From 15bd22849ee6a1ffb3fb3630f686c2870bdf1bbc Mon Sep 17 00:00:00 2001 From: Nicolas Geoffray Date: Tue, 5 Jan 2016 15:55:41 +0000 Subject: Implement irreducible loop support in optimizing. So we don't fallback to the interpreter in the presence of irreducible loops. Implications: - A loop pre-header does not necessarily dominate a loop header. - Non-constant redundant phis will be kept in loop headers, to satisfy our linear scan register allocation algorithm. - while-graph optimizations, such as gvn, licm, lse, and dce need to know when they are dealing with irreducible loops. Change-Id: I2cea8934ce0b40162d215353497c7f77d6c9137e --- compiler/optimizing/bounds_check_elimination.cc | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'compiler/optimizing/bounds_check_elimination.cc') diff --git a/compiler/optimizing/bounds_check_elimination.cc b/compiler/optimizing/bounds_check_elimination.cc index dc75ff1abc..da2f9cbed5 100644 --- a/compiler/optimizing/bounds_check_elimination.cc +++ b/compiler/optimizing/bounds_check_elimination.cc @@ -1295,8 +1295,13 @@ class BCEVisitor : public HGraphVisitor { */ bool DynamicBCESeemsProfitable(HLoopInformation* loop, HBasicBlock* block) { if (loop != nullptr) { + // The loop preheader of an irreducible loop does not dominate all the blocks in + // the loop. We would need to find the common dominator of all blocks in the loop. + if (loop->IsIrreducible()) { + return false; + } // A try boundary preheader is hard to handle. - // TODO: remove this restriction + // TODO: remove this restriction. if (loop->GetPreHeader()->GetLastInstruction()->IsTryBoundary()) { return false; } -- cgit v1.2.3-59-g8ed1b