indvars: Prototyping Sign/ZeroExtend elimination without canonical IVs.

No functionality enabled by default. Use -disable-iv-rewrite.
Extended IVUsers to keep track of the phi that represents the users' IV.
Added the WidenIV transform to replace a narrow IV with a wide IV
by doing a one-for-one replacement of IV users instead of expanding the
SCEV expressions. [sz]exts are removed and truncs are inserted.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131744 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 7 deletions

diff --git a/lib/Analysis/IVUsers.cpp b/lib/Analysis/IVUsers.cpp
index a8fe545..2fde73d 100644
--- a/lib/Analysis/IVUsers.cpp
+++ b/lib/Analysis/IVUsers.cpp
@@ -89,7 +89,7 @@ static bool isInteresting(const SCEV *S, const Instruction *I, const Loop *L,
 /// AddUsersIfInteresting - Inspect the specified instruction.  If it is a
 /// reducible SCEV, recursively add its users to the IVUsesByStride set and
 /// return true.  Otherwise, return false.
-bool IVUsers::AddUsersIfInteresting(Instruction *I) {
+bool IVUsers::AddUsersIfInteresting(Instruction *I, PHINode *Phi) {
   if (!SE->isSCEVable(I->getType()))
     return false;   // Void and FP expressions cannot be reduced.
 
@@ -136,13 +136,13 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
     bool AddUserToIVUsers = false;
     if (LI->getLoopFor(User->getParent()) != L) {
       if (isa<PHINode>(User) || Processed.count(User) ||
-          !AddUsersIfInteresting(User)) {
+          !AddUsersIfInteresting(User, Phi)) {
         DEBUG(dbgs() << "FOUND USER in other loop: " << *User << '\n'
                      << "   OF SCEV: " << *ISE << '\n');
         AddUserToIVUsers = true;
       }
     } else if (Processed.count(User) ||
-               !AddUsersIfInteresting(User)) {
+               !AddUsersIfInteresting(User, Phi)) {
       DEBUG(dbgs() << "FOUND USER: " << *User << '\n'
                    << "   OF SCEV: " << *ISE << '\n');
       AddUserToIVUsers = true;
@@ -150,7 +150,7 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
 
     if (AddUserToIVUsers) {
       // Okay, we found a user that we cannot reduce.
-      IVUses.push_back(new IVStrideUse(this, User, I));
+      IVUses.push_back(new IVStrideUse(this, User, I, Phi));
       IVStrideUse &NewUse = IVUses.back();
       // Transform the expression into a normalized form.
       ISE = TransformForPostIncUse(NormalizeAutodetect,
@@ -163,8 +163,8 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
   return true;
 }
 
-IVStrideUse &IVUsers::AddUser(Instruction *User, Value *Operand) {
-  IVUses.push_back(new IVStrideUse(this, User, Operand));
+IVStrideUse &IVUsers::AddUser(Instruction *User, Value *Operand, PHINode *Phi) {
+  IVUses.push_back(new IVStrideUse(this, User, Operand, Phi));
   return IVUses.back();
 }
 
@@ -192,7 +192,7 @@ bool IVUsers::runOnLoop(Loop *l, LPPassManager &LPM) {
   // them by stride.  Start by finding all of the PHI nodes in the header for
   // this loop.  If they are induction variables, inspect their uses.
   for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I)
-    (void)AddUsersIfInteresting(I);
+    (void)AddUsersIfInteresting(I, cast<PHINode>(I));
 
   return false;
 }