[PATCH] D135369: [DSE] Relax constraint on isGuaranteedLoopInvariant

[luxufan via Phabricator via llvm-commits]

StephenFan created this revision.
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If the location ptr to be killed is in no loop and the Function does not
have irreducible loops, then we can regard it as loop invariant.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D135369

Files:
  llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
  llvm/test/Transforms/DeadStoreElimination/multiblock-loops.ll
  llvm/test/Transforms/DeadStoreElimination/multiblock-malloc-free.ll


Index: llvm/test/Transforms/DeadStoreElimination/multiblock-malloc-free.ll
===================================================================
--- llvm/test/Transforms/DeadStoreElimination/multiblock-malloc-free.ll
+++ llvm/test/Transforms/DeadStoreElimination/multiblock-malloc-free.ll
@@ -170,7 +170,6 @@
 ; CHECK-NEXT:    br i1 true, label [[BB2:%.*]], label [[BB3:%.*]]
 ; CHECK:       bb2:
 ; CHECK-NEXT:    [[M:%.*]] = call noalias ptr @malloc(i64 10)
-; CHECK-NEXT:    store i8 1, ptr [[M]], align 1
 ; CHECK-NEXT:    br label [[BB3]]
 ; CHECK:       bb3:
 ; CHECK-NEXT:    [[R:%.*]] = phi ptr [ null, [[BB1:%.*]] ], [ [[M]], [[BB2]] ]
Index: llvm/test/Transforms/DeadStoreElimination/multiblock-loops.ll
===================================================================
--- llvm/test/Transforms/DeadStoreElimination/multiblock-loops.ll
+++ llvm/test/Transforms/DeadStoreElimination/multiblock-loops.ll
@@ -846,7 +846,6 @@
 ; CHECK-NEXT:    br label [[FIRST:%.*]]
 ; CHECK:       first:
 ; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds [10 x i16], ptr @x, i16 0, i32 [[I:%.*]]
-; CHECK-NEXT:    store i16 1, ptr [[ARRAYIDX]], align 1
 ; CHECK-NEXT:    br label [[DO_BODY:%.*]]
 ; CHECK:       do.body:
 ; CHECK-NEXT:    [[I_0:%.*]] = phi i16 [ 0, [[FIRST]] ], [ [[INC:%.*]], [[DO_BODY]] ]
Index: llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -1199,6 +1199,7 @@
     if (Current->getParent() == KillingDef->getParent())
       return true;
     const Loop *CurrentLI = LI.getLoopFor(Current->getParent());
+
     if (!ContainsIrreducibleLoops && CurrentLI &&
         CurrentLI == LI.getLoopFor(KillingDef->getParent()))
       return true;
@@ -1216,7 +1217,7 @@
         Ptr = GEP->getPointerOperand()->stripPointerCasts();
 
     if (auto *I = dyn_cast<Instruction>(Ptr))
-      return I->getParent()->isEntryBlock();
+      return !ContainsIrreducibleLoops && !LI.getLoopFor(I->getParent());
     return true;
   }
 


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