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);