[llvm] [LAA] Check if Ptr can be freed between Assume and CtxI. (PR #161725)

[Florian Hahn via llvm-commits]

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@@ -233,19 +233,26 @@ static bool evaluatePtrAddRecAtMaxBTCWillNotWrap(
   const SCEV *DerefBytesSCEV = SE.getConstant(WiderTy, DerefBytes);
 
   // Check if we have a suitable dereferencable assumption we can use.
-  if (!StartPtrV->canBeFreed()) {
-    Instruction *CtxI = &*L->getHeader()->getFirstNonPHIIt();
-    if (BasicBlock *LoopPred = L->getLoopPredecessor()) {
-      if (isa<BranchInst>(LoopPred->getTerminator()))
-        CtxI = LoopPred->getTerminator();
-    }
-
-    RetainedKnowledge DerefRK = getKnowledgeValidInContext(
-        StartPtrV, {Attribute::Dereferenceable}, *AC, CtxI, DT);
-    if (DerefRK) {
-      DerefBytesSCEV =
-          SE.getUMaxExpr(DerefBytesSCEV, SE.getSCEV(DerefRK.IRArgValue));
-    }
+  Instruction *CtxI = &*L->getHeader()->getFirstNonPHIIt();
+  if (BasicBlock *LoopPred = L->getLoopPredecessor()) {
+    if (isa<BranchInst>(LoopPred->getTerminator()))
+      CtxI = LoopPred->getTerminator();
+  }
+  RetainedKnowledge DerefRK;
+  getKnowledgeForValue(StartPtrV, {Attribute::Dereferenceable}, *AC,
+                       [&](RetainedKnowledge RK, Instruction *Assume, auto) {
+                         if (!isValidAssumeForContext(Assume, CtxI, DT))
+                           return false;
+                         assert(RK.AttrKind == Attribute::Dereferenceable);
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fhahn wrote:

Ah yes, that was left over, removed, thanks!

https://github.com/llvm/llvm-project/pull/161725