diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 75a681d98ec..20980bba3a4 100644 --- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -392,7 +392,8 @@ namespace { // operands of Inst to use the new expression 'NewBase', with 'Imm' added // to it. void RewriteInstructionToUseNewBase(const SCEVHandle &NewBase, - SCEVExpander &Rewriter, Pass *P); + SCEVExpander &Rewriter, Loop *L, + Pass *P); // Sort by the Base field. bool operator<(const BasedUser &BU) const { return Base < BU.Base; } @@ -415,7 +416,7 @@ void BasedUser::dump() const { // to it. void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase, SCEVExpander &Rewriter, - Pass *P) { + Loop *L, Pass *P) { if (!isa<PHINode>(Inst)) { SCEVHandle NewValSCEV = SCEVAddExpr::get(NewBase, Imm); Value *NewVal = Rewriter.expandCodeFor(NewValSCEV, Inst, @@ -443,7 +444,18 @@ void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase, for (unsigned Succ = 0; ; ++Succ) { assert(Succ != PredTI->getNumSuccessors() &&"Didn't find successor?"); if (PredTI->getSuccessor(Succ) == PN->getParent()) { + // First step, split the critical edge. SplitCriticalEdge(PredTI, Succ, P); + + // 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(PredTI->getParent()) && + !L->contains(PN->getParent())) { + BasicBlock *NewBB = PN->getIncomingBlock(i); + NewBB->moveBefore(PN->getParent()); + } break; } } @@ -796,7 +808,7 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride, // Add BaseV to the PHI value if needed. RewriteExpr = SCEVAddExpr::get(RewriteExpr, SCEVUnknown::get(BaseV)); - User.RewriteInstructionToUseNewBase(RewriteExpr, Rewriter, this); + User.RewriteInstructionToUseNewBase(RewriteExpr, Rewriter, L, this); // Mark old value we replaced as possibly dead, so that it is elminated // if we just replaced the last use of that value. |
