From 99224aec7815061b884b501f28c73cc8cc330778 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sat, 26 Apr 2003 19:34:18 +0000 Subject: [PATCH] Fix bug: LoopPreheaders/2003-04-25-AssertFail.ll git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5959 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/LoopInfo.cpp | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp index d7d8a5b9e56..7a1daa089e2 100644 --- a/lib/Analysis/LoopInfo.cpp +++ b/lib/Analysis/LoopInfo.cpp @@ -128,12 +128,12 @@ Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS) { std::vector TodoStack; // Scan the predecessors of BB, checking to see if BB dominates any of - // them. + // them. This identifies backedges which target this node... for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I) if (DS.dominates(BB, *I)) // If BB dominates it's predecessor... TodoStack.push_back(*I); - if (TodoStack.empty()) return 0; // Doesn't dominate any predecessors... + if (TodoStack.empty()) return 0; // No backedges to this block... // Create a new loop to represent this basic block... Loop *L = new Loop(BB); @@ -144,8 +144,29 @@ Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS) { TodoStack.pop_back(); if (!L->contains(X)) { // As of yet unprocessed?? + // Check to see if this block already belongs to a loop. If this occurs + // then we have a case where a loop that is supposed to be a child of the + // current loop was processed before the current loop. When this occurs, + // this child loop gets added to a part of the current loop, making it a + // sibling to the current loop. We have to reparent this loop. + if (Loop *SubLoop = const_cast(getLoopFor(X))) + if (SubLoop->getHeader() == X && X != BB) { + // Remove the subloop from it's current parent... + assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L); + Loop *SLP = SubLoop->ParentLoop; // SubLoopParent + std::vector::iterator I = + std::find(SLP->SubLoops.begin(), SLP->SubLoops.end(), SubLoop); + assert(I != SLP->SubLoops.end() && "SubLoop not a child of parent?"); + SLP->SubLoops.erase(I); // Remove from parent... + + // Add the subloop to THIS loop... + SubLoop->ParentLoop = L; + L->SubLoops.push_back(SubLoop); + } + + // Normal case, add the block to our loop... L->Blocks.push_back(X); - + // Add all of the predecessors of X to the end of the work stack... TodoStack.insert(TodoStack.end(), pred_begin(X), pred_end(X)); }