From a4ab2e8c726e1702d74eb207536bf953bd3d5c81 Mon Sep 17 00:00:00 2001 From: David Greene Date: Fri, 29 Jun 2007 02:48:09 +0000 Subject: [PATCH] Remove the "special tie breaker" because it resulted in inconsistent ordering and thus violated the strict weak ordering requirement of priority_queue. Uncovered by _GLIBCXX_DEBUG. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37794 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../SelectionDAG/ScheduleDAGRRList.cpp | 22 ++++++++++--------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp index dcdb9615cc6..50533580bf3 100644 --- a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp +++ b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp @@ -618,16 +618,18 @@ bool bu_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const { bool LIsTarget = left->Node->isTargetOpcode(); bool RIsTarget = right->Node->isTargetOpcode(); - // Special tie breaker: if two nodes share a operand, the one that use it - // as a def&use operand is preferred. - if (LIsTarget && RIsTarget) { - if (left->isTwoAddress && !right->isTwoAddress) - if (SPQ->isDUOperand(left, right)) - return false; - if (!left->isTwoAddress && right->isTwoAddress) - if (SPQ->isDUOperand(right, left)) - return true; - } + // Cray: There used to be a special tie breaker here that looked for + // two-address instructions and preferred the instruction with a + // def&use operand. The special case triggered diagnostics when + // _GLIBCXX_DEBUG was enabled because it broke the strict weak + // ordering that priority_queue requires. It didn't help much anyway + // because AddPseudoTwoAddrDeps already covers many of the cases + // where it would have applied. In addition, it's counter-intuitive + // that a tie breaker would be the first thing attempted. There's a + // "real" tie breaker below that is the operation of last resort. + // The fact that the "special tie breaker" would trigger when there + // wasn't otherwise a tie is what broke the strict weak ordering + // constraint. unsigned LPriority = SPQ->getNodePriority(left); unsigned RPriority = SPQ->getNodePriority(right); -- 2.34.1