[LAA] Support assumptions with non-constant deref sizes. (#156758)

Update evaluatePtrAddrecAtMaxBTCWillNotWrap to support non-constant
sizes in dereferenceable assumptions.

Apply loop-guards in a few places needed to reason about expressions
involving trip counts of the from (BTC - 1).

PR: https://github.com/llvm/llvm-project/pull/156758

1 files changed, 7 insertions, 7 deletions

diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index e18cc6b..cfddd99 100644
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -238,8 +238,8 @@ static bool evaluatePtrAddRecAtMaxBTCWillNotWrap(
         StartPtrV, {Attribute::Dereferenceable}, *AC,
         L->getLoopPredecessor()->getTerminator(), DT);
     if (DerefRK) {
-      DerefBytesSCEV = SE.getUMaxExpr(
-          DerefBytesSCEV, SE.getConstant(WiderTy, DerefRK.ArgValue));
+      DerefBytesSCEV =
+          SE.getUMaxExpr(DerefBytesSCEV, SE.getSCEV(DerefRK.IRArgValue));
     }
   }
 
@@ -259,6 +259,10 @@ static bool evaluatePtrAddRecAtMaxBTCWillNotWrap(
   const SCEV *StartOffset = SE.getNoopOrZeroExtend(
       SE.getMinusSCEV(AR->getStart(), StartPtr), WiderTy);
 
+  if (!LoopGuards)
+    LoopGuards.emplace(ScalarEvolution::LoopGuards::collect(AR->getLoop(), SE));
+  MaxBTC = SE.applyLoopGuards(MaxBTC, *LoopGuards);
+
   const SCEV *OffsetAtLastIter =
       mulSCEVOverflow(MaxBTC, SE.getAbsExpr(Step, /*IsNSW=*/false), SE);
   if (!OffsetAtLastIter) {
@@ -288,11 +292,7 @@ static bool evaluatePtrAddRecAtMaxBTCWillNotWrap(
     if (!EndBytes)
       return false;
 
-    if (!LoopGuards)
-      LoopGuards.emplace(
-          ScalarEvolution::LoopGuards::collect(AR->getLoop(), SE));
-
-    EndBytes = SE.applyLoopGuards(EndBytes, *LoopGuards);
+    DerefBytesSCEV = SE.applyLoopGuards(DerefBytesSCEV, *LoopGuards);
     return SE.isKnownPredicate(CmpInst::ICMP_ULE, EndBytes, DerefBytesSCEV);
   }