[llvm] [DA] Simplify runtime predicate collection and extend to all dependence tests (PR #157523)

[Sjoerd Meijer via llvm-commits]

================
@@ -3656,44 +3657,48 @@ DependenceInfo::depends(Instruction *Src, Instruction *Dst,
   if (!isLoopInvariant(SrcBase, SrcLoop) ||
       !isLoopInvariant(DstBase, DstLoop)) {
     LLVM_DEBUG(dbgs() << "The base pointer is not loop invariant.\n");
-    return std::make_unique<Dependence>(Src, Dst,
-                                        SCEVUnionPredicate(Assume, *SE));
+    return std::make_unique<Dependence>(Src, Dst, getRuntimeAssumptions());
   }
 
   uint64_t EltSize = SrcLoc.Size.toRaw();
   const SCEV *SrcEv = SE->getMinusSCEV(SrcSCEV, SrcBase);
   const SCEV *DstEv = SE->getMinusSCEV(DstSCEV, DstBase);
 
   // Check that memory access offsets are multiples of element sizes.
-  if (!SE->isKnownMultipleOf(SrcEv, EltSize, Assume) ||
-      !SE->isKnownMultipleOf(DstEv, EltSize, Assume)) {
+  SmallVector<const SCEVPredicate *, 4> TempAssumptions;
+  if (!SE->isKnownMultipleOf(SrcEv, EltSize, TempAssumptions) ||
+      !SE->isKnownMultipleOf(DstEv, EltSize, TempAssumptions)) {
     LLVM_DEBUG(dbgs() << "can't analyze SCEV with different offsets\n");
-    return std::make_unique<Dependence>(Src, Dst,
-                                        SCEVUnionPredicate(Assume, *SE));
+    return std::make_unique<Dependence>(Src, Dst, getRuntimeAssumptions());
   }
 
-  if (!Assume.empty()) {
-    if (!UnderRuntimeAssumptions)
-      return std::make_unique<Dependence>(Src, Dst,
-                                          SCEVUnionPredicate(Assume, *SE));
-    // Add non-redundant assumptions.
-    unsigned N = Assumptions.size();
-    for (const SCEVPredicate *P : Assume) {
-      bool Implied = false;
-      for (unsigned I = 0; I != N && !Implied; I++)
-        if (Assumptions[I]->implies(P, *SE))
-          Implied = true;
-      if (!Implied)
-        Assumptions.push_back(P);
+  // Add any new assumptions from the isKnownMultipleOf calls
+  if (!TempAssumptions.empty()) {
+    if (UnderRuntimeAssumptions) {
+      SmallVector<const SCEVPredicate *, 4> NewPreds(
+          Assumptions.getPredicates());
+      NewPreds.append(TempAssumptions.begin(), TempAssumptions.end());
+      const_cast<DependenceInfo *>(this)->Assumptions =
+          SCEVUnionPredicate(NewPreds, *SE);
+    } else {
+      // Runtime assumptions needed but not allowed.
+      // Return confused dependence since we cannot proceed with precise
+      // analysis.
+      LLVM_DEBUG(dbgs() << "Runtime assumptions needed for offset analysis but "
+                           "not allowed\n");
+      return std::make_unique<Dependence>(Src, Dst, getRuntimeAssumptions());
     }
   }
 
+  // Assert that we haven't added runtime assumptions when not allowed
----------------
sjoerdmeijer wrote:

Nit: full stop at the end.

https://github.com/llvm/llvm-project/pull/157523