commit 0ef2b10f16e4066ee6ee1bbdd759e97ea1065894
author Hal Finkel <hfinkel@anl.gov> Wed Aug 19 02:56:36 2015 +0000
committer Hal Finkel <hfinkel@anl.gov> Wed Aug 19 02:56:36 2015 +0000
tree da29f12ed67770e8daccccc75ae699bb71c69b0b
parent 46fc8168c23093684f261fe86a2653169084e32b

Fix how DependenceAnalysis calls delinearization

Fix how DependenceAnalysis calls delinearization, mirroring what is done in
Delinearization.cpp (mostly by making sure to call getSCEVAtScope before
delinearizing, and by removing the unnecessary 'Pairs == 1' check).

Patch by Vaivaswatha Nagaraj!

llvm-svn: 245408

llvm/lib/Analysis/DependenceAnalysis.cpp

diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index 0e6f222..5add828 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -3245,20 +3245,36 @@
 /// source and destination array references are recurrences on a nested loop,
 /// this function flattens the nested recurrences into separate recurrences
 /// for each loop level.
-bool DependenceAnalysis::tryDelinearize(const SCEV *SrcSCEV,
-                                        const SCEV *DstSCEV,
-                                        SmallVectorImpl<Subscript> &Pair,
-                                        const SCEV *ElementSize) {
+bool DependenceAnalysis::tryDelinearize(Instruction *Src,
+                                        Instruction *Dst,
+                                        SmallVectorImpl<Subscript> &Pair)
+{
+  Value *SrcPtr = getPointerOperand(Src);
+  Value *DstPtr = getPointerOperand(Dst);
+
+  Loop *SrcLoop = LI->getLoopFor(Src->getParent());
+  Loop *DstLoop = LI->getLoopFor(Dst->getParent());
+
+  // Below code mimics the code in Delinearization.cpp
+  const SCEV *SrcAccessFn =
+    SE->getSCEVAtScope(SrcPtr, SrcLoop);
+  const SCEV *DstAccessFn =
+    SE->getSCEVAtScope(DstPtr, DstLoop);
+
   const SCEVUnknown *SrcBase =
-      dyn_cast<SCEVUnknown>(SE->getPointerBase(SrcSCEV));
+      dyn_cast<SCEVUnknown>(SE->getPointerBase(SrcAccessFn));
   const SCEVUnknown *DstBase =
-      dyn_cast<SCEVUnknown>(SE->getPointerBase(DstSCEV));
+      dyn_cast<SCEVUnknown>(SE->getPointerBase(DstAccessFn));
 
   if (!SrcBase || !DstBase || SrcBase != DstBase)
     return false;
 
-  SrcSCEV = SE->getMinusSCEV(SrcSCEV, SrcBase);
-  DstSCEV = SE->getMinusSCEV(DstSCEV, DstBase);
+  const SCEV *ElementSize = SE->getElementSize(Src);
+  if (ElementSize != SE->getElementSize(Dst))
+    return false;
+
+  const SCEV *SrcSCEV = SE->getMinusSCEV(SrcAccessFn, SrcBase);
+  const SCEV *DstSCEV = SE->getMinusSCEV(DstAccessFn, DstBase);
 
   const SCEVAddRecExpr *SrcAR = dyn_cast<SCEVAddRecExpr>(SrcSCEV);
   const SCEVAddRecExpr *DstAR = dyn_cast<SCEVAddRecExpr>(DstSCEV);
@@ -3331,7 +3347,6 @@
 }
 #endif
 
-
 // depends -
 // Returns NULL if there is no dependence.
 // Otherwise, return a Dependence with as many details as possible.
@@ -3426,10 +3441,11 @@
     Pair[0].Dst = DstSCEV;
   }
 
-  if (Delinearize && Pairs == 1 && CommonLevels > 1 &&
-      tryDelinearize(Pair[0].Src, Pair[0].Dst, Pair, SE->getElementSize(Src))) {
-    DEBUG(dbgs() << "    delinerized GEP\n");
-    Pairs = Pair.size();
+  if (Delinearize && CommonLevels > 1) {
+    if (tryDelinearize(Src, Dst, Pair)) {
+      DEBUG(dbgs() << "    delinerized GEP\n");
+      Pairs = Pair.size();
+    }
   }
 
   for (unsigned P = 0; P < Pairs; ++P) {
@@ -3851,10 +3867,11 @@
     Pair[0].Dst = DstSCEV;
   }
 
-  if (Delinearize && Pairs == 1 && CommonLevels > 1 &&
-      tryDelinearize(Pair[0].Src, Pair[0].Dst, Pair, SE->getElementSize(Src))) {
-    DEBUG(dbgs() << "    delinerized GEP\n");
-    Pairs = Pair.size();
+  if (Delinearize && CommonLevels > 1) {
+    if (tryDelinearize(Src, Dst, Pair)) {
+      DEBUG(dbgs() << "    delinerized GEP\n");
+      Pairs = Pair.size();
+    }
   }
 
   for (unsigned P = 0; P < Pairs; ++P) {