1 files changed, 28 insertions, 18 deletions

diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index 1028b52..19c4393 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1113,10 +1113,6 @@ AliasResult BasicAAResult::aliasGEP(
     return BaseAlias;
   }
 
-  // Bail on analysing scalable LocationSize
-  if (V1Size.isScalable() || V2Size.isScalable())
-    return AliasResult::MayAlias;
-
   // If there is a constant difference between the pointers, but the difference
   // is less than the size of the associated memory object, then we know
   // that the objects are partially overlapping.  If the difference is
@@ -1146,24 +1142,38 @@ AliasResult BasicAAResult::aliasGEP(
     if (!VLeftSize.hasValue())
       return AliasResult::MayAlias;
 
-    const uint64_t LSize = VLeftSize.getValue();
-    if (Off.ult(LSize)) {
-      // Conservatively drop processing if a phi was visited and/or offset is
-      // too big.
-      AliasResult AR = AliasResult::PartialAlias;
-      if (VRightSize.hasValue() && Off.ule(INT32_MAX) &&
-          (Off + VRightSize.getValue()).ule(LSize)) {
-        // Memory referenced by right pointer is nested. Save the offset in
-        // cache. Note that originally offset estimated as GEP1-V2, but
-        // AliasResult contains the shift that represents GEP1+Offset=V2.
-        AR.setOffset(-Off.getSExtValue());
-        AR.swap(Swapped);
+    const TypeSize LSize = VLeftSize.getValue();
+    if (!LSize.isScalable()) {
+      if (Off.ult(LSize)) {
+        // Conservatively drop processing if a phi was visited and/or offset is
+        // too big.
+        AliasResult AR = AliasResult::PartialAlias;
+        if (VRightSize.hasValue() && !VRightSize.isScalable() &&
+            Off.ule(INT32_MAX) && (Off + VRightSize.getValue()).ule(LSize)) {
+          // Memory referenced by right pointer is nested. Save the offset in
+          // cache. Note that originally offset estimated as GEP1-V2, but
+          // AliasResult contains the shift that represents GEP1+Offset=V2.
+          AR.setOffset(-Off.getSExtValue());
+          AR.swap(Swapped);
+        }
+        return AR;
       }
-      return AR;
+      return AliasResult::NoAlias;
+    } else {
+      // We can use the getVScaleRange to prove that Off >= (CR.upper * LSize).
+      ConstantRange CR = getVScaleRange(&F, Off.getBitWidth());
+      bool Overflow;
+      APInt UpperRange = CR.getUnsignedMax().umul_ov(
+          APInt(Off.getBitWidth(), LSize.getKnownMinValue()), Overflow);
+      if (!Overflow && Off.uge(UpperRange))
+        return AliasResult::NoAlias;
     }
-    return AliasResult::NoAlias;
   }
 
+  // Bail on analysing scalable LocationSize
+  if (V1Size.isScalable() || V2Size.isScalable())
+    return AliasResult::MayAlias;
+
   // We need to know both acess sizes for all the following heuristics.
   if (!V1Size.hasValue() || !V2Size.hasValue())
     return AliasResult::MayAlias;