider references ouside the loop in all cases.
- // If User is already in Processed, we don't want to recurse into it again,
- // but do want to record a second reference in the same instruction.
+ // If this is an instruction defined in a nested loop, or outside this loop,
+ // don't recurse into it.
bool AddUserToIVUsers = false;
if (LI->getLoopFor(User->getParent()) != L) {
- if (isa<PHINode>(User) || Processed.count(User) ||
- !AddUsersIfInteresting(User, L, Processed)) {
- DOUT << "FOUND USER in other loop: " << *User
- << " OF SCEV: " << *ISE << "\n";
- AddUserToIVUsers = true;
- }
- } else if (Processed.count(User) ||
- !AddUsersIfInteresting(User, L, Processed)) {
+ DOUT << "FOUND USER in other loop: " << *User
+ << " OF SCEV: " << *ISE << "\n";
+ AddUserToIVUsers = true;
+ } else if (!AddUsersIfInteresting(User, L, Processed)) {
DOUT << "FOUND USER: " << *User
<< " OF SCEV: " << *ISE << "\n";
AddUserToIVUsers = true;
@@ -712,45 +704,34 @@
PHINode *PN = cast<PHINode>(Inst);
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
if (PN->getIncomingValue(i) == OperandValToReplace) {
- // If the original expression is outside the loop, put the replacement
- // code in the same place as the original expression,
- // which need not be an immediate predecessor of this PHI. This way we
- // need only one copy of it even if it is referenced multiple times in
- // the PHI. We don't do this when the original expression is inside the
- // loop because multiple copies sometimes do useful sinking of code in that
- // case(?).
- Instruction *OldLoc = dyn_cast<Instruction>(OperandValToReplace);
- if (L->contains(OldLoc->getParent())) {
- // If this is a critical edge, split the edge so that we do not insert the
- // code on all predecessor/successor paths. We do this unless this is the
- // canonical backedge for this loop, as this can make some inserted code
- // be in an illegal position.
- BasicBlock *PHIPred = PN->getIncomingBlock(i);
- if (e != 1 && PHIPred->getTerminator()->getNumSuccessors() > 1 &&
- (PN->getParent() != L->getHeader() || !L->contains(PHIPred))) {
-
- // First step, split the critical edge.
- SplitCriticalEdge(PHIPred, PN->getParent(), P, false);
-
- // Next step: move the basic block. In particular, if the PHI node
- // is outside of the loop, and PredTI is in the loop, we want to
- // move the block to be immediately before the PHI block, not
- // immediately after PredTI.
- if (L->contains(PHIPred) && !L->contains(PN->getParent())) {
- BasicBlock *NewBB = PN->getIncomingBlock(i);
- NewBB->moveBefore(PN->getParent());
- }
-
- // Splitting the edge can reduce the number of PHI entries we have.
- e = PN->getNumIncomingValues();
+ // If this is a critical edge, split the edge so that we do not insert the
+ // code on all predecessor/successor paths. We do this unless this is the
+ // canonical backedge for this loop, as this can make some inserted code
+ // be in an illegal position.
+ BasicBlock *PHIPred = PN->getIncomingBlock(i);
+ if (e != 1 && PHIPred->getTerminator()->getNumSuccessors() > 1 &&
+ (PN->getParent() != L->getHeader() || !L->contains(PHIPred))) {
+
+ // First step, split the critical edge.
+ SplitCriticalEdge(PHIPred, PN->getParent(), P, false);
+
+ // Next step: move the basic block. In particular, if the PHI node
+ // is outside of the loop, and PredTI is in the loop, we want to
+ // move the block to be immediately before the PHI block, not
+ // immediately after PredTI.
+ if (L->contains(PHIPred) && !L->contains(PN->getParent())) {
+ BasicBlock *NewBB = PN->getIncomingBlock(i);
+ NewBB->moveBefore(PN->getParent());
}
+
+ // Splitting the edge can reduce the number of PHI entries we have.
+ e = PN->getNumIncomingValues();
}
+
Value *&Code = InsertedCode[PN->getIncomingBlock(i)];
if (!Code) {
// Insert the code into the end of the predecessor block.
- Instruction *InsertPt = (L->contains(OldLoc->getParent())) ?
- PN->getIncomingBlock(i)->getTerminator() :
- OldLoc->getParent()->getTerminator();
+ Instruction *InsertPt = PN->getIncomingBlock(i)->getTerminator();
Code = InsertCodeForBaseAtPosition(NewBase, Rewriter, InsertPt, L);
// Adjust the type back to match the PHI. Note that we can't use
@@ -1187,10 +1168,6 @@
/// mode scale component and optional base reg. This allows the users of
/// this stride to be rewritten as prev iv * factor. It returns 0 if no
/// reuse is possible. Factors can be negative on same targets, e.g. ARM.
-///
-/// If all uses are outside the loop, we don't require that all multiplies
-/// be folded into the addressing mode; a multiply (executed once) outside
-/// the loop is better than another IV within. Well, usually.
int64_t LoopStrengthReduce::CheckForIVReuse(bool HasBaseReg,
bool AllUsesAreAddresses,
bool AllUsesAreOutsideLoop,
@@ -1228,30 +1205,6 @@
return Scale;
}
}
- } else if (AllUsesAreOutsideLoop) {
- // Accept nonconstant strides here; it is really really right to substitute
- // an existing IV if we can.
- // Special case, old IV is -1*x and this one is x. Can treat this one as
- // -1*old.
- for (unsigned NewStride = 0, e = StrideOrder.size(); NewStride != e;
- ++NewStride) {
- std::map<SCEVHandle, IVsOfOneStride>::iterator SI =
- IVsByStride.find(StrideOrder[NewStride]);
- if (SI == IVsByStride.end())
- continue;
- if (SCEVMulExpr *ME = dyn_cast<SCEVMulExpr>(SI->first))
- if (SCEVConstant *SC = dyn_cast<SCEVConstant>(ME->getOperand(0)))
- if (Stride == ME->getOperand(1) &&
- SC->getValue()->getSExtValue() == -1LL)
- for (std::vector<IVExpr>::iterator II = SI->second.IVs.begin(),
- IE = SI->second.IVs.end(); II != IE; ++II)
- // Accept nonzero base here.
- // Only reuse previous IV if it would not require a type conversion.
- if (!RequiresTypeConversion(II->Base->getType(), Ty)) {
- IV = *II;
- return -1;
- }
- }
}
return 0;
}
@@ -1596,18 +1549,6 @@
!cast<ConstantInt>(CommonBaseV)->isZero())
RewriteExpr = SE->getAddExpr(RewriteExpr,
SE->getUnknown(CommonBaseV));
- // If we're reusing an IV with a nonzero base (currently this happens
- // only when all reuses are outside the loop) subtract out that base here
- // This is the reverse of the above; the base HAS been used to initialize
- // the PHI node but we don't want it here.
- // (If the RewriteFactor is negative, we're effectively negating the
- // old IV in this use, so we add the base instead of subtract.)
- if (!ReuseIV.Base->isZero()) {
- if (RewriteFactor < 0)
- RewriteExpr = SE->getAddExpr(RewriteExpr, ReuseIV.Base);
- else
- RewriteExpr = SE->getMinusSCEV(RewriteExpr, ReuseIV.Base);
- }
}
// Now that we know what we need to do, insert code before User for the
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