diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Transforms/Scalar/LoopStrengthReduce.cpp | 24 |
1 files changed, 21 insertions, 3 deletions
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 6d66d14ec9..dbd22d90e0 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -543,6 +543,7 @@ namespace { // operands of Inst to use the new expression 'NewBase', with 'Imm' added // to it. void RewriteInstructionToUseNewBase(const SCEVHandle &NewBase, + Instruction *InsertPt, SCEVExpander &Rewriter, Loop *L, Pass *P, SmallPtrSet<Instruction*,16> &DeadInsts); @@ -603,8 +604,12 @@ Value *BasedUser::InsertCodeForBaseAtPosition(const SCEVHandle &NewBase, // Once we rewrite the code to insert the new IVs we want, update the // operands of Inst to use the new expression 'NewBase', with 'Imm' added -// to it. +// to it. NewBasePt is the last instruction which contributes to the +// value of NewBase in the case that it's a diffferent instruction from +// the PHI that NewBase is computed from, or null otherwise. +// void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase, + Instruction *NewBasePt, SCEVExpander &Rewriter, Loop *L, Pass *P, SmallPtrSet<Instruction*,16> &DeadInsts) { if (!isa<PHINode>(Inst)) { @@ -620,7 +625,10 @@ void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase, // value will be pinned to live somewhere after the original computation. // In this case, we have to back off. if (!isUseOfPostIncrementedValue) { - if (Instruction *OpInst = dyn_cast<Instruction>(OperandValToReplace)) { + if (NewBasePt) { + InsertPt = NewBasePt; + ++InsertPt; + } else if (Instruction *OpInst = dyn_cast<Instruction>(OperandValToReplace)) { InsertPt = OpInst; while (isa<PHINode>(InsertPt)) ++InsertPt; } @@ -1400,6 +1408,15 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride, SCEVHandle RewriteExpr = SE->getUnknown(RewriteOp); + // If we had to insert new instrutions for RewriteOp, we have to + // consider that they may not have been able to end up immediately + // next to RewriteOp, because non-PHI instructions may never precede + // PHI instructions in a block. In this case, remember where the last + // instruction was inserted so that we can use that point to expand + // the final RewriteExpr. + Instruction *NewBasePt = dyn_cast<Instruction>(RewriteOp); + if (RewriteOp == NewPHI) NewBasePt = 0; + // Clear the SCEVExpander's expression map so that we are guaranteed // to have the code emitted where we expect it. Rewriter.clear(); @@ -1426,7 +1443,8 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride, // Add BaseV to the PHI value if needed. RewriteExpr = SE->getAddExpr(RewriteExpr, SE->getUnknown(BaseV)); - User.RewriteInstructionToUseNewBase(RewriteExpr, Rewriter, L, this, + User.RewriteInstructionToUseNewBase(RewriteExpr, NewBasePt, + Rewriter, L, this, DeadInsts); // Mark old value we replaced as possibly dead, so that it is elminated |