From 8f40afe62db871230ac149de1c4ccc16ff48253a Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Sun, 15 Feb 2009 06:06:15 +0000 Subject: [PATCH] Fix pr3571: If stride is a value defined by an instruction, make sure it dominates the loop preheader. When IV users are strength reduced, the stride is inserted into the preheader. It could create a use before def situation. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64579 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/LoopStrengthReduce.cpp | 20 +++++++++++---- test/Transforms/LoopStrengthReduce/pr3571.ll | 27 ++++++++++++++++++++ 2 files changed, 42 insertions(+), 5 deletions(-) create mode 100644 test/Transforms/LoopStrengthReduce/pr3571.ll diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 9aa5fe27da3..055114c215d 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -400,7 +400,7 @@ static bool containsAddRecFromDifferentLoop(SCEVHandle S, Loop *L) { /// outer loop of the current loop. static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, SCEVHandle &Start, SCEVHandle &Stride, - ScalarEvolution *SE) { + ScalarEvolution *SE, DominatorTree *DT) { SCEVHandle TheAddRec = Start; // Initialize to zero. // If the outer level is an AddExpr, the operands are all start values except @@ -437,11 +437,21 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Start = SE->getAddExpr(Start, AddRec->getOperand(0)); -#ifndef NDEBUG - if (!isa(AddRec->getOperand(1))) + if (!isa(AddRec->getOperand(1))) { + // If stride is an instruction, make sure it dominates the loop header. + // Otherwise we could end up with a use before def situation. + if (SCEVUnknown *SU = dyn_cast(AddRec->getOperand(1))) { + if (Instruction *I = dyn_cast(SU->getValue())) { + BasicBlock *StrideBB = I->getParent(); + BasicBlock *Preheader = L->getLoopPreheader(); + if (!DT->dominates(StrideBB, Preheader)) + return false; + } + } + DOUT << "[" << L->getHeader()->getName() << "] Variable stride: " << *AddRec << "\n"; -#endif + } Stride = AddRec->getOperand(1); return true; @@ -549,7 +559,7 @@ bool LoopStrengthReduce::AddUsersIfInteresting(Instruction *I, Loop *L, // Get the start and stride for this expression. SCEVHandle Start = SE->getIntegerSCEV(0, ISE->getType()); SCEVHandle Stride = Start; - if (!getSCEVStartAndStride(ISE, L, Start, Stride, SE)) + if (!getSCEVStartAndStride(ISE, L, Start, Stride, SE, DT)) return false; // Non-reducible symbolic expression, bail out. std::vector IUsers; diff --git a/test/Transforms/LoopStrengthReduce/pr3571.ll b/test/Transforms/LoopStrengthReduce/pr3571.ll new file mode 100644 index 00000000000..79fcdb17338 --- /dev/null +++ b/test/Transforms/LoopStrengthReduce/pr3571.ll @@ -0,0 +1,27 @@ +; RUN: llvm-as < %s | opt -loop-reduce | llvm-dis +; PR3571 + +target triple = "i386-mingw32" +define void @_ZNK18qdesigner_internal10TreeWidget12drawBranchesEP8QPainterRK5QRectRK11QModelIndex() nounwind { +entry: + br label %_ZNK11QModelIndex7isValidEv.exit.i + +bb.i: ; preds = %_ZNK11QModelIndex7isValidEv.exit.i + %indvar.next = add i32 %result.0.i, 1 ; [#uses=1] + br label %_ZNK11QModelIndex7isValidEv.exit.i + +_ZNK11QModelIndex7isValidEv.exit.i: ; preds = %bb.i, %entry + %result.0.i = phi i32 [ 0, %entry ], [ %indvar.next, %bb.i ] ; [#uses=2] + %0 = load i32** null, align 4 ; <%struct.QAbstractItemDelegate*> [#uses=0] + br i1 false, label %_ZN18qdesigner_internalL5levelEP18QAbstractItemModelRK11QModelIndex.exit, label %bb.i + +_ZN18qdesigner_internalL5levelEP18QAbstractItemModelRK11QModelIndex.exit: ; preds = %_ZNK11QModelIndex7isValidEv.exit.i + %1 = call i32 @_ZNK9QTreeView11indentationEv(i32* null) nounwind ; [#uses=1] + %2 = mul i32 %1, %result.0.i ; [#uses=1] + %3 = add i32 %2, -2 ; [#uses=1] + %4 = add i32 %3, 0 ; [#uses=1] + store i32 %4, i32* null, align 8 + unreachable +} + +declare i32 @_ZNK9QTreeView11indentationEv(i32*) -- 2.34.1