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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127590 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 10 deletions

diff --git a/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index de91fd919b..1366231e9a 100644
--- a/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -485,10 +485,10 @@ processLoopStridedStore(Value *DestPtr, unsigned StoreSize,
   BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr);
 
   const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1),
-                                         true /*no unsigned overflow*/);
+                                         SCEV::FlagNUW);
   if (StoreSize != 1)
     NumBytesS = SE->getMulExpr(NumBytesS, SE->getConstant(IntPtr, StoreSize),
-                               true /*no unsigned overflow*/);
+                               SCEV::FlagNUW);
 
   Value *NumBytes =
     Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator());
@@ -581,10 +581,10 @@ processLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize,
   BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr);
 
   const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1),
-                                         true /*no unsigned overflow*/);
+                                         SCEV::FlagNUW);
   if (StoreSize != 1)
     NumBytesS = SE->getMulExpr(NumBytesS, SE->getConstant(IntPtr, StoreSize),
-                               true /*no unsigned overflow*/);
+                               SCEV::FlagNUW);
 
   Value *NumBytes =
     Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator());
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index ac4aea2e40..1bc6f5259d 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -253,7 +253,8 @@ static void DoInitialMatch(const SCEV *S, Loop *L,
       DoInitialMatch(AR->getStart(), L, Good, Bad, SE);
       DoInitialMatch(SE.getAddRecExpr(SE.getConstant(AR->getType(), 0),
                                       AR->getStepRecurrence(SE),
-                                      AR->getLoop()),
+                                      // FIXME: AR->getNoWrapFlags()
+                                      AR->getLoop(), SCEV::FlagAnyWrap),
                      L, Good, Bad, SE);
       return;
     }
@@ -455,7 +456,10 @@ static const SCEV *getExactSDiv(const SCEV *LHS, const SCEV *RHS,
       const SCEV *Start = getExactSDiv(AR->getStart(), RHS, SE,
                                        IgnoreSignificantBits);
       if (!Start) return 0;
-      return SE.getAddRecExpr(Start, Step, AR->getLoop());
+      // FlagNW is independent of the start value, step direction, and is
+      // preserved with smaller magnitude steps.
+      // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
+      return SE.getAddRecExpr(Start, Step, AR->getLoop(), SCEV::FlagAnyWrap);
     }
     return 0;
   }
@@ -520,7 +524,9 @@ static int64_t ExtractImmediate(const SCEV *&S, ScalarEvolution &SE) {
     SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
     int64_t Result = ExtractImmediate(NewOps.front(), SE);
     if (Result != 0)
-      S = SE.getAddRecExpr(NewOps, AR->getLoop());
+      S = SE.getAddRecExpr(NewOps, AR->getLoop(),
+                           // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
+                           SCEV::FlagAnyWrap);
     return Result;
   }
   return 0;
@@ -545,7 +551,9 @@ static GlobalValue *ExtractSymbol(const SCEV *&S, ScalarEvolution &SE) {
     SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
     GlobalValue *Result = ExtractSymbol(NewOps.front(), SE);
     if (Result)
-      S = SE.getAddRecExpr(NewOps, AR->getLoop());
+      S = SE.getAddRecExpr(NewOps, AR->getLoop(),
+                           // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
+                           SCEV::FlagAnyWrap);
     return Result;
   }
   return 0;
@@ -2236,7 +2244,9 @@ static void CollectSubexprs(const SCEV *S, const SCEVConstant *C,
     if (!AR->getStart()->isZero()) {
       CollectSubexprs(SE.getAddRecExpr(SE.getConstant(AR->getType(), 0),
                                        AR->getStepRecurrence(SE),
-                                       AR->getLoop()),
+                                       AR->getLoop(),
+                                       //FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
+                                       SCEV::FlagAnyWrap),
                       C, Ops, L, SE);
       CollectSubexprs(AR->getStart(), C, Ops, L, SE);
       return;
@@ -3047,7 +3057,7 @@ void LSRInstance::NarrowSearchSpaceByCollapsingUnrolledCode() {
   }
 }
 
-/// NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters - Call 
+/// NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters - Call
 /// FilterOutUndesirableDedicatedRegisters again, if necessary, now that
 /// we've done more filtering, as it may be able to find more formulae to
 /// eliminate.