[llvm] [LAA] Rewrite findForkedPointer (NFC) (PR #140298)

[Igor Kirillov via llvm-commits]

================
@@ -1238,42 +1255,25 @@ bool AccessAnalysis::createCheckForAccess(
     DenseMap<Value *, unsigned> &DepSetId, Loop *TheLoop,
     unsigned &RunningDepId, unsigned ASId, bool Assume) {
   Value *Ptr = Access.getPointer();
+  ScalarEvolution *SE = PSE.getSE();
+  assert(SE->isSCEVable(Ptr->getType()) && "Value is not SCEVable!");
 
-  SmallVector<PointerIntPair<const SCEV *, 1, bool>> TranslatedPtrs =
-      findForkedPointer(PSE, StridesMap, Ptr, TheLoop);
-  assert(!TranslatedPtrs.empty() && "must have some translated pointers");
-
-  /// Check whether all pointers can participate in a runtime bounds check. They
-  /// must either be invariant or AddRecs. If ShouldCheckWrap is true, they also
-  /// must not wrap.
-  for (auto &P : TranslatedPtrs) {
-    // The bounds for loop-invariant pointer is trivial.
-    if (PSE.getSE()->isLoopInvariant(P.getPointer(), TheLoop))
-      continue;
-
-    const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(P.getPointer());
-    if (!AR && Assume)
-      AR = PSE.getAsAddRec(Ptr);
-    if (!AR || !AR->isAffine())
-      return false;
-
-    // If there's only one option for Ptr, look it up after bounds and wrap
-    // checking, because assumptions might have been added to PSE.
-    if (TranslatedPtrs.size() == 1) {
-      AR =
-          cast<SCEVAddRecExpr>(replaceSymbolicStrideSCEV(PSE, StridesMap, Ptr));
-      P.setPointer(AR);
-    }
-
-    // When we run after a failing dependency check we have to make sure
-    // we don't have wrapping pointers.
-    if (!isNoWrap(PSE, AR, TranslatedPtrs.size() == 1 ? Ptr : nullptr, AccessTy,
-                  TheLoop, Assume)) {
-      return false;
-    }
-  }
+  // Find the ForkedSCEVs, and prepare the runtime-check pointers.
+  SmallVector<PointerIntPair<const SCEV *, 1, bool>> ForkedSCEVs;
+  findForkedSCEVs(SE, TheLoop, Ptr, ForkedSCEVs, MaxForkedSCEVDepth);
+  auto RTCheckPtrs =
+      getRTCheckPtrs(PSE, TheLoop, Ptr, ForkedSCEVs, StridesMap, Assume);
+
+  /// Check whether all pointers can participate in a runtime bounds check: they
+  /// must either be loop-invariant, or an affine AddRec that does not wrap.
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igogo-x86 wrote:

This comment doesn’t match the current behavior of the check

https://github.com/llvm/llvm-project/pull/140298