From 45a2d7d44ae697e28df383d31455145fb754ac58 Mon Sep 17 00:00:00 2001 From: Dale Johannesen Date: Fri, 19 Feb 2010 07:14:22 +0000 Subject: [PATCH] recommit 96626, evidence that it broke things appears to be spurious git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96662 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/ScalarEvolution.h | 5 ++++ lib/Analysis/ScalarEvolution.cpp | 29 ++++++++++++++++++++++++ lib/Transforms/Scalar/IndVarSimplify.cpp | 7 ++++++ 3 files changed, 41 insertions(+) diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h index 383ee88ad28..af5d10e6b78 100644 --- a/include/llvm/Analysis/ScalarEvolution.h +++ b/include/llvm/Analysis/ScalarEvolution.h @@ -586,6 +586,11 @@ namespace llvm { /// compute a trip count, or if the loop is deleted. void forgetLoop(const Loop *L); + /// forgetValue - This method should be called by the client when it has + /// changed a value in a way that may effect its value, or which may + /// disconnect it from a def-use chain linking it to a loop. + void forgetValue(Value *V); + /// GetMinTrailingZeros - Determine the minimum number of zero bits that S /// is guaranteed to end in (at every loop iteration). It is, at the same /// time, the minimum number of times S is divisible by 2. For example, diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 82200cd0281..c2284a8ab9b 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -3485,6 +3485,35 @@ void ScalarEvolution::forgetLoop(const Loop *L) { } } +/// forgetValue - This method should be called by the client when it has +/// changed a value in a way that may effect its value, or which may +/// disconnect it from a def-use chain linking it to a loop. +void ScalarEvolution::forgetValue(Value *V) { + Instruction *I = dyn_cast(V); + if (!I) return; + + // Drop information about expressions based on loop-header PHIs. + SmallVector Worklist; + Worklist.push_back(I); + + SmallPtrSet Visited; + while (!Worklist.empty()) { + I = Worklist.pop_back_val(); + if (!Visited.insert(I)) continue; + + std::map::iterator It = + Scalars.find(static_cast(I)); + if (It != Scalars.end()) { + ValuesAtScopes.erase(It->second); + Scalars.erase(It); + if (PHINode *PN = dyn_cast(I)) + ConstantEvolutionLoopExitValue.erase(PN); + } + + PushDefUseChildren(I, Worklist); + } +} + /// ComputeBackedgeTakenCount - Compute the number of times the backedge /// of the specified loop will execute. ScalarEvolution::BackedgeTakenInfo diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp index e699261b277..60492b02836 100644 --- a/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -246,6 +246,13 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L, if (!PN->getType()->isIntegerTy() && !PN->getType()->isPointerTy()) continue; + // It's necessary to tell ScalarEvolution about this explicitly so that + // it can walk the def-use list and forget all SCEVs, as it may not be + // watching the PHI itself. Once the new exit value is in place, there + // may not be a def-use connection between the loop and every instruction + // which got a SCEVAddRecExpr for that loop. + SE->forgetValue(PN); + // Iterate over all of the values in all the PHI nodes. for (unsigned i = 0; i != NumPreds; ++i) { // If the value being merged in is not integer or is not defined -- 2.34.1