- Teach LSR to avoid changing cmp iv stride if it will create an immediate that

  cannot be folded into target cmp instruction.
- Avoid a phase ordering issue where early cmp optimization would prevent the
  later count-to-zero optimization.
- Add missing checks which could cause LSR to reuse stride that does not have
  users.
- Fix a bug in count-to-zero optimization code which failed to find the pre-inc
  iv's phi node.
- Remove, tighten, loosen some incorrect checks disable valid transformations.
- Quite a bit of code clean up.

llvm-svn: 86969

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/IVUsers.cpp b/llvm/lib/Analysis/IVUsers.cpp
index 20b69f2a7ca..cf52320d1f2 100644
--- a/llvm/lib/Analysis/IVUsers.cpp
+++ b/llvm/lib/Analysis/IVUsers.cpp
@@ -267,6 +267,18 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
   return true;
 }
 
+void IVUsers::AddUser(const SCEV *Stride, const SCEV *Offset,
+                      Instruction *User, Value *Operand) {
+  IVUsersOfOneStride *StrideUses = IVUsesByStride[Stride];
+  if (!StrideUses) {    // First occurrence of this stride?
+    StrideOrder.push_back(Stride);
+    StrideUses = new IVUsersOfOneStride(Stride);
+    IVUses.push_back(StrideUses);
+    IVUsesByStride[Stride] = StrideUses;
+  }
+  IVUsesByStride[Stride]->addUser(Offset, User, Operand);
+}
+
 IVUsers::IVUsers()
  : LoopPass(&ID) {
 }