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!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@245408 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/DependenceAnalysis.h b/include/llvm/Analysis/DependenceAnalysis.h
index b05a72ebb6f639eac6a1d3648d47cc93baff7264..9cd2a1700c6f1e82d4946a73b2d7bf0f42d489f3 100644 (file)
--- a/include/llvm/Analysis/DependenceAnalysis.h
+++ b/include/llvm/Analysis/DependenceAnalysis.h
@@ -926,9 +926,8 @@ namespace llvm {
     void updateDirection(Dependence::DVEntry &Level,
                          const Constraint &CurConstraint) const;
 
-    bool tryDelinearize(const SCEV *SrcSCEV, const SCEV *DstSCEV,
-                        SmallVectorImpl<Subscript> &Pair,
-                        const SCEV *ElementSize);
+    bool tryDelinearize(Instruction *Src, Instruction *Dst,
+                        SmallVectorImpl<Subscript> &Pair);
 
   public:
     static char ID; // Class identification, replacement for typeinfo

diff --git a/lib/Analysis/DependenceAnalysis.cpp b/lib/Analysis/DependenceAnalysis.cpp
index 0e6f222e52ea71377b105f52a190917c438ac7c1..5add828770ffc9c2f1e50da2036a967bc09065ea 100644 (file)
--- a/lib/Analysis/DependenceAnalysis.cpp
+++ b/lib/Analysis/DependenceAnalysis.cpp
@@ -3245,20 +3245,36 @@ void DependenceAnalysis::updateDirection(Dependence::DVEntry &Level,
 /// 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 @@ static void dumpSmallBitVector(SmallBitVector &BV) {
 }
 #endif
 
-
 // depends -
 // Returns NULL if there is no dependence.
 // Otherwise, return a Dependence with as many details as possible.
@@ -3426,10 +3441,11 @@ DependenceAnalysis::depends(Instruction *Src, Instruction *Dst,
     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 @@ const  SCEV *DependenceAnalysis::getSplitIteration(const Dependence &Dep,
     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) {

diff --git a/test/Analysis/DependenceAnalysis/GCD.ll b/test/Analysis/DependenceAnalysis/GCD.ll
index 81d05a10cf1c08da1cfa1bc932aa689142f8e5c2..f9749d51bb333ca63c2ab99079ca471e6667f5d2 100644 (file)
--- a/test/Analysis/DependenceAnalysis/GCD.ll
+++ b/test/Analysis/DependenceAnalysis/GCD.ll
@@ -269,10 +269,10 @@ entry:
 ; CHECK: da analyze - none!
 
 ; DELIN: 'Dependence Analysis' for function 'gcd4'
-; DELIN: da analyze - output [* *]!
+; DELIN: da analyze - none!
 ; DELIN: da analyze - none!
 ; DELIN: da analyze - confused!
-; DELIN: da analyze - input [* *]!
+; DELIN: da analyze - none!
 ; DELIN: da analyze - confused!
 ; DELIN: da analyze - none!
 
@@ -339,10 +339,10 @@ entry:
 ; CHECK: da analyze - none!
 
 ; DELIN: 'Dependence Analysis' for function 'gcd5'
-; DELIN: da analyze - output [* *]!
-; DELIN: da analyze - flow [<> *]!
+; DELIN: da analyze - none!
+; DELIN: da analyze - flow [> *]!
 ; DELIN: da analyze - confused!
-; DELIN: da analyze - input [* *]!
+; DELIN: da analyze - none!
 ; DELIN: da analyze - confused!
 ; DELIN: da analyze - none!
 
@@ -410,10 +410,10 @@ entry:
 ; CHECK: da analyze - output [* *]!
 
 ; DELIN: 'Dependence Analysis' for function 'gcd6'
-; DELIN: da analyze - output [* *]!
+; DELIN: da analyze - none!
 ; DELIN: da analyze - none!
 ; DELIN: da analyze - confused!
-; DELIN: da analyze - input [* *]!
+; DELIN: da analyze - none!
 ; DELIN: da analyze - confused!
 ; DELIN: da analyze - output [* *]!