From a1d9cb1d4699c332baf47560292dd22b4e2d58ea Mon Sep 17 00:00:00 2001 From: Dale Johannesen Date: Thu, 18 Dec 2008 01:23:41 +0000 Subject: [PATCH] Revert previous patch, appears to break bootstrap. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61181 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/LoopStrengthReduce.cpp | 117 +++++-------------- 1 file changed, 29 insertions(+), 88 deletions(-) diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 7ee87b755dc..fc61b9e9a1e 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -508,22 +508,14 @@ bool LoopStrengthReduce::AddUsersIfInteresting(Instruction *I, Loop *L, if (isa(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(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 @@ void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase, PHINode *PN = cast(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(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 @@ bool LoopStrengthReduce::RequiresTypeConversion(const Type *Ty1, /// 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 @@ int64_t LoopStrengthReduce::CheckForIVReuse(bool HasBaseReg, 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::iterator SI = - IVsByStride.find(StrideOrder[NewStride]); - if (SI == IVsByStride.end()) - continue; - if (SCEVMulExpr *ME = dyn_cast(SI->first)) - if (SCEVConstant *SC = dyn_cast(ME->getOperand(0))) - if (Stride == ME->getOperand(1) && - SC->getValue()->getSExtValue() == -1LL) - for (std::vector::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 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride, !cast(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 -- 2.34.1