Added SCEV::NoWrapFlags to manage unsigned, signed, and self wrap

properties.
Added the self-wrap flag for SCEV::AddRecExpr.
A slew of temporary FIXMEs indicate the intention of the no-self-wrap flag
without changing behavior in this revision.

llvm-svn: 127590

1 files changed, 25 insertions, 12 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
index 76a94ea2746..c642f7ef0ca 100644
--- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -262,7 +262,8 @@ static bool FactorOutConstant(const SCEV *&S,
     const SCEV *Start = A->getStart();
     if (!FactorOutConstant(Start, Remainder, Factor, SE, TD))
       return false;
-    S = SE.getAddRecExpr(Start, Step, A->getLoop());
+    // FIXME: can use A->getNoWrapFlags(FlagNW)
+    S = SE.getAddRecExpr(Start, Step, A->getLoop(), SCEV::FlagAnyWrap);
     return true;
   }
 
@@ -314,7 +315,9 @@ static void SplitAddRecs(SmallVectorImpl<const SCEV *> &Ops,
       const SCEV *Zero = SE.getConstant(Ty, 0);
       AddRecs.push_back(SE.getAddRecExpr(Zero,
                                          A->getStepRecurrence(SE),
-                                         A->getLoop()));
+                                         A->getLoop(),
+                                         // FIXME: A->getNoWrapFlags(FlagNW)
+                                         SCEV::FlagAnyWrap));
       if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) {
         Ops[i] = Zero;
         Ops.append(Add->op_begin(), Add->op_end());
@@ -823,7 +826,9 @@ static void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest,
     Rest = SE.getAddExpr(Rest,
                          SE.getAddRecExpr(SE.getConstant(A->getType(), 0),
                                           A->getStepRecurrence(SE),
-                                          A->getLoop()));
+                                          A->getLoop(),
+                                          // FIXME: A->getNoWrapFlags(FlagNW)
+                                          SCEV::FlagAnyWrap));
   }
   if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) {
     Base = A->getOperand(A->getNumOperands()-1);
@@ -1005,10 +1010,11 @@ Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
   if (!SE.properlyDominates(Start, L->getHeader())) {
     PostLoopOffset = Start;
     Start = SE.getConstant(Normalized->getType(), 0);
-    Normalized =
-      cast<SCEVAddRecExpr>(SE.getAddRecExpr(Start,
-                                            Normalized->getStepRecurrence(SE),
-                                            Normalized->getLoop()));
+    Normalized = cast<SCEVAddRecExpr>(
+      SE.getAddRecExpr(Start, Normalized->getStepRecurrence(SE),
+                       Normalized->getLoop(),
+                       // FIXME: Normalized->getNoWrapFlags(FlagNW)
+                       SCEV::FlagAnyWrap));
   }
 
   // Strip off any non-loop-dominating component from the addrec step.
@@ -1019,7 +1025,10 @@ Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
     Step = SE.getConstant(Normalized->getType(), 1);
     Normalized =
       cast<SCEVAddRecExpr>(SE.getAddRecExpr(Start, Step,
-                                            Normalized->getLoop()));
+                                            Normalized->getLoop(),
+                                            // FIXME: Normalized
+                                            // ->getNoWrapFlags(FlagNW)
+                                            SCEV::FlagAnyWrap));
   }
 
   // Expand the core addrec. If we need post-loop scaling, force it to
@@ -1082,7 +1091,9 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
     SmallVector<const SCEV *, 4> NewOps(S->getNumOperands());
     for (unsigned i = 0, e = S->getNumOperands(); i != e; ++i)
       NewOps[i] = SE.getAnyExtendExpr(S->op_begin()[i], CanonicalIV->getType());
-    Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop()));
+    Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop(),
+                                       // FIXME: S->getNoWrapFlags(FlagNW)
+                                       SCEV::FlagAnyWrap));
     BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
     BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
     BasicBlock::iterator NewInsertPt =
@@ -1099,7 +1110,8 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
   if (!S->getStart()->isZero()) {
     SmallVector<const SCEV *, 4> NewOps(S->op_begin(), S->op_end());
     NewOps[0] = SE.getConstant(Ty, 0);
-    const SCEV *Rest = SE.getAddRecExpr(NewOps, L);
+    // FIXME: can use S->getNoWrapFlags()
+    const SCEV *Rest = SE.getAddRecExpr(NewOps, L, SCEV::FlagAnyWrap);
 
     // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
     // comments on expandAddToGEP for details.
@@ -1334,7 +1346,7 @@ void SCEVExpander::rememberInstruction(Value *I) {
     InsertedValues.insert(I);
 
   // If we just claimed an existing instruction and that instruction had
-  // been the insert point, adjust the insert point forward so that 
+  // been the insert point, adjust the insert point forward so that
   // subsequently inserted code will be dominated.
   if (Builder.GetInsertPoint() == I) {
     BasicBlock::iterator It = cast<Instruction>(I);
@@ -1362,8 +1374,9 @@ SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L,
   assert(Ty->isIntegerTy() && "Can only insert integer induction variables!");
 
   // Build a SCEV for {0,+,1}<L>.
+  // Conservatively use FlagAnyWrap for now.
   const SCEV *H = SE.getAddRecExpr(SE.getConstant(Ty, 0),
-                                   SE.getConstant(Ty, 1), L);
+                                   SE.getConstant(Ty, 1), L, SCEV::FlagAnyWrap);
 
   // Emit code for it.
   BasicBlock *SaveInsertBB = Builder.GetInsertBlock();