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Remove the "special tie breaker" because it resulted in inconsistent

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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
This commit is contained in:
David Greene 2007-06-29 02:48:09 +00:00
parent 8a46d342d8
commit a4ab2e8c72
1 changed files with 12 additions and 10 deletions
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22
lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
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@ -618,16 +618,18 @@ bool bu_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
bool LIsTarget = left->Node->isTargetOpcode(); bool LIsTarget = left->Node->isTargetOpcode();
bool RIsTarget = right->Node->isTargetOpcode(); bool RIsTarget = right->Node->isTargetOpcode();
// Special tie breaker: if two nodes share a operand, the one that use it // Cray: There used to be a special tie breaker here that looked for
// as a def&use operand is preferred. // two-address instructions and preferred the instruction with a
if (LIsTarget && RIsTarget) { // def&use operand. The special case triggered diagnostics when
if (left->isTwoAddress && !right->isTwoAddress) // _GLIBCXX_DEBUG was enabled because it broke the strict weak
if (SPQ->isDUOperand(left, right)) // ordering that priority_queue requires. It didn't help much anyway
return false; // because AddPseudoTwoAddrDeps already covers many of the cases
if (!left->isTwoAddress && right->isTwoAddress) // where it would have applied. In addition, it's counter-intuitive
if (SPQ->isDUOperand(right, left)) // that a tie breaker would be the first thing attempted. There's a
return true; // "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 LPriority = SPQ->getNodePriority(left);
unsigned RPriority = SPQ->getNodePriority(right); unsigned RPriority = SPQ->getNodePriority(right);