[LoopInterchange] Fix depends() check parameters

Author: ShivaChen

llvm/lib/Transforms/Scalar/LoopInterchange.cpp

@@ -120,6 +120,9 @@ static bool populateDependencyMatrix(CharMatrix &DepMatrix, unsigned Level,
       // Ignore Input dependencies.
       if (isa<LoadInst>(Src) && isa<LoadInst>(Dst))
         continue;
+      // Swap if Src is no a store.
+      if (!isa<StoreInst>(Src))
+        std::swap(Src, Dst);
       // Track Output, Flow, and Anti dependencies.
       if (auto D = DI->depends(Src, Dst, true)) {
         assert(D->isOrdered() && "Expected an output, flow or anti dep.");

llvm/test/Transforms/LoopInterchange/interchange-s231.ll

@@ -10,11 +10,11 @@
 ;;      for (int j = 1; j < 256; j++)
 ;;        aa[j][i] = aa[j - 1][i] + bb[j][i];
 
-; CHECK: Found anti dependency between Src and Dst
-; CHECK:  Src:  %1 = load float, ptr %arrayidx10, align 4
-; CHECK:  Dst:  store float %add, ptr %arrayidx18, align 4
+; CHECK: Found flow dependency between Src and Dst
+; CHECK:  Src:  store float %add, ptr %arrayidx18, align 4
+; CHECK:  Dst:  %1 = load float, ptr %arrayidx10, align 4
 ; CHECK: Processing InnerLoopId = 2 and OuterLoopId = 1
-; CHECK: Not interchanging loops. Cannot prove legality.
+; CHECK: Loops interchanged.
 
 define float @s231() {
 entry: